JPH05223020A - Evaporated fuel disposal device for internal combustion engine - Google Patents

Abstract

PURPOSE:To efficiently carry out adsorption and separation of fuel by alternately connecting an evaporated fuel disposal device to two canisters in an internal combustion engine. CONSTITUTION:Two canisters 10, 12 are provided. A selector valve 22 changes over a fuel tank between the canisters 10, 12, and a selector valve 30 changes over a purge port 33 between the canisters 10, 12. Heaters 20a, 20b are provided in the canisters 10, 12, respectively. A switch 60 changes over the heaters. In a first trip, evaporated fuel is adsorbed and separated in the canister 10, and the heater 20a is energized. Until a fist soaking after stopping, adsorption is made in the canister 12 which has been rested until then. In the next operation (second trip), evaporated fuel is adsorbed and separated in the canister 12, and the heater 20b is energized. Until a second soaking after stopping, adsorption is carried out in the canister 10 which has been rested until then.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporated fuel processing apparatus having a canister for adsorbing and desorbing evaporated fuel from a fuel tank of an internal combustion engine.

[0002]

2. Description of the Related Art In an internal combustion engine, a canister is provided to prevent vaporized fuel from a fuel tank from being released to the outside. That is, the canister is filled with activated carbon inside, the fuel evaporated from the fuel tank is adsorbed on the activated carbon, and the fuel adsorbed on the activated carbon is generated by the purge air flow caused by the negative pressure of the intake pipe during engine operation. It is released and used for combustion in the engine. In order to efficiently perform the adsorption and desorption operations in such a canister, it is known that it is preferable to accelerate the adsorption operation by heating the activated carbon layer during adsorption and to keep the activated carbon layer as low as possible during desorption. Therefore, JP-A-60-
In the 6061 publication, a canister is provided with a Peltier effect type thermoelement, and when the engine is operating, the canister is heated by heating the thermoelement,
It discloses that the cooling operation is performed by changing the direction of the thermoelement when the engine is stopped as compared with the time when heat is generated, and the canister is cooled to improve the adsorption efficiency of the evaporated fuel. The energization time of the thermoelement is set to the time required for the temperature of the canister to drop to a considerable extent.

[0003]

In the prior art, switching between heat generation and cooling is performed by changing the direction of energization of the Peltier element between when the engine is operating and when the engine is stopped, when heat is generated and when it is stopped. Even when is stopped, electricity is supplied for a considerable period of time until the desired temperature reduction is obtained. Since electricity is supplied for a considerable time at the time of stop, the burden on the battery for electric power is large and the battery may be consumed quickly.

It is an object of the present invention to provide a structure capable of efficiently adsorbing evaporated fuel at the time of stoppage while avoiding the possibility of battery exhaustion.

[0005]

The vaporized fuel processing apparatus for an internal combustion engine according to the present invention includes a plurality of canisters for adsorbing the vaporized fuel, heaters provided in the canisters, and a plurality of vaporizers connected to the canisters. A first switching means for switching the fuel passage and the fuel evaporation source of the internal combustion engine between the plurality of evaporated fuel passages so that the selected canister adsorbs the evaporated fuel, and a plurality of fuel purges connected to the respective canisters. Second switching means for switching the passage and the intake pipe of the internal combustion engine between a plurality of fuel purge passages, purging fuel from the selected canister and introducing the fuel into the internal combustion engine from the intake pipe, first switching means, and first switching means. Control means for actuating the switching means of No. 2 and the control means alternately performs adsorption and desorption operations of fuel by some canisters and the remaining canisters every time the internal combustion engine is operated. The first and second switching means are operated simultaneously, and at the same time, the heater provided in the canister that performs the fuel desorption operation is operated, and the first switching means operates when the internal combustion engine is stopped before the fuel is stopped. It is characterized in that the vapor fuel passage is switched so that the canister, which has been suspended from the detachment operation, can adsorb the vaporized fuel from the fuel vaporization source.

[0006]

When the engine is operating, the control means switches the vaporized fuel passage so that the first switching means alternately adsorbs the vaporized fuel between the plurality of canisters every time the engine is activated. Further, the second switching means switches the fuel purge passage so that the fuel is alternately released from the plurality of canisters every time the engine is operated. The control means actuates the heater of the canister that releases the evaporated fuel. Further, the operation of the first switching means by the control means is performed so that the evaporated fuel is introduced into the canister which had stopped the fuel desorption operation before the engine was stopped when the engine was stopped. Therefore, the adsorption of the evaporated fuel when the engine is stopped is performed in the canister whose temperature is low because the heater was stopped before the engine was stopped.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, two canisters 10 and 12 are provided. Although the structure of the canister itself is well known, its details are not shown, but the canister has an activated carbon layer for adsorbing fuel vapor therein. First canister 1
Reference numeral 0 denotes an evaporated fuel inlet 10a for introducing evaporated fuel from the fuel tank 14, and an evaporated fuel outlet 10b for taking out the evaporated fuel adsorbed in the canister 10 toward the downstream side of the throttle valve 18 of the intake pipe 16 of the internal combustion engine. And a purge air introduction port 10c for introducing purge air for releasing the fuel adsorbed in the first canister 10 and a connection port 10d for series connection with the second canister 12. The second canister 12 also has a similar structure, and has an evaporated fuel inlet 12a and an evaporated fuel outlet 12b.
And a purge air introduction port 12c and a connection port 12d. Further, heaters 20a and 20b are installed in the activated carbon layers of the canisters 10 and 12, respectively.

The first switching valve 22 has a common port 22a,
The first switching valve 22 includes a first switching port 22b and a second switching port 22c, and the first switching valve 22 has a first common port 22a.
1st position (represented in black) to connect to the switching port 22b of
And the common port 22a is switched to the second position (indicated by white space) where it is connected to the second switching port 22c. The common port 22a is opened to a space above the fuel liquid level of the fuel tank 14 via a pipe 24, and the first switching port 22b is connected to the evaporative fuel introduction port 10a of the first canister 10 via a pipe 26. , The second switching port 22c is connected to the fuel introduction port 12 of the second canister 12 via the pipe 28.
connected to a. Therefore, when the first switching valve 22 is in the first state represented by black coating, the space above the liquid surface of the fuel tank 14 is connected to the first canister 10 via the pipes 24 and 26.
Of the fuel tank 14 and the first switching valve 22 is in the second state, which is shown in white, the space above the liquid level of the fuel tank 14 is connected to the second canister 12 via the pipes 24 and 28. Is connected to the fuel introduction port 12b.

The second switching valve 30 has a common port 30a and
The second switching valve 30 includes a first switching port 30b and a second switching port 30c. The common port 30a of the second switching valve 30 is the first port.
1st position (represented by black paint) connected to the switching port 30b of
And the common port 30a is switched to the second position (shown in white) where the common port 30a is connected to the second switching port 30c. The common port 30a is opened via the pipe 32 to the purge port 33 slightly upstream of the idle position of the throttle valve 18 of the intake pipe 16 of the engine, and the first switching port 30b is connected to the pipe 3
Fuel vapor outlet 10 of the first canister 10 via
b, and the second switching port 30c is connected to the fuel outlet 12b of the second canister 12 via the pipe 36. Therefore, when the second switching valve 30 is in the first state represented by black coating, the evaporated fuel outlet 10b of the first canister 10 is connected to the purge port 33 of the intake pipe 16 via the pipes 34 and 32. , When the second switching valve 30 is in the second state represented by white, the evaporated fuel outlet 12b of the second canister 12 is connected to the intake pipe 1 via the pipes 36 and 32.
6 purge port 33.

The third switching valve 40 has a common port 40a and
The first switching port 40b and the second switching port 40c are provided, and the third switching valve 40 has the common port 40a as the first port.
1st position (represented in black) to connect to the switching port 40b of
, And the common port 40a is switched to the second position (represented by outline) connecting to the second switching port 40c. The common port 40a is connected to the purge air introduction port 10c of the first canister 10 via a pipe 42, and the first switching port 40b is connected to the connection port 12d of the second canister 12 via a pipe 44. The second switching port 40c is opened to the atmosphere via the pipe 46. Therefore, when the third switching valve 40 is in the first state represented by black coating, the purge air introduction port 10c of the first canister 10 is connected to the pipes 42, 4
4 is connected to the connection port 12d of the second canister, the first canister 10 and the second canister 12 are in series, and the third switching valve 40 is in the second state represented by the outline. At this time, the purge air introduction port 10c of the first canister 10 is connected to the atmosphere via the pipes 42 and 46.

The fourth switching valve 50 has a common port 50a,
The first switching port 50b and the second switching port 50c are provided, and the fourth switching valve 50 has the first common port 50a.
1st position (represented in black) to connect to the switching port 50b of
, And the common port 50a is switched to the second position (represented by outline) connecting to the second switching port 50c. The common port 50a is connected to the purge air introduction port 12c of the second canister 12 via the pipe 52, the first switching port 50b is connected to the atmosphere via the pipe 54, and the second switching port 50c is connected to the pipe 56. Is connected to the connection port 10d of the first canister 10 via. Therefore, when the fourth switching valve 50 is in the first state represented by black coating, the purge air introduction port 12c of the second canister 12 is connected to the pipes 52, 5
When the fourth switching valve 50 is in the second state represented by white, the second canister 12
The purge air introduction port 12c is connected to the connection port 10d of the first canister 10 via the pipes 52 and 56.

The above-mentioned first switching valve 22, second switching valve 30,
The third switching valve 40 and the fourth switching valve 50 are configured as self-holding switching valves, and each take a black coating position by the first trigger signal, and thereafter maintain the state even when the energization is released. , The white position is taken by the second trigger signal, and thereafter, that state is maintained even if the energization is released. The heater 20 a of the first canister 10 and the heater 20 b of the second canister are connected to the battery 62 by the changeover switch 60.
The energization is controlled alternately with respect to. That is, the changeover switch 6
0 consists of a common contact 60a, a first switching contact 60b, and a second switching contact 60c, and the first position is the first position of the switch 60 in which the common contact 60a is connected to the first switching contact 60b.
Of the battery 62 is energized by the battery 62 and the second heater 20b is connected to the battery 62 by the second position of the switch 60 in which the common contact 60a is connected to the second switching contact 60c.
Is energized by. The changeover switch 60 has a neutral position, and in the state where the energization is released, the common contact 60a maintains the state of being separated from both the first changeover contact 60b and the second changeover contact 60c.

The control circuit 64 is composed of a microcomputer, and includes a first switching valve 22, a second switching valve 30, and a third switching valve 30.
Changeover valve 40, fourth changeover valve 50, and changeover switch 6
Drive 0. Further, the control circuit 64 is provided with a delay circuit 68 which is energized by an ignition key switch 66 of the engine and maintains energization for a while (several seconds) even after the ignition key switch 66 is turned off.

FIG. 2 is a flow chart for explaining the operation of the control circuit 64 for carrying out the evaporated fuel introduction control of the present invention. The routine of FIG. 2 is the ignition key switch 6
It is assumed to be located in the main routine that is executed when 6 is turned on. At step 70, it is judged if the flag C = 1. This flag C is changed between 0 and 1 for each trip from when the ignition key switch is turned on to when it is turned off. C is stored in the non-volatile memory, so that even if the ignition key switch is turned off, the stored contents are secured without being lost. C =
If 0 (that is, the previous trip is C = 0), the process proceeds to step 72, C = 1 is set, and the process proceeds to step 74. The first switching valve 22, the second switching valve 30, the third switching valve 40, and the fourth switching valve. Each of the valves 50 is set to the first position (black port connection state). The state of these switching valves is called the first trip state. Further, in step 76, the changeover switch 60 is positioned on the side of the first changeover contact 60b in order to turn on the first heater 20a in the first canister 10. The flow of the evaporated fuel in this case is shown in FIG. That is, the flow of the evaporated fuel from the fuel tank 14 is shown with diagonal lines, and the first canister 10 passes through the pipe 24, the first switching valve 22, and the pipe 26.
Further, the evaporated fuel that has been introduced into the second canister 12 is introduced into the second canister 12 through the pipe 42, the third switching valve 40, and the pipe 44. Second canister 12
Is opened to the atmosphere through the pipe 52, the fourth switching valve 50, and the pipe 54. Further, the negative pressure generated in the purge port when the throttle valve 18 is opened from the purge port 33 causes the pipe 54, the fourth switching valve 50, the pipe 52, the second canister 12, the pipe 44, the third switching valve 40, and the pipe 42. , The pipe 34, the second switching valve 30, and the pipe 32 in this order, the flow of purge air is induced, and the first canister 10,
The fuel in the second canister 12 is separated from the activated carbon layer and introduced into the intake pipe 16. The heater 20a arranged in the first canister 10 can efficiently separate the collected fuel from the activated carbon layer in the first canister 10. The heater 20b in the second canister 12 remains off during the first trip.

The processing of steps 70 to 76 is executed only once when the ignition key switch 66 is turned on, the switching valves 22, 30, 46, 56 maintain their first trip states, and the heater 20a is turned on. Stay in the state.
In the meantime, since the answer of Step 78 is No, the processing in the main routine is repeated. Even after the first trip is completed and the ignition key switch 66 is turned off, immediately after that, the control circuit 64 is kept energized by the function of the delay circuit 68 and continues to execute the routine of FIG. Yes in step 78
Then, the routine proceeds to 80, where it is judged if the flag C = 1. Since C = 1, the process proceeds to step 82, and the first switching valve 22, the second switching valve 30, the third switching valve 40, and the fourth switching valve 50 are set to the second position (white port connection state), respectively. .. The operation time of the delay circuit 68 is a very short time required to complete the switching of the switching valve. After deenergizing the control circuit 64, the switch 60 returns to the neutral state and the heater 20a is turned off. The state after switching of these switching valves is called the first soak state. The flow of the evaporated fuel in this case is shown in FIG. That is, the flow of the evaporated fuel from the fuel tank 14 is shown by hatching, and the pipe 24, the first switching valve 22, and the pipe 2 are shown.
8 is introduced into the second canister 12 through
The evaporated fuel that overflows the canister 12 is introduced into the first canister 10 via the pipe 52, the fourth switching valve 50, and the pipe 56. The first canister 10 also includes a pipe 42 and a third
It communicates with the atmosphere through the switching valve 40 and the pipe 46. Recovery of evaporated fuel while the engine is stopped
Of the first canister 12 and the second canister 12 on the upstream side of the first canister 10.
Since the heater 20b in the second canister 12 was turned off during engine operation (during the first trip) immediately before stopping, the temperature of the second canister 12 is low, and the evaporated fuel from the fuel tank 14 is Adsorption can be performed efficiently.

Turn on the ignition key switch 66,
When the engine is in the traveling state again (this is called the second trip), the flag C = 1 at step 70, so the routine proceeds to step 84, C = 0 is set, and the routine proceeds to step 86, where the first switching valve 22, the second 2 switching valve 30, 3rd switching valve 40
The fourth switching valve 50 is set to the second position (white port connection state). The state of these switching valves is called the second trip state. Further, in step 88, the changeover switch 60 is positioned on the second changeover contact 60c side so as to turn on the second heater 20b in the second canister 12. The flow of the evaporated fuel in this case is shown in FIG. That is, the flow of the evaporated fuel from the fuel tank 14 is shown by diagonal lines, and is introduced into the second canister 12 via the pipe 24, the first switching valve 22, and the pipe 28, and further, the vaporized fuel overflowing the first canister 10 is evaporated. The fuel is the pipe 52, the fourth switching valve 50, the pipe 56.
Is introduced into the first canister 10 via. The first canister 10 is opened to the atmosphere via the pipe 42, the third switching valve 40, and the pipe 46. Further, the negative pressure generated in the purge port when the throttle valve 18 is opened from the purge port 33 causes the pipe 46, the third switching valve 40, the pipe 42, the first canister 10, the pipe 56, and the fourth switching valve 5 to operate.
0, the pipe 52, the second canister 12, the pipe 36, the second switching valve 30, and the pipe 32 in this order, the flow of purge air is induced, and the fuel of the second canister 12 and the first canister 10 is separated from the activated carbon layer, It is introduced into the intake pipe 16.
The heater 20b arranged in the second canister 12 can efficiently separate the collected fuel from the activated carbon layer in the second canister 12. The first canister 1
The heater 20a in 2 maintains the OFF state in the second trip.

Immediately after finishing the second trip, step 78
Then, it is determined to be Yes, the process proceeds to 80, and since C = 0, the process proceeds to step 90, where the first switching valve 22 and the second switching valve 3
0, the third switching valve 40, and the fourth switching valve 50 are set to the first position (black-painted port connection state), respectively. After the control circuit 64 is de-energized, the switch 60 returns to the neutral state and the heater 20b
Is turned off. The state after switching of these switching valves is called the second soak state. The flow of the evaporated fuel in this case is shown in FIG. That is, the flow of the evaporated fuel from the fuel tank 14 is shown by hatching, and the pipe 24, the first switching valve 22,
The evaporated fuel that is introduced into the first canister 10 through the pipe 26 and overflows the first canister 10 is pipe 4
2, introduced into the second canister 12 via the third switching valve 40 and the pipe 44. The third canister 12 is also in communication with the atmosphere via the pipe 52, the fourth switching valve 50, and the pipe 54. The recovery of the evaporated fuel while the engine is stopped is mainly performed by the first canister 10 on the upstream side of the first canister 10 and the second canister 12 connected in series. Then, the heater 2 in the first canister 10
0a is during engine operation (during second trip) immediately before stop
Since it has been turned off, the temperature of the first canister 10 is low, and the evaporated fuel from the fuel tank 14 can be efficiently adsorbed.

As described above, the first switching valve 22, the second switching valve 30, the third switching valve 40, and the fourth switching valve 50 are configured as self-holding switching valves, each of which is black by the first trigger signal. The state is maintained even when the coating position is taken and the energization is released thereafter, and the state is maintained even when the energization is released after the white position is taken by the second trigger signal.
An example of the specific configuration is shown in FIG. In FIG.
The casing 100 includes a common port 102, a first switching port 104, and a second switching port 105. The spool valve 106 moves up and down between a solid line position where the common port 102 communicates with the first switching port 104 and a solid line broken line position where the common port 102 communicates with the second switching port 105. The spool valve 106 is connected to the valve rod 108, and a flange 110 is formed at the lower end of the valve rod 108. A spring 114 is arranged below the flange 110.
The first solenoid 116 is arranged around the valve rod 108, and generates an electromagnetic force for moving the valve rod 108 up and down according to ON / OFF thereof. A stopper rod 118 is provided so as to be reciprocally movable in the horizontal direction.
Reference numeral 8 holds the position of the spool valve 106 by engaging with the flange 110. Stopper rod 1
A second solenoid 120 is arranged around 18
The stopper rod 118 is retracted depending on whether it is ON or OFF.
The spring 122 biases the stopper rod 118 so as to project to the left in the figure.

In the state of FIG. 7, the solenoids 116, 120
Are not excited, the stopper rod 118 is projected by the spring 122, and the tip end is the flange 11
0 on the top side, and the spool valve 106 is connected to the common port 10
2 maintains the position of the solid line communicating with the first switching port 104. When the second solenoid 120 is excited from this state, the stopper rod 118 is moved to the right in the figure, the flange 110 is released from the engagement with the stopper rod 118, the spring 114 raises the valve rod 108, and the spool valve Reference numeral 106 indicates the position of the broken line where the common port 102 communicates with the second switching port 105. The position of this broken line is maintained even when the solenoid 120 is de-energized.
Next, when the first solenoid 116 is energized, the valve rod 108 is lowered against the spring 114, and the flange 110 is engaged with the tip upper surface 118a of the stopper rod 118 in the middle of its descending motion. Has a downward inclination, the stopper rod 118 is momentarily pushed back to the right in the figure against the spring 122 when the flange 110 is lowered, but when the flange 110 is lowered beyond the tip of the stopper rod 118, The stopper rod 118 is pushed out to its original position by the spring 122, and the flange 110 reaches the position where it engages the stopper rod 118 at its lower surface. This state is maintained even when the first solenoid 116 is de-energized, and the common port 102 of the spool valve 106 is the first switching port 104.
The position of the solid line communicating with can be maintained.

[0020]

EFFECTS OF THE INVENTION A plurality of canisters for adsorbing vaporized fuel and a heater for each canister are provided, and when the engine is operating, the fuel is released from some of the canisters and the fuel is released. Perform the operation of the heater of the canister and introduce the evaporated fuel into the remaining canisters where the heater was stopped before the engine was stopped when the engine was stopped. By alternately operating also, the desorption is performed at a high temperature and the adsorption is performed at a low temperature, and there is an effect that the desorption and the adsorption can be efficiently performed without substantially consuming electric power at the time of stop.

[Brief description of drawings]

FIG. 1 is a schematic view of the entire configuration of an evaporated fuel processing device of the present invention.

FIG. 2 is a flow chart illustrating the operation of the device of FIG.

FIG. 3 is a diagram for explaining a fuel adsorption route to a canister and a fuel desorption route from the canister in the apparatus of FIG. 1 in the first trip.

FIG. 4 is a diagram for explaining a fuel release path from a canister in the apparatus of FIG. 1 in the first soak.

5 is a diagram illustrating a fuel adsorption route to a canister and a fuel desorption route from the canister in the apparatus of FIG. 1 in the second trip.

FIG. 6 is a diagram for explaining a fuel release path from a canister in the apparatus of FIG. 1 in the second soak.

FIG. 7 is a diagram illustrating an example of a specific structure of a 3-port valve used in the embodiment. 10 ... 1st canister 12 ... 2nd canister 14 ... Fuel tank 20a ... 1st heater 20b ... 2nd heater 22 ... 1st switching valve 30 ... 2nd switching valve 40 ... 3rd switching valve 50 ... 4th Changeover valve 60 ... Changeover switch 64 ... Control circuit 66 ... Ignition key switch

Claims (1)

[Claims] 1. A plurality of canisters for adsorbing evaporated fuel, a heater provided in each canister, a plurality of evaporated fuel passages connected to each canister, a fuel evaporation source of an internal combustion engine, and a plurality of evaporated fuels. First switching means for switching between the passages to adsorb the evaporated fuel to the selected canister, a plurality of fuel purge passages connected to each canister, and an intake pipe of the internal combustion engine between the plurality of fuel purge passages. And a control means for operating the first switching means and the second switching means, the second switching means introducing the fuel into the internal combustion engine through the intake pipe after purging the fuel from the selected canister. When the internal combustion engine is activated, the control means activates the first and second switching means so that the partial canister and the remaining canister alternately perform the adsorption and desorption operations of the fuel. at the same time , The heater provided in the canister for performing the fuel desorption operation is activated, and the first switching means causes the canister that has suspended the fuel desorption operation before the internal combustion engine is stopped when the internal combustion engine is stopped. An evaporated fuel processing apparatus for an internal combustion engine, characterized in that the evaporated fuel passage is switched to adsorb the fuel.