JPH01147154A - Fuel evaporative emission preventing device - Google Patents

Abstract

PURPOSE:To raise the extent of adsorptive capacity of evaporative fuel with an improvement in emission capacity by installing a heat source for accelerating the emission of absorbed fuel, additionally in the inner part of a canister. CONSTITUTION:Fuel evaporative emission out of a fuel tank is taken out of an inlet port at the upper part of a canister body 28, and adsorbed to activated charcoal 29 inside the body. At the time of engine starting, the outside air is inhaled through a filter 31 for inflow, and adsorbed fuel volatilized with self-heating of the activated charcoal 29 is emitted out of an outlet port 32 as emission fuel. A heater 33 is arranged just under the filter 31 thereby heating the inflow air to about 60 deg.C-80 deg.C, and thus the volatile force of the absorbed fuel on the activated charcoal is heightened.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a fuel evaporation prevention device, and particularly to a canister (c)
This relates to a gasoline evaporation prevention device called anister.

Conventionally, in passenger cars, etc., as shown in Fig. 7, an electromagnetic fuel pump 1 sends gasoline through a pipe 2 to a carburetor 3, but a canister 4 is provided in the middle of the pump to pump gasoline. Efforts are being made to suppress evaporation. That is, the gasoline 6 evaporated from the gasoline tank 5 passes through the bidirectional pulp 7 and enters the canister 4, where it enters the canister 4.
It is adsorbed by the activated carbon 9 in the canister body 8 before and after A, and is prevented from being released into the atmosphere. Then, after a certain period of time has elapsed, when gasoline vapor is released into the combustion system (engine) in the next engine starting stage, external air 10 is sucked in from the bottom of the canister and caused to flow into the canister. As a result, the adsorbed fuel is gasified by self-heating caused by the reaction between the incoming air and the activated carbon, and is supplied from the canister 4 to the combustion system (ie, the carburetor 3) via the check pulp 11.
That is, the canister 4 repeatedly adsorbs and releases fuel. In addition, 12 in the figure is an air cleaner, 13
14 is a float chamber on the main chamber side, 14 is a float chamber on the sub-chamber side, 15 is pulp, 16 is an inlet manifold, and 17 is a fuel strainer.

However, the canister 4 described above has a reduced ability to release or evaporate adsorbed fuel (ability to release or purge fuel adsorbed by activated carbon into the combustion system) at low temperatures.

This is because the volatility decreases at low temperatures, which results in poor working capacity of the canister.
Furthermore, since the adsorption area of the activated carbon is relatively reduced, the adsorption capacity (ability to adsorb evaporated fuel from the fuel tank) also decreases.

Also, based on the above, if regulations on preventing evaporation are strengthened in the future, the capacity of conventional canisters will be insufficient, so 61-7I! A very large canister with a capacity of

This increases the space available to accommodate the canister.
It's inconvenient.

OBJECTS OF THE INVENTION An object of the present invention is to provide an apparatus that can increase the ability to release adsorbed fuel, improve the working capacity, and reduce the size of the apparatus.

20 Structure of the Invention That is, the present invention provides a fuel evaporation prevention device configured to adsorb evaporated fuel and release the adsorbed fuel into a combustion system in the presence of incoming air. This invention relates to a fuel evaporation prevention device characterized in that it is equipped with a heat source for promoting fuel evaporation.

E, Example The present invention will be explained in detail below.

FIG. 1 shows a first embodiment of the invention.

According to the canister 24 of this example, the vaporized fuel 6 from the fuel tank 5 described above is introduced from the door inlet 30 at the top of the canister body 28, and is adsorbed by the activated carbon 29 loaded in the canister body. When the engine is started after a certain period of time, external air 2 is passed through the filter 31 from the bottom of the main body.
0 is sucked in and allowed to flow in, and activated carbon 29 is added in the same manner as described above.
The adsorbed fuel volatilized by self-heating is released from the outlet 32 as released fuel 26 and sent to the combustion system.

What should be noted here is that there is a PTC (positive temperature) directly below the filter 31 at the bottom of the main body.
A heater 33 is disposed, and the incoming air 20 is supplied to the filter 31 through the central opening 35 while being in contact with the heater plate 34 of the heater, and introduced into the activated carbon 29. Therefore,
When entering the activated carbon 29, the incoming air 20 is heated to a predetermined temperature, preferably 60 to 80°C, by the heater plate 34, and comes into contact with the activated carbon 29 as moderately heated air 25, so that the air-activated carbon reaction described above occurs. likely to occur (i.e.
(promotion of self-heating), the volatility of the adsorbed fuel on the activated carbon 29 increases. As a result, the release capacity (evaporation capacity or purge capacity) of the adsorbed fuel is improved, and even at low temperatures, where the capacity tends to decrease, or during long-term use, the release capacity can be sufficiently maintained or improved, and the working capacity of the canister can be maintained. City can be improved.

Furthermore, the improvement in the release ability also improves the adsorption ability for the next evaporated fuel, thereby increasing the evaporation prevention efficiency.

In addition, sufficient capacity can be exhibited without increasing the canister capacity, making it possible to downsize the canister itself.

The canister 24 according to this example is a so-called bottom open type, and consists of an insulating box 36 made of synthetic resin with an air inflow hole 35 at the bottom, and the above-mentioned PTC heater 33 is arranged inside this box. ing. This heater has a PTC heater element 3 on the bottom surface of the heater plate 34.
One electrode side of the element 7 is fixed, and the other electrode of this element is connected to an external circuit via a contact spring 38 and a power terminal 39 (note that the terminal taken out from the heater plate 34 is not shown). Therefore, power is supplied to the heater element 37 from the terminal 39 via the spring 38,
This heater element 37 is caused to generate heat.

FIG. 2 shows another example of the invention, in which a bottom single-hole canister 24 is provided with an inverted conical heater plate 3 having a central air inlet 45 directly below a filter 41.
A plurality of PTC heater elements 37 are fixed to the outer bottom surface of 4, and a terminal 39 is commonly taken out from these elements.

In the canister of this example as well, the inlet 4 is heated by the heater 33.
Since the air 20 from the activated carbon 5 can be efficiently heated to a predetermined temperature by the plate 34 and then supplied into the activated carbon 29, the ability to release adsorbed fuel can be increased, efficiency can be improved, and the adsorption capacity can also be increased. Moreover, the heating by the heater 33 is
Although it is a single-hole type, it can be used satisfactorily, but this is because multiple heater elements are arranged as shown in the figure, and the heater plate 3
4 is provided in an inverted conical shape.

3 and 4 show a canister 24 according to another embodiment of the present invention, but in this example, the heater 33 is attached to the circumferential surface (i.e., around the trunk) of the canister body 28 instead of the bottom. . That is, a pair of belt-shaped heater plates 34 to which the PTC heater element 37 is fixed are brought into contact with the entire circumference of the canister body 28 and fixed with a fixture 50, and a contact spring 38 is attached to the heater element 37.
Power is supplied from the power supply terminal 39 via the power supply terminal 39.

In this example, the canister body 28 itself is heated from the entire circumference to indirectly heat the activated carbon inside, so not only can the same effects as those described above be obtained, but the heater can be easily installed, and the canister itself can be heated from all around. The advantage is that the conventional one can be used as is. Note that the heater plate 34 may be fixed by a combination of bolt donuts, a band, or the like.

5 and 6 show still another embodiment of the present invention. In this example, a heater 63 for heating the incoming air is connected to the air conduit system for the air inlet (pipe) 45 at the bottom of the canister body 24. The heater 63 is a honeycomb type PTC heater element 6 as shown in FIG.
7, and a contact spring 68 may be brought into contact with one surface 70 of this element 67 and led to a power supply terminal 69, and the other surface 71 may be grounded. Therefore, while the air 20 passes through the name tag 72 of the heater element 67, it is directly heated to a predetermined temperature, and immediately thereafter is sent to the canister as heated air. The heater 63 is housed in a cylindrical body 64, and the upper and lower connecting pipe portions 73 and 74 of this body 64 are connected to the air inflow pipe 45 or the air pipe 76 via (or without) a connector 75. . Note that this connection may be made by a screwing method or the like other than the insertion method.

Since the heater in this example heats the air immediately before it enters the canister, it produces the same effect as described above, and since the heater is only connected to the air conduit system,
Its installation is easy, and the canister structure can be the same as the conventional one. Since the heater is of honeycomb type, heating efficiency is improved.

Although the present invention has been illustrated above, the above-mentioned example can be further modified based on the technical idea of the present invention.

For example, the arrangement and structure of the PTC heater as the heat source described above may be changed in various ways. Moreover, this heater may be arranged inside the canister main body other than the above. That is, a heater whose periphery is sealed can be placed inside the canister to directly heat the activated carbon. Heater is PTC
In addition to the heater, other types such as a nichrome wire heater can also be used.

Furthermore, in the above example, heating of the incoming air and heating of the canister body may be performed simultaneously (for example,
(It is possible to combine the example in Figure 1 and the example in Figure 3). As the adsorption means, materials other than the above-mentioned activated carbon may be used. In addition,
The present invention is also effective in preventing evaporation of fuel evaporating from a fuel float chamber, etc., and can be applied to preventing evaporation of not only the above-mentioned fuels but also other fuels.

Effects of the Invention As described above, the present invention is equipped with a heat source to promote the release of adsorbed fuel, so even at low temperatures where the ability to release adsorbed fuel tends to decrease, or when used for a long time, the release can be prevented. ability can be sufficiently maintained or improved. Furthermore, the improvement in the release ability also improves the adsorption ability for the next evaporated fuel, thereby increasing the evaporation prevention efficiency. In addition, sufficient performance can be achieved without increasing the capacity of the device, making it possible to downsize the device itself.

[Brief explanation of the drawing]

1 to 6 show embodiments of the present invention, FIG. 1 is a cross-sectional view of a canister according to the first embodiment, FIG. 2 is a cross-sectional view of a canister according to the second embodiment, FIG. 3 is a sectional view of a canister according to the third embodiment, FIG. 4 is a right side view of a portion of FIG. 3, FIG. 5 is a sectional view of a canister according to the fourth embodiment, and FIG. FIG. 2 is a plan view of a honeycomb type heater used for. FIG. 7 is a schematic diagram showing a conventional fuel flow. In addition, in the symbols shown in the drawings, 1---------------------- Pump 3----- Carburetor 5----- Fuel tank 6-------- -1--Vaporized fuel 20--------First-class air 4.24.--Canister 9.29---1 Activated carbon 25.--1 ---
--- Warmed air 26 --- Released fuel 2B --- Canister body 31.41-
--------・- Filter 33.63 ------1 --- Heater 34 --- --- Heater plate 37.67 --- ---
-PTC heater element 38--Contact spring 3! 1-----------Power terminal. Agent Patent Attorney Hiroshi Osaka

Claims (1)

[Claims] 1. A fuel evaporation prevention device configured to adsorb evaporated fuel and release the adsorbed fuel to a combustion system in the presence of incoming air, which is provided with a heat source for promoting release of the adsorbed fuel. A fuel evaporation prevention device characterized by: