JPH06280694A - Canister device - Google Patents

Abstract

PURPOSE:To promote the desorption of evaporated fuel efficiently with a simple mechanism by controlling electrification of a pair of electrodes disposed at both sides of activated carbon in a canister. CONSTITUTION:A pair of electrode plates 40, 41 opposed to each other are embedded in activated carbon 36 in a canister C along the inner peripheral surface of a receptacle 30. An electrifying means 42 for applying voltage across the electrode plates 40, 41 is operated under the control of an ECU 15. The activated carbon sandwiched between the electrode plates 40, 41 has large electric resistance, but is conductive in electric current to generate heat by itself. When the temperature of the activated carbon 36 itself rises to some degree, adsorbed evaporated fuel gets liable to be desorbed. The control of the electrifying means 42 detects the running condition of an engine according to signals of an absolute pressure sensor 10 in an exhaust pipe, an engine rotational frequency sensor 11, etc. The electrifying means 42 is turned on to apply electricity after warming-up is completed after start and O2 feed-back control is started, and the desorption of the evaporated fuel is urged nearly at the same time as the purge to improve the purge efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a canister for temporarily storing evaporated fuel in a fuel tank of an internal combustion engine and supplying it to the engine as needed.

[0002]

2. Description of the Related Art Such a canister is one that adsorbs vaporized fuel by activated carbon contained therein, and conventionally adsorbs vaporized fuel generated in a fuel tank and separates vaporized fuel from activated carbon during a predetermined engine operating state. An evaporative fuel processing device that supplies (purges) an intake system is known.

Further, as the property of activated carbon, it is easy to separate the evaporated fuel at a high temperature. Therefore, when the heated air is introduced from the atmosphere introducing port at the time of purging from the canister, the efficiency of the separated evaporated fuel from the activated carbon is improved. A method (Japanese Patent Laid-Open No. 56-121856) has been proposed.

[0004]

However, in the above example, the atmosphere is heated from the outside of the canister, and the activated carbon is heated through the heated atmosphere, so that the efficiency is poor and the mechanism becomes complicated. .

The present invention has been made in view of the above points, and an object of the present invention is to provide a canister device capable of efficiently promoting the removal of evaporated fuel with a simple mechanism.

[0006]

In order to achieve the above object, the present invention is directed to a canister that adsorbs evaporated fuel from a fuel tank and separates the evaporated fuel according to a predetermined engine operating condition and supplies it to the engine. In the above, a canister device is provided in which a pair of electrodes are provided with an activated carbon formed in the canister sandwiched therebetween, and the pair of electrodes is energized during a predetermined engine operating state.

The canister has a simple structure in which a pair of electrodes are disposed between the activated carbon and the energization is controlled. Since the activated carbon in the inside generates heat by the energization, the temperature of the activated carbon is efficiently raised to generate the evaporated fuel. Withdrawal can be promoted and responsiveness is good.

[0008]

EXAMPLES An example of the present invention shown in FIGS. 1 to 3 will be described below. FIG. 1 is an overall configuration diagram of a fuel supply device including an evaporated fuel supply device (purge mechanism) according to the present embodiment.

In FIG. 1, an engine E is an internal combustion engine in which a mixture of fuel and air is sucked from an intake pipe 1 to obtain power by combustion, and exhaust gas after combustion is discharged from an exhaust pipe 2. 1, a throttle body 3 is formed, a throttle valve 4 is disposed inside the throttle body 3, and a fuel injection valve 5 is provided downstream of the throttle body 4 and slightly upstream of an intake valve (not shown) of the engine E. It is provided. The fuel injection valve 5 is connected to the fuel tank T via a fuel pump 6.

The operating state of the engine E is detected by each load detecting means, and the absolute pressure PbA in the intake pipe 1 is provided in the branch pipe 9 immediately downstream of the throttle valve 4.
An intake pipe absolute pressure sensor 10 for detecting the engine speed is provided, and the engine speed Ne is detected by an engine speed sensor 11 mounted around a cam shaft or a crank shaft (not shown) of the engine E. A signal pulse (TDC signal pulse) is output at a predetermined crank angle position each time the crankshaft of the engine E rotates 180 degrees.

The exhaust pipe 2 of the engine E has an O ₂ sensor 12
Is provided to detect the oxygen concentration in the exhaust gas. The valve opening of the throttle valve 4 is also detected by the throttle valve opening sensor 13.

All the detection signals of the above various sensors are input to the electronic control unit ECU15, the ECU15 performs arithmetic processing based on these information, and outputs various control signals to each drive device to perform optimum control.

For example, the ECU 15 controls various engine operating states such as a feedback control operating region and an open loop control operating region according to the oxygen concentration in the exhaust gas of the O ₂ sensor 12 based on signals from various sensors. to together, in synchronism with generation of TDC signal pulses to calculate the fuel injection time T _OUT of the fuel injection valve 5 according to the engine operating conditions, required by the fuel injection valve 5 based on the fuel injection time T _OUT and duty control The fuel supply amount is supplied to the engine E.

In the engine E equipped with such an electronically controlled fuel injection device, a purge mechanism is provided for processing the evaporated fuel in the fuel tank T without leaking to the outside.

That is, from the upper wall of the fuel tank T, a vent passage 20 communicating with the upper space in the fuel tank T extends, and is connected to the canister C via a two-way valve 21 which keeps the internal pressure in the fuel tank T appropriate. It is connected.

The canister C has an activated carbon 36 inside the container.
Are filled up leaving spaces above and below, and air is taken in through an air inlet 31 extending from the bottom wall. The end opening of the vent passage 20 is located in the activated carbon 22, and when the evaporated fuel is generated in the fuel tank T and the internal pressure becomes high, the two-way valve 21 is opened and the evaporated fuel is introduced into the canister C and adsorbed to the activated carbon 36. To be captured.

The upper space of the canister C communicates with a purge passage 24. The purge passage 24 is provided with a purge control valve 25 of an on / off control type on the way, and its end is downstream of the throttle body 3 in the intake pipe 1 of the engine E. Connected and communicated.

When the purge control valve 25 is opened, the negative pressure of the intake pipe 1 draws in the atmosphere from the atmosphere introducing port 31 of the canister C, removes the fuel adsorbed on the activated carbon 36, and mixes the air and the fuel vapor. It is supplied as air to the intake pipe 1 via the purge passage 24 and is used for combustion in the engine E. In this way, the evaporated fuel in the fuel tank T is processed and prevented from leaking to the outside and causing air pollution.

The structure of the canister C will be described in detail. As shown in FIG. 2, the container 30 has a bottom wall that is tapered so that the air inlet 31 extends downward, and the inside space is a gas that is an upper space. An exhaust chamber 32 and a space of an atmosphere introducing chamber 33 are formed below, and an upper and lower sides are sandwiched between a mesh plate 34 and a filter 35 and filled with activated carbon 36.

A vaporized fuel introduction pipe 37 is inserted into the activated carbon 36 through the upper wall of the container 30 and the center of the mesh plate 34, and the vaporized fuel introduction pipe 37 is connected to the vent passage 20. Further, an evaporated fuel outlet 38 is formed on the upper wall of the container 30, and the evaporated fuel outlet 38 is connected to the purge passage 24.

A container 30 is placed in the activated carbon 36 of the canister C.
A pair of electrode plates 40 and 41 are embedded along the inner peripheral surface of the so as to face each other. The energizing means 42 for applying a voltage to the electrode plates 40, 41 operates under the control of the ECU 15 as shown in FIG.

The activated carbon 36 sandwiched between the electrode plates 40 and 41 has a large electric resistance, but a current is passed through the activated carbon 36 to generate heat by itself. If the temperature of the activated carbon 36 itself rises to some extent, the adsorbed fuel vapor will be easily released.

Therefore, if the electrode plates 40 and 41 are energized when the purge control valve 25 is opened and purging is performed, the evaporated fuel is easily separated and the purging efficiency can be improved.

To control the energizing means 42, as shown in the flow chart of FIG. 3, first, the operating state of the engine is detected by signals from the intake pipe absolute pressure sensor 10, the engine speed sensor 11, etc. (step 1). .

Next, it is judged whether or not the purging is permitted (step 2). Purge is permitted after warm-up is completed after the engine is started and O ₂ feedback control is started. If purging is not allowed, energizing means
Turn off 42 and do not energize (step 3).

When the purging is permitted, the energizing means 42
Is turned on to energize (step 4), and at the same time as the purge, the activated carbon 36 in the canister C is caused to generate heat, and the separation of the evaporated fuel can be captured to improve the purge efficiency. Since the temperature rise of the activated carbon 36 is caused by its own heat generation, it is efficient and excellent in responsiveness.

The temperature of the activated carbon 36 of the canister C is detected and input to the ECU 15, and the temperature of the activated carbon 36 easily separates the evaporated fuel and abnormal high temperature accelerates the deterioration, so that the deterioration can be suppressed as much as possible. By controlling the drive of the energizing means 42 so as to be maintained at, it is possible to increase the purging efficiency and at the same time suppress the deterioration of the activated carbon 36. At this time, the energizing means 42 changes the amount of energization by changing the amount of current by duty control or adjusting the applied voltage.

Next, a modification of the arrangement of electrodes is shown in FIG. The structure of the canister C is substantially the same as that of the above-mentioned embodiment, but the positions of the electrodes 50 and 51 embedded in the activated carbon 52 are different.

The places where the vaporized fuel adsorbed on the activated carbon 52 is particularly liable to be separated are a place near the atmosphere introducing port 53 where the atmosphere is introduced and a place near the vaporized fuel outlet port 54 where the evaporated fuel is discharged. Detachment is unlikely to occur at locations far from the atmospheric flow that connects the locations.

Therefore, the electrode 5 is placed at a place where such separation is unlikely to occur.
By arranging 0 and 51 in particular, it is possible to promote desorption at this portion and to disengage the activated carbon 52 as a whole evenly, and it is possible to sufficiently improve the purging efficiency even with a small amount of activated carbon, and to reduce the size of the canister C. It can be realized.

FIG. 5 is a schematic view of a canister C showing the state of the electrodes of another embodiment. A rod-shaped electrode 60 is arranged on the central axis of a cylindrical container 62, and a cylindrical electrode is formed along the inner circumference of the container 62.
61 is disposed, and activated carbon is interposed between the electrodes 60 and 61.
By energizing the electrodes 60 and 61, the entire activated carbon heats up substantially uniformly, and the evaporated fuel can be removed efficiently.

Further, FIG. 6 shows another embodiment,
The upper and lower plates that support the activated carbon in the canister C by sandwiching it from above and below are electrodes 70 and 71. Note that electrode 7
Nos. 0 and 71 are formed with a large number of holes so that the evaporated fuel and the atmosphere can pass through. Similar to the example shown in FIG. 5, the entire activated carbon can be heated substantially uniformly.

Of course, the present invention is also applicable to a so-called closed bottom type in which the canister structure has the atmosphere introducing port in the upper part of the canister.

[0034]

According to the present invention, since a pair of electrodes are provided between the activated carbons in the canister to control the energization, the structure is simple, and the activated carbon itself generates heat due to the energization, and the evaporated fuel can be removed efficiently. The purging efficiency can be improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a fuel supply device including a purge mechanism according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the internal structure of the canister of the same embodiment.

FIG. 3 is a flowchart of energization control.

FIG. 4 is a cross-sectional view showing the internal structure of a canister of another embodiment.

FIG. 5 is a schematic perspective view showing the internal structure of a canister of another embodiment.

FIG. 6 is a schematic perspective view showing the internal structure of a canister of yet another embodiment.

[Explanation of symbols]

E ... Engine, T ... Fuel tank, C canister, 1 ... Intake pipe, 2 ... Exhaust pipe, 3 ... Throttle body, 4 ... Throttle valve, 5 ... Fuel injection valve, 6 ... Fuel pump, 9 ... Branch pipe,
10 ... Absolute pressure sensor in intake pipe, 11 ... Engine speed sensor, 12 ... O ₂ sensor, 13 ... Throttle valve opening sensor, 15
... ECU, 20 ... Vent passage, 21 ... Two-way valve, 22 ... Activated carbon, 24 ... Purge passage, 25 ... Purge control valve, 30 ... Vessel, 31
… Atmosphere inlet, 32… Gas exhaust chamber, 33… Atmosphere inlet, 34…
Mesh plate, 35 ... Filter, 36 ... Activated carbon, 37 ... Evaporative fuel introduction pipe, 38 ... Evaporated fuel outlet, 40, 41 ... Electrode plate, 42 ... Energizing means, 50, 51 ... Electrode, 52 ... Activated carbon, 53 ... Atmosphere Inlet, 54 ... Evaporative fuel outlet, 60, 61 ... Electrode, 62 ... Vessel, 70, 71 ... Electrode.

Front page continued (72) Inventor Tomoyuki Kawakami 143 Hagadai, Haga-cho, Haga-gun, Tochigi Prefecture PSG Co., Ltd.

Claims (1)

[Claims] 1. A canister for adsorbing evaporated fuel from a fuel tank and releasing the evaporated fuel according to a predetermined engine operating condition to supply the engine to a pair of electrodes with an activated carbon formed in the canister interposed therebetween. And a canister device for energizing the pair of electrodes during a predetermined engine operating state.