JPS5925104B2 - air valve for fuel injector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air valve for an automobile fuel injection device, and more particularly to an air valve for an automobile fuel injection device.
This invention relates to an improvement of a double-stage air valve.

Conventional air valves for fuel injection devices have been formed into a cylindrical shape with low air resistance, allowing high horsepower to be obtained.

However, since the throttle valve is large in size, even a small change in the opening degree causes a large change in the metered air amount, making it difficult for the driver to maintain a constant vehicle speed.

Furthermore, since it is not possible to obtain a sufficient suction negative pressure depending on the load condition of the engine, there is a drawback that the EGR pulp etc. cannot be controlled by the suction negative pressure signal.

An object of the present invention is to provide an air valve for a fuel injection device that can stably obtain the negative pressure necessary to control the operating state of an automobile. The first of the first passage of the two-stage, two-set air valve.
A venturi section is provided upstream of the throttle valve, the narrowest part of this venturi section is formed into a planar circumferential wall, and the circumferential wall has a diameter smaller than the axial length of the circumferential wall at approximately the center when viewed from the axial direction. The reason is that the negative pressure outlet hole is opened.

FIG. 1 is a front view of an air valve according to an embodiment of the present invention, FIG. 2 is a vertical sectional view of the air valve shown in FIG. 1, and FIG.
FIG.

The air valve 1 is a substantially cylindrical tube whose lower half bulges to one side, and the lower half of the air passage has a first passage 2 and a second passage with circular cross sections.
It is divided into passages 3, and a first throttle valve 4 is installed in the first passage 2, and a second throttle valve 5 is installed in the second passage 3.

The upper end of this air valve 1 is connected to an air cleaner, and the lower end is connected to the engine via an intake pipe equipped with a fuel injection valve, so that the amount of clean air sucked in by the negative intake pressure generated by engine rotation is reduced. is controlled by a throttle valve, mixed with fuel injected into the intake pipe, and supplied to the engine.

In FIG. 1, the first throttle valve 4 and the second throttle valve 5 are attached to respective throttle valve shafts 6 and 7.
A fan-shaped lever 8 is fixed to the outside of the air valve 1.

The lever 8 is provided with a groove 9 centered on the throttle valve shaft 6, into which the tip of the connecting rod 10 is fitted.

On the other hand, a lever 11 having a projection 13 is fixed to a portion of the throttle valve shaft 7 outside the air valve 1, and the other end of the connecting rod 10 is locked.

Further, a return spring 12 whose both ends are engaged with a protrusion 13 of the soba 11 and a protrusion provided on the outside of the air valve 1 is installed so as to wind around the throttle valve shaft 7.

Therefore, when the driver depresses the accelerator pedal to rotate the throttle valve shaft 6 and the opening degree of the first throttle valve 4 increases to a predetermined opening degree or more, the lever 8 pushes the connecting rod 10 and rotates the lever 11 counterclockwise. The second throttle valve 5 is opened.

On the other hand, when the amount of depression of the accelerator pedal is decreased, the lever 11 is returned by the spring force of the return spring 12, and the lever 11 is returned to the second position.
After the throttle valve 5 is closed, only the first throttle valve 4 changes its opening degree.

That is, this air valve 1 has a two-stage, two-stage throttle valve, and can precisely control the amount of intake air at low speeds, as well as control the amount of air at high loads, so that suitable intake air can be sent during full operation. .

The first passage 2 has a relatively small diameter bore, and the second passage 2 has a relatively small diameter bore.
As shown in Fig. 3, the passage 3 has a large diameter bore, and the first passage 2 in particular is provided directly below the air valve 1, that is, within the projected area, to allow air flow to pass through with little turbulence. I try to let them do it.

Figure 2 shows the internal structure of the air valve 1.
A venturi section 15 is provided at the entrance of the passage 2, a negative pressure outlet hole 17 is opened at the narrowest part of the venturi section 15, and the negative pressure is extracted through a pipe 16.

Since this part is the main point of the present invention, the fourth part is further expanded.
This will be explained with a diagram.

In FIG. 4, the venturi portion 15 is provided with a planar circumferential wall portion having a diameter D2 smaller than the bore diameter D1 of the first passage 2, and a negative pressure having a diameter d is provided in the intermediate portion. A take-out hole 17 is opened.

When the engine is rotated and the first throttle valve 4 is opened, suction negative pressure is generated in the first passage 2, air passes through the venturi section 15, and a negative pressure proportional to the amount of intake air is generated in the negative pressure outlet hole 17.
occurs in

The negative pressure is guided to necessary locations by a pipe connected to the negative pressure tube 16, and is used to control normal operating conditions.

For example, it is used to control an exhaust gas recirculation valve (EGR valve), which is indispensable as an exhaust purification measure, or as a negative pressure source for an acceleration sensor or the like.

Figure 5 is a diagram showing the relationship between the cross-sectional area of the venturi section and the negative pressure generated in the venturi section, and the horizontal axis is the ratio of the square of the bore diameter D1 of the first passage to the square of the diameter D2 of the venturi section. The vertical axis indicates the negative pressure generated in the venturi section in -mmAq.

As shown by the line 21, when the cross-sectional area of the venturi portion 15 becomes smaller than the cross-sectional area of the first passage 2, a large negative pressure can be obtained, but the amount of air passing through the first passage 2 is limited, and the pressure is not required for normal operation. Air volume cannot be obtained.

Therefore, it is necessary to open the large second throttle valve 5 at an early stage, and the intake air amount control during normal operation becomes inaccurate, resulting in unstable operating conditions.

Furthermore, if the diameter D2 of the venturi portion 15 is brought close to the bore diameter D1 of the first passage 2, the necessary negative pressure cannot be obtained and a means for amplifying the negative pressure signal is required. The negative pressure changes become a dog, making it unsuitable for controlling the EGR valve, etc.

Taking these things into consideration, the practical range is 0.2 to 0.
, 7 is appropriate.

Note that the bore cross-sectional area ratio of the first passage 2 and the second passage 3 is usually 1.5 to 3, and this embodiment is also formed with this ratio.

FIG. 6 is a diagram showing the relationship between the size of the negative pressure outlet hole and the amount of variation in negative pressure generated in the venturi section, where the horizontal axis represents the diameter d of the negative pressure outlet hole 17 and the inner surface of the narrowest part of the venturi section 15. and the length l of the cylindrical part, and the vertical axis represents the amount of fluctuation in the negative pressure generated in the venturi part 15, that is, the fluctuation width of the negative pressure in mmAq.
It is shown in

When d is large relative to the dimension l, the negative pressure fluctuates significantly and stable negative pressure cannot be obtained, but the negative pressure outlet hole 17 opens in the circumferential wall formed at the narrowest part of the venturi part. This will allow you to generate stable negative pressure.

That is, the line 22 shows that 7/d of 1 or more is a stable range that can be used practically.

FIG. 7 is a diagram showing the relationship between the position of the negative pressure outlet hole and the amount of variation in the negative pressure generated in the venturi section. The amount of negative pressure fluctuation is shown in gmAq.

The diameter d of the negative pressure outlet hole 17 is approximately 2 to 3 m1n, but it is clear from FIG. 6 that it is desirable to have one dimension 2 to 3 times larger than this.

However, the amount of negative pressure fluctuation varies depending on the opening position of the negative pressure outlet hole 17, and the line 23 shows the measured value.

In other words, the amount of variation is minimum when the negative pressure outlet hole 17 is opened at approximately the center when viewed from the axial direction of the circumferential wall formed at the narrowest part, and even if the opening position is eccentric in any direction, the variation is The amount increases.

This also relates to the machining accuracy of the negative pressure outlet hole 17, and if the negative pressure outlet hole 17 is machined at the center position, the amount of fluctuation will not deteriorate much even if the hole position is slightly shifted.

Taking these into consideration, the permissible eccentricity range of the negative pressure outlet hole 17 is set to a range of ±15 mm from the center O of the 1-dimensional portion.

When the amount of fluctuation in the negative pressure signal exceeds 10 mmAq, the operating point of the vehicle speed controlled by this will differ by about 1 hour, and the NOx value in the exhaust at that time will be 20% compared to the normal value.
It has been observed that the condition worsens.

The air valve 1 is made of aluminum alloy or zinc alloy and can be integrally cast including the venturi part 15, so mass production is easy. It is easy and does not require particularly high processing accuracy.

As described above, the air valve of this embodiment has a venturi portion in which the narrowest part having a cross-sectional area of 20% to 70% of the cross-sectional area of the first passage is formed as a circumferential wall at the first passage inlet of the two-stage, double-stage intake passage. By opening a negative pressure outlet hole smaller than the axial length l of the circumferential wall in the circumferential wall of the venturi part at approximately the center of the circumferential wall when viewed from the axial direction, relatively high fluctuations can be suppressed. It has the effect of being able to extract negative pressure.

In the above embodiment, the negative pressure outlet hole 17 is opened in the wall surface of the venturi portion 15, but a nozzle protruding from the wall surface may be provided and negative pressure may be obtained from this nozzle.

In this way, the negative pressure can be taken out from the stable air flow path portion, so that the amount of fluctuation in the negative pressure is further reduced.

The air valve for a fuel injection device of the present invention can take out stable and relatively high negative pressure, so this negative pressure can be used to suitably control the driving state of a car, purify exhaust gas, and reduce fuel costs. It has the effect of being able to

[Brief explanation of drawings]

Fig. 1 is a front view of an air valve which is an embodiment of the present invention;
The figure is a vertical sectional view of Fig. 1, Fig. 3 is a plan view of Fig. 1, Fig. 4 is an enlarged view of Fig. 2, and Fig. 5 shows the cross-sectional area of the venturi section and the negative pressure generated in the venturi section. Figure 6 is a diagram showing the relationship between the size of the negative pressure outlet hole and the amount of variation in negative pressure generated in the venturi part, Figure 7 is a diagram showing the relationship between the position of the negative pressure outlet hole and the amount of variation in negative pressure generated in the venturi part. FIG. 3 is a diagram showing the relationship between the amount of variation in the generated negative pressure; DESCRIPTION OF SYMBOLS 1... Air valve, 2... First passage, 3... Second passage, 4... First throttle valve, 5... Second throttle valve, 6, 7.
... Throttle valve shaft, 15...-Venturi section, 17... Negative pressure outlet hole.

Claims (1)

[Claims] 1. An intake passage through which engine intake air passes is divided into a first passage and a second passage, and when a first throttle valve installed in the first passage opens a predetermined opening degree or more. A second throttle valve installed in the second passage is configured to open in conjunction with the throttle valve, and a venturi part is provided upstream of the throttle valve in the first passage, and a negative pressure outlet hole is provided in the narrowest part of the venturi part. In the air valve for a fuel injection device, the venturi part has the narrowest part formed in a planar circumferential wall, and the axial length of the circumferential wall is approximately at the center of the circumferential wall when viewed from the axial direction. 1. An air valve for a fuel injection device, characterized in that the negative pressure outlet hole is a venturi portion having a diameter smaller than that of a venturi portion. 2. The air valve for a fuel injection device according to claim 1, wherein the narrowest part of the venturi part has a cross-sectional area of 20% to 70% of the bore cross-sectional area of the first passage. . 3. The air valve for a fuel injection device according to claim 1, wherein the air valve, including the venturi portion, is formed by processing a material that is integrally cast from a light alloy material.