JP3773406B2 - Evaporative fuel processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an evaporated fuel processing apparatus that adsorbs evaporated fuel (vapor) released from a fuel tank to a canister, desorbs the evaporated fuel from the canister, releases it to an intake system of an internal combustion engine, and processes it.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in automobiles equipped with gasoline engines that use highly volatile oil (for example, fuel such as gasoline), in order to prevent the evaporated fuel volatilized in the fuel tank from being released into the atmosphere, Evaporative fuel treatment device is installed in This evaporative fuel processing apparatus includes a canister in which activated carbon is sealed as an adsorbent for adsorbing the evaporated fuel volatilized in the fuel tank, and adsorbs and holds the evaporated fuel. The adsorbed evaporated fuel is desorbed by the outside air introduced from the atmospheric port of the canister due to the negative pressure of the intake pipe when the internal combustion engine is operated, and is introduced into the intake pipe and burned together with the injected fuel from the injector.
[0003]
By the way, in recent years, the direct injection and HEV of internal combustion engines are increasing, and it is known that the intake pipe negative pressure is reduced in such engines. However, in the conventional evaporative fuel processing apparatus, the intake pipe negative pressure is used as a pressure feed source for sending the evaporated fuel adsorbed in the canister to the intake pipe of the internal combustion engine. This makes it difficult to feed the fuel into the intake pipe of the internal combustion engine. As a countermeasure, for an engine with a low intake pipe negative pressure, a purge pump is installed on the purge passage or the atmospheric port side of the canister, and the evaporated fuel adsorbed in the canister is sucked and / or pumped by the purge pump. It is conventionally known from Japanese Patent Application Laid-Open No. 11-30185 and Japanese Patent Application Laid-Open No. 5-340315.
[0004]
However, in an evaporative fuel processing apparatus that pumps evaporative fuel adsorbed to a canister using this purge pump, if the purge pump is operated with combustible evaporative fuel flowing into the purge pump, a purge pump drive source motor or There was a risk of ignition due to friction between the impeller of the purge pump and the housing. In addition, since the purge pump is driven by a motor, there is a problem in that extra power is consumed.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and its purpose is to allow the evaporated fuel adsorbed in the canister to be fed into the intake pipe even when the intake pipe negative pressure is small, and at the same time when the purge pump is stopped. By providing safety measures when combustible vaporized fuel flows into the purge pump, preventing accidents in the purge pump, and providing a vaporized fuel treatment device that reduces fuel consumption by limiting pump operating conditions. is there.
[0006]
[Means for Solving the Problems]
The present invention provides an evaporative fuel processing apparatus as described in each of the claims as means for solving the above-mentioned problems.
The evaporative fuel processing apparatus according to claim 1 is provided with a purge pump installed on the atmospheric port side of the canister, and as a safety measure when combustible evaporative fuel flows into the purge pump when the purge pump is stopped, An inlet connected to the purge pump housing is provided in the motor case housing the motor, and the evaporated fuel in the purge pump is scavenged by the intake negative pressure of the internal combustion engine before starting the motor. Accidents in the purge pump are prevented and safety is ensured.
[0007]
According to another aspect of the present invention, there is provided an evaporative fuel treatment apparatus in which an evaporative fuel introduction port of a canister is provided with a tank internal pressure valve, and an air valve is provided on the inlet side of the purge pump. In addition to communicating in both directions so as not to rise and fall beyond the pressure, the atmospheric valve of the purge pump is opened by the intake negative pressure of the internal combustion engine so that the evaporated fuel in the purge pump can be scavenged.
[0008]
The evaporative fuel treatment apparatus according to claims 3, 4 and 5 defines means for confirming that the evaporative fuel in the purge pump has been scavenged. In claim 3, the intake negative pressure of the internal combustion engine is predetermined. When the pressure becomes less than the value, the purge by the intake negative pressure becomes insufficient, so the forced purge by the purge pump is started. According to a fourth aspect of the present invention, the purge pump is started after confirming that the evaporated fuel does not remain in the purge pump by the HC concentration sensor installed in the purge pump or that the combustion limit is reached. According to the fifth aspect of the present invention, the time required for scavenging the volume of the purge pump known in advance is calculated from the purge flow rate obtained from the opening of the purge valve installed in the purge passage, and the intake negative pressure is calculated only for that time. After purging by pressure, the purge pump is started.
[0009]
The evaporative fuel processing devices according to claims 6, 7 and 8 each define a determination condition for stopping the operation of the purge pump. In claim 6, when the intake negative pressure of the internal combustion engine becomes a predetermined value or more Therefore, it is determined that the purge by the negative intake pressure is possible, and the forced purge by the purge pump is terminated. According to the seventh aspect of the present invention, when the HC concentration detected by the HC concentration sensor installed in the purge passage becomes a predetermined value or less, it is judged that there is not much evaporated fuel remaining in the canister and the operation of the purge pump is stopped. According to the eighth aspect of the present invention, when the fuel tank internal pressure becomes a predetermined value or less, it is determined that the evaporated fuel is not flowing into the canister and the operation of the purge pump is stopped.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an evaporated fuel processing apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an evaporative fuel processing apparatus according to the present invention, and FIG. 2 is a cross-sectional view of a purge pump. The evaporative fuel processing apparatus of the present invention comprises a canister 2 that adsorbs and holds evaporative fuel generated from a fuel tank 1, and a purge pump 3 that forcibly purges evaporative fuel adsorbed by the canister 2 into an intake pipe 9 of an internal combustion engine. is doing.
[0011]
The canister 2 communicates with the fuel tank 1 via an internal pressure valve 6. The canister 2 is filled with, for example, activated carbon as an adsorbent, and the evaporated fuel volatilized in the fuel tank 1 is introduced through the internal pressure valve 6 to be adsorbed and held. The internal pressure valve 6 is a valve that is bidirectionally controlled so that the internal pressure of the fuel tank does not rise and fall above a certain pressure due to the evaporated fuel.
[0012]
Further, the canister 2 is communicated with an intake pipe 9 of the internal combustion engine by a purge passage 5, and an HC concentration sensor 7, an internal combustion engine speed, a negative pressure of the intake pipe, an HC concentration sensor 7, etc. A purge valve 4 that is controlled by an ECU (electronic control unit) 10 according to the state is installed. The purge valve 4 outputs information on the opening degree to the ECU 10, calculates the time required to suck the volume of the purge pump known in advance, and outputs an operation signal to the purge pump 3 after the time has elapsed. To do.
A purge pump 3 is installed on the atmospheric port side of the canister 2 to forcibly purge the evaporated fuel adsorbed by the canister 2 into the intake pipe 9.
[0013]
FIG. 2 shows the details of the purge pump 3 in a sectional view. The purge pump 3 includes a housing 13, an impeller 14 that is rotatably disposed in the housing 13, and a motor 16 that drives the impeller 14, and is controlled by the ECU 10. An inlet 12 and an outlet 11 are connected to the purge pump 3, and the inlet 12 is installed in a motor case 15 that houses a motor 16.
The motor case 15 communicates with the atmosphere via the atmosphere valve 18. The atmospheric valve 18 is a bidirectionally controlled valve that closes communication with the atmosphere as necessary. The motor case 15 is provided with an HC concentration sensor 17 for detecting HC, and the HC concentration in the motor case 15 is input to the ECU 10.
The ECU 10 controls the purge valve 4 and the purge pump 3 and the like based on the input signals from the sensors and the control program stored in advance.
[0014]
A pressure sensor 8 is provided above the fuel tank 1, and the tank internal pressure is input to the ECU 10. The ECU 10 controls the operation of the purge pump 3 by the tank internal pressure. In addition, a filler neck 19 that forms a fuel supply passage is provided on the side of the fuel tank 1 so as to extend obliquely upward, and a filler cap 20 is attached to the tip of the filler neck 19.
[0015]
Next, the operation of the evaporated fuel processing apparatus of the present invention will be described.
FIG. 3 is a flowchart showing operating conditions of the purge pump of the evaporated fuel processing apparatus of the present invention. When the ignition is turned on in step S1, the process proceeds to step S2 where the purge valve 4 is turned on and opened. Next, in step S3, it is determined whether or not the intake negative pressure known from the throttle opening and the rotational speed of the internal combustion engine is equal to or less than a predetermined value PO. If the intake negative pressure is larger than the predetermined value PO, the purge by the intake negative pressure is possible. Therefore, it is determined that the forced purge by the purge pump 3 is not necessary, and the process ends. That is, in this case, the purge pump 3 is not driven. If the intake negative pressure is not more than the predetermined value PO in step S3, the process proceeds to step S4.
[0016]
In step S4, the atmospheric valve 18 of the purge pump 3 is opened by the intake negative pressure of the internal combustion engine, and the evaporated fuel in the purge pump 3 is scavenged. Next, in step S5, it is confirmed by the HC concentration sensor 17 installed in the purge pump 3 that there is no evaporated fuel in the purge pump 3, and in step S6, the purge pump 3 is operated to perform forced purge.
[0017]
Next, in steps S7, S8, and S9, the intake negative pressure is smaller than the predetermined value PO, the tank internal pressure is equal to or higher than the predetermined value P1, and the purge gas concentration detected by the HC concentration sensor 7 in the purge passage 5 is equal to or higher than the predetermined value CO. If there is, it is determined that it is necessary to continue the forced purge by the purge pump 3, and the operation of the purge pump 3 is continued.
[0018]
When the intake negative pressure is equal to or lower than the predetermined value PO in step S7, the purge by the intake negative pressure is insufficient, so that it is determined that the forced purge by the purge pump 3 is necessary and the process proceeds to step S8. In step S8, when the tank internal pressure of the fuel tank 1 is equal to or less than the predetermined value P1, it is determined that there is no inflow of evaporated fuel to the canister 2. In step S9, it is determined whether the purge gas concentration detected by the HC concentration sensor 7 in the purge passage 5 is equal to or greater than a predetermined value CO. At this time, if the purge gas concentration is equal to or less than the predetermined value CO, it is determined that no evaporated fuel remains in the canister 2, and the operation of the purge pump 3 is stopped and terminated in step S10.
[0019]
If the intake negative pressure is greater than the predetermined value PO in step S7, it is determined that forced purge by the purge pump 3 is not required, and the operation of the purge pump 3 is stopped and terminated in step S10.
In step S11, the operation described above is repeated after a predetermined time t has passed since the time since the purge pump 3 was stopped or the time determined as NO in step S3.
[0020]
As described above, the evaporated fuel processing apparatus of the present invention can have a safe structure by scavenging the evaporated fuel in the purge pump by the intake negative pressure of the internal combustion engine before starting the purge pump. Further, since the purge pump drive time can be shortened according to the purge pump operation determination conditions and power can be saved, the fuel consumption can be reduced.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a configuration of a fuel vapor processing apparatus according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a purge pump of the evaporated fuel processing apparatus of the present invention.
FIG. 3 is a flowchart showing operating conditions of the purge pump of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fuel tank 2 ... Canister 3 ... Purge pump 4 ... Purge valve 5 ... Purge passage 6 ... Internal pressure valve 7, 17 ... HC concentration sensor 8 ... Pressure sensor 11 ... Outlet 12 ... Inlet 15 ... Motor case 16 ... Motor

Claims (8)

The atmosphere in a canister vessel having activated carbon having adsorption / desorption action, having an evaporative fuel introduction port communicating with a fuel tank, a purge port communicating with an intake pipe of an internal combustion engine, and an atmosphere port communicating with the atmosphere In the evaporative fuel processing apparatus in which the motor-driven purge pump that can desorb the vaporized fuel adsorbed in the canister by pumping air is installed in the port.
As a safety measure when evaporated fuel flows into the purge pump when the purge pump is stopped, an inlet connected to the purge pump housing is provided in a motor case that houses the purge pump motor, and before the motor is started. An evaporative fuel processing apparatus that scavenges evaporative fuel in the purge pump by an intake negative pressure of an internal combustion engine. A tank internal pressure valve that controls the fuel tank internal pressure bidirectionally so that the fuel tank internal pressure does not rise and fall by a certain value or more due to the vaporized fuel is provided at the vaporizer fuel introduction port of the canister, The evaporative fuel processing apparatus according to claim 1, further comprising an atmospheric valve that closes communication and is controlled in both directions. The evaporated fuel processing apparatus according to claim 1, wherein the purge pump is started when an intake negative pressure of the internal combustion engine becomes a predetermined value or less. An HC concentration sensor is installed in the purge pump, and the purge pump is started by confirming that the evaporated fuel has disappeared in the purge pump by the HC concentration sensor or is below the lower combustion limit. The evaporative fuel processing apparatus according to claim 1 or 2. A purge valve is installed in the purge passage connecting the purge port of the canister and the intake pipe of the internal combustion engine. 3. The evaporative fuel processing apparatus according to claim 1, wherein the time required for the suction is calculated, and the engine is started after the elapse of the time. The evaporated fuel processing apparatus according to any one of claims 3 to 5, wherein the purge pump stops operating when an intake negative pressure of the internal combustion engine becomes a predetermined value or more. 6. An HC concentration sensor is installed in the purge passage, and the operation of the purge pump is stopped when the HC concentration detected by the HC concentration sensor falls below a predetermined value. The evaporative fuel processing apparatus as described in any one of these. The evaporated fuel processing apparatus according to any one of claims 3 to 5, wherein the purge pump stops operating when a fuel tank internal pressure becomes a predetermined value or less.

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