JPS6123644Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an evaporated fuel processing device that prevents fuel components evaporated from a vehicle-mounted fuel tank or the like from being released into the atmosphere.

Discharging evaporated fuel components (HC) directly from automobile fuel tanks, etc. to the outside contributes to air pollution, so this evaporated fuel is temporarily stored and introduced into the intake air of the engine to recover its original content. A device in which the fuel is burned in a combustion chamber along with the supplied fuel is in practical use. (Reference document, Japanese Unexamined Patent Publication No. 54-20231) In this method, evaporated fuel from a fuel tank or the like is introduced into a container called a canister containing an adsorbent such as activated carbon, and the fuel components are temporarily adsorbed by the adsorbent. is removed during engine operation and introduced into the engine intake.

The fuel components adsorbed and held in the canister come into contact with the outside air sucked through the activated carbon layer in response to the intake pipe negative pressure during engine operation, are released, and are introduced into the intake pipe together with the outside air.

However, this introduced air has an extremely high air-fuel ratio, that is, it contains a small amount of fuel, so if a large amount is introduced when the intake pipe negative pressure is strong, such as during low load, the intake air-fuel mixture will If the air becomes too thin, it will affect the exhaust composition and operational performance. Therefore, it is necessary to install a control valve in the introduction path so that the introduced air is sucked only at medium to high loads when the amount of intake air is large, or to Countermeasures are being taken by narrowing down the airflow and limiting the maximum flow rate of the introduced air.

However, in such a canister device, if the fuel tank capacity is large or the amount of evaporated fuel is large, such as at high temperatures, the amount of introduced air is relatively insufficient, so excess fuel components are transferred to the canister. There was a risk that it could not be absorbed completely (overflow) and would be released outside.

In addition, a solenoid valve is installed in the introduction path that communicates the canister and the fuel tank (for example,
12571), however, gum in the fuel may adhere to the solenoid valve, making it impossible to open and close the solenoid valve.

Therefore, the present invention provides a load detection means for detecting the engine load, a solenoid valve having a valve that opens and closes an evaporative fuel introduction passage and operates integrally with a diaphragm that partitions the introduction passage, and a solenoid valve that operates based on the engine load. A memory value that presets the opening area of the electromagnetic valve and a control means for controlling the pulse width of a control voltage of a predetermined frequency according to the memory value are provided, and the opening area of the solenoid valve is controlled by the control means according to the load. The purpose of this control is to achieve both desorption of adsorbed fuel in the canister and improved drivability, as well as stable opening and closing of the solenoid valve.

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 shows a schematic configuration of an embodiment of the present invention,
In the figure, 1 is an internal combustion engine main body, 2 is an intake passage, 3 is a throttle valve, and 4 is a canister (main body).

The details of the canister 4 are as shown in FIG.
A filter 10 is housed in the lower chamber 5, and an adsorbent 11 made of activated carbon or the like is housed in the middle chamber 6.

The lower chamber 5 has an outside air intake hole 12 provided in the bottom part 4a of the main body.
The middle chamber 6 communicates with the atmosphere through the porous material 9.
It communicates with the lower chamber 5 through the filter 10, and further communicates with the atmosphere side through the filter 10.

On the other hand, the upper chamber 7 includes a central space 7a that communicates with an inlet pipe 13 provided on the top portion 4b of the main body, and a side space 7 that also communicates with an outlet pipe 15 via a solenoid valve 14.
b. These spaces 7a and 7b are
Both communicate with the middle chamber 6 via their respective porous materials 8.

The electromagnetic valve 14 includes a saw-shaped valve body 17 when disposed coaxially with the relay pipe 16 protruding above the side space 7a, and urges the valve body 17 toward the open end of the relay pipe 16. It consists of a coil spring 18 and a diaphragm 17' that partitions the solenoid 19 introduction path 20 and moves integrally with the valve body 17. Normally, the valve body 17 comes into contact with the relay pipe 16 based on the elastic force of the coil spring 18, The side space 7b is connected to the outlet pipe 1
However, when the solenoid 19 is energized, the valve body 17 is attracted and separated from the relay pipe 16, as shown in FIG.
communicate with. Note that, as shown in FIG. 1, the outlet pipe 15 communicates with the intake passage 2 (downstream of the throttle valve 3) via the introduction passage 20, and the inlet pipe 13 communicates with a fuel tank space (not shown). .

Here, the electromagnetic valve 14 (solenoid 19) is energized via the control circuit 23 based on the crankshaft rotation signal output from the crank angle sensor 21 and the intake air amount signal output from the air flow meter (intake flow meter) 22. pulse control.

The crank angle sensor 21 detects a reference crank position according to the rotation of a toothed disk 25 directly connected to the crankshaft 24, and the control circuit 23 determines the crank angle or rotational speed according to this detection signal. calculate. Moreover, the air flow meter 22 is
It is installed in the intake passage 2 (upstream side of the throttle valve 3) and outputs a signal corresponding to the amount of intake air to the control circuit 23.

In this case, the control circuit 23 detects the intake air amount every revolution of the crankshaft based on the crankshaft rotation signal and the intake air amount signal, and outputs pulses to the solenoid valve 14 according to a preset memory map. Modulate.

That is, the control circuit 23 changes the pulse ratio (duty ratio) of the control voltage applied to the solenoid valve 14 to control the energization time ratio for opening and closing the solenoid valve 14, that is, the pulse width. In this case, the greater the amount of intake air per intake, the greater the open time percentage of the solenoid valve 14.
That is, the opening area is set to be large. This means that the present invention can be easily applied to a fuel injection system controlled by a microcomputer.

Next, the operation based on the above configuration will be explained.

First, when the engine is stopped, fuel components evaporated in the fuel tank enter the canister 14 based on their vapor pressure and are adsorbed by the adsorbent 11.

Then, when the engine is started, since the opening degree of the throttle valve 3 is extremely small at this time, a strong negative pressure acts on the downstream side of the throttle valve 3 or the introduction passage 20.

Therefore, when the solenoid valve 14 opens, based on this strong negative pressure, outside air is sucked in through the intake hole 12 of the canister bottom 4a, and evaporated fuel is sucked in through the inlet 13, and is sucked in through the adsorbent 11. The air is introduced into the space 7b and further into the intake passage 2 via the introduction pipe 20, and mixed into the intake air.

At this time, the fuel component adsorbed and held by the adsorbent 11 comes into contact with the introduced outside air and leaves the adsorbent 11, and is introduced into the intake air together with the outside air and some of the newly entered evaporated fuel.

However, as already explained, the opening ratio of the solenoid valve 14 is relatively reduced at such low speeds and low loads, so even if a strong negative pressure acts, the flow rate of the introduced air sucked into the intake passage 2 will be reduced. Can be kept small.

On the other hand, at high speeds and high loads, the amount of intake air increases and the opening ratio of the solenoid valve 14 also increases proportionally. A quantity of inlet air is introduced into the intake air.

Therefore, the ratio of the amount of introduced air to the amount of intake air does not become excessive, and stable engine performance can be maintained. Therefore, even if a large amount of evaporated fuel is generated at a high temperature, for example, there is no fear that the canister 14 will overflow and dissipate fuel components into the atmosphere.

In addition, since the diaphragm 17' separates the sliding part of the inlet passage 20 (outlet pipe 15) and the solenoid valve 14, gum in the fuel does not adhere to the coil spring 18, etc., and the valve body 17 can be opened and closed stably. The operation is measured. Furthermore, in this embodiment, when controlling the energization of the solenoid valve 14, the intake air amount and crankshaft rotation are used as input conditions to the control circuit 23. Since a control unit can be used, there are many manufacturing and cost advantages.

As described above, the present invention includes a means for detecting the amount of intake air in the engine and a means for detecting the number of engine revolutions, and pulse-controls the opening area of the solenoid valve based on the amount of intake air per revolution of the engine. By reducing the amount of air introduced in the low speed and low load range,
When the amount of intake air is small, changes in the amount of fuel introduced into the intake air due to the state of adsorption of fuel to the canister have a large effect on the air-fuel ratio.
Since the amount introduced from the solenoid valve is reduced, it has the effect of reliably preventing fluctuations in the air-fuel ratio.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention;
FIG. 2 is a sectional view of the canister, and FIG. 3 is an enlarged view of section A thereof. 2...Intake passage, 4...Canister (main body),
DESCRIPTION OF SYMBOLS 11...Adsorbent, 14...Solenoid valve, 20...Introduction path, 23...Control circuit.

Claims (1)

[Scope of utility model registration request] In an evaporated fuel processing device that is provided with a canister that adsorbs and holds evaporated fuel in a fuel tank or the like on an adsorbent material, and in which the adsorbed fuel from the canister is released during engine operation and introduced into the engine intake air through an introduction passage, the engine rotational speed is an intake air amount detection means for detecting the engine intake air amount; a solenoid valve having a valve body that opens and closes the introduction passage and moves integrally with a diaphragm that partitions the introduction passage; and a memory value in which the opening area of the electromagnetic valve is preset based on the engine intake air amount, and a control means for controlling the control pulse width of a predetermined frequency according to the memory value, and the opening area of the electromagnetic valve is is controlled by the control means according to the amount of intake air per engine revolution, and the opening time of the solenoid valve is shortened as the intake air amount per engine revolution is smaller. Fuel processing equipment.