JPH0219657A - Fuel feeding device for internal combustion engine - Google Patents

Abstract

PURPOSE:To make good cylinder distributability securable by opening a bypass air intake in a topmost position in an intake passage at the more upstream side than a throttle valve. CONSTITUTION:A bypass air intake 21 and a bypass air outlet 22 of a bypass passage 20 are opened in a topmost position of a mixture body 4 at both upstream and downstream sides of a throttle valve 7. With this constitution, the bypass passage 20 is formed on a center line of the mixture body 4 and thereby it is made into symmetricalness when projecting the mixture body 4 in looking from the upside. Therefore a flow of bypass air comes to be almost symmetrical, so that its distributing performance at each branch passage in an intake manifold 5 is almost uniformized without being one-sided.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a fuel injection system for an internal combustion engine equipped with a side draft type intake passage and having a 5PI (single point injection S system) that injects fuel upstream of a throttle valve. Regarding the supply device.

[Conventional technology]

Recently, SPI injects fuel upstream of the throttle valve.
In an internal combustion engine with a system, if you want to provide a bypass passage by bypassing the throttle valve in the intake passage to ensure a fast idle after starting the engine, etc.
Means have been developed to supply fuel and air through this bypass passage.

This device supplies fuel and air to the engine through the bypass passage when the engine is at low temperature and the throttle valve is closed, such as during warm-up after engine startup, thereby maintaining stable operation. It is something to do.

[Problem to be solved by the invention]

However, such a bypass passage may cause imbalance in cylinder distribution performance depending on its installation position.

In other words, because the vehicle height of the engine is low in one-box cars, for example, the intake passage is formed almost horizontally, and so-called side draft types tend to be often used.
In this side draft type, the intake passage is branched in the horizontal direction downstream of the throttle valve via the intake manifold, each of which is communicated with an intake port.

In such a configuration, if the bypass passage is formed by opening on the side surface of the intake passage, the distribution in the left-right direction will be biased to one side, resulting in uneven distribution.

Furthermore, if the bypass passage is opened on the lower surface of the intake passage, in the side draft type, there is a problem in that the injected fuel collects on the lower surface of the intake passage due to gravity and accumulates in the bypass passage opened there.

The present invention was made based on the above circumstances, and an object of the present invention is to provide a fuel supply system for an internal combustion engine that is equipped with a bypass passage that provides good cylinder distribution.

[Means for Solving the Problems] The present invention has a side draft type intake passage, connects a plurality of horizontally branched intake ports downstream of a throttle valve of the intake passage, and has the above-mentioned In a fuel supply system for an internal combustion engine, in which a fuel injection valve is provided upstream of a throttle valve, and a bypass passage is formed by bypassing the throttle valve, the bypass air intake of the bypass passage is connected to a side upstream of the throttle valve. It is characterized by opening at the highest position in the intake passage.

[Effect]

According to the present invention, since the bypass air intake of the bypass passage is opened at the uppermost position of the intake passage, the bypass air intake is formed at a symmetrical position in the left-right direction of the intake passage. Even if the fuel flows by gravity, it will not accumulate in this bypass passage because it is provided on the upper surface side.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In the figure, 1 represents the engine, and 2 represents its intake passage.

The intake passage 2 includes an air cleaner 3 provided at an upstream end, a mixture body 4, an intake manifold 5, and an intake port 6.

The mixture body 4 and intake manifold 5 from the air cleaner 3 to the intake port 6 are placed horizontally as a whole to form an intake passage in the horizontal direction, forming a so-called side draft type intake passage.

Further, as shown in FIG. 3(A) or (B), the intake manifold 5 has a structure in which passages are branched horizontally to the left and right.

The mixture body 4 is provided with a throttle valve 7, which is attached to a shaft 8 and is rotated integrally with the rotation of the shaft 8, thereby changing the effective area of the intake passage. Therefore, increase or decrease the air flow rate.

One fuel injection valve 10 is provided in the mixture body 4 upstream of the throttle valve 7. The fuel injection valve 10 receives high-pressure fuel supplied by a fuel pump 12 that pumps up and pressurizes fuel from a fuel tank 11, and injects the fuel into a mist from an injection port 10a toward a throttle valve 7. Note that 13 is a fuel pressure control valve.

The fuel injection valve 10 includes an electronic control unit (ECU), which will be described later.
) 70, the high-pressure fuel is injected for a predetermined fuel injection time, and as a result, the intake air adjusted by the throttle valve 7 and the fuel are mixed in the mixture body 4, and the predetermined air pressure is increased. A mixture with the same fuel ratio is generated.

Such air-fuel mixture is distributed to each cylinder by the intake manifold 5, and is drawn into the combustion chamber 16 from the intake port 6 when the intake valve 15 is opened.

The fuel injection system with such a configuration distributes and supplies fuel from one fuel injection valve 10 to a plurality of cylinders, so there is a 5PI (single point injection).

It is called ``Jiekunyo''n stem.

A bypass passage 20 is formed in the mixture body 4, bypassing the throttle valve 7.

This bypass passage 2o is, as shown in FIG. ,
The above-mentioned mixture body 4 is installed on the upstream side of the throttle valve 7.
A bypass air intake port 21 is opened at the uppermost position (ceiling surface) of the mixture body 4, and a bypass air outlet 22 is opened at the uppermost position (ceiling surface) of the mixture body 4 downstream of the throttle valve 7. . Therefore, when the mixture body 4 is viewed from above and projected, the bypass passage 20 is formed on the center line of the mixture body 4 and is symmetrical.

A flow rate restriction valve 23 is installed in the middle of the bypass passage 20 to regulate the flow rate of bypass air. The flow rate restriction valve 23 is, for example, an idle speed control valve that controls the amount of air during idle operation of the engine.
Alternatively, it consists of a manually adjustable throttle adjustment screw, or an air valve that automatically opens using thermowax or bimetallic material when the engine is cold.

On the other hand, high voltage generated by an ignition coil (not shown) built into the igniter 30 is distributed to the spark plugs 32 of each cylinder by the distributor 31.
When the piston 2 sparks, the air-fuel mixture in the combustion chamber 16 is ignited, which burns to generate a force that pushes down the piston 17, generating engine torque.

The gas after combustion passes through an exhaust valve 25 that is opened in synchronization with the rise of the piston 17, an exhaust port 26, an exhaust pipe 27, a catalytic converter 28, and is exhausted from a muffler (not shown).

In order to operate the engine 1 in a desired operating state,
It is necessary to supply an amount of fuel corresponding to the amount of intake air from the fuel injection valve 1°, and to execute ignition by the ignition plug 32 in synchronization with a predetermined stroke of the piston 17.

In order to execute these controls with higher precision, the fuel injection valve 10 and the igniter 3o are controlled by an electronic control device 70, which will be described later.
Its drive is controlled by.

In order to obtain the information necessary for such control, an intake pressure sensor 50 for measuring the amount of intake air by the intake air pressure in the mixture body 4, an intake air temperature sensor 52 attached to the air cleaner 3 to detect the intake air temperature, and a throttle A throttle opening sensor 54 is attached to the shaft 8 of the valve 7 to detect the rotation angle of the throttle valve 7, an idle switch 55 is attached to the exhaust pipe 27 to detect the fully closed state of the throttle valve 7, and a throttle opening sensor 54 is attached to the exhaust pipe 27 to detect the oxygen concentration in the exhaust gas. An air-fuel ratio sensor 56 for detecting the engine cooling water temperature, a water temperature sensor 58 for detecting the engine cooling water temperature, and the like are provided.

In addition, the distributor 31 that distributes the output of the igniter 30 has one rotation of the distributor 31,
That is, a rotation angle sensor 60 that outputs a pulse signal 24 times per two revolutions of the crankshaft, and a cylinder discrimination sensor 61 that outputs a pulse signal once per one revolution of the distributor 31 are provided.

Detection signals from each intake pressure sensor 50, intake temperature sensor 52, throttle opening sensor 54, idle switch 55, air-fuel ratio sensor 56, water temperature sensor 58, rotation angle sensor 60, and cylinder discrimination sensor 61 are sent to the electronic control unit 70.
is input.

The electronic control unit 70 is mainly composed of a microcomputer, and its internal structure is comprised of an RO that actually performs arithmetic processing.
M72, - executes storage of temporal information to the CPU 71;
RAM 73 that assists logical operation processing; input port door 4 that converts the above sensor signals into signals that can be processed by CPU 71 ;
It is composed of an output port door 5 and a timer 76, which converts the signal into a drive signal and outputs the signal to the igniter 30, etc.

When a fuel injection start command is issued from the CPU 71, the output port door 5 outputs a valve opening control signal to the fuel injection valve 10,
As a result, the fuel injection valve 10 injects fuel, and this control signal continues to be output until the output port door 5 receives a command from the CPU 71 to terminate fuel injection.

The command to end the fuel injection is issued when the fuel injection end time set by the CPU 71 matches the real time that the timer 76 continues to count, and the fuel injection valve 10 thereby ends the fuel injection.

In the fuel supply system configured in this way, the throttle valve 7 may be operated with a small opening degree during idling operation when the engine is not yet sufficiently warmed up immediately after starting the engine. At times, the flow rate restriction valve 23 of the bypass passage 20 is opened, and fuel and air are supplied to the cylinder side via this bypass passage 20.

For this reason, more fuel and air are taken into the combustion chamber 16, and reliable combustion can be performed, so stable operation is possible.

In this embodiment, the bypass air intake 21 of the bypass passage 20 is located upstream of the throttle valve 7.
It is opened at the top position of the mixture body 4,
In addition, since the bypass air outlet 22 is opened at the uppermost position of the mixture body 4 on the downstream side of the throttle valve 7, this bypass passage 20 is located at the uppermost position of the mixture body 4 when viewed from above. 4
It is formed on the center line of , and is symmetrical.

For this reason, the flow of bypass air is almost symmetrical on the left and right,
The distribution performance in each branch passage in the intake manifold 5 shown in FIG. 3(A) or (B) is substantially equalized without being biased to one side.

In particular, the smaller the opening degree of the throttle valve 7, the higher the proportion of the air flow passing through the bypass passage 20, and in this case, even a slight bias in the bypass air has a large effect on the distribution performance in the intake manifold 5 on the downstream side. As in this embodiment, when the bypass air intake 21 and the bypass air outlet 22 of the bypass passage 20 are projected from above, the mixture body 4
Since it is formed on the center line of the intake manifold 5, it is symmetrical, so that the flow of bypass air is almost symmetrical on the left and right, and the distribution performance in the intake manifold 5 is approximately equalized.

In addition, in the side draft type SPI system a, the fuel injected from the fuel injection valve 10 gathers on the lower surface of the intake passage due to gravity, but the flow of the bypass air is almost symmetrical on the left and right, and the intake manifold Since the distribution performance in No. 5 is approximately equalized, the distribution flow of fuel is also approximately equal, and there is no possibility of variations in the mixing ratio when the load increases.

FIG. 4 is a characteristic diagram showing the results of measuring the degree of variation in the air-fuel ratio in order to examine the effects of this embodiment.

The solid line indicates the case of this embodiment, in which the bypass air intake 21 of the bypass passage 20 is provided at the uppermost position upstream of the throttle valve 7 of the mixture body 4, and the bypass air outlet 22 is also provided at the uppermost position upstream from the throttle valve 7 of the mixture body 4. It can be seen that when the intake manifold 5 is provided at the uppermost position on the downstream side, the distribution performance in the intake manifold 5 is approximately symmetrical, and there is little variation in the air-fuel ratio between the cylinders.

In the dashed line, the bypass air intake 121 is opened on the side surface of the mixture body 4 upstream of the throttle valve 7, and the bypass air outlet 22 is opened on the side surface.
is installed at the highest position downstream of the throttle valve 7 of the mixture body 4, the air-fuel ratio of the cylinder on the side where the bypass air intake is opened will be higher, and the air-fuel ratio between each cylinder may vary widely. I understand.

In the above embodiment, the bypass air outlet 22 of the bypass passage 20 is provided at the uppermost position downstream of the throttle valve 7 of the mixture body 4, but the bypass air outlet 22 is provided downstream of the throttle valve 7. The openings may be branched and opened symmetrically on the upper surface of the mixture body 4.

〔Effect of the invention〕

As explained above, according to the present invention, in a side draft type SPI system, the bypass air intake port of the bypass passage is opened at the uppermost position of the intake passage.
The bypass air intake ports are formed at symmetrical positions in the left-right direction of the intake passage, so that the distribution is approximately equal. Furthermore, since the bypass air intake port is provided on the upper surface side 1 as described above, even if fuel flows due to gravity, it will not accumulate in this bypass passage.

[BRIEF DESCRIPTION OF THE DRAWINGS] The drawings show one embodiment of the present invention, and FIG. 1 is a control system diagram of a fuel supply device, FIG. 2 is an enlarged cross-sectional view of the main part, and FIG. 3 (A) and (B) is a plan view showing a different configuration example of the inch manifold, and FIG. 4 is a characteristic diagram showing the relationship between the opening position of the bypass air intake and the air-fuel ratio of the cylinder. DESCRIPTION OF SYMBOLS 1... Engine, 2... Intake passage, 4... Mixture body, 5... Intake manifold, 7...
Throttle Louis (Lube, 10...Fuel injection valve, 20...
・Bypass passage, 21... Bypass air intake, 2
2...Bypass air outlet, 23...Flow rate restriction valve. Applicant's agent Patent attorney Takehiko Suzue (A) (B) Figure 3

Claims (1)

[Claims] The intake passage is of a side draft type, and a plurality of horizontally branched intake ports are connected downstream of the throttle valve of the intake passage, and fuel is injected upstream of the throttle valve. In a fuel supply system for an internal combustion engine, the bypass air intake port of the bypass passage is opened at the uppermost position of the intake passage upstream of the throttle valve. A fuel supply device for an internal combustion engine, characterized by: