JPS6337265B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a single point fuel injection system, and more particularly to a single point fuel injection system including an injector and a hot wire air flow meter upstream of a throttle valve.

Recently, as disclosed in Japanese Unexamined Patent Publication No. 57-73858, when supplying fuel to an engine, an injector is placed upstream of the throttle valve to pressurize the fuel and adjust the amount of fuel according to the intake air amount and operating conditions. Devices that perform fuel injection are attracting attention.

This type of fuel injection system uses a method that calculates the amount of intake air using a microcomputer based on information such as engine speed, intake pressure, throttle valve opening, and atmospheric pressure, a vane-type air flow meter, and a Karman vortex flow meter. A method using , etc. has been proposed.

However, the method for measuring the amount of intake air cannot measure the mass flow rate of air, and therefore has the disadvantage that it is difficult to control the air-fuel ratio in response to changes in atmospheric pressure. Further, such devices have the problem of increasing the size of the structure and reducing the ease of mounting the measuring device. Furthermore,
In a conventional fuel injection device, an air amount measuring device and a device for fuel injection are installed separately, and the air-fuel ratio characteristics are checked after installation in the engine. This makes mass production difficult due to poor production procedures.

The present invention focuses on the above-mentioned conventional problems, and aims to provide a single-point fuel injection device that can manage air-fuel ratio characteristics and improve productivity.

To achieve the above object, the present invention provides a single point fuel injection device in which an injector 7 is disposed upstream of a throttle valve 1, in which an intake pipe upstream of a throttle chamber 2 supporting the throttle valve 1 is connected to a bench lily. Bench lily body 5 having section 6 and air cleaner 3
an arm 11 formed by an air chamber 4 connected to the side, and a lower injector holder 9 having a built-in injector 7 at the center position of the pipe of the bench lily body 5 and disposed radially between the inner walls of the pipe. A concave groove is formed along the upper edge of the bench lily body 5, and an upper injector holder 10 is attached to the air chamber 4 by an arm corresponding to the arm 11 corresponding to the lower injector holder 9. Further, a groove corresponding to the groove of the bench lily body 5 is provided along the lower end periphery, and at the joint surface between the upper end of the bench lily body 5 and the lower end of the air chamber 4, air is A passage 13 is formed to bypass the passage, and this bypass passage 1
3 is formed with an inlet that communicates with the inside of the air chamber 4 and an outlet that communicates with the bench lily portion 6. A hot wire air flow meter 16 is disposed in the bypass passage 13, and a hot wire air flow meter 16 is disposed in the bypass passage 13. It is characterized in that the support shaft and the arm 11 are arranged in the same direction.

With this configuration, the mass flow rate of air can be measured through the bypass passage, and the amount and timing of fuel injection from the injector can be determined based on this, so the air-fuel ratio characteristics can be determined in advance without using the engine. In addition, since the suction pipe is divided into parts and a bypass passage is formed at the joint surface, and the injector holding part is formed by this division, the air flow meter and the injector can be easily controlled. The installation can be carried out in one piece, simplifying the structure and improving productivity.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a plan view of a single point fuel injection device according to this embodiment, and FIG. 2 is a sectional view taken along the line -- in FIG. 1.
As shown in the figure, an air chamber 4 and a bench lily body 5 constituting an intake pipe are attached between a throttle chamber 2 equipped with a throttle valve 1 and an air cleaner 3, and the intake pipe is divided into two parts. It has a structure. The air chamber 4 has one end attached to the outlet pipe of the air cleaner 3,
The other end surface is joined to the bench lily body 5.
Further, the vent lily body 5 is joined to the air chamber 4 to form an intake passage therein, and the opposite end thereof is joined to the throttle chamber 2 and attached thereto. In particular, the inner circumferential surface of the bench lily body 5 is formed into a bench lily portion 6, and the connecting portion with the air chamber 4 is opened in a bell mouth shape to reduce the diameter of the intake pipe.

Here, an injector holder 8 is provided at the center of the conduit between the air chamber 4 and the vent lily body 5, and is formed to accommodate the injector 7. The injector holder 8 consists of a lower injector holder 9 attached and supported by the bench body 5 and an upper injector holder 10 attached and supported to the air chamber 4. The lower injector holder 9 is open on the upstream side, and is formed to receive the injector 7 and direct its injection nozzle toward the throttle valve 1 . Further, the upper injector holder 10 is open on the downstream side and is connected to the lower injector holder 9 at the open surface, so that the injector 7 is housed therein in a sealed state. Upper and lower injector holders 9, 10
are fixedly supported by arms 11 to the bench lily body 5 and the air chamber 4, respectively. For this reason, the intake passage is an annular passage 12 through which air is supplied to the shutoff valve 1 side. The tip end surface of the lower injector holder 9 is a conical surface, so that the fuel injected from the nozzle portion of the injector 7 and air are mixed well.

Further, at the joint surface between the air chamber 4 that divides the intake pipe into two and the vent lily body 5, the joint surface between the two is formed into a groove shape, thereby forming a bypass passage 13 that bypasses the amount of intake air. . This bypass passage 13 is formed concentrically with the annular passage 12, as can be understood from FIG.
4, and an outlet 15 that opens to the 6 surface of the bench lily portion of the bench lily body 5. Said entrance 14
are opened along the circumferential direction on the inner circumferential surface of the air chamber 4. Therefore, the inlet 14 is opened concentrically with the annular passage 12. On the other hand, inside the bypass passage 13, a hot wire air flow meter is disposed near the outlet 15. That is, a hot wire 16 is arranged inside the outlet 15 of the bypass passage 13, and this hot wire 16
The bypassed air is now available for cooling. Further, the hot wire 16 is electrically connected to an air flow meter main body 17 attached to the outer surface of the bench lily body 5, so that the amount of supplied air can be measured.

In addition, the throttle chamber 2 equipped with the throttle valve 1
An annular groove 18 is formed in the side wall of. This annular groove 18 is connected so that engine cooling water or the like can be circulated, thereby heating the throttle chamber 2 and the throttle valve 1. Therefore, the air-fuel mixture passing around the outer periphery of the throttle valve 1 can be heated, fuel atomization can be promoted, and throttle icing, which tends to occur under conditions of high humidity, can be prevented.

According to the single point fuel injection device configured in this way, air taken into the engine is supplied through the annular passage 12. Further, a part of the intake air is introduced into the bypass passage 13 by the pressure difference between the inlet 14 and the outlet 15 of the bypass passage 13 formed by the joint surface of the air chamber 4 and the ventilator body 5, and cools the hot wire 16. It is used to measure the amount of intake air. The amount of fuel supplied is pressurized by a fuel pump (not shown), is supplied to the injector 7 from the fuel pipe 19, and is controlled by the valve opening time and the number of valve openings of the injector 7.

Here, the air-fuel ratio of the mixture supplied to the engine is calculated by a microcomputer using information such as the intake air amount, the opening of the throttle valve 1, the intake pressure, the engine speed, the atmospheric pressure, and the engine environmental temperature. ,
The amount and timing of fuel injected from the injector 7 is determined and controlled.

According to the single point fuel injection device according to this embodiment, the hot wire air flow meter for specifically detecting the amount of intake air is arranged in the bypass passage 13, so that the hot wire 1
It is also possible to prevent contamination and damage caused by backup fire. In addition, the injector 7, annular passage 12, and throttle valve 1 can be arranged symmetrically with respect to the intake passage, making it possible to supply a mixture with a uniform air-fuel ratio to each cylinder of the engine, making the combustion state uniform, and reducing the exhaust gas. performance,
Demonstrates practical effects such as fuel efficiency. Furthermore, the uniformity of the intake inertia depending on the type of engine and the shape of the air cleaner is also improved, making it possible to match the performance of a wide range of engines. In addition, the intake pipe has a divided structure into the air chamber 4 and the vent lily body 5, so that the injector 7 can be attached at the same time as the bypass passage 13 is formed. Therefore, it is not necessary to separately install and manage the air flow meter and the injector 7, and it is possible to improve productivity.

Next, FIGS. 3 and 4 show other embodiments of the present invention. The single point fuel injection device according to this embodiment differs from the previous embodiments in that the inlet 20 of the bypass passage 13 is of a dynamic pressure type. That is, the inlet 20 of the bypass passage 13 is opened toward the upstream side of the intake passage, and a portion of the intake air is directly introduced into the bypass passage 13 from the air cleaner 3.

According to such an embodiment, air in the vortex region that tends to occur at the starting end of the bench lily portion 6 is not introduced into the bypass passage 13. Therefore, output fluctuations in the amount of intake air caused by introducing air in the vortex area are prevented, and there is no need to add a correction circuit to the control circuit of the hot wire air flowmeter. Furthermore, the control circuit can be simplified and a relatively stable amount of intake air can be detected.

As explained above, according to the present invention, the fuel injection device can be made smaller and easier to assemble, and the air-fuel ratio characteristics can be managed in advance without using an engine. It is.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a single point fuel injection device according to this embodiment, FIG. 2 is a sectional view taken along the - line in FIG. 1, and FIG. 3 is a plan view of a single point fuel injection device according to another embodiment.
FIG. 4 is a sectional view taken along the line -- in FIG. 3. 1... Throttle valve, 2... Throttle chamber, 4
... Air chamber, 5 ... Bench lily body, 7
...Injector, 8...Injector presser, 1
3... Bypass passage, 14... Inlet, 15... Outlet, 16... Hot wire, 17... Air flow meter body.

Claims (1)

[Scope of Claims] 1. A single point fuel injection device in which an injector 7 is disposed upstream of a throttle valve 1, comprising: a throttle chamber 2 that supports the throttle valve 1;
A lower injector whose upstream intake pipe is formed by a bench lily body 5 having a bench lily portion 6 and an air chamber 4 connected to the air cleaner 3 side, and which supports the injector 7 built in at the center position of the pipe line of the bench lily body 5. A presser foot 9 is provided by an arm 11 disposed radially between the inner walls of the conduit, and a concave groove is formed along the upper edge of the vent body 5, and the air chamber 4 is provided with the lower injector. An upper injector presser 10 is provided by an arm corresponding to the arm 11 corresponding to the presser foot 9,
and the bench lily body 5 along the lower end periphery.
A concave groove corresponding to the concave groove of is provided, and a passage 13 for bypassing the intake passage is formed by both the concave grooves at the joint surface of the upper end of the bench lily body 5 and the lower end of the air chamber 4, and in this bypass passage 13. An inlet is formed in communication with the inside of the air chamber 4, and an outlet is formed in communication with the bench lily part 6. A hot wire air flow meter 16 is disposed in the bypass passage 13, and a support shaft of the throttle valve is formed. and the arm 11 are arranged in the same direction.