JPH10246156A - Evaporation fuel recovering device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent liquid fuel from leaking to an atmosphere in the case where an evaporation passage is in an opening condition by arranging a flow-in fuel stagnating chamber on the way of an evaporation pipe, and arranging a sub-float for opening the evaporation passage in the case where fuel flows into the stagnating chamber and is stagnated therein. SOLUTION: When fuel is filled into a filler passage by an oil feeding gun at the time of oil feeding, a re-fuel vapor control valve 30 is opened, and evaporation fuel flows from an evaporation passage 46 to a canister main body 56 side. In the case where a main float 50 becomes in an abnormal condition after oil feeding and is separated from a main float seat part 52, fuel in a fuel tank 16 flows into the evaporation passage 46 bypassing the re-fuel vapor control valve 30, and flows into a flow-in fuel stagnating chamber 60. When fuel is stagnated in the flow-in fuel stagnating chamber 60, the sub-float 64 is operated upward, and the evaporation passage 46 is closed. It is thus possible to prevent fuel in the fuel tank 16 from leaking from the canister main body 56 to an atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporative fuel recovery system for an engine, and more particularly to an evaporative fuel recovery system for an engine capable of preventing liquid fuel from flowing into a canister body after refueling a fuel tank.

[0002]

2. Description of the Related Art In a vehicle, evaporated fuel leaking into the atmosphere from a fuel tank or the like contains a large amount of hydrocarbons (HC) and is one of the causes of air pollution, and also leads to fuel loss. For this reason, various techniques for preventing this are known. As a typical example, there is an evaporative fuel recovery device (evaporation system) that supplies (evaporates) the evaporative fuel from a fuel tank to a canister containing an adsorbent such as activated carbon during operation of the engine.

In this evaporative fuel recovery device, a canister is provided between an evaporative pipe having an evaporative passage communicating with the fuel tank and a purge pipe having a purge passage communicating with the intake system of the engine. A purge valve is provided in the middle of the purge pipe to open and close the purge passage in accordance with the operation state of the engine to control the amount of fuel evaporated to the intake system, and moves up and down in accordance with the amount of fuel in the fuel tank to open the evaporation passage. In some cases, a float that opens and closes is provided in a fuel tank.

[0004] Such an evaporative fuel recovery system for an engine is disclosed, for example, in Japanese Utility Model Laid-Open No. 4-89846. In the fuel tank described in this publication, a second vent branching in parallel from a vent passage between the canister and the pressure valve is provided in a fuel tank provided with a pressure valve that opens at a set pressure difference in a vent passage communicating with the canister. In the passage,
A float valve is provided that floats on the oil level when the fuel amount is equal to or more than a predetermined amount and closes the second vent passage.

[0005]

However, in the conventional evaporative fuel recovery system for an engine, if the float does not close the evaporative passage due to an abnormality after the fuel is supplied to the fuel tank, the fuel tank cannot be removed. Since the liquid fuel inside the canister flows into the canister body via the evaporative passage, there is a disadvantage that the liquid fuel leaks to the atmosphere, and
When the engine is started, since this liquid fuel is supplied to the intake system, there is a problem that the engine malfunctions.

[0006]

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned disadvantages, the present invention provides an evaporative pipe having an evaporative passage communicating with a fuel tank and a purge passage communicating with an intake system of an engine. A canister is provided between the engine and the purge pipe, and a purge valve is provided in the middle of the purge pipe to open and close the purge passage in accordance with an operation state of the engine to control an amount of fuel evaporated to the intake system. In the fuel recovery device, a main float that moves up and down according to the amount of fuel in the fuel tank to open and close the evaporative passage is provided in the fuel tank. A sub-float, which operates when fuel flows into and stays in the retention chamber and closes the evaporative passage, is provided.

A canister is provided between an evaporative pipe having an evaporative passage communicating with the fuel tank and a purge pipe having a purge passage communicating with an intake system of the engine. In the evaporative fuel recovery device for an engine provided with a purge valve for controlling the amount of fuel vapor to the intake system by opening and closing the purge passage according to the operating state of the fuel tank, the fuel cell moves up and down according to the amount of fuel in the fuel tank. A main float for opening and closing the evaporative passage is provided in the fuel tank, an inflow fuel retention chamber is provided in the canister body of the canister, and the canister operates when fuel flows into and accumulates in the inflow fuel retention chamber. A sub-float for preventing fuel from flowing into the main body is provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a method for reducing the amount of liquid in a fuel tank when the main float has an abnormality due to some cause after the fuel tank is refilled and the evaporation passage is in an open state. When the fuel flows into the evaporative passage and the liquid fuel stays in the inflow fuel retaining chamber, the sub-float is operated by the fuel amount to close the evaporative passage. This prevents the liquid fuel from flowing into the canister body, prevents the liquid fuel from leaking to the atmosphere, and prevents the liquid fuel from flowing into the intake system when the engine starts. As a result, it is possible to prevent engine malfunction.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; 1 to 4 show a first embodiment of the present invention. In FIG. 1, 2 is an engine mounted on a vehicle (not shown), 4 is an intake manifold, 6
Is an intake passage, 8 is a surge tank, 10 is an intake pipe, 12 is an air cleaner, 14 is an exhaust manifold, and 16 is a fuel tank.

The fuel tank 16 is provided with a filler tube 20 for forming a filler passage 18 for injecting fuel.

The filler tube 20 is of a so-called liquid seal type in which one end is immersed in fuel in a liquid chamber body 22 of the fuel tank 16. That is, one end of the filler tube 20 is immersed in the fuel so that the evaporated fuel does not leak from the fuel supply port 24 on the other end of the filler tube 20 when the fuel is supplied to the fuel tank 16. A filler cap 24 is provided at a filler port 24 of the filler tube 20.
6 are provided.

A level gauge 28 for detecting the amount of fuel is provided in the fuel tank 16.

The fuel tank 16 is provided with a fuel vapor control valve 30. The fuel vapor control valve 30 presses the diaphragm 34 toward the passage communication chamber 38 in the pressure housing 36 and the passage communication chamber 38 defined by the diaphragm 34 in the first housing 32. And a spring 40.

The fuel tank 16 is provided with a fuel cut valve 42. The fuel cut valve 42 has a second housing 44.

Fuel vapor control valve 3
0 is connected to one end of an evaporative pipe 48 forming an evaporative passage 46. One end of the evaporation passage 46 is opened and closed by the operation of the diaphragm 34.

A main float 50 is provided in the fuel tank 16 so as to open and close the evaporating passage 46 by moving up and down in accordance with the amount of fuel. That is, the main float 50 comes into contact with or separates from the main float seat 52 provided in the fuel tank 16 according to the amount of fuel. The main float seat 52 is connected to the first housing 32 of the fuel vapor control valve 30. Therefore, the main float 50 is connected to the main float seat 52.
The evaporative passage 46 is opened and closed by contacting with and separating from the evaporating passage.

At the other end of the evaporation pipe 48, a canister 54 is provided. The canister 54 contains an adsorbent such as activated carbon for adsorbing and holding the evaporated fuel in the canister body 56.

In the middle of the evaporative pipe 48, an inflow fuel retaining chamber 60 formed by a chamber forming portion 58 is provided. The inflow fuel retaining chamber 60 retains fuel flowing from the fuel tank 16 side. The fuel accumulating chamber 60 moves up and down in accordance with the amount of fuel that has flowed in and accumulates.
Sub-float 6 that opens and closes the evaporator passage 46 by contacting and separating with the evaporator passage 2
4 are provided.

Further, one end of a purge pipe 68 in which a purge passage 66 is formed is connected to the canister body 56. The other end of the purge pipe 68 is connected to the surge tank 8 of the intake system. The purge pipe 68 is provided with a purge valve 70 that opens and closes the purge passage 66 depending on the operation state of the engine 2 and controls the amount of purge (evaporated fuel) from the canister body 56 to the surge tank 8.

In the filler passage 18, a restrictor 72 and a check valve 74 are sequentially provided from the oil supply port 24 side. The restrictor 72 is used to refuel the fuel gun 76 when refueling.
(See FIG. 3). The check valve 74 closes the filler passage 18 immediately after refueling the fuel tank 16.

Fuel vapor control valve 3
The zero pressure action chamber 36 and the filler passage 18 on the upstream side of the restrictor 72 are communicated by a tank-side communication passage 80 formed by a tank-side communication pipe 78.

One end of a first communication passage 84 formed by a first communication pipe 82 communicates with the tank-side communication passage 80. The other end of the first communication passage 84 communicates with the canister body 56.

The first communication pipe 82 is provided with a first two-way check valve 86 and a separator 88.

One end of a second communication passage 92 formed by a second communication pipe 90 communicates with the fuel cut valve 42. The other end of the second communication passage 92 communicates with a first communication passage 84 between the first two-way check valve 86 and the separator 88 so as to communicate with the canister body 56. The second connecting pipe 90 is provided with a second two-way check valve 94.

In the fuel tank 16, a cut valve side float 96 is provided so as to move up and down in accordance with the amount of fuel to open and close the second communication passage 92. That is,
The cut valve side float 96 is provided on the cut valve side float seat 9 installed in the fuel tank 16 in accordance with the amount of fuel.
8 comes and goes. The cut valve side float seat 98 is connected to the second housing 44 of the fuel cut valve 42. Therefore, the cut valve side float 96 opens and closes the second communication passage 92 by coming into contact with and separating from the cut valve side float seat 98.

One end of a third communication passage 102 formed by a third communication pipe 100 is communicated with the second communication passage 92 so as to bypass the second two-way check valve 94. The other end of the third communication passage 102 communicates with a first communication passage 84 between the first two-way check valve 86 and the separator 88 so as to communicate with the canister body 56. The third communication pipe 100 is provided with a two-way solenoid valve 104.

The canister main body 56 is connected to one end of an atmosphere-side tube 108 in which an atmosphere-side passage 106 is formed. The other end of the atmosphere side tube 108 is a cross member 1 which is a body frame on the body 110 side.
12 is opened through a tube guide 114.
An air inlet 116 is formed in the cross member 112. The atmosphere side tube 108 is provided with an air cut valve 118, and an air filter 120 for removing air dust is provided upstream of the air cut valve 118.

Level gauge 28 and purge valves 70 and 2
Way solenoid valve 104 and air cut valve 11
8 communicates with the control means 122. Further, a pressure sensor 124 provided in the fuel tank 16 is connected to the control means 122 so as to detect the pressure in the fuel tank 16.

Next, the operation of the first embodiment will be described.

Before refueling, as shown in FIG. 2, the main float 50 is separated from the main float seat 52, but since the internal pressure in the fuel tank 16 is low, the fuel vapor control valve 30 is closed. Thus, the evaporation passage 46 is closed.

At the time of refueling, as shown in FIG. 3, when fuel is injected into the filler passage 18 by the refueling gun 76, the internal pressure in the fuel tank 16 increases, and the fuel vapor control valve 30 is opened. Evaporated fuel flows from the evaporation passage 46 to the canister body 56 side.

When the main float 50 becomes abnormal and separates from the main float seat 52 after refueling, as shown in FIG. 4, the liquid fuel in the fuel tank 16 is filled with a fuel vapor control valve. The air flows through the evaporative passage 46 through the fuel tank 30, and then flows into the fuel inflow chamber 60.

When the liquid fuel flowing into the inflow fuel storage chamber 60 is stored, the sub-float 64 operates upward,
When the sub-float 64 comes into contact with the sub-float seat 62, the evaporation passage 46 is closed.

Thus, the liquid fuel from the fuel tank 16 is prevented from flowing into the canister body 56, so that the liquid fuel can be prevented from leaking from the canister body 56 to the atmosphere.

Further, since the liquid fuel does not flow into the intake passage 6 when the engine 2 is started, it is possible to prevent engine malfunction.

FIGS. 5 and 6 show a second embodiment of the present invention.

In the second embodiment, parts having the same functions as those in the first embodiment will be described with the same reference numerals.

The features of the second embodiment are as follows. That is, the first,
An inflow fuel retention chamber 204 and a flow passage 206 formed by the second chamber forming portions 202-1 and 202-2 are provided. The inflow fuel retention chamber 204 has a sub-float 208
Is provided. The sub-float 208 moves up and down in accordance with the amount of liquid fuel flowing into the inflow fuel retaining chamber 204, and comes into contact with the sub-float seat 210 provided in the first and second chamber forming portions 202-1 and 202-2. To release.

According to the structure of the second embodiment, the same operation and effects as those of the first embodiment can be obtained, and the inflow fuel retaining chamber 204 can be manufactured integrally with the canister body 56. It can be.

[0040]

As is apparent from the above detailed description, according to the present invention, a main float which moves up and down in accordance with the amount of fuel in the fuel tank to open and close the evaporative passage is provided in the fuel tank, and is provided in the middle of the evaporative pipe. Has a sub-float that provides an inflow fuel retention chamber and operates when fuel flows into and stays in the inflow fuel retention chamber and closes the evaporative passage. Prevents the liquid fuel from flowing into the canister body, thereby preventing the liquid fuel from leaking to the atmosphere, and also allows the liquid fuel to flow into the intake system when the engine is started. To prevent the engine from malfunctioning.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an evaporative fuel recovery device.

FIG. 2 is a partial configuration diagram of a fuel vapor recovery device before refueling.

FIG. 3 is a partial configuration diagram of an evaporative fuel recovery device during refueling.

FIG. 4 is a partial configuration diagram of the fuel vapor recovery device when the main float is abnormal after refueling.

FIG. 5 is a configuration diagram of a canister when a main float is normal in the second embodiment.

FIG. 6 is a configuration diagram of a canister when a main float is abnormal in the second embodiment.

[Explanation of symbols]

 2 Engine 6 Intake passage 16 Fuel tank 30 Fuel vapor control valve 46 Evaporation passage 50 Main float 54 Canister 56 Canister main body 60 Inflow fuel retention chamber 64 Sub-float 66 Purge passage

Claims (2)

[Claims] 1. A canister is provided between an evaporative pipe having an evaporative passage communicating with a fuel tank and a purge pipe having a purge passage communicating with an intake system of an engine. In the evaporative fuel recovery device for an engine provided with a purge valve for controlling the amount of fuel vapor to the intake system by opening and closing the purge passage according to the operating state of the fuel tank, the fuel cell moves up and down according to the amount of fuel in the fuel tank. A main float for opening and closing the evaporative passage is provided in the fuel tank. An evaporative fuel recovery device for an engine, comprising a sub-float that closes. 2. A canister is provided between an evaporative pipe having an evaporative passage communicating with a fuel tank and a purge pipe having a purge passage communicating with an intake system of an engine. In the evaporative fuel recovery device for an engine provided with a purge valve for controlling the amount of fuel vapor to the intake system by opening and closing the purge passage according to the operating state of the fuel tank, the fuel cell moves up and down according to the amount of fuel in the fuel tank. A main float for opening and closing the evaporative passage is provided in the fuel tank, an inflow fuel retention chamber is provided in the canister body of the canister, and the canister operates when fuel flows into and accumulates in the inflow fuel retention chamber. An evaporative fuel recovery device for an engine, comprising a sub-float for preventing fuel from flowing into the main body.