JP5742786B2 - Fuel tank internal pressure regulator - Google Patents

Description

  The present invention relates to a fuel tank internal pressure adjusting device in an evaporative fuel processing system including a fuel tank, a canister, an evaporative fuel passage, a blocking valve, a purge passage, and a purge control valve of an internal combustion engine.

  In order to prevent the fuel vapor generated in the fuel tank of the internal combustion engine from being released into the atmosphere during refueling, the fuel tank is adsorbed to the canister by connecting the fuel tank and the canister through the evaporative fuel passage. An evaporative fuel processing apparatus is known. During operation of the internal combustion engine, the evaporative fuel processing device releases and processes the fuel vapor adsorbed by the canister into the intake air of the internal combustion engine by purge control.

  In such a fuel evaporation processing device, the fuel tank is separated from the canister by disposing a blocking valve in the evaporated fuel passage between the fuel tank and the canister, and closing the sealing valve except when refueling. A system for sealing the inside of a tank is known (for example, see Patent Document 1).

  In the system of Patent Document 1, in order to prevent the fuel vapor from blowing out from the tank cap at the time of refueling, when the inside of the fuel tank is at a high pressure, the sealing valve is opened and the pressure relief process is executed. Yes. This allows refueling after the tank internal pressure has sufficiently decreased.

  Further, in Patent Document 1, in order to shorten the pressure release processing time, when the internal pressure of the fuel tank is higher than the atmospheric pressure to some extent during the operation of the internal combustion engine, the blocking valve is opened under the purge control. By doing so, the tank internal pressure is reduced to atmospheric pressure in advance.

  However, even if the internal pressure of the tank is lowered to the atmospheric pressure during the operation of the internal combustion engine as described above, if the internal combustion engine is stopped for a long time due to parking or the like, the fuel vapor pressure rises due to the external temperature and the tank internal pressure There is a risk of high pressure. For this reason, in the configuration of Patent Document 1, it is necessary to increase the rigidity of the fuel tank and the seal of the sealing valve, and it is not possible to avoid an increase in weight and cost.

  There has been proposed a technique for diagnosing a fuel leak abnormality in a canister and a fuel tank by introducing a negative pressure into the canister and the fuel tank (see, for example, Patent Document 2). However, such negative pressure is introduction of negative pressure for determining a leak abnormality, and a technique for continuously maintaining the negative pressure state of the fuel tank is not employed. Therefore, in the configuration of Patent Document 2, the tank internal pressure is returned to the atmospheric pressure after the leak abnormality determination, and the negative pressure state cannot be maintained. Therefore, in the configuration of Patent Document 2, since the tank internal pressure is increased while the vehicle is stopped, it is necessary to increase the rigidity of the fuel tank and to increase the sealing valve, and it is not possible to avoid an increase in weight and cost. .

  In order to solve such a problem, a technique has been proposed in which the internal pressure of the fuel tank and the canister are integrated into a negative pressure by a negative pressure pump while the internal combustion engine is stopped, thereby suppressing an increase in the internal pressure of the tank even when the outside air temperature rises. (For example, refer to Patent Document 3).

JP 2004-156499 A (pages 4-9, FIGS. 1-4) JP 2008-51039 A (Page 6, FIGS. 1-2) Japanese Patent Laying-Open No. 2009-74445 (pages 14 to 17, FIGS. 10 and 14)

  However, Patent Document 3 is basically a system in which a fuel tank and a canister are integrated into a negative pressure. For this reason, when the negative pressure state is maintained even when the internal combustion engine is stopped, the negative pressure continues to act on the canister and the purge control valve and the air opening / closing valve adjacent thereto.

  In particular, when the canister is negatively pressured and left for a long time, the release of the fuel vapor adsorbed by the adsorbent of the canister is promoted by the negative pressure, and the purge passage may be filled with rich fuel vapor during parking. is there.

  If purge control is started after the internal combustion engine is started in this state, a very rich fuel vapor may be temporarily released into the intake air, which is not preferable for purge control or internal combustion engine emissions.

  Therefore, the negative pressure while the internal combustion engine is stopped is applied to a configuration in which the canister and the fuel tank can be separated and only the fuel tank can be sealed as in Patent Document 1, so that the negative pressure is maintained only in the fuel tank. It is necessary to adopt a method.

  However, as in Patent Document 2 and Patent Document 3, a system for negatively integrating a fuel tank and a canister is provided, and as in Patent Document 1, a sealing valve that can separate only the fuel tank by separating the canister and the fuel tank is provided. There is no known method to apply to existing systems. Furthermore, there is no known method for maintaining the negative pressure.

  In particular, Patent Document 3 describes an example in which a switching valve and a positive / negative pressure valve exist between a fuel tank and a canister as a fourth embodiment. However, the timing relationship between the driving / stopping of the negative pressure pump and the switching of the switching valve for reducing and holding only the tank internal pressure is not shown. Therefore, it is unclear whether the negative pressure state can be reliably maintained after the tank internal pressure is made negative, and therefore it is unknown whether the tank internal pressure rise can be sufficiently suppressed when the outside air temperature rises.

  The present invention relates to an evaporative fuel processing system in which an evaporative fuel passage connecting a canister and a fuel tank is provided with a block valve, and while the internal combustion engine is stopped, the pressure in the fuel tank is reduced and the negative pressure state of the fuel tank is reduced. The purpose is to hold it securely.

In the following, means for achieving the above-mentioned purpose, and its operation and effect are described.
The fuel tank internal pressure adjusting device according to claim 1 , wherein the fuel tank of the internal combustion engine, the canister, the evaporative fuel passage connecting the canister and the fuel tank, the blocking valve provided in the evaporative fuel passage, the intake passage of the canister and the internal combustion engine The internal pressure of the fuel tank in the evaporative fuel processing system provided with a purge passage that connects to the purge passage, a purge control valve provided in the purge passage, an atmospheric passage that connects the canister and the atmospheric side, and an atmospheric on-off valve provided in the atmospheric passage A negative pressure pump connected to the evaporative fuel processing system on the side opposite to the fuel tank with respect to the blocking valve and depressurizing the evaporative fuel processing system, and the purge control valve is closed When the internal combustion engine is stopped, the fuel valve which opens the block valve and closes the atmospheric on-off valve and executes negative pressure processing in the fuel tank by driving the negative pressure pump After the negative pressure process by the negative pressure generating means and the fuel tank negative pressure means, before the opening of the atmospheric on-off valve and the stop of the negative pressure pump is executed, the shutoff valve is closed to And a fuel tank negative pressure holding means for holding the tank internal pressure.

  When introducing negative pressure into the fuel tank, the fuel tank negative pressure means opens the blocking valve and closes the air on-off valve while the internal combustion engine is stopped, and the purge control valve is closed, thereby closing the negative pressure pump. The negative pressure process is performed on the inside of the fuel tank by driving of.

  At the time of this negative pressure, the sealing valve between the canister and the fuel tank is in an open state, so that the inside of the fuel tank can also be detected by a negative pressure pump arranged on the side opposite to the fuel tank with respect to the sealing valve. Negative pressure can be achieved. However, when the negative pressure is reached, the canister is also negatively pressured.

  However, after the negative pressure treatment by the fuel tank negative pressure means, the fuel tank negative pressure holding means closes the shutoff valve and opens the internal pressure of the fuel tank before opening the atmospheric on-off valve and stopping the negative pressure pump. Therefore, the internal pressure of the fuel tank is reliably maintained in a negative pressure state.

  Since the canister is not sealed because the atmospheric on-off valve is subsequently opened, the canister is returned to the atmospheric pressure by the air introduced from the atmospheric passage after the negative pressure processing is completed.

  Therefore, in an evaporative fuel processing system in which a sealing valve is provided in the evaporative fuel passage connecting the canister and the fuel tank, the fuel tank can be made negative while the internal combustion engine is stopped, and the fuel tank can be maintained without holding the canister in a negative pressure state. It is possible to reliably maintain the negative pressure state.

The fuel tank internal pressure adjusting device according to claim 2 , wherein the fuel tank internal pressure adjusting device according to claim 1 further comprises tank internal pressure detecting means for detecting a tank internal pressure in the fuel tank, and the fuel tank negative pressure adjusting means. Is characterized in that the negative pressure process is not executed when the tank internal pressure detected by the tank internal pressure detecting means does not exist in the pressure region near the atmospheric pressure.

Here, the vicinity of the atmospheric pressure is a pressure region having a certain pressure width on the high-pressure side and the low-pressure side around the atmospheric pressure.
While the internal combustion engine is stopped, the tank internal pressure changes depending on the outside air temperature, but when the block valve is opened while the tank internal pressure is higher than the atmospheric pressure, high-pressure gas blows out from the fuel tank. Therefore, there are cases where high pressure is applied to the canister or the fuel vapor cannot be sufficiently adsorbed by the canister.

However, there is no such problem as long as it is at atmospheric pressure or slightly higher than atmospheric pressure.
Further, in the state where the tank internal pressure is lower than the atmospheric pressure, the fuel tank is already at a negative pressure, so the negative pressure processing itself is not necessary. That is, if the pressure is sufficiently lower than the atmospheric pressure, the inside of the fuel tank may be kept in a sealed state.

  Therefore, when the tank internal pressure detected by the tank internal pressure detecting means does not exist in the pressure region near the atmospheric pressure, the fuel tank negative pressure generating means does not execute the negative pressure processing and opens the block valve. The fuel vapor is prevented from being blown out vigorously at the time of valve operation, and wasteful processing is prevented.

In the fuel tank internal pressure control apparatus according to claim 3 is the fuel tank internal pressure control apparatus according to claim 1 or 2, wherein the negative pressure pump is provided in the air passage, the negative pressure treatment, the canister It is the process which discharges | emits the gas in the said fuel tank via this.

  As described above, the negative pressure pump may be disposed in the atmospheric passage on the side opposite to the fuel tank with respect to the blocking valve. By driving the negative pressure pump, the inside of the fuel tank as well as the canister can be surely reduced to a negative pressure when the blocking valve is opened.

In the fuel tank internal pressure control apparatus according to claim 4, in the evaporative fuel processing apparatus according to claim 3, wherein the fuel tank negative pressure means, the negative pressure processed as part of the leakage diagnosis process for the fuel tank The fuel tank negative pressure holding means closes the shutoff valve to reduce the internal pressure of the fuel tank before opening the atmospheric on-off valve and stopping the negative pressure pump after the leak diagnosis process. It is characterized by holding.

  As described above, in the system in which the leak diagnosis process for reducing the pressure in the fuel tank is executed as the leak diagnosis process, the leak diagnosis is performed by using the negative pressure in the fuel tank that is executed by the negative pressure pump during the leak diagnosis process. You may make it hold | maintain the negative pressure state reliably after a process.

This eliminates the need to drive a negative pressure pump specially for reducing the pressure in the fuel tank, leading to improved fuel efficiency.
According to a fifth aspect of the present invention , in the fuel tank internal pressure adjusting device according to the fourth aspect , the leak diagnosis process is performed by the negative pressure pump to the evaporated fuel processing system while the internal combustion engine is stopped. It is a process for detecting a leak in the evaporated fuel processing system based on a pressure change in the evaporated fuel processing system when a negative pressure is introduced.

  An example of the leak diagnosis process is a system that detects a leak based on a pressure change accompanying the negative pressure of the evaporated fuel processing system while the internal combustion engine is stopped. By using such a leak diagnosis process, In addition, it is not necessary to drive the negative pressure pump specially for the negative pressure of the fuel tank, which can improve the fuel consumption.

The fuel tank internal pressure adjusting device according to claim 6 , wherein the internal combustion engine is mounted on a vehicle together with an electric motor as a drive source for vehicle travel in the fuel tank internal pressure adjusting device according to any one of claims 1 to 5. It is characterized by that.

  As described above, in a vehicle in which the internal combustion engine and the electric motor are mounted as a vehicle driving source, that is, a so-called hybrid vehicle, especially when only the electric motor travels, that is, the so-called EV travel continues, the chance of purge control is reduced. It becomes difficult to release the pressure of the fuel tank using.

  However, even in such a hybrid vehicle, by applying the present invention, the negative pressure in the fuel tank can be surely reduced every time there is an opportunity, so even if there is no long-term purge control opportunity, the fuel tank internal pressure is excessively increased. There is no state.

For this reason, it is not necessary to stop the EV travel and forcibly shift to the travel by the internal combustion engine and the electric motor, so-called HV travel, and execute the purge control, so that the fuel consumption is improved.
Furthermore, it is not necessary to increase the rigidity of the fuel tank and the seal of the sealing valve for pressure resistance, thereby avoiding an increase in weight and cost.

FIG. 2 is a block diagram showing a drive system in the hybrid vehicle of the first embodiment. (A), (B) The detailed structure of the pump module used in Embodiment 1, and explanatory drawing of the function. 6 is a flowchart of fuel tank internal pressure adjustment execution determination processing according to the first embodiment. The flowchart of a fuel tank internal pressure adjustment process similarly. 4 is a timing chart illustrating an example of control according to the first embodiment. The timing chart which similarly shows an example of control. 9 is a timing chart showing purge system leak diagnosis processing according to the second embodiment. 9 is a flowchart of a fuel tank internal pressure holding process after leak diagnosis according to the second embodiment.

[Embodiment 1]
<Configuration of Embodiment 1> FIG. 1 is a block diagram of a drive system in a hybrid vehicle to which the above-described invention is applied. This drive system includes an internal combustion engine 2 and electric motors (motor generators MG1, MG2 to be described later) as vehicle driving sources. The internal combustion engine 2 is a gasoline engine. The internal combustion engine 2 includes a fuel supply system 4 and a control system 6.

  This hybrid vehicle is a plug-in hybrid vehicle. Therefore, the battery 12 can be charged from the external power source 8 through the charging mechanism 10. When the electric power of the battery 12 is supplied to the motor generator MG2 by the power control unit 14, a rotational driving force is output from the motor generator MG2.

The rotational driving force from the internal combustion engine 2 and the motor generator MG2 is decelerated by the speed reduction mechanism 16 and transmitted to the drive wheels 18.
A power split mechanism 20 is disposed between the internal combustion engine 2 and the speed reduction mechanism 16, and the rotational driving force of the internal combustion engine 2 is transmitted to the speed reduction mechanism 16 side and another motor generator MG1 side as a generator. It is possible to supply it divided into two.

The two motor generators MG1 and MG2 function as a generator and an electric motor, respectively, and the functions between them can be switched as necessary.
A fuel injection valve 24 is disposed in each intake port 22 corresponding to each cylinder of the internal combustion engine 2. The fuel stored in the fuel tank 26 is pumped to these fuel injection valves 24 by the fuel pump module 28 via the fuel path 28b. By fuel injection control, fuel is injected from the fuel injection valve 24 during intake at a predetermined timing, and is sucked into each cylinder and burned. As a result, the internal combustion engine 2 is operated.

  Further, a fuel temperature sensor 28 a is arranged in a form attached to the fuel pump module 28. The fuel temperature sensor 28 a detects the fuel temperature of the fuel supply system 4, particularly the fuel temperature Tf in the fuel tank 26 here.

  The fuel supply system 4 has a fuel supply function to the internal combustion engine 2 and an evaporative fuel processing function, and includes a fuel tank 26, a canister 36, various passages attached thereto, various valves, various pumps, and the like.

  In the fuel tank 26, a fuel sender gauge 30 for detecting the fuel level SGL in the fuel tank 26 by the float 30a is provided. A tank internal pressure sensor 32 (corresponding to tank internal pressure detection means) is provided at the upper part of the fuel tank 26 to detect the pressure in the upper space 26a of the fuel tank 26 (tank internal pressure Ptf). This tank internal pressure Ptf (kPa) is actually a differential pressure between the atmospheric pressure and the upper space 26a. Accordingly, the tank internal pressure Ptf = 0 kPa indicates that the inside of the fuel tank 26 is in the atmospheric pressure state.

  The fuel is introduced into the fuel tank 26 at the time of refueling from the fuel inlet pipe 34. The upper space 26 a of the fuel tank 26 is connected to a canister 36 by an evaporated fuel passage 35. In the middle of the evaporative fuel passage 35, a blocking valve 38 provided with a solenoid valve 38 a and a relief valve 38 b in parallel for blocking the fuel tank 26 is provided.

  The solenoid valve 38a is a solenoid valve that is controlled to open by energization, and the solenoid valve 38a is controlled to be in a valve-open state during refueling. As a result, the upper space 26 a of the fuel tank 26 and the inside of the canister 36 communicate with each other through the evaporated fuel passage 35. For this reason, at the time of refueling, the fuel vapor generated in the upper space 26a of the fuel tank 26 is discharged to the canister 36 side. In the canister 36, the fuel vapor is adsorbed by an adsorbent such as activated carbon housed therein. This prevents the fuel vapor from leaking outside.

  When the electromagnetic valve 38a is closed, that is, when the evaporated fuel passage 35 is blocked and the fuel tank 26 is sealed, the fuel vapor generated in the upper space 26a of the fuel tank 26 is released from the relief valve 38b. Is not discharged to the canister 36 side unless the valve is opened.

  Connected to the canister 36 is an air passage 40 communicating with a fuel inlet box 34 a provided in the fuel inlet pipe 34. The air passage 40 is provided with an air filter 40a on the way. Further, a leak diagnosis pump module 42 is provided in the atmospheric passage 40 at a position closer to the canister 36 than the air filter 40a.

  FIG. 2 shows the configuration of the pump module 42. The pump module 42 includes an atmospheric opening / closing valve 42a, a pressure sensor 42b, a negative pressure pump 42c, a reference orifice 42d, and a check valve 42e. The atmospheric on / off valve 42a is configured as a normally open electromagnetic valve having two passages 43a and 43b. The switching actuator 43c causes the valve closed state (ON) shown in FIG. The valve open state (OFF) shown can be switched.

In the closed state of the atmospheric on-off valve 42a shown in FIG. 2A (switching actuator 43c: ON), the negative pressure pump 42c and the canister 36 are connected by the passage 43a.
In the open state (switching actuator 43c: OFF) of the atmospheric opening / closing valve 42a shown in FIG. 2B, the atmospheric side and the canister 36 are connected via the air filter 40a by the passage 43b.

  The pressure sensor 42b detects the pressure Pc in the canister 36, and the reference orifice 42d is a reference hole (for example, φ0.5 mm) provided for measuring a reference pressure used for leak determination.

  The canister 36 is connected to an intake passage 46 of the internal combustion engine 2 by a purge passage 44. In particular, it is connected at a position downstream of the throttle valve 48 for adjusting the intake air amount. In the middle of the purge passage 44, a purge control valve 50 as a normally closed electromagnetic valve is arranged. The purge is executed by opening the purge control valve 50 and the air opening / closing valve 42a when the internal combustion engine 2 is in operation.

  That is, when the intake negative pressure in the intake passage 46 is introduced into the canister 36 from the purge passage 44 side, the fuel vapor is released from the adsorbent in the canister 36 and the air flow introduced from the atmospheric passage 40 side To be released. The fuel vapor is released from the purge passage 44 through the purge control valve 50 and into the intake air flowing through the intake passage 46 along the airflow. The intake air including the purged fuel vapor flowing into the surge tank 52 is distributed to the intake port 22 of each cylinder, and flows into the combustion chamber of each cylinder together with the fuel injected from the fuel injection valve 24 to be combusted. Become.

  In the intake passage 46, an air flow meter 56 is provided between the air filter 54 and the throttle valve 48 to detect an intake air amount GA (g / sec) supplied to the internal combustion engine 2.

  An air-fuel ratio sensor (or oxygen sensor) 60 is provided in the exhaust passage 58 for discharging exhaust gas after combustion from the internal combustion engine 2, and detects the air-fuel ratio or oxygen concentration from the exhaust component for air-fuel ratio feedback control. .

  In addition, an accelerator opening sensor 62 that is provided on an accelerator pedal operated by the vehicle driver and detects the accelerator opening ACCP, an engine speed sensor 64 that detects the crank speed NE of the internal combustion engine 2, an IGSW (ignition switch) 66) Other sensors and switches are provided to output signals, respectively. Examples of other signals include cooling water temperature, intake air temperature, and vehicle speed.

  Fuel temperature sensor 28a, fuel sender gauge 30, tank internal pressure sensor 32, pressure sensor 42b, throttle opening sensor 48a, air flow meter 56, air-fuel ratio sensor 60, accelerator opening sensor 62, engine speed sensor 64, IGSW 66, and other signals Is input to an ECU (electronic control circuit) 70 that is configured around a microcomputer.

  Then, based on such signal data and data stored or calculated in advance, the ECU 70 executes arithmetic processing to control the fuel injection amount from the fuel injection valve 24, the opening degree TA of the throttle valve 48, and the like. To do.

  Further, the ECU 70 performs purge control during the period when the internal combustion engine 2 is operating. In this purge control process, the fuel valve adsorbed from the fuel tank 26 side through the evaporated fuel passage 35 to the canister 36 side by opening the electromagnetic valve 38a with the refueling is taken into the intake passage during the operation of the internal combustion engine. 46 is a process to be released.

In this purge control process, the purge rate is adjusted by duty-controlling the opening of the purge control valve 50, and the fuel vapor adsorbed by the canister 36 is discharged to the intake passage 46 via the purge passage 44. Note that the concentration of the fuel vapor purged at this time (purge fuel concentration) is obtained as a learning value by a calculation performed periodically based on the control deviation amount of the air-fuel ratio in the air-fuel ratio feedback control executed by the ECU 70. ing.
<Operation of Embodiment 1> The operation of this embodiment will be described with reference to FIGS. FIG. 3 is a flowchart of the fuel tank internal pressure adjustment execution determination process executed by the ECU, and FIG. 4 is a flowchart of the fuel tank internal pressure adjustment process. These processes are repeatedly executed in a short period (for example, 50 ms period). The steps in the flowchart corresponding to the individual processing contents are represented by “S˜”.

The fuel tank internal pressure adjustment execution determination process in FIG. 3 will be described. When this process is started, it is first determined whether or not the internal combustion engine 2 is stopped (S102).
For example, in a state where the IGSW 66 is actually turned off and the vehicle is parked, or in an EV traveling state where the internal combustion engine 2 is stopped and the vehicle is traveling only by the motor generator MG2, it is determined that the internal combustion engine 2 is stopped.

If the internal combustion engine 2 is in operation (NO in S102), the process is exited as it is.
If the internal combustion engine 2 is stopped (YES in S102), whether or not the negative pressure process (S122 to S138) of the fuel tank internal pressure adjustment process (FIG. 4) described later is not executed while the internal combustion engine is stopped this time. Is determined (S104).

If the negative pressure process is currently being executed, or if the negative pressure process has already been completed while the internal combustion engine is stopped (NO in S104), the present process is exited.
If the negative pressure process has not been executed (YES in S104), it is determined whether or not there is a valve opening request other than this process for the block valve 38 (S106). For example, when a request for opening the blocking valve 38 is made at the time of refueling or the like (NO in S106), the present process is exited as it is.

If there is no request for opening the seal valve 38 other than this processing (YES in S106), it is next determined whether or not the tank internal pressure Ptf is near atmospheric pressure (S108).
Here, the vicinity of the atmospheric pressure is a pressure region having a certain pressure width on the high-pressure side and the low-pressure side around the atmospheric pressure. That is, on the high pressure side from this pressure region, when the blocking valve 38 is opened, a high pressure is applied to the canister 36 side through the evaporated fuel passage 35, or the fuel vapor cannot be sufficiently adsorbed by the canister 36. . Further, on the low pressure side from this pressure region, a sufficient negative pressure state is realized without performing the negative pressure processing described later.

If it is not near atmospheric pressure (NO in S108), the present process is exited as it is.
If it is near atmospheric pressure (YES in S108), execution of fuel tank internal pressure adjustment is permitted (S110).

The fuel tank internal pressure adjustment process of FIG. 4 will be described. When this process is started, it is first determined whether or not the execution of the fuel tank internal pressure adjustment is permitted (S120).
If the fuel tank internal pressure adjustment execution permission (S110) has not been made (S110: NO) by the fuel tank internal pressure adjustment execution determination process (FIG. 3) while the internal combustion engine is stopped this time, the present process is left as it is.

  If the fuel tank internal pressure adjustment execution permission is granted (YES in S120), it is next determined whether or not the tank internal pressure Ptf is higher than the target negative pressure (<0 kPa) in the negative pressure process (S122).

  When the negative pressure process is started and the tank internal pressure Ptf> the target negative pressure (YES in S122), the atmospheric on-off valve 42a is closed (S124) and the block valve 38 is opened (S126). ). Note that either the closing of the air opening / closing valve 42a or the opening of the blocking valve 38 may be performed first or simultaneously.

  Next, the negative pressure pump 42c is driven (S128). As a result, as shown by the arrow in FIG. 2A, the gas in the upper space 26a of the fuel tank 26 is discharged to the atmosphere passage 40 side via the evaporated fuel passage 35, the blocking valve 38, and the canister 36. . During this discharge, the fuel vapor in the gas is adsorbed by the adsorbent by the canister 36.

  Thereafter, as long as the tank internal pressure Ptf> the target negative pressure (YES in S122), the atmosphere open / close valve 42a is closed and the block valve 38 is opened, and the negative pressure pump 42c is used to make the internal pressure of the fuel tank 26 negative. Processing (S124 to S128) continues.

  Accordingly, when the tank internal pressure Ptf ≦ the target negative pressure (NO in S122), the blocking valve 38 is closed (S130). Next, it is determined whether or not the closing of the blocking valve 38 is completed (S132). This is because when the opening / closing valve 42a is opened before the closing valve 38 is completely closed, air is sucked from the atmosphere side through the atmosphere passage 40, and the tank internal pressure Ptf becomes higher than the target negative pressure. This is to prevent this. Here, the completion of closing of the blocking valve 38 is waited by waiting for a predetermined time.

Therefore, before the standby time elapses (NO in S132), the present process is exited as it is.
When the standby time has elapsed (YES in S132), the atmospheric on-off valve 42a is opened (S134), and the negative pressure pump 42c is stopped (S136). Then, the execution of the fuel tank internal pressure adjustment is prohibited (S138), and this processing is exited.

By closing the closing valve 38 in this way, the inside of the fuel tank 26 is sealed in a target negative pressure state.
FIG. 5 shows an example of the control of the present embodiment. Before the timing t0, the internal combustion engine 2 is stopped, and thus the purge control is also stopped (OFF). As the fuel temperature decreases, the tank internal pressure Ptf decreases to a pressure close to atmospheric pressure at timing t0.

  As a result, if all the conditions of steps S102 to S108 of the fuel tank internal pressure adjustment execution determination process (FIG. 3) are satisfied, the execution of the fuel tank internal pressure adjustment is permitted (S110).

  As a result, in the fuel tank internal pressure adjustment process (FIG. 4), YES is determined in step S120, and YES is determined in step S122, thereby closing the atmospheric on-off valve 42a (S124) and opening the closing valve 38 ( Thereafter, the driving of the negative pressure pump 42c is started at timing t1 (S128).

Accordingly, the tank internal pressure Ptf decreases from the timing t1 toward the target negative pressure.
When the tank internal pressure Ptf ≦ target negative pressure is satisfied at timing t2 (NO in S122), the blocking valve 38 is closed to reliably maintain the negative pressure state in the fuel tank 26 (S130). After waiting until the valve is completely closed (YES in S132), the atmospheric on-off valve 42a is opened at timing t3 (S134). Thereafter, the negative pressure pump 42c is stopped at timing t4 (S136). Thereafter, during the current stop of the internal combustion engine, execution of fuel tank internal pressure adjustment is prohibited (S138).

  As a result, at the timing t0, the tank internal pressure Ptf that has been in the vicinity of the atmospheric pressure is reliably held in a state in which the pressure is sufficiently lower than the atmospheric pressure after the fuel tank internal pressure adjustment process (FIG. 4).

FIG. 6 shows a transition state of the tank internal pressure Ptf and the fuel temperature Tf in a state where the vehicle is parked and left after the internal combustion engine 2 is stopped (ta˜).
In the present embodiment, the tank internal pressure Ptf fluctuates during parking as indicated by the solid line with a change in the fuel temperature Tf. However, when the tank internal pressure Ptf becomes close to atmospheric pressure during parking (tb), the negative pressure process as shown in FIG. 5 is executed. Thereafter, the tank internal pressure Ptf fluctuates up and down to the same extent while sandwiching the atmospheric pressure (0 kPa) during parking.

If the negative pressure process is not executed as in the prior art, the fluctuation range on the high pressure side is larger than the atmospheric pressure as indicated by the broken line (1).
Further, when the vehicle is parked while the tank internal pressure Ptf is kept in a high pressure state without performing the negative pressure processing during EV traveling, the pressure may be further increased as indicated by a broken line (2).

In the present embodiment, since the negative pressure process can be performed even during EV traveling, the tank internal pressure Ptf is as shown by a solid line and does not greatly deviate from the atmospheric pressure as a whole. Therefore, in the present embodiment, there is no need to increase the rigidity of the fuel tank 26 and the sealing valve 38, and weight and cost can be avoided.
<Relationship between Embodiment 1 and Claims> In the configuration described above, the ECU 70 corresponds to a fuel tank negative pressure generating means and a fuel tank negative pressure holding means. The fuel tank internal pressure adjustment execution determination process (FIG. 3) and steps S120 to S128 of the fuel tank internal pressure adjustment process (FIG. 4) executed by the ECU 70 correspond to the process as the fuel tank negative pressure adjusting means, and the fuel tank internal pressure adjustment process. Steps S130 to S136 in FIG. 4 correspond to processing as a fuel tank negative pressure holding means.
<Effect of Embodiment 1>
(1) While the internal combustion engine in which the purge control valve 50 is in the closed state is stopped, the block valve 38 is opened and the atmospheric on-off valve 42a is closed. To perform negative pressure processing.

  At the time of the negative pressure, since the sealing valve 38 between the canister 36 and the fuel tank 26 is in an open state, the negative pressure pump 42c disposed on the side opposite to the fuel tank 26 with respect to the sealing valve 38 is used. In addition, the pressure in the fuel tank 26 can be reduced. Therefore, the negative pressure is also applied to the canister 36 during the negative pressure.

  After this negative pressure processing, before the opening of the atmospheric on-off valve 42a and the stop of the negative pressure pump 42c are executed, the blocking valve 38 is closed to hold the tank internal pressure Ptf. From this, the tank internal pressure Ptf is reliably maintained in the negative pressure state.

  Then, the canister 36 is not closed because the atmospheric on-off valve 42a is opened thereafter, so that the canister 36 is returned to the atmospheric pressure by the atmospheric air introduced from the atmospheric passage 40 after the completion of the negative pressure process.

  Therefore, in the evaporative fuel processing system in which the sealing valve 38 is provided in the evaporative fuel passage 35 connecting the canister 36 and the fuel tank 26, the inside of the fuel tank 26 can be negative while the internal combustion engine 2 is stopped, and the canister 36 is It is possible to reliably maintain the negative pressure state of the fuel tank 26 without maintaining the pressure state.

  Since the canister 36 is not left for a long time in a negative pressure state, the detachment of the fuel vapor adsorbed by the adsorbent in the canister 36 is not promoted. Therefore, the rich fuel vapor is not filled in the purge passage 44 during parking, and there is no problem in purge control or emission of the internal combustion engine 2.

(2) The negative pressure process for the fuel tank 26 is not executed when the tank internal pressure Ptf does not exist in the pressure region near the atmospheric pressure.
Therefore, when the tank internal pressure Ptf is higher than the pressure region near the atmospheric pressure, the blocking valve 38 is not opened, so that the high pressure gas does not blow out from the fuel tank 26 toward the canister 36 and the canister 36 or the like has a high pressure. It is possible to prevent a situation where the canister 36 cannot be sufficiently adsorbed by the canister 36.

  Even when the tank internal pressure Ptf is lower than the pressure region near atmospheric pressure, the blocking valve 38 is not opened and the negative pressure pump 42c is not driven. For this reason, useless energy is not consumed for unnecessary negative pressure processing, and fuel consumption can be improved.

  (3) The vehicle used in the present embodiment is a hybrid vehicle, particularly a plug-in hybrid vehicle. In such a hybrid vehicle, when the traveling of only the motor generator MG2 that is an electric motor, that is, the so-called EV traveling is continued, the chance of the purge control is reduced and it is difficult to release the pressure of the fuel tank 26 during the purge control.

  However, even in such a hybrid vehicle, by applying the present invention, the negative pressure in the fuel tank 26 can be reliably reduced every time there is an opportunity. Therefore, the tank internal pressure Ptf is excessively increased even if there is no opportunity for purge control over a long period of time. There is no high pressure.

  For this reason, it is not necessary to stop the EV travel and forcibly shift to the travel by the internal combustion engine 2 and the motor generator MG2, that is, so-called HV travel, and execute the purge control, thereby improving the fuel efficiency.

Further, because of the pressure resistance, there is no need to improve the rigidity of the fuel tank 26 and the sealing performance of the blocking valve 38, and the weight and cost of the fuel tank 26 and the blocking valve 38 can be avoided.
[Embodiment 2]
<Configuration of Embodiment 2> In this embodiment, the closing valve 38 is closed by utilizing the negative pressure processing in the fuel tank 26 performed in accordance with the purge system leak diagnosis processing as shown in FIG. Thus, the tank internal pressure Ptf is reliably held in the negative pressure state.

For this process, the fuel tank internal pressure holding process after the leak diagnosis shown in FIG. 8 is executed instead of those shown in FIGS. Other than this, the configuration is the same as the configuration of the first embodiment. Therefore, description will be made with reference to FIG.
<Operation of Second Embodiment> The operation of this embodiment will be described with reference to FIGS.

  The purge system leak diagnosis process shown in FIG. 7 is executed in a state where a predetermined time, for example, several hours have elapsed after the ready-off (t20). First, it is determined whether or not the tank internal pressure Ptf is in the vicinity region including the atmospheric pressure (the region between the alternate long and short dash line: different from the vicinity of the atmospheric pressure in FIG. 3) (t21). When the tank internal pressure Ptf is in the vicinity of the atmospheric pressure as shown by the solid line, the diameter is adjusted as a calibration by the negative pressure pump 42c while the atmospheric on-off valve 42a is kept open as shown in FIG. The atmosphere is sucked through the 0.5 mm reference orifice 42d (t22 to t23). In this suction state, the pressure sensor 42b detects the pressure Pc between the negative pressure pump 42c and the reference orifice 42d. As a result, the same pressure Pc as when a 0.5 mm leak hole is present on the side of the canister 36 to be sucked from now on is stored as the φ0.5 hole determination pressure.

  Next, as shown in FIG. 2A, the atmospheric on-off valve 42a is closed and gas is discharged from the canister 36 to the atmospheric side by the negative pressure pump 42c without passing through the reference orifice 42d (t23 to t24). . As a result, the pressure Pc on the canister 36 side decreases as shown by the solid line. At this time, if the decrease in the pressure Pc is slow as indicated by a broken line, it can be determined that the canister 36 has a leak abnormality. If the tank internal pressure Ptf also decreases, it can be determined that there is an open sticking of the blocking valve 38.

  The negative pressure pump 42c is stopped with the pressure Pc sufficiently lowered (t24). Thereafter, the blocking valve 38 is temporarily opened (t24 to t25). Accordingly, it is determined whether or not the closed valve 38 is closed from the change in the pressure Pc. The broken line indicates the pressure Pc in the case of closed adhesion.

Next, the purge control valve 50 is temporarily opened (t26 to t27), and the pressure Pc of the canister 36 is set to atmospheric pressure.
Next, the blockade valve 38 is opened, and the negative pressure pump 42c is driven to diagnose the leakage of the fuel tank 26 from the change in the pressure Pc (t28 to t29). If there is a leak abnormality in the fuel tank 26, the pressure Pc decreases slowly as shown by the broken line.

  The fuel tank internal pressure holding process after the leak diagnosis shown in FIG. 8 is executed at the end of the leak diagnosis for the fuel tank 26 (from t29), so that the tank internal pressure Ptf of the fuel tank 26 can be held after the leak diagnosis.

  The fuel tank internal pressure holding process after leak diagnosis (FIG. 8) will be described. This process is a process executed in a short cycle. When this process is started, it is first determined whether or not the leak diagnosis of the fuel tank 26 has been completed (S202).

If the timing t29 has not been reached (NO in S202), this processing is exited as it is.
When the leak diagnosis of the fuel tank 26 is completed and the timing t29 is reached (YES in S202), steps S204 to S210 are executed. These processes are the same as steps S130 to S136 shown in FIG.

  That is, first, the closing valve 38 is closed (S204). Next, it is determined whether or not the closing of the blocking valve 38 is completed (S206). Before the standby time elapses (NO in S206), the present process is exited.

  When the standby time has elapsed (YES in S206), it is determined that the blocking valve 38 is surely closed, so the atmospheric on-off valve 42a is opened (S208) and the negative pressure pump 42c is stopped (S210). . Then, this processing is exited (t30).

By closing the closing valve 38 in this manner, the fuel tank 26 is sealed in a state where the negative pressure is maintained at the time of leak diagnosis after the timing t29.
At time t21, when the tank internal pressure Ptf is not in the vicinity of the atmospheric pressure, the fuel tank 26 can be determined to be normal, so that the fuel tank 26 is not subjected to negative pressure processing. Therefore, in this case, the negative pressure processing in the fuel tank 26 using the leak diagnosis is not performed.
<Relationship between Embodiment 2 and Claims> In the configuration described above, the ECU 70 corresponds to a fuel tank negative pressure generating means and a fuel tank negative pressure holding means. The negative pressure processing in the fuel tank 26 in the leak diagnosis processing executed by the ECU 70 corresponds to the processing as the fuel tank negative pressure means, and the fuel tank internal pressure holding processing (FIG. 8) after the leak diagnosis is the fuel tank negative pressure holding means. It corresponds to the processing as.
<Effect of Embodiment 2> In this embodiment, since the leak diagnosis processing for reducing the pressure in the fuel tank 26 is executed, the negative pressure processing in the fuel tank 26 at the time of this leak diagnosis processing is used. Thus, the negative pressure state in the fuel tank 26 is reliably maintained after the leak diagnosis process.

Thus, in addition to the effect of the first embodiment, it is not necessary to drive the negative pressure pump 42c specially for the negative pressure processing in the fuel tank 26, leading to an improvement in fuel consumption.
[Other embodiments]
In each of the above embodiments, while the same internal combustion engine is stopped, the negative pressure processing of the fuel tank 26 by the fuel tank internal pressure adjustment processing is performed only once, but may be performed a plurality of times. For example, when the internal combustion engine has been stopped for a long time after the negative pressure process, the negative pressure process may be repeated.

  -Negative pressure processing using the original negative pressure processing and leak diagnosis by combining the negative pressure processing uniquely executed by the first embodiment and the negative pressure processing using the leak diagnosis according to the second embodiment. You may perform both a pressure-ized process.

  In each of the above embodiments, the applied vehicle is a plug-in hybrid vehicle. In addition to this, a hybrid vehicle that is not a plug-in may be used, and further, a vehicle in which only the internal combustion engine 2 is mounted and the fuel tank 26 is provided with a blocking valve 38 can be applied.

  DESCRIPTION OF SYMBOLS 2 ... Internal combustion engine, 4 ... Fuel supply system, 6 ... Control system, 8 ... External power supply, 10 ... Charging mechanism, 12 ... Battery, 14 ... Electric power control unit, 16 ... Deceleration mechanism, 18 ... Drive wheel, 20 ... Power split Mechanism: 22 ... intake port, 24 ... fuel injection valve, 26 ... fuel tank, 26a ... upper space, 28 ... fuel pump module, 28a ... fuel temperature sensor, 28b ... fuel path, 30 ... fuel sender gauge, 30a ... float, 32 ... Tank internal pressure sensor, 34 ... Fuel inlet pipe, 34a ... Fuel inlet box, 35 ... Evaporative fuel passage, 36 ... Canister, 38 ... Sealing valve, 38a ... Solenoid valve, 38b ... Relief valve, 40 ... Atmospheric passage, 40a ... Air filter, 42 ... pump module, 42a ... atmospheric on-off valve, 42b ... pressure sensor, 42c ... negative pressure pump, 42d Reference orifice, 42e ... check valve, 43a, 43b ... passage, 43c ... switching actuator, 44 ... purge passage, 46 ... intake passage, 48 ... throttle valve, 48a ... throttle opening sensor, 50 ... purge control valve, 52 ... Surge tank, 54 ... Air filter, 56 ... Air flow meter, 58 ... Exhaust passage, 60 ... Air-fuel ratio sensor, 62 ... Accelerator opening sensor, 64 ... Engine speed sensor, 66 ... Ignition switch, 70 ... ECU, MG1, MG2 ... motor generator.

Claims (6)

Fuel tank of internal combustion engine, canister, evaporative fuel passage connecting canister and fuel tank, block valve provided in evaporative fuel passage, purge passage connecting canister and intake passage of internal combustion engine, provided in purge passage A fuel tank internal pressure adjusting device in an evaporative fuel processing system comprising a purge control valve, an atmospheric passage connecting the canister and the atmospheric side, and an atmospheric opening / closing valve provided in the atmospheric passage,
A negative pressure pump connected to the evaporative fuel processing system on the opposite side of the fuel tank with respect to the blocking valve and depressurizing the evaporative fuel processing system;
While the internal combustion engine is stopped when the purge control valve is closed, the blocking valve is opened and the atmospheric on-off valve is closed, and the negative pressure pump is driven to reduce the pressure inside the fuel tank. A fuel tank negative pressure means for performing processing;
A fuel tank that holds the internal pressure of the fuel tank by closing the block valve before opening the atmospheric on-off valve and stopping the negative pressure pump after the negative pressure processing by the fuel tank negative pressure means Negative pressure holding means;
A fuel tank internal pressure adjusting device comprising: The fuel tank internal pressure adjusting device according to claim 1 , further comprising tank internal pressure detecting means for detecting a tank internal pressure in the fuel tank,
The fuel tank negative pressure unit does not execute the negative pressure process when the tank internal pressure detected by the tank internal pressure detection unit does not exist in a pressure region near atmospheric pressure. Internal pressure adjustment device. 3. The fuel tank internal pressure adjusting device according to claim 1 , wherein the negative pressure pump is provided in the atmospheric passage, and the negative pressure process is a process of discharging the gas in the fuel tank through the canister. A fuel tank internal pressure adjusting device characterized by the above. 4. The fuel vapor processing apparatus according to claim 3 , wherein the fuel tank negative pressure means executes the negative pressure process as part of a leak diagnosis process for the fuel tank, and the fuel tank negative pressure holding means includes: A fuel tank internal pressure adjusting device that holds the fuel tank internal pressure by closing the block valve before opening the atmospheric on-off valve and stopping the negative pressure pump after the leak diagnosis processing. 5. The fuel tank internal pressure adjusting device according to claim 4 , wherein the leak diagnosis processing is performed in the evaporative fuel processing system when a negative pressure is introduced into the evaporative fuel processing system by the negative pressure pump while the internal combustion engine is stopped. A fuel tank internal pressure adjusting device, characterized in that it is a process for detecting a leak in the evaporated fuel processing system based on a change in pressure. In the fuel tank internal pressure control apparatus according to any one of claims 1 to 5, wherein the internal combustion engine fuel tank internal pressure control, characterized in that those installed on the vehicle with the electric motor as the vehicle traveling drive source apparatus.