JPS593183Y2 - Evaporated fuel introduction device in engine - Google Patents

Description

[Detailed description of the invention] The present invention uses an adsorber (canister) that captures evaporated fuel, an evaporated fuel collection tank, and a hollow structure of the vehicle body to collect evaporated fuel generated in the fuel tank or float chamber of the carburetor in an engine. The present invention relates to a device for introducing air into the intake system through a reservoir such as the like.

The evaporated fuel generated in the fuel tank or the float chamber of the vaporizer is guided into a reservoir such as an evaporated fuel absorber while the engine is stopped, and the evaporated fuel is captured in the reservoir to prevent it from being released into the atmosphere. During engine operation, the evaporative fuel collected in the reservoir is gradually introduced into the intake system along with the evaporated fuel generated from the fuel tank, etc., in order to regenerate the collection capacity in the reservoir. ing.

In this case, conventionally, a passage from a storage part such as an adsorber for evaporated fuel is connected to one purge port provided in the carburetor slightly upstream from the closed position of the throttle valve.
Evaporative fuel from a reservoir such as an adsorber is introduced into the intake system in the operating range except when the engine is idling, and a purge port located slightly upstream of the closed position of the throttle valve is used. The negative pressure is highest at the beginning of partial load when the throttle valve is slightly opened, and in this state, even though the amount of air intake to the engine is small, the largest amount of evaporated fuel from the reservoir such as the adsorber is introduced. , the intake air mixture into the combustion chamber may become too rich, causing misfires, etc.
Alternatively, there was a problem in which the engine speed increased or the tracking ability became impaired.

On the other hand, Utility Model Application Publication No. 53-3221 as a prior art
No. 5 discloses that by reducing the diameter of the purge port and providing a second purge port on the upstream side thereof, when the throttle valve is slightly open, a smaller amount of evaporated fuel is delivered to the intake system than by the small-diameter purge port. The proposed method is to introduce the air into the intake system at both purge ports and increase the amount introduced into the intake system as the throttle valve opening increases.

However, the amount of evaporated fuel generated from a fuel tank or the like is proportional to the temperature; a large amount is generated when the temperature is high, but a small amount is generated when the temperature is low.

Therefore, when the temperature is low, almost only air is introduced from both purge ports, and when the throttle valve is connected to the second purge port, a large amount of air with less evaporated fuel is introduced than from both purge ports. This causes the air-fuel ratio of the intake mixture to the engine to become lean, resulting in ignition failure, resulting in a decrease in engine output and deterioration of exhaust gas.

In this way, the present invention connects the purge ports to the intake system to a first purge port located slightly upstream from the closed position of the throttle valve, and a second purge port I located further upstream from the first purge port. - Which two configurations can be used to reduce the amount of purge to the intake system when the throat valve is slightly open?
In order to increase the temperature as the throttle valve is opened, the second purge port is provided with a variable opening area adjuster that increases the opening area of the purge port as the temperature increases. This prevents the air-fuel ratio of the intake air-fuel mixture to the engine from becoming lean at low engine speeds.

The present invention will be described below with reference to drawings of embodiments. In the drawings, 1 is a carburetor equipped with a throttle valve 2, 3 is a fuel tank, 4 is an adsorbent containing a layered adsorbent 5 such as activated carbon, The upper chamber 6 of the adsorber 4 communicates with the upper part of the fuel tank 3 via a passage 7 to guide the evaporated fuel generated within the fuel tank 3, and the lower chamber 8 communicates with the atmosphere side via a pipe 9. It's communicating.

The carburetor 1 has a first purge port 10 at a position slightly upstream of the closed position of the throttle valve 2, and a second purge port 11 at a position further upstream from the first purge port 10. 1-10.1.
1 are connected to each other through a passage 12, and then connected to the upper chamber 6 of the adsorber 4 via a passage 14 with a check valve 13,
Variable adjustment of the opening area of the second purge port 11 with respect to the second purge port 11 such that the opening area of the second purge port 11 increases as the temperature rises so that more evaporated fuel is generated in the fuel tank 3. A mechanism 15 is provided.

In this configuration, when idling with the throat valve 2 of the carburetor 1 closed, both purge ports 1o, Tt
is located upstream of the throttle valve 2, and the purge port is at atmospheric pressure, so the check valve 13, which opens due to the negative pressure in the intake system, is closed, and the vaporized fuel from the adsorber 4 is directed to the intake system. is not introduced, but when the throttle valve 2 is slightly opened, the negative pressure in the first purge port 10 becomes high and vaporized fuel is introduced from the adsorber 4.

However, when the throttle valve 2 is slightly opened, the second purge port 11 is located on the atmospheric side, and the increase in negative pressure is less than when there is no second purge port, and the check valve 13
Since the opening area of the adsorber 4 is also reduced, the introduction of evaporated fuel from the adsorber 4 can be restricted to a small level, so that combustion at the initial stage of partial loading when the throttle valve 2 is slightly opened is inhibited by the introduction of evaporated fuel from the adsorber 4. can be suppressed, and when the throttle valve 2 is opened until the throttle valve 2 is located upstream of both purge ports 10 and 11, the negative pressures of both purge ports 10 and 11 are both suppressed. As the size increases, the amount of vaporized fuel introduced from the adsorber 4 increases.

In this case, in a low temperature range where less evaporated fuel is generated in the fuel tank 3 etc., the opening area of the second purge port 11 is
Since the opening area is reduced or fully opened by the variable opening area adjustment mechanism 15, the purge from the adsorber 4 to the intake system is regulated in a small amount only from the first purge port 10, so that the temperature is low. This purge prevents the air-fuel ratio of the intake mixture to the engine from becoming excessively lean.
When the temperature rises and the amount of evaporated fuel generated in the fuel tank 3 increases, the opening area of the second purge boat 11 increases, so that evaporated fuel can be introduced in accordance with the opening degree of the throttle valve 2. be.

Note that the present invention is applicable not only to the introduction of evaporated fuel from a reservoir such as an adsorber in a fuel tank, but also to the introduction of evaporated fuel from a reservoir such as an adsorber in a float chamber of a vaporizer or from the reservoirs of both adsorbers. Needless to say, it can also be applied to the introduction of

As described above, the present invention provides a first purge port in a part of the carburetor slightly upstream of the closed position of the throttle valve, and a second purge port in a part further upstream of the first part. , in an evaporated fuel introducing device in which both of these purge ports are connected to an evaporated fuel reservoir connected to a fuel tank or a float chamber of a vaporizer, an opening of the second purge port is connected to the second purge port; It is equipped with a variable opening area adjustment mechanism that increases the area according to the temperature, and the introduction of evaporated fuel from the evaporated fuel reservoir to the intake system is controlled according to the opening degree of the throttle valve using two purge ports. In controlling the air-fuel ratio to increase, the air-fuel ratio of the intake air mixture to the engine becomes excessively lean due to purge to the intake system when the temperature is low and therefore less evaporated fuel is generated. Since this can be prevented by the variable opening area adjustment mechanism provided for the second purge port, there is an effect that a reduction in engine output and deterioration of exhaust gas due to lean air-fuel ratio will not occur.

[Brief explanation of the drawing]

The drawing is a sectional view of the device implementing the present invention. 1... Carburizer, 2... Throttle valve,
3...Fuel tank, 4...Evaporative fuel adsorber, 1o, ii...Purge port, 15...
...Variable opening area adjustment mechanism.

Claims (1)

[Scope of utility model registration request] The carburetor is provided with a first purge port at a location slightly upstream from the closed position of the throttle valve, and a second purge port at a location further upstream from the first purge port. In an evaporated fuel introduction device connected to an evaporated fuel reservoir connected to a float chamber of a tank or a vaporizer, the opening area of the second purge port is increased in accordance with the temperature of the second purge port. An evaporative fuel introduction device for an engine, which is provided with a variable opening area adjustment mechanism.