JPS5924271B2 - Fuel tank in internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel tank structure for preventing fuel evaporated from the fuel tank of an internal combustion engine from dissipating into the atmosphere.

In recent years, the amount of transportation and traffic has increased with the development of transportation, and emissions from gasoline engines used in various automobiles, aircraft, motor boats, etc., diesel engines used in various ships, power generation, pumps, construction machinery, etc. Exhaust gas,
The negative effects of evaporated fuel vapor on the human body and living things have become a problem, and measures to regulate the emissions of the exhaust gas and evaporated fuel vapor are being considered.

Therefore, there is an urgent need for measures and research to prevent the release of these toxic gases.

Known methods for preventing fuel vapor dissipation include treating fuel vapor with blow-by gas and adsorbing fuel vapor using activated carbon powder. However, if the activated carbon layer is increased in order to improve the adsorption effect, the pressure loss will increase (which will cause problems with air suction during operation).

The inventors of the present invention have conducted intensive research to solve the above-mentioned drawbacks, and as a result, have arrived at the structure of the fuel tank of the present invention.

That is, the present invention incorporates an adsorbent that is connected to the vent hole of the fuel tank and adsorbs fuel vapor, and when the engine is stopped, the evaporated fuel is adsorbed by the adsorbent, and when the engine is running, it is desorbed from the adsorbent. In a fuel tank equipped with a fuel vapor diffusion prevention device having a mechanism for sending desorbed fuel to an engine part, it is preferable that the adsorbent is a fiber aggregate such as a web or tow mainly made of activated carbon fibers. This is a characteristic feature.

According to the present invention, in the case of conventional activated carbon, fuel vapor dissipation has a structure in which evaporated fuel is adsorbed by activated carbon when the engine is stopped, and desorbed from the activated carbon during engine operation, and the desorbed fuel evaporation is sent to the engine part. Compared to a fuel tank equipped with a prevention mechanism, the surface area is much larger, so the rate of adsorption of fuel vapor, especially gasoline vapor, is extremely fast (which is difficult to achieve when fuel vapor is adsorbed in a short period of time through an adsorption layer). It is very advantageous.

In addition, since the activated carbon fiber has a large surface area, its desorption rate is fast (it is very convenient to use it in a gasoline vapor diffusion prevention device using an adsorption method that repeatedly performs adsorption and desorption).

Furthermore, the activated carbon fiber has a residual amount of fuel vapor (adsorption/retention amount) when it is desorbed with fresh air after equilibrium adsorption of fuel vapor.
The difference is larger than that of activated carbon, which is also advantageous when used in fuel vapor diffusion prevention devices.

Furthermore, if an activated carbon fiber layer is used, the pressure loss on both sides of the fiber layer is small, so air can be easily sucked in during operation, and fuel vapor once adsorbed can be easily desorbed by fresh air.

Activated carbon fibers also have the advantage of being easier to powder (and easier to handle) than activated carbon.

The activated carbon fibers to be equipped in the fuel tank according to the present invention are cellulose-based fibers such as rayon and cotton, which are preferred because of their large ability to adsorb fuel vapor.

Especially phosphoric acid, ammonium phosphate, condensed phosphoric acid, S:J
Phosphorus-containing compounds such as urea condensates and tetrakishydroxymethylphosphonium compounds, sulfuric acid compounds such as sulfuric acid, ammonium sulfate, and sulfuric acid-urea condensates, acids such as hydrochloric acid and boric acid, aluminum chloride, and tin chloride. It is more preferable to pre-treat the cellulose fibers with salts and then carbonize them, as these have particularly high adsorption power.

The above-mentioned carbon fiber is manufactured, for example, as follows.

That is, after impregnating cellulose fibers with the above pretreatment agent (preferably at a concentration below 60% by weight),
Heat treated at a temperature of 400°C, carbonized to a loss rate of 5o or higher relative to the dry weight of the original cellulose fiber, and then carbonized in a gas such as oxygen, carbon dioxide, water vapor, etc.
It is manufactured by heating to 0'C or above to make the loss rate 65-95 and the carbon content 60% by weight.

The activated carbon fibers are used as breathable fiber aggregates such as webs such as fabrics and nonwoven fabrics, or tows.

Furthermore, in addition to activated carbon fibers, natural fibers and synthetic fibers may be mixed in these fiber aggregates (and inorganic fibers such as asbestos fibers and metal fibers may also be mixed as reinforcing materials).

The above-mentioned carbon fiber not only has the above-mentioned effects even better, but also has less temperature dependence in the adsorption amount of fuel vapor compared to activated carbon (this means that the fuel vapor, which is exposed to considerable cost during and after operation, This is extremely advantageous for the application of steam diffusion prevention devices.

Since the activated carbon fiber aggregate of the present invention has various excellent custom features as mentioned above, it can be attached to the gasoline tank of a gasoline engine to adsorb the evaporated gas vapor when the engine is stopped, and when the engine is running, it can be passed through the fiber aggregate. By sucking in air, the adsorbed gasoline is desorbed and finally sent to the combustion chamber, which is extremely effective in preventing gasoline vapor from dissipating into the atmosphere.

Next, an example will be described.

The gasoline adsorption test method used in the examples is as follows.

Gasoline adsorption test method: This was carried out according to the test method for benzene adsorption power of granular activated carbon shown in JIS K 1412.

Figure 1 shows the test equipment.

1 is a constant temperature water tank, and the water in 2 is adjusted to 20°C.

3, 4, and 5 each indicate a bottle, and bottle 3 is filled with approximately 1/3 of the regular gasoline from 6.

7 and 8 indicate thin glass tubes into which a certain amount of air is blown as indicated by the arrows.

Gasoline vapor saturated air generated in the bottle 3 is temperature-controlled with a flexible pipe 9, passes through an empty bottle 4, is diluted appropriately in a mixing bottle 5 with air from a glass tube 7, and is then filled into a U-shaped tube 10 as a sample. 11 and is adsorbed by the sample.

The diameter of the sample 11 of the U-shaped tube 10 is about 16 mm - its length is about 200 rran.

Example 1.10J of felt made of polynosic fiber of 5d
After being immersed for 30 minutes in a solution of ammonium phosphorus hydrogen sulfate with a concentration of i, it was dried under light at 50°C.

Next, this felt was placed in an air bath kept at 250°C and heated at a heating rate of 3°C/min until the temperature reached 310°C.

The weight loss rate after the above treatment with respect to the dry weight of the raw felt was 59 times.

Further, the atmosphere in the bath was changed to nitrogen containing 35 volumes of carbon dioxide gas, and the bath was heated from 310'C at a heating rate of 5°C/min until the temperature reached 600°C.

The activated carbon fiber felt thus obtained had a phosphorus content of 0.5% by weight and a carbon content of 75% by weight and a weight loss rate of 82%.

Using the above activated carbon fiber, the adsorption rate and adsorption amount were first measured.

In Fig. 1, the weighed U-shaped tube 10 has approximately 1
Precisely weigh and fill the 0S' sample, feed air at a constant flow rate (2,36 x 10-31/5 ec) through the glass tube 8, bubble gasoline in the bottle 3 to create saturated vapor, and then pour it through the glass tube 7. is directly heated to 20℃ without blowing air.
The sample was adsorbed with saturated gasoline vapor.

The U-shaped tube 10 was removed at regular intervals and its weight was measured to determine the amount of gasoline vapor adsorbed on the sample per unit weight.

The results are shown in Figure 2.

A is the time change in the adsorption amount of gasoline vapor when activated carbon fiber is used, and B is activated carbon ((pulverized coconut shell charcoal)).

From FIG. 2, it is confirmed that the activated carbon fiber has a significantly high gasoline adsorption rate and adsorption amount.

Next, the gasoline vapor desorption rate of the activated carbon fiber was measured.

The above U-shaped tube was filled with the activated carbon fiber and activated carbon samples that had adsorbed gasoline vapor to saturation, and fresh air was fed through the glass tube 8 at a constant flow rate (2.36 x 10-3 g/5
ec) While stirring, the U-shaped tube 10 was removed at regular intervals and its weight was measured to determine the amount of gasoline vapor remaining in the sample per unit weight.

The results are shown in Figure 3.

A and B are cases of activated carbon fiber and activated carbon of the present invention, respectively.

From FIG. 3, it was confirmed that the desorption rate of gasoline vapor from activated carbon fibers was significantly higher than that from activated carbon.

From the above, it can be seen that the activated carbon fiber of the present invention is extremely excellent as a material for preventing the diffusion of gasoline vapor from the fuel tank of an internal combustion engine.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the equipment used for the gasoline vapor adsorption test, Figure 2 is a graph showing the adsorption rate of gasoline vapor on the sample per unit weight, and Figure 3 is a sample that has reached adsorption equilibrium with gasoline vapor. 2 is a graph showing the desorption rate of . 1... Constant temperature bath, 2... Water, 3... Gasoline bottle,
4...Empty bottle, 5...Mixed bottle, 6...Regular gasoline, 7, 8...Glass tube, 9...Snap tube,
10... U-shaped tube, 11... Sample, A... Curve in case of activated carbon fiber, B... Curve in case of activated carbon.

Claims (1)

[Claims] 1. It is connected to the vent of the fuel tank and has a built-in adsorbent that adsorbs fuel vapor. When the engine is stopped, evaporated fuel is adsorbed by the adsorbent, and when the engine is running, it is desorbed from the adsorbent to release the desorbed fuel vapor. In a fuel tank equipped with a fuel vapor diffusion prevention mechanism having a mechanism for feeding fuel vapor into the engine part, the adsorbent is composed of a fiber aggregate such as a web or tow mainly made of activated carbon fiber. Characteristics of fuel tanks in internal combustion engines.