JPS62153553A - Apparatus for preventing dispersion of evaporated fuel gas - Google Patents

Abstract

PURPOSE:To improve fuel consumption and drivability and prevent the leak of fuel by installing a purge valve for adjusting the purge flow rate according to the opening degree of a throttle valve in a suction passage and a valve opening means for compulsorily operating the purge valve in the opening direction in specific case. CONSTITUTION:The collected fuel in a canister 5 is sucked into a suction passage 3 through a purge passage 22. A purge valve 14 is installed into the purge passage 22, and adjusts the urge flow rate according to the opening degree of a throttle valve 14 in the suction passage 3. A valve opening means 7 for compulsorily operating the purge valve 14 in the opening direction when the negative pressure on the downstream side of the throttle valve 4 is less than a prescribed value is installed. Therefore, even with any used load, the proper purge control is permitted, and fuel consumption and drivability can be improved, and the leak of fuel from the canister can be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fuel evaporative gas emission prevention device that burns evaporative fuel gas generated in a fuel tank or the like in a combustion chamber without releasing it to the outside. In particular, the present invention relates to a fuel evaporative gas emission prevention device that can improve the combustion efficiency of an engine by controlling a canister that temporarily collects evaporative gas in accordance with the load condition of the engine.

[Prior Art] It is known that fuel in a fuel tank provided in a vehicle evaporates due to an increase in ambient temperature.

Since this evaporative gas increases the internal pressure of the tank, an evaporative fuel III control system for an internal combustion engine (Japanese Utility Model Publication No. 123654/1983) has been proposed, which uses the evaporative gas as fuel without emitting it to the outside.

This proposal, as shown in FIG. 6, forms a purge passage d that connects the activated carbon chamber C of the canister b that temporarily collects fuel vapor and the intake passage C1 on the downstream side of the throttle valve 4; d is interposed with a control valve e that reduces the purge flow rate as the negative pressure downstream of the throttle valve increases.

[Problems to be Solved by the Invention] However, the above proposal does not apply when the negative pressure value is below a predetermined value, that is,
At high loads when the throttle valve is fully open, the O1L control valve is fully open, and on the high load side where relatively rich combustion is required to improve drivability, the fuel collected in the canister is not used and the O1L valve is fully open. child .

The reason for this is, as shown in Fig. 4, the purge signal 0 pressure characteristic 9 of the negative pressure passage f that predominantly controls the canister, and the barge negative pressure r1 characteristic 1 generated depending on the opening degree of the throttle valve.
There is a lot to know from the relationship with 1. As shown in the figure, when the throttle valve opening exceeds the predetermined value I, the purge signal negative pressure value and the purge C-4IE ('a) become approximately the same and decrease together, and at the throttle valve fully open position Mj, Almost no negative pressure is generated.For this reason, it can be assumed that valves 11 and 11 are fully open at the front side of the high port, but there is no pressure in the purge passage.
Setting up the purge signal negative pressure-purge flow fii? as shown in Figure 3. It will show 1 and 2 in the 5 genders. In other words, no problem occurs on the low load side where the purge flow is high, but on the high load side where the purge flow 1c+ is constant depending on the control valve, the purge flow 1c+ is constant due to the opening control. Purging of the Tonen H inside the Nistar etc. is suppressed. Gil for this?
It is assumed that the amount of evaporated fuel collected in the second tank exceeds the allowable value, and the problem remains that the collected fuel is dripped from the fresh air introduction [1β].

In any case, these problems are undesirable in terms of fuel economy, drivability, and public welfare, and there is a demand for their solution.

[Object of the Invention] This defense has been devised to solve the above-mentioned problems i and π. The purpose of the present invention is to reduce the negative pressure in the intake oil passage downstream of the throttle valve (1
When f1 is above a predetermined value, the purge flow rate from the canister to the intake passage is adjusted according to the opening degree of the throttle valve, and the fuel collected in the canister is purged to the intake passage even when the load is high, which is below the predetermined value. It is designed to enable optimal purge control under any usage load, improve fuel efficiency and drivability, and prevent fuel leakage from the canister.

[Summary of the Invention] The present invention achieves the above object by providing a purge passage for sucking fuel collected in a canister or the like into an intake passage;
A purge valve is installed in the purge passage and adjusts the purge flow rate according to the opening degree of the throttle valve in the intake passage, and the purge valve opens when the negative pressure value in the intake passage on the downstream side of the throttle valve is below a predetermined value. The system consists of a valve opening means that is forcibly operated in the direction of the engine load, and attempts to achieve stable combustion with good drivability by supplying an appropriate amount of collected fuel from the ignitor etc. into the intake passage according to the load condition of the engine. It is something.

Embodiment 1 The fuel evaporative scum diffusion prevention device of the present invention will be described below with reference to the accompanying drawings.

1 shown in Fig. 1 is an outside air introduction passage, 2 is an air cleaner, and 3
4a and 4b are intake passages, and 4a and 4b are rotatable stages relative to the intake passage 3 to adjust the intake air volume. Inside the intake passage 3, there is a throttle valve for inhaling oil, and a canister 5 collects the evaporated gas of the fuel produced in the fuel tank (not shown).

Now, the feature of the fuel focusing/sparkling prevention device of the present invention is that it supplies evaporated gas from the fuel tank into the intake passage 3 according to the f-16Xi during any use, and The key is to achieve stable combustion with good stability.

Therefore, the canister 5, purge passage 22, volume valve means 7, and purge valve 14 are constructed as follows.

The canister 5 has a filter 9 at the bottom of a tightly closed cylindrical casing 8, a fresh air inlet 10 is provided at the bottom, and an activated carbon adsorption layer 11 such as charcoal is formed on the filter 91. There is. A space 12 having an appropriate volume is formed above the activated carbon adsorption layer 11,
A steam gas passage 13 from a fuel tank is connected to the upper part of the casing 8. Further, a purge valve 14 is integrally attached to the upper part of the casing 8, and this purge valve 14 is connected to an evaporative gas passage 1 extending to the upper part of the casing 8.
6, a biasing element 17 such as a tension coil spring that surrounds the evaporative gas passage 16 and has a predetermined tension, and a valve portion 18 whose tip fits into the upper end side of the evaporative gas passage 16 to open and close it.
A die A7 flamm 19 which is biased in the direction of closing the evaporative gas passage 16 by the biasing element 17, and one Guya flamm are integrally accommodated; 17 and a purge valve main body 15 which is integrally joined to the casing 8. Therefore, a negative pressure v20 is formed above the diaphragm 19 of the purge valve 14, and a purge chamber 33 is formed below the diaphragm 19.

The zero pressure chamber 20 is connected to the intake passage 3 near the throttle valves 4a, b, and the die 1 is connected to the intake passage 3 near the throttle valves 4a, b.
A purge signal passage 21 is formed to operate the 7 flamm 19 in the direction of the volume valve, and a purge passage 22 is formed to connect the intake passage 3 on the downstream side of the calibration valves 4a and 4b to the purge chamber 20 of the purge valve 14. It is formed.

Now, when the openings of the throttle valves 4a and 4b are adjusted to near the full position and the suction negative pressure value is set below a predetermined value, the valve opening means 7 that operates the purge valve 14 in the opening direction is as follows. It is configured as follows.

23 is a vacuum reserve tank, and in this embodiment, its suction passage 24 is the throttle valve 4a.

b It is connected to the intake passage 3 on the downstream side, and a check valve 25 is interposed in the intake passage 24 . The negative pressure passage 26 of the vacuum reserve tank 23 is connected to the purge signal passage 21.
The electromagnetic switching valve 27 is connected to the electromagnetic switching valve 27 through the negative pressure of the second negative pressure passage 28 connected to the downstream side of the intake passage 3, as shown in FIG. As shown, the predetermined value a, that is, the n pressure 1 that occurs when the engine is under high load.
A vacuum switch 30 is connected that closes two contacts (ON) when the temperature drops below the peak.
0, the electromagnetic switching valve 27 is configured to close the purge signal passage 21 between the electromagnetic switching valve 27 and the intake passage 3, thereby communicating the negative pressure seedling 20 with the vacuum reserve tank 23.

31 is a power supply, and 32 is a ground.

Hereinafter, the operation of the fuel evaporative gas light absorption prevention device of the present invention will be explained based on the accompanying drawings.

Before the engine starts fJll, the electromagnetic switching valve 27 and the vacuum switch 30 are OFF, and the purge signal passage 21 is open. At this time, biasing element 1
7 biases the diaphragm 19 in the opening direction J5, so that the fuel adsorbed (collected) from the activated carbon adsorption layer 11 of the canister 5 is not supplied into the intake passage 3.

When the throttle valves 4a and 4b are operated in the opening direction, negative pressure is generated in the intake passage 3 according to the degree of opening, and the purge signal passage 21
Negative pressure is also generated. At the time of starting, the throttle valve 4a,
Since the opening degree b is at its minimum, the negative pressure generated in the purge signal passage 21 is at its maximum value. This causes diaphragm 1
9 and the valve portion 1B are operated in the opening direction to open the evaporative gas passage 16.
is in between, and the purge passage 22, purge chamber 33, and space 12 are in between. Therefore, from the fresh air inlet 10 to the purge passage 2
Fresh air is introduced according to the negative pressure of step 2, and this fresh air removes the HC, which is the collected fuel, adsorbed on the activated carbon adsorption layer 11, so that purge fuel and fresh air are created in the intake passage 3. The mixture is mixed and inhaled as a mixture.

) When the interlayer is started and the opening degrees of the throttle valves 4a and 4b gradually increase, the negative pressure in the intake passage 3 decreases accordingly. Therefore, as the f1 pressure in A decreases, the pressure in the purge signal passage 21 (1) also decreases, and the opening degree of the valve portion 18 is adjusted, thereby reducing the amount of fuel sucked into the purge passage 22 and the intake passage 3. adjusted.

During this period, the load level is close to high, that is, the throttle valve 4a.

(b) Dominantly performed when the downstream negative pressure is equal to or higher than a predetermined value.

When the angular pressure on the downstream side of the throttle valves 4a and 4b falls below a predetermined value, the two contacts are turned ON by the resilient element 34 in the vacuum switch 30, and the electromagnetic switching valve 27 closes between the intake passage 3 and the purge signal passage 21. , negative pressure chamber 20 and negative pressure passage 24
Leave some time between. Therefore, at this time, the negative Lf in the purge signal passage 21 acts on one diaphragm, causing the high f1
Purge fuel is supplied from the purge passage 22 to the intake passage 3 even if the fuel is near the intake passage.

In any case, since the air-fuel mixture to the combustion stage commensurate with negative 68 is supplied by the throttle valves 4a and 4b, the overall air-fuel mixture consisting of this air-fuel mixture, the purged air-fuel mixture, and the ! The fuel ratio is determined by adjusting the relationship between the engine and the V-bullet.

FIG. 3 shows a schematic cross-sectional view of the carburetor,
A bypass passage 13a connected to the steam gas passage 13 of the canister 5 and a pent passage passage 37 for sucking evaporated gas from the float chamber 36 into the intake passage 3 are formed in the upper part of the casing of the float chamber 36 of the carburetor 35. has been done.

However, as mentioned above, there is a limit to the collection ability of the canister 5, and when that limit is exceeded, the bypass passage 1
Fuel flows backward from 3a to the float chamber 36, and the fuel pressure causes the fuel to leak from the fuel jet port of the capretor 35, resulting in over-richness, making it difficult to start the engine, and causing rough idling.

Therefore, a pent switching valve 38 is provided in the carburetor 35, and this vent switching valve 38 closes the outlet 40 of the pent passage 37 when extended, and drains the bypass passage 13a. With the outlet 41 in between, the outlet 41 of the bypass passage 13a is closed during contraction, and the pent passage 3 is closed.
A valve body 42 for opening the discharge port 40 of No. 7 is integrally provided. This vent switching valve 38 is normally linked to ON/OFF of the starter switch, and can also prevent backflow of fuel to the carburetor 35 by opening and closing the switching pulp 38.

[Effects of the Invention] As is clear from the above explanation, the fuel evaporative gas emission prevention device of the present invention can exhibit the following excellent effects.

(1) A purge valve that adjusts the flow rate of the purge passage according to the angular pressure inside the intake passage is installed in the purge passage that draws the collected fuel in the canister etc. into the intake passage, and a negative pressure downstream of the throttle valve is installed. Since a valve opening means is provided that forcibly operates the purge valve in the opening direction when the value is below a predetermined value, the collected fuel in the canister etc. is transferred into the intake passage according to the intake load of the engine, that is, the opening degree of the throttle valve. While it is possible to make adjustments according to the intake load, it is also possible to achieve reliable purging even near high loads where the suction load pressure value is below a predetermined value, reducing fuel consumption and
Drivability can be improved.

+21 Since purging can be performed in all operating load ranges, evaporated gas exceeding the collection limit of the canister will not drip from the fresh air inlet of the canister and be released to the outside, making it possible to take measures against the external environment. .

(3) The configuration is simple and can be easily applied to existing systems.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a preferred embodiment of the fuel evaporative emission prevention device of the present invention, Fig. 2 is a timing diagram showing the opening and closing of the vacuum switch, and Fig. 3 is a schematic diagram showing the carburetor. 6 to 6 show the steam light combustion of the conventional internal combustion RIIJ [
1 is a schematic diagram of a control device and a diagram showing its characteristics; FIG. In the figure, 3 is an intake passage, 4 is a throttle valve, 5 is a canister, and 7
14 is a valve opening means, and 14 is a purge valve. 3... aL viscous image Figure 2 Figure 3

Claims (1)

[Claims] A purge passage that sucks the collected fuel in a canister etc. into the intake passage, a purge valve that is interposed in the purge passage and adjusts the purge flow rate according to the opening degree of the throttle valve in the intake passage, and a negative pressure downstream of the throttle valve. What is claimed is: 1. A fuel evaporative gas emission prevention device comprising: valve opening means for forcibly operating a purge valve in the opening direction when the temperature is below a predetermined value.