JP2002188530A - Vaporized fuel processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vaporized fuel processor which can improve purge efficiency and adsorption efficiency of a canister of type performing a forced purge moreover to be at a low cost. SOLUTION: A PTC heater 5 for warming an adsorbing material is provided in a canister 1 or in its external surface, by making a power source of the PTC heater 5 so as to be on/off turned in accordance with an output of a temperature sensor 10 provided in an intake passage, vaporization of vaporized fuel adsorbed to the adsorbing material is accelerated, to improve purge efficiency and adsorption efficiency. By eliminating necessity for complicated control, a device simple at a low cost can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel vapor treatment system for a motor vehicle, and more particularly, to an improvement in the processing capability of a canister of a type that performs a forced purge.

[0002]

2. Description of the Related Art For the purpose of reducing fuel consumption and improving fuel economy, so-called lean burn engines and other evaporative fuel processing apparatuses which operate at an air-fuel ratio leaner than the stoichiometric air-fuel ratio or the economic air-fuel ratio are known. Since the negative pressure in the intake pipe is small due to the operation at a lean air-fuel ratio, the purge capability of the canister performed using the negative pressure in the intake pipe is reduced. Therefore, a technique for improving the purging capability of the canister is required. A technique for improving the purging capability of a canister by providing a heater in the canister and heating the filled adsorbent is disclosed in Japanese Utility Model Laid-Open No. 7-22059.

According to the above publication, a canister for adsorbing fuel vapor from a fuel tank, a heater for heating the canister, and a feedback correction coefficient are compared with predetermined upper and lower limits during purging. It is described that the purging can be promoted while controlling the fluctuation of the air-fuel ratio by the heater control means for variably controlling the applied voltage or the energizing time ratio of the heater so that the value becomes a value.

[0004]

However, in the above-mentioned invention, although the purge efficiency is improved by the temperature rise due to heating, the adsorption efficiency may be reduced.
Further, the control of the heater becomes complicated, and the device becomes complicated and expensive. SUMMARY OF THE INVENTION It is an object of the present invention to provide an inexpensive fuel vapor treatment apparatus that can improve the purge efficiency and adsorption efficiency of a canister of a type that performs forced purge, and that is inexpensive.

[0005]

According to a first aspect of the present invention, an evaporative fuel generated from a fuel tank is adsorbed on a canister, and the canister is operated by a purge pump together with the operation of the engine. In the evaporative fuel processing apparatus of the type for forcibly purging the evaporated fuel adsorbed in the engine to the engine, a PTC heater for warming an adsorbent is provided in the canister or on an outer surface of the canister, and the PTC heater is provided in the intake passage. Turns on the power of the PTC heater according to the output of the provided temperature sensor.
-It is characterized in that it is turned off. The invention according to claim 2 is an air pump, wherein the purge pump is directly attached to the engine and driven by the output of the engine, and has the same structure as a diaphragm type fuel pump having a check valve at each of an intake port and a discharge port. Or an air pump having a vane type or a turbo fan driven by an electric motor. Further, the invention according to claim 3 is configured such that a discharge port of the purge pump is communicated with an atmospheric port of the canister, and the engine is purged of evaporated fuel adsorbed in the canister by a positive pressure of the purge pump. It is characterized by.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram of a fuel vapor processing apparatus according to a first embodiment of the present invention. In FIG. 1, a canister 3 filled with an adsorbent (not shown) is provided in the middle of a purge passage 4 that connects an intake pipe 1a of the engine 1 and a fuel tank 2. The canister 3 is heated inside the canister 3 to warm the adsorbent. PTC heater 5 is provided. A purge pump 6 is provided on the intake pipe side of the canister 3, and a flow control valve 7 is provided between the purge pump 6 and the intake pipe 1a. The purge pump 6 is an air pump driven by an electric motor, and is an EC for controlling the engine 1.
Driven by a signal from U8.

The flow control valve 7 is an electromagnetic opening / closing valve whose duty is controlled by a signal from the ECU 8 according to the air-fuel ratio, and is a so-called VSV (Vacuum Switching V).
alve). A temperature sensor 10 for detecting an intake air temperature is provided in an air cleaner 9 provided at an inlet of the intake pipe 1a, and an output of the temperature sensor 10 is sent to the ECU 8. One of the outputs of the ECU 8 is PT
It is configured to be electrically connected to the C heater 5 and send an ON / OFF signal to the PTC heater 5 in response to a signal from the temperature sensor 10.

Next, the operation of the first embodiment will be described. The fuel in the fuel tank 2 evaporates due to a rise in the temperature of the fuel tank 2 or fuel agitation at the time of fuel supply, and the evaporated fuel is adsorbed by the adsorbent in the canister 3, thereby preventing leakage to the atmosphere. You. With the operation of the engine 1, the flow control valve 7, the purge pump 6, and the PT
The C heater 5 is operated by an electric signal from the ECU 8.
The fuel vapor in the canister 3 is forcibly sucked by the purge pump 6, and is purged to the intake pipe 1a via the flow control valve 7 together with the air flowing from the atmospheric port 3a.

The adsorbent in the canister 3 is a PTC heater 5
Therefore, the vaporization of the evaporated fuel adsorbed by the adsorbent is promoted, and the purge is reliably performed. When the PTC heater 5 reaches a predetermined Curie point after energization, the resistance value sharply increases and the current is limited to a substantially constant temperature, and has a self-temperature control function. Therefore, complicated control by the ECU 8 is not required. If the adsorbent is excessively heated, the adsorption capacity is reduced. Therefore, the PTC heater capacity is selected to an appropriate value, and after purging for a predetermined time, the power supply to the PTC heater 5 is cut off. Further, the temperature sensor 10 and the ECU 8 provided in the air cleaner 9 are configured so that the PTC heater 5 is not energized at a predetermined temperature or lower, and the energization is cut off when the fuel with a low outside air temperature is less evaporated.

Next, a second embodiment of the present invention will be described. FIG. 2 is a conceptual diagram of a fuel vapor processing apparatus according to a second embodiment of the present invention. In FIG. 2, the purge pump 12 is constituted by a diaphragm type air pump which is directly attached to the engine 11 and driven by the output of the engine 11. That is, it has the same structure as a diaphragm-type fuel pump known as an engine-driven mechanical fuel pump, which has a check valve (not shown) at each of the suction port 12b and the discharge port 12a. Purge pump 12 and canister 3
Between them, the flow control valve 7 shown in the first embodiment is provided. The flow control valve 7 may be provided between the purge pump 12 and the intake pipe 11a. Since the operation of the second embodiment is the same as that of the first embodiment, the same reference numerals are given and the description is omitted.

Next, a third embodiment of the present invention will be described. FIG. 3 is a conceptual diagram of a fuel vapor processing apparatus according to a third embodiment of the present invention. In FIG. 3, the engine 11
The discharge port 12a of the diaphragm type air pump which is directly attached to the
The flow control valve 7 shown in the first embodiment is provided between the purge port 3b of the canister 3 and the intake pipe 1a.

Next, the operation of the third embodiment will be described first.
Only different points from this embodiment will be described. The air pumped at a positive pressure by the purge pump 12 is supplied to the canister 3.
Is purged from the purge port 3b to the intake pipe 11a through the flow control valve 7 together with the evaporated fuel adsorbed by the adsorbent. Since the atmosphere port 3a side of the canister 3 is open to the atmosphere through two check valves (not shown) of the purge pump 12, even if the fuel vapor leaks from the atmosphere port 3a of the canister 3, It is blocked by two check valves, preventing leakage to the atmosphere.

[0013]

Since the present invention is configured as described above, the following effects can be obtained. That is, in the first and second aspects of the present invention, a PTC heater for warming the adsorbent is provided in the canister, and the power of the PTC heater is turned ON / OFF according to the output of the temperature sensor provided in the intake passage.
As a result, the vaporization of the evaporated fuel adsorbed by the adsorbent is promoted, and the purge efficiency is improved. Further, since complicated control is not required, a simple and inexpensive device can be provided. When the fuel with a low outside air temperature is less evaporated, the power supply is cut off, so that the power consumption can be reduced. The same effect can be obtained by attaching the PTC heater to the outer surface of the canister. According to the third aspect of the present invention, since the air port side of the canister is closed by the two check valves, even if the fuel vapor leaks from the canister, it is blocked by the two check valves,
Leakage to the atmosphere is prevented.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an evaporative fuel processing device according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of an evaporative fuel processing device according to a second embodiment of the present invention.

FIG. 3 is a conceptual diagram of an evaporative fuel processing apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Fuel tank 3 Canister 3a Atmospheric port 5 PTC heater 6 Purge pump 10 Temperature sensor 12 Purge pump 12a Discharge port 12b Suction port

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomoki Toki 1-1-1 Kyowa-cho, Obu-shi, Aichi F-term in Ai San Kogyo Co., Ltd. 3G044 AA05 BA29 DA06 DA07 EA04 GA02 GA06 GA07 GA27 GA29

Claims (3)

[Claims] 1. A type of evaporation in which fuel vapor generated from a fuel tank is adsorbed in a canister, and the engine is operated and a purge pump forcibly purges the fuel vapor adsorbed in the canister to the engine. In the fuel processing apparatus, a PTC heater for warming an adsorbent is provided in the canister or on the outer surface of the canister, and the power of the PTC heater is turned ON / OFF according to an output of a temperature sensor provided in an intake passage. An evaporative fuel treatment apparatus characterized in that the evaporative fuel treatment apparatus is characterized in that: 2. An air pump having the same structure as a diaphragm type fuel pump, wherein the purge pump is directly attached to the engine and driven by the output of the engine, and has a check valve at each of an intake port and a discharge port, or an electric pump. 2. An evaporative fuel processing apparatus according to claim 1, wherein the air pump has a vane type or a turbo fan driven by a motor. 3. A discharge port of the purge pump is communicated with an atmosphere port of the canister, and a positive pressure of the purge pump purges fuel vapor adsorbed in the canister to an engine. Claim 2
The evaporative fuel treatment device according to any one of the preceding claims.