JP2009085036A - Evaporated fuel processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaporated fuel treatment device purging a canister as required even if driving time of an engine is short. <P>SOLUTION: An ECU (electronic control unit) 60 estimates an absorption state such as a purge concentration in the canister 14 during EV travelling (travelling with driving force only by a motor) and changes a criterion of a travelling load when switching from the EV travelling to HV travelling (travelling with driving force by an engine), based on the absorption state. Even in the case of a vehicle having a short engine driving time, such as a plug-in hybrid vehicle, purging of the canister 14 is surely conducted by driving the engine 16 by the HV travelling as required. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel vapor processing apparatus.

  As a vehicle (hybrid car) of a type that travels using a driving force from an electric motor (motor) in addition to an internal combustion engine (engine), Patent Document 1 reads the amount of charge of the battery after the engine starts driving and completes charging. It is described that the engine is continuously driven after reaching the equivalent value, and the purge process of the evaporated fuel is performed while the power generation is continued.

  By the way, in such a hybrid car, the canister is purged with a negative pressure generated by driving the engine and the evaporated fuel is sent to the engine. Therefore, the purge is sufficiently performed when the engine driving time is short. I will not. In particular, in the case of a so-called plug-in hybrid type automobile that can be charged from a household outlet or the like, a sufficient amount of charge is secured in the battery in many cases, so that the engine drive time is shortened. For example, traveling may be terminated without driving the engine.

Therefore, an evaporative fuel processing apparatus that can purge the canister as needed even when the engine drive time is short is desired.
Japanese Patent Laid-Open No. 10-2240

  In view of the above facts, an object of the present invention is to obtain an evaporative fuel processing apparatus capable of purging a canister as needed even when the engine drive time is short.

  According to the first aspect of the present invention, a canister for adsorbing the evaporated fuel generated in the fuel tank, and an internal combustion engine that is driven by the combustion of the fuel and that can purge the canister by applying a negative pressure generated by the drive to the canister. And switching from a first driving state in which only the electric motor is driven to a second driving state in which at least the internal combustion engine is driven, in accordance with a traveling load of the vehicle. Drive control means to perform, wherein the drive control means changes the judgment criterion for switching according to the state of the vehicle.

  In this fuel vapor processing apparatus, the drive control means, depending on the state of the vehicle, from the first driving state in which only the electric motor is driven to at least the second driving state in which the internal combustion engine is driven (this includes driving only the internal combustion engine). In addition to the above state, a state in which both the electric motor and the internal combustion engine are driven is also included). When the internal combustion engine is driven, the generated negative pressure can be applied to the canister to perform purging (desorption of adsorbed evaporated fuel).

  Here, the drive control means changes a determination criterion for switching from the first drive state to the second drive state according to the traveling state of the vehicle. For example, if the running resistance increases due to sudden acceleration, hills, etc. during running in the first driving state, control is performed to switch to the second driving state when this running resistance exceeds a predetermined value. Is lower than before. As a result, the internal combustion engine is driven earlier as compared with the engine not having the configuration of the present invention, so that the canister purge is also started earlier. In this way, by changing the determination criterion for switching from the first drive state to the second drive state, the canister can be purged as necessary.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the drive control means uses the suction state of the canister as the state of the vehicle.

  By using the adsorption state of the canister as the vehicle state, it is possible to appropriately change the determination criterion for switching from the first drive state to the second drive state, and it is possible to purge the canister more appropriately.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, an adsorption state measuring unit that measures the adsorption state of the canister is provided, and the drive control unit is measured by the adsorption state measuring unit. The purge start time is changed based on the adsorption state.

  In this way, the drive control unit can appropriately purge the canister by changing the purge start timing based on the adsorption state of the canister measured by the adsorption state measurement unit. For example, when the amount of evaporated fuel adsorbed by the canister is large, it is possible to perform control such as performing an appropriate purge by driving the internal combustion engine at an early stage.

  According to a fourth aspect of the present invention, in the second or third aspect of the invention, the drive control means can predict a purgeable amount by driving the internal combustion engine, and the predicted purgeable amount The purge start timing is changed based on the adsorption state of the canister measured by the adsorption state measuring means.

  That is, when the amount of fuel vapor adsorbed to the canister exceeds the predicted amount of purge by driving the internal combustion engine, the purge start timing (drive start timing of the internal combustion engine) is advanced and not exceeded. In this case, the purge start time can be delayed. Thereby, it is possible to reduce the excess or deficiency of the driving time of the internal combustion engine used for the purge.

  According to a fifth aspect of the present invention, in the invention according to any one of the second to fourth aspects, the adsorption state measuring means is capable of detecting the temperature of the outside air of the vehicle, and a fuel tank. An internal pressure sensor capable of detecting the internal pressure of the vehicle, wherein the drive control means detects the purge concentration learning value in the canister in the previous travel of the vehicle, the external air temperature detected by the external air temperature sensor, and the internal pressure sensor. The adsorption state of the canister can be calculated from the amount of evaporated fuel estimated from the internal pressure of the fuel tank detected in step (b).

  That is, the drive control means learns and stores the purge concentration in the canister from the drive time of the internal combustion engine in the previous travel of the vehicle. Further, the drive control means estimates the amount of evaporated fuel generated after the previous stoppage of the vehicle from the outside air temperature detected by the outside air temperature sensor and the tank internal pressure detected by the inside pressure sensor. From these, the drive control means calculates the adsorption state of the canister. This eliminates the need for a special device or structure for measuring the purge concentration.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, when the drive control means shifts the internal combustion engine from a cold state to a warm-up operation. Is characterized in that the warm-up operation is continued until the internal combustion engine reaches a predetermined temperature set in advance.

  Thereby, the influence (adverse effect on the internal combustion engine) due to the internal combustion engine being stopped during the warm-up can be eliminated.

  According to a seventh aspect of the present invention, in the first aspect of the present invention, the generator is capable of generating electricity by driving the internal combustion engine, and is charged with the electric power generated by the generator. And a storage battery capable of supplying this electric power to the electric motor, wherein the drive control means predicts the amount of power generated by the generator due to a warm-up operation of the internal combustion engine and can be charged by the storage battery. The warm-up operation is permitted when the amount exceeds the predicted power generation amount.

  Therefore, the storage battery can be charged with the electric power generated by the generator by driving the internal combustion engine, and the electric power of the storage battery can be supplied to the electric motor to drive the electric motor.

  Further, the drive control means permits the warm-up operation when the chargeable amount in the storage battery exceeds the power generation amount prediction in the generator due to the warm-up operation of the internal combustion engine. For this reason, since the warm-up of the internal combustion engine is completed before the storage battery is fully charged, the warm-up operation of the internal combustion engine is not excessively continued even after the charge of the storage battery is completed. In addition, the internal combustion engine can be warmed up.

  According to an eighth aspect of the present invention, in the invention according to the sixth or seventh aspect, the drive control means is in a state where the warm-up operation of the internal combustion engine is completed and the canister purge is completed. And when the charge remaining amount of the said storage battery is more than the electric energy required for vehicle driving | running | working, a vehicle is made to drive only with the driving force of the said electric motor.

  That is, since the internal combustion engine has been warmed up and the canister purge has been completed, there is no need to drive the internal combustion engine any further. Therefore, if the remaining charge (remaining voltage) of the storage battery is greater than or equal to the amount required for vehicle travel, fuel efficiency can be improved by running the vehicle only with the driving force of the electric motor.

  Since the present invention is configured as described above, purging can be performed as necessary even when the engine drive time is short.

  FIG. 1 shows an evaporated fuel processing apparatus 10 according to an embodiment of the present invention. FIG. 2 shows the configuration of the control system of the evaporated fuel processing apparatus 10. As can be seen from FIG. 2, the vehicle on which the fuel vapor processing apparatus 10 is mounted is a hybrid vehicle having a hybrid motor 76 in addition to the engine 16. Further, the connector 68 is inserted into, for example, a household outlet. It is a so-called plug-in hybrid vehicle that can be supplied with electric power. In this vehicle, the state where only the hybrid motor 76 is driven is the first drive state according to the present invention, and the state where only the engine 16 or both the engine 16 and the hybrid motor 76 is driven is the second drive state according to the present invention. Drive state. Hereinafter, traveling of the vehicle using only the driving force of the hybrid motor 76 is appropriately abbreviated as EV traveling, and traveling of the vehicle using both the engine 16 and the driving force is abbreviated as HV traveling.

  As shown in FIG. 1, the evaporative fuel processing apparatus 10 temporarily adsorbs the evaporated fuel in the fuel tank 12 with a canister 14, then purges the adsorbed evaporated fuel to the intake passage 18 of the engine 16. send.

  An oil supply pipe 20 and a ventilation pipe 22 are connected to the fuel tank 12. An oil supply port 20 </ b> H is set at the upper end of the oil supply pipe 20, and fuel is supplied from the oil supply pipe 20 to the fuel tank 12. Further, during refueling, air (gas) in the fuel tank 12 escapes from the vent pipe 22 to the vicinity of the refueling port 20H.

  In the fuel tank 12, a remaining amount detection unit 26 that detects the remaining amount of fuel at the position of the float 24 that floats on the fuel, and a fuel pump 28 that sends the fuel to the engine 16 are provided.

  A fuel supply pipe 30 is connected to the fuel tank 12 and the fuel in the fuel tank 12 is sent out. The delivered fuel is atomized by an injector 32 that injects fuel, and is injected into the fuel chamber of the engine 16.

  The fuel tank 12 and the canister 14 are connected by a breather pipe 34. A vent valve 36 is provided outside the fuel tank 12 at a connection portion between the breather pipe 34 and the fuel tank 12, and a cut-off valve 38 and a rollover valve 40 are provided inside the fuel tank 12.

  The vent valve 36 opens when the internal pressure of the fuel tank 12 becomes higher than that of the breather pipe 34, and allows air including fuel vapor in the fuel tank 12 to flow to the canister 14 through the breather pipe 34.

Further, the rollover valve 40 is closed due to a rise in the liquid level during refueling, and disconnects the connection between the vent valve 36 and the fuel tank 12. The rollover valve 40 has a function of closing a connection portion between the vent valve 36 and the fuel tank 12 when the vehicle falls or the like and preventing a large amount of fuel from leaking to the outside through the breather pipe 34. ing. The cut-off valve 38 is arranged in parallel with the rollover valve 40 and shuts off the communication between the vent valve 36 and the fuel tank 12 when the liquid level rises further than the rollover valve 40. The cut-off valve 38 is opened even after the rollover valve 40 is closed when the liquid level rises during refueling, and the fuel tank 12 and the vent valve 36 are communicated with each other. When the liquid level has reached, or when the vehicle falls, etc., the valve is closed to prevent the fuel from entering the breather pipe 34 through the vent valve 36. The canister 14 also includes the breather pipe 34 described above. In addition, an atmospheric pipe 42 communicating with the atmosphere, a purge pipe 44 for purging the fuel vapor adsorbed on the canister 14, and a concentration sensor 46 are provided at a connection portion of the atmospheric pipe 42. The concentration sensor 46 detects the concentration of HC (hydrocarbon) in order to detect the amount of fuel vapor adsorbed on the canister 14.

  The atmospheric pipe 42 is provided with a CCV (Canister Closure Valve) 48 and an air filter 50, and the atmospheric air is taken into the canister 14 by opening and closing the CCV 48.

  The purge pipe 44 is provided with a purge pump 52 for forcibly purging the fuel vapor adsorbed on the canister 14 into the intake passage 18 of the engine 16, and a purge control valve is provided between the purge pipe 44 and the intake passage 18. 54 is provided.

  Next, the configuration of the control system of the evaporated fuel processing apparatus according to this embodiment will be described.

  In the present embodiment, the processing of the fuel vapor adhering to the canister 14 and the driving of the engine 16 and the hybrid motor 76 are controlled by an ECU (Electronic Control Unit) 60 as drive control means according to the present invention. In particular, in the present embodiment, as described above, since the hybrid motor 76 is provided as a vehicle driving source other than the engine 16, the ECU 60 controls the engine 16 and the hybrid motor 76 in accordance with the traveling state and the like. The driving force of the engine 16 is transmitted to the power distribution mechanism 62. Further, the power and the driving force from the hybrid motor 76 are transmitted to the wheels 64 via the speed reducer 63.

  In the present embodiment, the driving force of the engine 16 is not only transmitted to the wheels 64 but also transmitted to the generator 67 via the power distribution mechanism 62. The electric power generated by the engine driving force can be stored in the battery 66 via the inverter 69. The state of charge (SOC) of the battery 66 is sent to the ECU 60.

  The ECU 60 is connected to an outside air temperature sensor 70 that detects the temperature of the outside air of the vehicle. Further, an internal pressure sensor 72 for detecting the internal pressure of the fuel tank 12 and a water temperature sensor 74 for detecting the water temperature of the engine 16 are respectively in contact with the ECU 60. Further, a battery 66 is connected to the ECU 60, and data on the remaining charge of the battery 66 is sent.

  The ECU 60 controls the engine 16, the canister 14, the hybrid motor 76, and the like based on data obtained from these various sensors.

  Here, the purge control of the canister 14 performed by the ECU 60 of the evaporated fuel processing apparatus 10 of the present embodiment configured as described above will be described in detail. FIG. 3 is a flowchart showing an example of the flow of the fuel purge process performed by the ECU 60 of the evaporated fuel processing apparatus 10 of the present embodiment. In this fuel purge process, the adsorption state of the evaporated fuel in the canister 14 is measured (estimated) in advance, and when the engine 16 is warmed up, the canister 14 can be purged immediately after the warmup starts. It is.

  That is, while the vehicle is stopped, in step S102, the amount of evaporated fuel generated in the fuel tank 12 is estimated from the outside air temperature detected by the outside air temperature sensor 70 and the tank internal pressure detected by the inside pressure sensor 72. .

  In step S104, the purge concentration (the amount of evaporated fuel adsorbed in the canister 14) when the engine 16 is started next time is estimated. That is, the ECU 60 stores the purge concentration at the previous travel as a learned value. The purge concentration at the next start-up of the engine 16 can be estimated from the learned vapor concentration value and the changes in the outside air temperature and the tank internal pressure that have already been obtained in step S102. The adsorption state of the evaporated fuel in the canister 14 can be known without using a special device or system for detecting the purge concentration.

  After the travel (EV travel) is started in step S106, in step S108, the amount of evaporated fuel generated is estimated from the outside air temperature and the tank internal pressure during travel. In step S110, the running purge concentration is estimated. That is, the purge concentration at the next start during traveling can be estimated from the estimated purge concentration value at the start obtained at step S104 and the outside air temperature and tank internal pressure during traveling obtained at step S108.

  In step S112, the time required to warm up the engine 16 is estimated from the water temperature value. In step S114, the amount that can be purged during warm-up is estimated from this time. During warm-up, the hybrid motor 76 can be used as a generator to generate power, so the power generation amount is estimated at the same time. Furthermore, in step S116, the SOC of the battery 66 is confirmed, and its value is obtained.

  In step S118, a switching point from EV traveling to HV traveling is calculated based on the purge amount (purge concentration) obtained by the above processing, that is, the evaporated fuel adsorption state of the canister 14. For example, when the purge concentration is high, the switching point is set low. This switching point is a threshold value for switching from EV traveling to HV traveling. Further, when the amount of fuel that can be purged during warm-up predicted in step S114 (the amount of evaporated fuel desorbed) is smaller than the amount of evaporated fuel actually adsorbed on the canister 14, the engine 16 is warmed up. The threshold value is set low so that the evaporated fuel in the canister 14 can be reliably purged during the time. Although it is theoretically possible to delay the warm-up start timing of the engine 16 depending on the threshold value, it is set so that the warm-up start timing of the engine 16 is substantially advanced.

  In step S120, it is determined whether or not the actual travel resistance is equal to or greater than the switching point calculated in step S118, that is, a threshold value for switching from EV travel to HV travel. This running resistance increases, for example, when the vehicle is traveling on an uphill road or when the vehicle is accelerated. If the running resistance is not greater than or equal to the threshold value, the EV running is continued in step S122, and the process returns to step S108.

  If it is determined in step S120 that the running resistance is equal to or greater than the threshold value, the engine 16 is driven in step S124, and the warm-up operation is started. At this time, the adsorption state of the evaporated fuel with respect to the canister 14 has already been estimated. Accordingly, the canister 14 can be purged by applying a negative pressure to the canister 14 immediately after the start of driving of the engine 16 by the warm-up operation. Further, the generator 67 can be driven by driving the engine 16, and the obtained power can be charged in the battery 66. During the canister 14 purge, the fuel injection amount from the injector 32 can be reduced, so that the fuel consumption can be improved accordingly.

  In step S126, it is determined whether or not the warm-up operation should be terminated. That is, once the warm-up operation is started, it is preferable for the engine 16 to continue the warm-up operation until the predetermined temperature is reached. For this reason, the drive of the engine 16 is continued until the water temperature detected by the water temperature sensor 74 reaches a predetermined value.

  If it is determined that the warm-up is to be terminated (the water temperature detected by the water temperature sensor 74 has reached a predetermined value), it is determined in step S128 whether or not the canister 14 purge is to be terminated. That is, since the amount of evaporated fuel and the purge concentration (purge amount) during running or warm-up are estimated at the previous stage, the canister 14 is purged based on these values. Here, as described above, since the negative pressure is applied to the canister 14 immediately after the start of the driving of the engine 16 by the warm-up operation, the canister 14 is purged. Compared to a configuration in which no purging is performed, the canister 14 can be purged early.

  Then, after the warm-up is completed, in step S130, it is determined whether or not the SOC of the battery 66 is sufficient for EV traveling. If sufficient, the driving of the engine 16 is stopped and switched to EV traveling in step S122. After that, the process returns to step S108. If the SOC is not sufficient, HV traveling is continued in step S132, and the process returns to step S108.

  As can be seen from the above description, in the evaporated fuel processing apparatus 10 of the present embodiment, the switching point (threshold value) for switching from EV traveling to HV traveling according to the state of the vehicle, in particular, the adsorption state of the evaporated fuel to the canister 14. ) Has changed. For this reason, the canister 14 can be purged as accurately as necessary. For example, in a plug-in hybrid vehicle that does not have the configuration of the present embodiment, depending on the travel resistance, it is assumed that there are many cases where the vehicle travel ends only at EV travel (arrives at the destination). In the embodiment, the canister 14 can be purged by driving the engine as necessary by lowering the switching point (threshold value) for switching from EV traveling to HV traveling.

  Moreover, in this embodiment, only the switching point (threshold value) for switching from EV traveling to HV traveling is changed, and the switching timing to HV traveling is substantially changed. Therefore, there is little discomfort given to the vehicle occupant (actually, there is almost no discomfort).

  In addition, as a judgment material for changing the switching point (threshold value) in this way, it is not limited to the above-described one. For example, the amount of evaporated fuel adsorbed on the canister 14 is directly or indirectly measured. You may use this as one of the judgment materials. In particular, when the vehicle is traveling while purging the canister 14, the switching point (threshold value) can be changed while taking into account the amount of CO2 in the exhaust gas, the amount of fuel injected into the engine 16, and the like.

  For example, in step S114 of FIG. 3, if the chargeable amount of battery 66 (a value obtained by subtracting the actual charge amount from the full charge amount) is smaller than the estimated power generation amount, Control in which the machine is permitted (for example, setting a flag indicating this state) is also possible. Thereby, it is possible to charge the battery 66 with the amount of power generated during the warm-up operation of the engine 16 without waste, and it is possible to suppress the generation of electric power that cannot be charged and causes energy loss.

  Moreover, although the example in which the evaporated fuel processing apparatus 10 of the present invention is applied to a plug-in hybrid vehicle has been described in the above embodiment, it can also be applied to a general hybrid vehicle. However, as described above, in a plug-in hybrid vehicle, depending on the running resistance, the EV traveling time becomes long or the vehicle traveling is often ended only by EV traveling. Can be preferably applied.

It is sectional drawing which shows schematic structure of the evaporative fuel processing apparatus of 1st embodiment of this invention. It is a block diagram which shows the control system which comprises the evaporative fuel processing apparatus of 1st embodiment of this invention. It is a flowchart which shows an example of the evaporative fuel process in the evaporative fuel processing apparatus of 1st embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Evaporative fuel processing apparatus 12 Fuel tank 14 Canister 16 Engine (internal combustion engine)
60 ECU (drive control means)
66 Battery (storage battery)
67 Generator
68 Connector 69 Inverter 70 Outside air temperature sensor (adsorption state measuring means)
72 Internal pressure sensor (adsorption state measuring means)
74 Water temperature sensor 76 Hybrid motor (electric motor)

Claims (8)

A canister that adsorbs the evaporated fuel generated in the fuel tank;
An internal combustion engine that is driven by the combustion of fuel and that can purge the canister by applying negative pressure generated by the drive to the canister;
An electric motor that receives power supply and exerts driving force;
Drive control means for switching from a first drive state in which only the electric motor is driven to a second drive state in which at least the internal combustion engine is driven in accordance with a running load of the vehicle;
Have
The evaporative fuel processing apparatus, wherein the drive control means changes the judgment criterion for switching according to a state of the vehicle.   The evaporated fuel processing apparatus according to claim 1, wherein the drive control unit uses an adsorption state of the canister as a state of the vehicle. Comprising adsorption state measuring means for measuring the adsorption state of the canister;
The evaporated fuel processing apparatus according to claim 2, wherein the drive control unit changes a start time of the purge based on the adsorption state measured by the adsorption state measurement unit.   The drive control means can predict the purgeable amount by driving the internal combustion engine, and determines the purge start timing based on the predicted purgeable amount and the adsorption state of the canister measured by the adsorption state measurement means. The evaporative fuel processing apparatus according to claim 2, wherein the evaporative fuel processing apparatus is changed. The adsorption state measuring means is
An outside air temperature sensor capable of detecting the temperature of the outside air of the vehicle,
An internal pressure sensor capable of detecting the internal pressure of the fuel tank;
Have
The drive control means includes a purge concentration learning value in the canister in the previous travel of the vehicle, an outside air temperature detected by the outside air temperature sensor, and an evaporative fuel estimated from the fuel tank internal pressure detected by the internal pressure sensor. The evaporative fuel processing apparatus according to any one of claims 2 to 4, wherein the adsorption state of the canister can be calculated based on the generation amount.   2. The drive control unit according to claim 1, wherein when the internal combustion engine shifts from a cold state to a warm-up operation, the warm-up operation is continued until the internal combustion engine reaches a predetermined temperature set in advance. The evaporative fuel processing apparatus of any one of Claims 5-5. A generator capable of generating electricity by driving the internal combustion engine;
A storage battery that is charged with power generated by the generator and capable of supplying this power to the motor;
Have
The drive control means predicts the amount of power generated by the generator due to the warm-up operation of the internal combustion engine, and permits the warm-up operation when the chargeable amount of the storage battery exceeds the predicted power generation amount. The evaporative fuel processing apparatus of any one of Claims 1-6 characterized by the above-mentioned.   When the drive control means is in a state where the warm-up operation of the internal combustion engine is finished and the purge of the canister is completed, and the remaining charge of the storage battery is greater than or equal to the amount of power required for vehicle travel The evaporative fuel processing device according to claim 6 or 7, wherein the vehicle is driven only by the driving force of the electric motor.

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