JPS6034768Y2 - Engine exhaust gas recirculation device - Google Patents

Description

[Detailed description of the invention] This invention is equipped with a coil spring at the outlet of the exhaust gas recirculation passage connected to the intake passage of the engine, and the self-vibration of the coil spring prevents the accumulation of deposits such as carbon on the engine exhaust gas. Regarding a reflux device.

Conventionally, nitrogen oxides (hereinafter referred to as NO) emitted from engines
In order to reduce the amount of exhaust gas (referred to as Since the inner wall surface of the discharge port part C is wetted by fuel such as gasoline flowing through the intake passage, fine particles such as carbon in the exhaust recirculation gas are exposed to the same inner wall surface wet with fuel. It gradually solidifies and becomes a deposit.
Moreover, since the temperature of the inner wall surface of the intake passage decreases due to the vaporization of fuel, the moisture in the exhaust recirculation gas is cooled and condenses and liquefies, and the fine particles mainly flow into the outlet area of the intake passage. When the engine is operated for a long time, the amount of deposit d gradually increases, and the inner diameter of the discharge port portion C becomes substantially smaller, causing the amount of exhaust gas recirculation flowing into the intake passage to become lower than the set value. Get low, NO
There is a drawback that the effect of reducing x is reduced.

In contrast, conventionally, as shown in, for example, Japanese Utility Model Application Publication No. 54-81021, a ring is provided inside the discharge port C of the exhaust gas recirculation passage a, and this ring is connected to an external operation means to provide an external operation. There is a device that removes the deposit d by swinging the ring by a manual operation, but it is a complicated device and is troublesome to operate.

Another example is a device that removes the deposit d in the exhaust gas recirculation passage a by attaching a bimetal to the discharge port C of the exhaust gas recirculation passage a by temperature change. It does not operate all the time,
It operates intermittently depending on the temperature difference between when the exhaust gas is recirculated and when it is not recirculated, or when the engine is running and when it is stopped, and there is a problem that the effect of preventing deposit d from accumulating is small.

In view of these conventional drawbacks, the present invention simply provides a coil spring at the discharge port of the exhaust gas recirculation passage, eliminates the need for external operating means or bimetals in the above embodiment, and eliminates the secondary component of engine vibration. By making the coil spring resonate as an excitation source and self-cleaning,
An object of the present invention is to provide an exhaust gas recirculation device for an engine that prevents the accumulation of deposits such as carbon.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below with reference to the drawings.

1 is an exhaust gas recirculation passage, one end of which is connected to the intake passage 2;
The other ends are respectively connected to the exhaust passage 3, and an exhaust gas recirculation amount control valve 5 is interposed in the middle of the exhaust gas recirculation passage 1.

A large diameter portion 7 with a slightly enlarged inner diameter of the passage is formed at the connection portion between the intake passage 2 and the exhaust gas recirculation passage 1, that is, at the discharge port portion 6 of the exhaust gas recirculation passage 1, and a coil spring is attached to the large diameter portion 7. 8 is held so that its center line coincides with the direction in which exhaust gas recirculation gas flowing through the discharge port portion 6 flows into the intake passage 2 .

The coil spring 8 has a spring body 8a made of steel and a fluorine material made of 1 to 5% by weight of carbon material such as carbon powder or carbon fiber, and the balance being a heat-resistant synthetic resin such as Teflon (tetrafluoroethylene polymer). Using a coating of resin 8b prevents carbon, etc. in the exhaust recirculation gas from easily adhering to the static electricity generated by friction with the coil spring 8. Furthermore, it also reduces the wettability of the coil spring 8 itself. Prevents adhesion of carbon, etc.

If the carbon content exceeds 5% by volume, it will become brittle and break easily, resulting in poor durability; if the content is below 1% by volume, it will have good wettability with binders such as water and oil. In addition, it was set based on the characteristics of carbon, that is, the antistatic effect on the surface of the synthetic resin disappears, and the surface of the synthetic resin is charged with static electricity, making it easier for carbon to adhere.

In addition, the natural frequency of the coil spring 8 is 100 to 11
It is set to 5Hz.

The exhaust gas recirculation amount control valve 5 has a valve body 10 connected to a rod 11.
A diaphragm 12 supported via a negative pressure chamber 13 and an atmospheric chamber 14 partitioned by this diaphragm 12.
and a spring 15 that urges the valve body 10 to close.The negative pressure acting on the negative pressure chamber deflects the diaphragm 12 against the spring force of the spring 15, and this displacement causes the valve body 10 to close. The device is configured to open the device.

In the figure, 16 is a venturi, 17 is an intake manifold, and 18
is a throttle valve.

Next, to explain the effect, exhaust gas recirculation occurs most frequently in the engine speed range of 3000 to 3500 rpm, where the amount of NOx emissions increases. As shown in FIG. 3, for example, at an engine speed of 300 rpm, the vibration of the intake manifold 17 reaches its maximum amplitude around 100H2.

At this time, the coil spring 8 resonates with the vibration of the intake manifold 17, and vibrates as shown by the arrow in FIG.

Therefore, deposits such as carbon that adhere to the inner wall surface of the discharge port 6 of the exhaust gas recirculation passage 1 and the surface of the coil spring 8 are removed by the vibration of the coil spring 8, and the deposits on the discharge port 6 are removed. FIG.
As shown in the figure, the exhaust gas recirculation device according to the present invention (indicated by A) can significantly improve the effect of preventing deposit accumulation compared to the conventional device (B).

Incidentally, the engine rotation speed when exhaust gas is recirculated varies depending on various conditions such as the engine model and operating conditions, but is generally 2000 to 4500 rpm, and the vibration of the intake manifold 17 at that time is around 66 to 150 Hz. Since the amplitude is maximum at , it is preferable that the natural frequency of the coil spring 8 is arbitrarily set within the frequency range based on the time when exhaust gas recirculation occurs most frequently.

The spring body 8a of the coil spring 8 is coated with a fluorine-based resin to reduce the adhesion resistance between the coil spring 8 and deposits such as carbon in the exhaust recirculation gas, and to prevent deposits from forming on the surface of the coil spring 8. This is to improve the shaking-off effect, but for the same purpose, a composition of carbon and other heat-resistant synthetic resins such as urea resin, phenol resin, and melamine alkyd resin may be coated.

As described above, the present invention has the above-mentioned configuration in which the coil spring vibrates with the vibration of the engine and causes deposits such as carbon that have adhered to the inner wall surface of the exhaust gas recirculation passage and the surface of the coil spring to fall. An excellent effect can be obtained in that the deposition of the liquid on the outlet portion is prevented.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the present invention, in which Fig. 1 is a sectional view with a part of the exhaust gas recirculation device omitted, Fig. 2 is a partially enlarged sectional view of the coil spring, and Fig. 3 shows the vibration of the intake manifold. FIG. 4 is a graph showing the characteristics, FIG. 4 is a graph showing the deposit amount of the present invention and the conventional device, and FIG. 5 is a cross-sectional view of a part of the conventional device. 1...exhaust gas recirculation passage, 2. curve/intake passage,
3...Exhaust passage, 5...Exhaust gas recirculation amount control valve, 6...Discharge port part, end/bent coil spring, 8a...Spring body , 8b・bent・fluorine-based resin, 1゜・・・valve body, 11・bent・rod, 12・bent・diaphragm, 13・・・・negative pressure chamber, 14・・・・・・Atmospheric chamber, 15...Curved spring, 1
6...Venturi, 17.Curve/Intake Manifold, 18...Throttle valve.

Claims (2)

[Scope of utility model registration request] (1) A coil spring is installed at the discharge port of the exhaust gas recirculation passage connected to the intake passage so that the center line of the spring coincides with the direction in which the exhaust gas recirculation flowing through the discharge port flows into the intake passage. The featured engine exhaust gas recirculation device. (2) The exhaust gas recirculation device for an engine according to claim 1, wherein the coil spring has a surface coated with a fluororesin containing carbon.