KR19980068178A - Automatic purifier of car canister and control method - Google Patents

Abstract

The present invention is an automatic purifier of the canister to ensure that the normal operation of the canister to ensure the normal operation of the canister by automatically removing and purifying when the canister collecting the evaporation gas evaporated naturally evaporated in the fuel tank more than the specified capacity and its It relates to a control method.

According to the present invention, the pressure sensor for measuring the pressure of the fuel boil-off gas evaporated from the fuel tank, the canister for absorbing and storing the fuel boil-off gas, and is provided in the supply passage between the fuel tank and the canister to complete the canister Shut-off valve that shuts off the supply passage during charging and supplies external air to the canister. A combustor for sucking and burning the evaporated gas charged in the canister, and determining whether or not the canister is fully charged based on the fuel tank pressure measurement and the time since the engine stops. An electronic control unit (ECU) which includes an electronic control unit (ECU) to operate, and when the canister is fully charged, it automatically burns, removes and purifies the fuel boil-off gas charged in the canister. The control method is provided.

Description

Automatic purifier of car canister and control method

The present invention relates to an automatic canister (canister) automatic purifying apparatus and a control method thereof, and more particularly, when the canister collecting the evaporated gas spontaneously evaporated from the fuel tank is filled with the evaporated gas more than the specified capacity automatically The present invention relates to an automatic purifier of a canister and a control method thereof so that the normal operation of the canister can be ensured by purification.

In general, an automobile is provided with an evaporation gas control system for preventing the emission of fuel boil-off gas generated by the vaporization of fuel in the fuel tank to the atmosphere. As shown in FIG. 1, the canister 101 can absorb and store the boil-off gas of fuel generated from the fuel tank 102 when the engine is stopped, as shown in FIG. 1. It functions to introduce the evaporated gas stored at the start-up back into the intake manifold 103.

In general, the canister 101 includes activated carbon capable of adsorbing the vaporized fuel therein, thereby adsorbing hydrocarbons on the surface of the activated carbon from the gaseous fuel introduced from the fuel tank 102. When the engine is operated, a portion of the intake air passes through the activated carbon of the canister 101 to separate hydrocarbon adsorbed on the surface of the activated carbon and supply it to the intake manifold 103 again.

The problem with these canisters is the saturation of canister activated carbon due to prolonged parking.

When the vehicle is parked for a long time, the amount of evaporated fuel evaporated from the fuel tank 102 is increased. When the amount of boil-off gas flowing into the canister 101 is increased to be greater than or equal to the filling capacity of the canister, the activated carbon provided in the canister 101 is saturated with the boil-off gas, thereby preventing the function of absorbing the boil-off gas further. Evaporated gas that is not adsorbed is released into the atmosphere in a defenseless state, so that the car smells badly fuel odor.

Therefore, in order to keep the interior of a car comfortable, it is necessary to prevent the air emission phenomenon of the boil-off gas, and in order to do this, if the boil-off gas of the fuel evaporated from the fuel tank exceeds the filling capacity of the canister, It is required to adequately process or properly remove the boil-off gas already filled in the canister in a timely manner to ensure sufficient filling capacity of the canister.

The present invention has been developed to properly prepare for the case where the fuel boil-off gas from the fuel tank exceeds the canister's charging capacity due to a long engine shutdown as described above. By measuring the canister's state of charge based on the boil-off pressure in the fuel tank, and when the canister is filled to a certain level or more, it automatically burns and removes the boil-off gas filled in the canister to release uncharged evaporated gas into the atmosphere. It is an object of the present invention to provide an automatic canister purifier and a control method thereof, by which the canister can always maintain a sufficient filling capacity by preventing the inflow into the canister and removing the boil-off gas charged in the canister in advance.

In order to achieve the above object, in the present invention, the fuel tank pressure sensor for measuring the pressure of the fuel boil-off gas evaporated in the fuel tank, the canister for absorbing and storing the fuel boil-off gas, between the fuel tank and the canister And a shutoff valve installed in the provided supply passage to shut off the supply passage from the fuel tank when the canister is charged and to supply external air to the canister. A combustor that sucks and burns the evaporated gas charged in the canister, and the pressure measurement value from the fuel tank pressure sensor and the time from the engine stop are counted to determine whether the canister is fully charged and the shutoff when judged to be fully charged. It includes a valve and an ECU (Electronic Control Unit) that operates the combustor. When the canister is fully charged, the canister is characterized by automatically burning and removing and purifying the fuel boil-off gas charged in the canister. An automatic purifier is provided.

In addition, in the present invention, determining whether the engine is stopped, measuring the evaporation gas pressure in the fuel tank using a pressure sensor, counting the elapsed time from the engine stop by the timer built in the ECU, Calculating the charge amount of the canister based on the pressure measurement value and the elapsed time by the ECU, and operating the combustor by determining that the charged amount of the canister is equal to or greater than a predetermined threshold value as a fully charged state. A control method of the canister automatic purifier is provided.

1 is a block diagram of a canister device according to the prior art,

2 is a block diagram of a canister automatic purifying apparatus according to the present invention,

Figure 3 is a schematic diagram of a shutoff valve provided in the canister purifier of the present invention,

Figure 3a shows a state in which the evaporation gas supply passage is opened and the air passage is blocked,

3b shows a state in which the evaporation gas supply passage is blocked and the air passage is opened.

4 is a flowchart illustrating each step of the method for controlling the canister automatic purifier according to the present invention.

Explanation of symbols on the main parts of the drawings

1: fuel tank 2: pressure sensor

3: ECU 4: Canister

5: Supply passage 6: Shut-off valve

7: air passage 8: solenoid

9: valve rod 10: first valve body

11: second valve body 12: combustor

13: suction fan 14: exhaust manifold

15: combustion gas discharge passage 16: suction pipe

17: exhaust gas exhaust passage 18: intake manifold

Hereinafter, the structure of the automatic canister purifier and its control method according to the present invention will be described in detail with reference to the accompanying drawings.

2 schematically shows a configuration of an embodiment of the canister automatic purifying apparatus according to the present invention. Whether or not the canister is fully charged is determined based on the pressure of the boil-off gas in the fuel tank. To this end, the fuel tank 1 of the vehicle is equipped with a pressure sensor 2 for measuring the pressure of the boil-off gas of the fuel. The boil-off gas pressure measurement in the fuel tank measured by the pressure sensor 2 is input to the ECU 3.

The boil-off gas generated in the fuel tank 1 flows into the canister 4 through the supply passage 5, and the supply passage 5 is provided with a shutoff valve 6. The shutoff valve 6 is controlled by the ECU 3 to block the inflow of air through the air passage 7 while the canister 4 is not fully charged to a predetermined level or more, and at the same time the supply passage 5 is closed. The evaporation gas is introduced to the canister 4 by opening, and when the canister 4 is fully filled, the supply passage 5 is blocked and the external air is supplied to the canister 4.

3A and 3B, one embodiment of the shut-off valve 6 is shown. The shut-off valve 6 employed in this embodiment includes a valve rod 9 reciprocating by a solenoid 8 and the valve. A first valve body 10 mounted to a rod rod 9 to block the air passage 7 through which air is introduced from the outside, and a second valve body 11 to block the supply passage 5; Consists of

In the shut-off valve 6, the distance between the first valve body 10 and the second valve body 11 is larger than the distance between the air passage 7 and the supply passage 5. As can be seen from 3a, when the first valve body 10 blocks the air passage 7, the second valve body 11 opens the supply passage 5 so that the boil-off gas passes through the supply passage 5. It flows into the canister 4. Meanwhile, as shown in FIG. 3B, when the valve rod 9 is raised by the operation of the solenoid 8 to block the supply passage 5 from the second valve body 11, the air passage 7 is opened to the outside. The air is configured to flow into the canister 4 through the air passage 7.

The combustor 12 is controlled by the ECU 3 to forcibly suck and burn the boil-off gas charged in the canister 4. To this end, the combustor 12 is provided with a suction fan 13 for forcibly suctioning boil-off gas from the canister 4.

A combustion gas discharge passage 15 is formed between the combustor 12 and the exhaust manifold 14 so that the combusted boil-off gas can be discharged.

The canister 4 includes a material such as activated carbon so as to absorb and store the fuel boil-off gas evaporated from the fuel tank 1, and the suction fan 13 is disposed between the canister 4 and the combustor 12. A separate suction tube 16 is formed to allow the evaporated gas to flow by.

The ECU 3 incorporates basic electronic control elements such as a microprocessor, a timer, and a memory, and the evaporation gas pressure value in the fuel tank 1 measured by the pressure sensor 2 and the elapsed time after the engine stops. On the basis of this, the amount of filling of the canister 4 is calculated, and the amount of filling of the canister 4 is determined by comparing the calculated amount of filling of the canister 4 with a predetermined set value. When the canister 4 is fully filled above a predetermined threshold, the shutoff valve 6 and the combustor 12 are controlled to suck, burn, and remove the evaporated gas in the canister 4.

Next, a control method of the canister automatic purifying apparatus of the present invention having the above-described configuration will be described.

4 is a flowchart illustrating each step of the method for controlling the canister automatic purifier according to the present invention.

The fuel evaporated from the fuel tank 1 becomes the evaporated gas and flows into the canister 4 through the supply passage 5. First, the engine speed sensor (not shown) is used to determine whether the engine is stopped. To judge. When the engine is in operation, the boil-off gas filled in the canister 4 by external air is supplied to the intake manifold 18 through the exhaust passage 17. Therefore, the canister 4 can always maintain sufficient charge capacity.

If the engine is stopped for a long time, the amount of fuel evaporation in the fuel tank 1 is increased so that the amount of boil-off gas flowing through the supply passage 5 becomes larger than the filling capacity of the canister 4, and the pressure sensor 2 ) Measures the boil-off gas pressure in the fuel tank 1 and outputs the pressure measurement to the ECU 3, and the ECU 3 shows the boil-off gas pressure from the pressure sensor 2 and the elapsed time from the engine stop. On the basis of this, it is determined whether the current canister 4 is fully charged.

Specifically, the amount of filling of the canister's boil-off gas is proportional to the pressure of the fuel tank. Evaporative gas charge of the canister after ) Is obtained as in Equation 1 below.

[Equation 1]

Where K is a proportionality constant, P _i is the measurement of the boil-off gas pressure at engine shutdown, and C _i-1 is the boil-off gas fill of the canister at engine shutdown.

In the ECU 3, it is determined whether the evaporation gas filling amount C _i of the canister 4 obtained by Equation 1 is larger than a predetermined threshold compared with a predetermined set value. If the boil-off gas filling amount C _i of the canister 4 is larger than the predetermined value, the supply valve 5 is shut off by controlling the shutoff valve 6 in consideration of the full charge state of the canister 4. Open the furnace (7).

That is, the solenoid 8 of the shut-off valve 6 is operated by the operation signal of the ECU 3 so that the valve rod 9 is lowered and the second valve body 11 supplies the supply passage 5. By preventing the evaporation gas from flowing into the canister 4 any more, the first valve body 10 opens the air passage 7 to allow external air to flow into the canister 4.

Subsequently, the ECU 3 applies an operation start signal of the combustor 12, and the suction fan 13 sucks the boil-off gas from the canister 4. Inhaled boil-off gas is combusted in the combustor 12 and discharged to the exhaust manifold 14 through the combustion gas discharge passage 15.

As such, the excess boil-off gas flowing into the canister 4 may be forcibly combusted to prevent leakage of the boil-off gas to the outside, and the boil-off gas filled in the canister may also be automatically purified. .

As described above, according to the present invention, when the canister is completely filled with the fuel evaporated gas generated in the fuel tank, the vaporized gas not filled by forcibly sucking the boiled gas filled by the suction fan and burning it by the combustor It can be removed automatically.

Therefore, even if the engine boils down for a long time and the fuel evaporated gas evaporated from the fuel tank flows into the canister more than the filling capacity of the canister, all the evaporated gas can be removed without leaking to the outside. This can prevent fuel odors in advance.

In addition, by removing and purifying the evaporated gas charged in the canister in advance, it is possible to always maintain a sufficient filling capacity of the canister, thereby ensuring the normal operation of the canister.

Claims (4)

The fuel tank pressure sensor 2 for measuring the pressure of the fuel boil-off gas evaporated from the fuel tank 1, the canister 4 for absorbing and storing the fuel boil-off gas, and the canister 4 are at least a predetermined level. And a shutoff valve 6 for blocking the boil-off gas supply passage 5 from the fuel tank 1 and supplying the outside air to the canister 4 when it is filled with. The amount of charge of the canister 4 based on the combustor 12 which sucks and burns the boil-off gas filled in the canister 4, and the pressure measurement value from the fuel tank pressure sensor 2 and the elapsed time from the engine stop. ECU 3 for burning and removing the boil-off gas charged in the canister 4 by operating the shutoff valve 6 and the combustor 12 when the calculated charge amount is calculated and compared with a predetermined threshold. Canister automatic purifier, characterized in that configured to include. 2. The canister automatic purifier as set forth in claim 1, characterized in that the combustor (12) is equipped with a suction fan (13) for sucking the evaporated gas filled in the canister (4). Determining whether the engine is stopped, measuring the evaporated gas pressure in the fuel tank 1 using the pressure sensor 2, and counting the elapsed time from when the engine is stopped by a timer built in the ECU 3 Calculating the charge amount of the canister 4 based on the pressure measurement value and the elapsed time by the ECU 3, and when the calculated charge amount of the canister 4 is greater than or equal to a predetermined threshold, the combustion unit (12) operating the control method of the canister automatic purifier, characterized in that it comprises a step. 4. The method of claim 3, wherein the amount of boil-off gas of the canister after a predetermined time after the engine is stopped is calculated by Equation 1 below. Where K is the proportionality constant, P _i is the boil-off gas pressure measurement at engine shutdown, C _i-1 is the boil-off gas charge at the canister when the engine is stopped, Is the elapsed time since the engine stopped.)