JPS59180055A - Preventive device for release of vaporized fuel - Google Patents

Abstract

PURPOSE:To prevent the vaporized fuel from being released into atmosphere surely by a method wherein the vaporized fuel is purged upon low speed revolution through a control valve opened by utilizing a vacuum near a throttle valve while the same is purged through another control valve opened by a supercharging pressure upon middle and high speed revolution. CONSTITUTION:Upon the low speed revolution, in which the opening degree of the throttle valve 15 is small, the compressor 8 of a supercharger 5 rotates at a low speed and second purge control valve 4, not receiving the supercharging pressure, is kept in closed condition. A vacuum, generated near the throttle valve 15, is supplied to a vacuum chamber 33 of the first purge control valve 3, therefore, the valve part 37 of the same valve 3 is separated from a cylinder 35 through a diaphragm 31. Accordingly, the vaporized fuel, separated from active carbon 7 in a canister 2, is supplied to an internal-combustion engine from a purge chamber 32 through a conduit 9. On the other hand, upon middle and high speed revolution, in which the opening degree of the throttle valve 15 is large, a positive pressure in the downstream of the compressor 8 is supplied to the purge control valve 4 to open the same valve 4. Then, the vaporized fuel is purged to the upstream of the compressor 8 through an outflow pipe 22.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vaporized fuel release prevention device used in an internal combustion engine.

Recently, an increasing number of cars have been equipped with fuel cell systems to improve fuel efficiency and provide high output even with small engine displacements.

Even if there is one car equipped with this turbocharger, in order to prevent air pollution, the evaporated fuel generated from the fuel tank, tank, etc. is retained in activated carbon in the canister, and released from the activated carbon while the engine is running. A combustion fuel vapor release prevention device must be installed.

By the way, the canister is equipped with a purge control valve that controls when the vaporized fuel is desorbed, and this purge control valve is located in the intake pipe of the internal combustion engine. The purge control valve is activated by negative pressure fluctuations caused by the opening and closing of the throttle valve, but in cars equipped with a turbocharger, the purge control valve will no longer operate. That is, in A, which is the conventional negative pressure pipe circuit in FIG. Since the negative pressure chamber 56 becomes a positive pressure and the diaphragm 57 remains closed, vaporized fuel cannot be purged, and the canister 51
The activated carbon remains saturated and cannot hold any more vaporized fuel in the fuel tank 54, and is released into the atmosphere through the opening 58 of the canister 51. On the other hand, in circuit B in which the negative pressure conduit is located upstream of the turbocharger 53, the negative pressure in the air chamber 59 is several tens of mAq.
The diaphragm 57 of the purge control valve 52 cannot be moved. At this time, in order to move the diaphragm 57, there are two methods: to apply a low load to the spring, and to move the diaphragm 57.
There is a method of increasing the load area of the canister 51, but the former causes malfunction due to vibrations of the car, and the latter cannot be realized due to space considerations, and the vaporized fuel is released into the atmosphere from the opening 58 of the canister 51 as described above. There is a drawback that it makes you

The present invention provides an evaporative fuel release prevention device that eliminates these drawbacks, and has two ends that are fully open and one end that is F! The first purge control valve #:, the second
A discharge pipe connected to the purge control valve and an introduction pipe connected to the fuel tank are arranged, and the negative pressure chamber of the first purge control valve is connected to the top just above the throttle valve closing position, and the purge chamber is connected to the throttle chamber. , and the pressurizing chamber of the second purge control valve is connected to the downstream side of the compressor of the turbocharger, and the purge chamber is connected to the upstream side of the compressor.
The first purge control valve performs purging during low-speed driving, and the second purge control valve performs purging during turbocharging, so that it can be used over a wide range of driving. This will be explained below using examples.

The evaporative fuel release prevention device 1 shown in FIG.
and a second purge control valve 4. The canister 2 is a container having an opening 23 at one end and a closed end at the other end, and is filled with activated carbon 7, which adsorbs evaporated fuel, through upper and lower filters. At the other end, there is an inlet pipe 21 connected to a conduit 11 through which evaporated fuel from the fuel tank 6 passes.
The first purge control valve 3 and a discharge pipe 22 connected to the conduit 12 through which the vaporized fuel desorbed from the activated carbon 7 passes to the purge chamber 44 of the second purge control valve 4 are provided.

The first purge control valve 3 has a valve case divided into a purge chamber 32 and a negative pressure chamber 33 by a diaphragm 31, and the purge chamber 32 is provided with an opening 34 communicating with the container and a cylinder 35 connected to the purge pipe. A spring 36 is disposed in the negative pressure chamber 33 to press the diaphragm 31 against the cylinder 35, and forms a valve with the diaphragm central portion 37. The purge chamber 32 and the throttle chamber 16 downstream from the closed position of the throttle valve 15 are connected by a conduit 9. Further, the negative pressure chamber 33 and the area immediately above the closed position of the throttle valve 15 are connected through five conduits 10.

A second pipe connected to the discharge pipe 22 of the canister 2 and the conduit 12
In the purge control valve 4, an atmospheric chamber 43 in FIG. 3 is provided with a spring 48 that urges a diaphragm 45 upward and an opening 49 that communicates with the atmosphere. Valve case 4
The valve body 41, which is integrally provided under the valve r! I
? A purge chamber 44 is formed between the connection port 5o and the conduit 12. A stem 47 is provided which penetrates through the bottom of the valve case 40 and has one end fixed to the diaphragm 45 of the valve case 40 and the other end connected to a valve body 46 which is in contact with the valve seat 50 of the valve body 41. There is. The pressurizing chamber 42 and a chamber downstream of the compressor 8 of the turbocharger 5 are connected by a conduit 14 . Also, the purge chamber 441 of the valve body 41! The opening of Ill is connected to the outflow pipe 22 of the canister 2, and the other opening is connected to the upstream side of the compressor 8 of the turbocharger 6-5 by respective conduits 12, 13.

The evaporative fuel release prevention bag (case 1 is
When the opening of the throttle valve 15 is small and the compressor 8 of the turbocharger 5 rotates at a low speed, no force is applied to the pressurizing chamber 42 of the second purge control valve 4 to push down the diaphragm 45 against the spring 48. , negative pressure is generated near the throttle valve 15. This negative pressure causes the negative pressure chamber 33 of the first purge control valve 3 to
Negative pressure acts on diaphragm 3 against spring 3G.
1 is lifted to create a gap between the diaphragm central portion 37 and the cylinder 35, and the vaporized fuel released from the activated carbon 7 is sent from the purge chamber 32 to the internal combustion engine to be burned. When the opening of the throttle valve 15 is large and the engine rotates at medium and high speeds, the turbocharger 5 supercharges the engine and the pressure downstream of the compressor 8 becomes positive.

Then, positive pressure is applied to the pressurizing chamber 42 of the purge control valve 4 through the conduit 14 connected downstream of the compressor 8, pushing down the diaphragm 45 against the spring 48. The stem 47 fixed to the diaphragm 45 also lowers at the same time, separating the valve body 46 from the valve seat 50 and opening the canister 2.
The vaporized fuel is purged from the outflow pipe 22 to the upstream side of the compressor 8 of the turbocharger 5 via the evaporative fuel storage chamber 44.

At this time, the negative 1'E of the first purge control valve 3
The chamber 33 has a positive pressure just above the throttle valve 15 closing position, which brings the diaphragm central portion 37 and the cylinder 35 into close contact.
Do not purge from the first purge control valve 3.

As described above, in the present invention, when the turbocharger is not supercharging and is rotating at a low speed, the first purge control valve installed in the canister opens the valve and purges using the negative pressure near the throttle valve, and the turbocharger supercharges the valve. During medium and high speed rotation, the second purge control valve opens the valve and purges using compressor pressure, so it can be purged even when driving, and the activated carbon in the canister always has adsorption capacity to remove evaporated fuel to the atmosphere. It will not be released to.

[Brief explanation of drawings]

FIG. 1 is a detailed view of a conventional evaporative fuel release prevention device, FIG. 2 is a detailed view of the evaporative fuel release prevention device of the present invention, and FIG. 3 is a detailed view of a second purge control valve. 1... Fuel vapor release prevention device 2... Canister 3... First purge control valve 4...
...Second purge control valve 5...Turbocharger 31.45...Diaphragm 32.44...
... Purge chamber 33 ... Negative pressure chamber 42 ...
... Pressure chamber 22 ... Release pipe 9.10.11.12.13.14 ... Conduit patent applicant Tsuchiya Seisakusho Co., Ltd. 9-

Claims (1)

[Claims] A canister filled with activated carbon has an opening at one end and a closed end at the other end.
A purge control valve is provided, the inflow pipe is connected to the fuel tank by a conduit, the negative pressure chamber of the first purge control valve is connected to the area just above the throttle valve closing position by a conduit, and the purge control valve of the first purge control valve is connected to the fuel tank by a conduit. The chamber is connected to the throttle valve closed position downstream by a conduit, the discharge pipe of the canister is connected to a second purge control valve by a conduit, and the pressurized chamber of the second purge control valve is connected to the downstream of the compressor of the turbocharger. ``Evaporative fuel release 1 prevention device, which is connected by a conduit, and further connects the purge chamber of the second purge control valve and the upstream of the turbocharger compressor by a conduit.