JP2019112999A - Fuel evaporative gas detection device and fuel evaporative gas detection method - Google Patents

Abstract

To provide a fuel evaporative gas detection device capable of reducing a detection error of evaporative gas supply amount when detecting the evaporative gas supply amount in an internal combustion engine configured to supply fuel evaporative gas and exhaust gas to an intake pipe.SOLUTION: A fuel evaporative gas detection device detects evaporative gas supply amount that is supply amount of fuel evaporative gas to an intake pipe in an internal combustion engine, and includes a signal reception section and a supply amount calculation section. The signal reception section receives an oxygen concentration signal corresponding to an oxygen concentration at a portion downstream of an exhaust gas supply section and a fuel evaporative gas supply section of the intake pipe. The supply amount calculation section calculates evaporative gas supply amount on the basis of the oxygen concentration signal. Since the fuel evaporative gas detection device has the supply amount calculation section for calculating the evaporative gas supply amount on the basis of the oxygen concentration signal, the evaporative gas supply amount can be detected appropriately, so as to reduce a detection error of the evaporative gas supply amount.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a fuel evaporative gas detection device and a fuel evaporative gas detection method that detect an evaporative gas supply amount that is a supply amount of fuel evaporative gas to an intake pipe of an internal combustion engine.

  In a fuel tank of an internal combustion engine, fuel evaporative gas (purge gas) generated by evaporation of fuel in a liquid state may be accumulated. If the fuel evaporative gas is discharged to the atmosphere as it is, problems such as air pollution may occur. Therefore, there is a technology (fuel evaporation gas purge) that suppresses the release of fuel evaporation gas as it is to the atmosphere by supplying fuel evaporation gas to the intake pipe and burning the fuel evaporation gas in the cylinder of the internal combustion engine together with the intake gas. Proposed.

  In addition, in internal combustion engines, exhaust gas is supplied to the intake pipe and the exhaust gas is burned again by the cylinder of the internal combustion engine, and technology (exhaust gas recirculation. EGR.) For reducing NOx and improving fuel efficiency is known. There is.

  As an internal combustion engine, an internal combustion engine configured to supply fuel evaporative gas and exhaust gas to an intake pipe is known (Patent Document 1).

JP 2003-003879 A

  However, in the internal combustion engine configured to supply the fuel evaporative gas and the exhaust gas to the intake pipe, the amount of the fuel evaporative gas supplied to the intake gas (evaporative gas supply amount) may not be accurately detected due to the influence of the exhaust gas. If the detection error of the evaporative gas supply amount becomes large, the air-fuel ratio control (A / F control) of the internal combustion engine may be adversely affected.

  Therefore, the present disclosure relates to a fuel evaporative gas detection device capable of reducing an evaporative gas supply amount detection error in detecting an evaporative gas supply amount in an internal combustion engine configured to supply fuel evaporative gas and exhaust gas to an intake pipe, and fuel evaporation It aims at providing a gas detection method.

  According to an aspect of the present disclosure, in an internal combustion engine configured such that exhaust gas for exhaust gas recirculation and fuel evaporative gas of a fuel tank are supplied to an intake pipe, an evaporative gas supply amount that is a supply amount of fuel evaporative gas to the intake pipe. The fuel evaporative gas detection apparatus detects a fuel evaporative gas, and includes a signal reception unit, a recirculation determination unit, a purge determination unit, and a supply amount calculation unit.

  The signal receiving unit receives an oxygen concentration signal corresponding to the oxygen concentration in a portion downstream of the exhaust gas supply unit to which the exhaust gas is supplied and the fuel evaporation gas supply unit to which the fuel evaporation gas is supplied in the intake pipe. The recirculation determination unit determines whether or not the exhaust gas recirculation process in which the exhaust gas is supplied to the intake pipe is being performed. The purge determination unit determines whether or not the purge process in which the fuel evaporative gas is supplied to the intake pipe is being performed. The supply amount calculation unit calculates the evaporation gas supply amount based on the determination result by the recirculation determination unit, the determination result by the purge determination unit, and the oxygen concentration signal.

  Since the oxygen concentration in the portion downstream of the exhaust gas supply unit and the fuel evaporation gas supply unit in the intake pipe changes according to at least the evaporation gas supply amount, the evaporation gas supply amount is calculated based on the oxygen concentration signal. Can.

  Since this fuel evaporative gas detection device includes the supply amount calculation unit that calculates the evaporative gas supply amount based on the oxygen concentration signal, the evaporative gas supply amount can be appropriately detected, and a detection error of the evaporative gas supply amount can be obtained. It can be reduced.

  The oxygen concentration signal can be used not only for the evaporative gas supply amount but also for calculating the exhaust gas supply amount, which is the supply amount of exhaust gas to the exhaust pipe. That is, this fuel evaporative gas detection device can also calculate the exhaust gas supply amount.

  Next, the fuel evaporative gas detection apparatus described above further includes a reference concentration calculation unit, and the supply amount calculation unit is after calculation of the reference concentration, and the recirculation determination unit stops the exhaust gas recirculation processing. It may be configured to calculate the evaporative gas supply amount based on the oxygen concentration signal and the reference concentration during the recirculation stop period determined to be medium.

  When the recirculation determination unit determines that the exhaust gas recirculation processing is stopped and the purge determination unit determines that the purge processing is stopped, the reference concentration calculation unit is based on the oxygen concentration signal, and the reference of the intake pipe is determined. It is configured to calculate the concentration.

  Since the oxygen concentration in the intake pipe is not affected by the exhaust gas during the recirculation stop period (in other words, during the stop of the exhaust gas recirculation process), the change due to the influence of the fuel evaporation gas tends to occur. Therefore, the fuel evaporative gas detection device can suppress the influence of the exhaust gas by calculating the evaporative gas supply amount based on the oxygen concentration signal and the reference concentration while the exhaust gas recirculation processing is stopped. The amount of supply can be detected accurately.

  Next, the above-described fuel evaporative gas detection device including the reference concentration calculation unit includes the new air flow volume information acquisition unit, the evaporative gas flow rate calculation unit, and the integrated amount calculation unit, and the supply amount calculation unit During the circulation process, the evaporative gas supply amount may be determined by estimating a change state of the evaporative gas supply amount based on the evaporative gas integrated amount and the new air flow amount information.

  The new air flow information acquisition unit is configured to acquire new air flow information that is the flow rate of the air supplied to the intake pipe. The evaporation gas flow rate calculating unit is configured to calculate an evaporation gas flow rate which is a flow rate of the evaporation gas supply unit. During the recirculation process in which the recirculation determination unit determines that the exhaust gas recirculation process is in progress, the integrated amount calculation unit determines the integrated amount of evaporative gas based on the new air flow information and the evaporative gas flow rate, and During the stop period, the accumulated evaporation amount is calculated based on the oxygen concentration signal, the new air flow rate information, and the evaporation gas flow rate.

  This fuel evaporative gas detection device supplies evaporative gas by estimation based on the evaporative gas integrated amount and the fresh air flow rate information without using the oxygen concentration signal affected by the exhaust gas for recirculation during the recirculation process. You can determine the quantity.

Thus, the fuel evaporation gas detection device can reduce the influence of the exhaust gas for recirculation during the recirculation process, and can reduce the detection error of the evaporation gas supply amount.
Next, the above-described fuel evaporative gas detection apparatus including the reference concentration calculation unit may include the new air flow rate information acquisition unit and the exhaust gas flow rate calculation unit.

  The new air flow information acquisition unit is configured to acquire new air flow information that is the flow rate of the air supplied to the intake pipe. The exhaust gas flow rate calculating unit is configured to calculate an exhaust gas flow rate which is a flow rate of the exhaust gas supply unit.

  The supply amount calculation unit obtains the exhaust gas supply rate based on the new air flow amount information and the exhaust gas flow rate, and the exhaust gas is determined during the exhaust gas recirculation processing by the recirculation judgment unit. The evaporative gas supply amount is calculated based on the supply rate and the oxygen concentration signal.

  Since the fuel evaporation gas detection apparatus uses the exhaust gas supply rate in the calculation of the evaporation gas supply amount during the recirculation process, the evaporation gas is used to reduce the influence of the exhaust gas for recirculation in the oxygen concentration signal. The supply amount can be calculated.

Thus, the fuel evaporation gas detection device can reduce the influence of the exhaust gas for recirculation during the recirculation process, and can reduce the detection error of the evaporation gas supply amount.
Next, the fuel evaporative gas detection device described above has an exhaust gas supply unit provided upstream of the fuel evaporative gas supply unit in the intake pipe, and includes an intermediate signal reception unit and a reference concentration calculation unit. May be

  The intermediate signal receiving unit is configured to receive an intermediate oxygen concentration signal corresponding to the oxygen concentration between the exhaust gas supply unit and the fuel evaporative gas supply unit in the intake pipe. When the recirculation determination unit determines that the exhaust gas recirculation processing is stopped and the purge determination unit determines that the purge processing is stopped, the reference concentration calculation unit is based on the oxygen concentration signal, and the reference of the intake pipe is determined. It is configured to calculate the concentration.

The supply amount calculation unit is configured to calculate the evaporation gas supply amount based on the reference concentration, the oxygen concentration signal, and the intermediate oxygen concentration signal.
The fuel evaporative gas detection apparatus configured as described above uses the intermediate oxygen concentration signal in addition to the oxygen concentration signal to reduce the influence of the exhaust gas for recirculation while performing the exhaust gas recirculation process while supplying the evaporative gas. The amount can be detected.

  Thus, the fuel evaporation gas detection apparatus can reduce the influence of the exhaust gas for recirculation by using the intermediate oxygen concentration signal during the recirculation process, thereby reducing the detection error of the evaporation gas supply amount. it can.

  Another aspect of the present disclosure is an evaporative gas that is a supply amount of fuel evaporative gas to an intake pipe in an internal combustion engine configured such that exhaust gas for exhaust gas recirculation and fuel evaporative gas of a fuel tank are supplied to the intake pipe. A fuel evaporative gas detection method for detecting a supply amount, comprising a signal receiving step, a recirculation determination step, a purge determination step, and a supply amount calculation step.

  In the signal receiving step, an oxygen concentration signal corresponding to the oxygen concentration in a portion downstream of the exhaust gas supply unit to which the exhaust gas is supplied and the fuel evaporation gas supply unit to which the fuel evaporation gas is supplied in the intake pipe is received. In the recirculation determination step, it is determined whether or not the exhaust gas recirculation process, in which exhaust gas is supplied to the intake pipe, is being performed. In the purge determination step, it is determined whether or not the purge process in which the fuel evaporative gas is supplied to the intake pipe is being performed. In the supply amount calculation step, the evaporation gas supply amount is calculated based on the determination result by the recirculation determination unit, the determination result by the purge determination unit, and the oxygen concentration signal.

  Since the oxygen concentration in the portion downstream of the exhaust gas supply unit and the fuel evaporation gas supply unit in the intake pipe changes according to at least the evaporation gas supply amount, the evaporation gas supply amount is calculated based on the oxygen concentration signal. Can.

  Since this fuel evaporation gas detection method includes the supply amount calculation unit that calculates the evaporation gas supply amount based on the oxygen concentration signal, the evaporation gas supply amount can be appropriately detected, and a detection error of the evaporation gas supply amount can be obtained. It can be reduced.

  The oxygen concentration signal can be used not only for the evaporative gas supply amount but also for calculating the exhaust gas supply amount, which is the supply amount of exhaust gas to the exhaust pipe. That is, this fuel evaporation gas detection method can also calculate the exhaust gas supply amount.

It is an explanatory view showing a schematic structure of a fuel evaporative gas detection device which detects fuel evaporative gas in an internal combustion engine. It is a flow chart which shows processing contents of fuel evaporative gas detection processing in a 1st embodiment. It is a time chart showing the change state of each part in the internal combustion engine of a 1st embodiment. It is a flow chart which shows processing contents of fuel evaporative gas detection processing in a 2nd embodiment. It is explanatory drawing of the map showing the correlation of flow volume ratio Rf, purge integration flow volume Qf, and purge gas concentration RB2. It is a time chart showing the change state of each part in an internal combustion engine of a 2nd embodiment. It is a flow chart which shows processing contents of fuel evaporative gas detection processing in a 3rd embodiment. It is a time chart showing the change state of each part in an internal combustion engine of a 3rd embodiment.

Hereinafter, embodiments to which the present disclosure is applied will be described using the drawings.
The present disclosure is not limited to the following embodiments at all, and it goes without saying that various forms can be adopted within the technical scope of the present disclosure.

[1. First embodiment]
[1-1. overall structure]
As a first embodiment, a fuel evaporative gas detection device 1 for detecting fuel evaporative gas in the internal combustion engine 11 using the first intake oxygen sensor 4 and the second intake oxygen sensor 5 provided in the internal combustion engine 11 will be described.

  As shown in FIG. 1, the internal combustion engine 11 is a multi-cylinder gasoline engine (four cylinders in the present embodiment) provided with an intake passage 12 and an exhaust passage 13. The internal combustion engine 11 is provided with four fuel injection valves 14 (hereinafter also referred to as injectors 14) for directly injecting fuel into the respective cylinders. The internal combustion engine 11 is configured such that exhaust gas for exhaust gas recirculation (hereinafter also referred to as EGR gas) and fuel evaporative gas (hereinafter also referred to as purge gas) generated in the fuel tank are supplied to the intake passage 12. .

  The intake path 12 is a path for supplying air (atmosphere) to the cylinder, and is provided with a plurality of branched intake manifolds on the most downstream side. The intake manifold is connected to the plurality of cylinders to supply air to each cylinder. An EGR gas supply unit 12a, a first intake oxygen sensor 4, a throttle valve 15, a purge gas supply unit 12b, and a second intake oxygen sensor 5 are disposed in the intake passage 12 from the upstream side to the downstream side.

  The throttle valve 15 is configured to control the amount of air supplied to a plurality of cylinders via the intake passage 12. The first intake oxygen sensor 4 and the second intake oxygen sensor 5 are configured by full-range air-fuel ratio sensors, and are configured to detect the oxygen concentration in the gas flowing through the intake passage 12.

  The EGR gas supply unit 12 a is connected to the exhaust path 13 via the EGR gas path 21, and is a portion of the intake path 12 to which the EGR gas is supplied. An EGR valve 23 for controlling the flow rate of the EGR gas supplied to the intake passage 12 is disposed in the EGR gas passage 21.

  The purge gas supply unit 12 b is connected to the canister 16 via the purge gas path 17 and is a portion of the intake path 12 to which the fuel evaporation gas is supplied. The purge gas path 17 is provided with a purge valve 18 for controlling the flow rate of the purge gas supplied to the intake path 12.

  The canister 16 is configured to temporarily adsorb purge gas generated in a fuel tank (not shown). The purge gas adsorbed to the canister 16 evaporates from the canister 16 at a predetermined timing thereafter, and the purge gas generated by the evaporation is adjusted in gas flow rate by the purge valve 18, and the throttle valve 15 and the second intake in the intake path 12 It is supplied between the oxygen sensor 5 and the sensor.

  The exhaust path 13 is a path for discharging the exhaust gas generated by the combustion of the fuel from the cylinder to the outside. An exhaust oxygen sensor 8 and a three-way catalyst 9 are disposed in the exhaust passage 13 from the upstream side to the downstream side. The exhaust oxygen sensor 8 is configured of a full range air-fuel ratio sensor, and is configured to detect the oxygen concentration of the exhaust gas flowing through the exhaust path 13. The three-way catalyst 9 is configured to remove harmful substances (hydrocarbon (HC), carbon monoxide (CO), nitrogen oxide (NOx), etc.) contained in the exhaust gas.

  The fuel evaporative gas detection device 1 includes an electronic control unit 2 (ECU 2) that performs various processes. The ECU 2 is an example of a computer system provided with a microcomputer (hereinafter, also referred to as a microcomputer (not shown)). The microcomputer includes a CPU, a ROM, a RAM, and a signal input / output unit. The various functions of the ECU 2 are realized by the CPU executing a program stored in the non-transitional tangible storage medium. In this example, the ROM corresponds to the non-transitional tangible storage medium storing the program. Also, by executing this program, a method corresponding to the program is executed. The signal input / output unit transmits / receives various signals to / from an external device. The number of CPUs, ROMs, RAMs, and signal input / output units that constitute the microcomputer may be one or more. Further, part or all of the functions executed by the microcomputer may be configured as hardware by one or a plurality of ICs or the like.

  The ECU 2 is configured to receive (acquire) signals from various sensors such as the first intake oxygen sensor 4, the second intake oxygen sensor 5, the exhaust oxygen sensor 8 and a mass flow sensor (not shown), and the purge valve 18, Control signals are output to various actuators such as the throttle valve 15 and the injector 14. The ECU 2 is configured to output control signals relating to on / off of the first intake oxygen sensor 4, the second intake oxygen sensor 5, and the exhaust oxygen sensor 8.

[1-2. Fuel evaporative gas detection processing]
Next, among various processes performed by the ECU 2, the fuel evaporative gas detection process will be described based on the flowchart of FIG.

  When the ECU 2 starts the fuel evaporative gas detection process, first, at S110 (S represents a step), whether or not the oxygen concentration in the atmosphere (first atmospheric oxygen concentration CA1 and second atmospheric oxygen concentration CA2 described later) is calculated If yes, the process proceeds to S160. If not, the process proceeds to S120.

  When the ECU 2 makes a negative determination in S110 and proceeds to S120, it determines whether or not the EGR valve 23 is in the open state, and when making a positive determination (when it is in the open state), the same step is repeatedly executed to make a negative determination. In the case (in the closed state), the process proceeds to S130.

  When the ECU 2 makes a negative determination in S120 and proceeds to S130, it determines whether or not the purge valve 18 is in the open state, and proceeds to S120 when making a positive determination (when open), making a negative determination (closed If it is in the state), the process proceeds to S140.

  When the ECU 2 makes a negative determination in S130 and proceeds to S140, the sensor output of the first intake oxygen sensor 4 (hereinafter, also referred to as first sensor output S1) and the sensor output of the second intake oxygen sensor 5 (hereinafter, second sensor) To obtain an output S2). At this time, since both the EGR valve 23 and the purge valve 18 are closed, neither the exhaust gas (EGR gas) nor the fuel evaporation gas (purge gas) is supplied to the intake passage 12, and only the atmosphere passes through. State. Therefore, the first sensor output S1 and the second sensor output S2 at this time indicate values corresponding to the oxygen concentration of the air passing through the intake passage 12.

  At the next S150, the ECU 2 calculates the oxygen concentration of the atmosphere based on the sensor output acquired at S140. In the present embodiment, the ECU 2 calculates the first atmospheric oxygen concentration CA1 based on the first sensor output S1, and calculates the second atmospheric oxygen concentration CA2 based on the second sensor output S2. The ECU 2 stores the first atmospheric oxygen concentration CA1 and the second atmospheric oxygen concentration CA2 in a storage unit (such as a RAM).

When the process in S150 is completed, the process returns to S110.
When the ECU 2 makes an affirmative determination in S110 and proceeds to S160, the first sensor output S1 of the first intake oxygen sensor 4 and the second sensor output S2 of the second intake oxygen sensor 5 are acquired, and the first sensor output S1 and The oxygen concentration is calculated based on the second sensor output S2.

  At this time, the states (open state, closed state) of the EGR valve 23 and the purge valve 18 are indeterminate, but the first sensor output S1 at this time is the state of the EGR valve 23 (in other words, EGR to the intake path 12 It changes according to the supply amount of gas). Further, the second sensor output S2 at this time changes in accordance with the state of the EGR valve 23 and the state of the purge valve 18 (in other words, the supply amount of the purge gas to the intake passage 12).

  At this time, the ECU 2 calculates the first oxygen concentration CF based on the first sensor output S1, and calculates the second oxygen concentration CS based on the second sensor output S2. The ECU 2 stores the first oxygen concentration CF and the second oxygen concentration CS in a storage unit (such as a RAM).

  The ECU 2 calculates the volume ratio (EGR ratio RA1 [%]) of the EGR gas contained in the gas flowing in the intake passage 12 based on [Equation 1] in the next S170.

CA1 is the first atmospheric oxygen concentration CA1 calculated in S150, and CF is the first oxygen concentration CF calculated in S160.
The ECU 2 calculates the purge gas concentration RB1 [%] based on [Equation 2] in the next S180.

  CA2 is the second atmospheric oxygen concentration CA2 calculated in S150, CS is the second oxygen concentration CS calculated in S160, and K1 is a predetermined coefficient. The coefficient K1 is a proportionality constant determined in accordance with the characteristics of the second intake oxygen sensor 5.

  The ECU 2 determines in the next S190 whether or not the detection ends, and in the case of a positive determination (in the case of the detection end), ends the fuel evaporative gas detection processing, and in the case of a negative determination (in the case of not the detection end) The process shifts to S160 again. In S190 of the present embodiment, it is determined that the detection is ended, for example, at the end of the operation of the internal combustion engine, the occurrence of an abnormality of the internal combustion engine, or the occurrence of an abnormality of the fuel evaporative gas detection device 1.

[1-3. Change state of each part]
Next, the changing state of each part in the internal combustion engine 11 will be described using the time chart shown in FIG.

  The purge permission flag Fp and the EGR permission flag Fe are internal flags used for the processing of the ECU 2. The ECU 2 executes the flag state setting process to judge the operating state of the internal combustion engine 11, and based on the judgment result, the states of the purge permission flag Fp and the EGR permission flag Fe (ON state, OFF state) Set

  In the time chart shown in FIG. 3, the internal combustion engine 11 is started at time t0, and the purge permission flag Fp is turned on at time t1 when the operating state of the internal combustion engine 11 (cooling water temperature, lubricating oil temperature, etc.) satisfies predetermined conditions. It is set to the state.

  After starting the internal combustion engine 11, the ECU 2 executes the above-described S140 and S150 during the period in which the purge permission flag Fp is set to the OFF state (during the period from time t0 to time t1 in FIG. 3). The first atmospheric oxygen concentration CA1 and the second atmospheric oxygen concentration CA2 are calculated.

  When the purge permission flag Fp is set to the ON state, the ECU 2 executes a purge valve control process to control the state (opened state, closed state) of the purge valve 18. In FIG. 3, the purge valve 18 is set to the open state three times during the period from time t1 to time t2, and along with this, the second oxygen concentration CS fluctuates and the purge gas concentration RB1 fluctuates. The first oxygen concentration CF at this time does not change.

  When the EGR permission flag Fe is set to the ON state, the ECU 2 executes the EGR control process to control the state (opened state, closed state) of the EGR valve 23. In FIG. 3, after time t2, the purge valve 18 is set to the open state once, and the EGR valve 23 is set to the open state twice. Along with this, the first oxygen concentration CF and the second oxygen concentration CS change, and the purge gas concentration RB1 and the EGR rate RA1 change.

[1-4. effect]
As described above, the fuel evaporative gas detection device 1 of the present embodiment is configured such that the concentration of the purge gas supplied to the intake passage 12 (purge gas concentration) in the internal combustion engine 11 configured to supply the EGR gas and the purge gas to the intake passage 12 It is configured to detect RB1). The purge gas concentration RB1 is a state quantity that can be used as the supply amount of the purge gas to the intake passage 12.

The fuel evaporative gas detection device 1 includes an ECU 2 that executes a fuel evaporative gas detection process.
The ECU 2 acquires the first sensor output S1 of the first intake oxygen sensor 4 and the second sensor output S2 of the second intake oxygen sensor 5 by executing S140 and S160 of the fuel evaporation gas detection process. Among these, the second sensor output S2 corresponds to an oxygen concentration signal according to the oxygen concentration in the portion downstream of the EGR gas supply unit 12a and the purge gas supply unit 12b in the intake passage 12.

  The ECU 2 executes S150 and S160 of the fuel evaporation gas detection process to calculate the first atmospheric oxygen concentration CA1 and the second atmospheric oxygen concentration CA2 based on the first sensor output S1 and the second sensor output S2. The first oxygen concentration CF and the second oxygen concentration CS are calculated.

  Since the oxygen concentration in the portion downstream of the EGR gas supply unit 12a and the purge gas supply unit 12b in the intake passage 12 changes at least in accordance with the evaporative gas supply amount (purge gas concentration RB1), the ECU 2 outputs the second sensor output S2 The evaporative gas supply amount can be calculated based on

  Since the fuel evaporative gas detection device 1 includes the ECU 2 (specifically, the ECU 2 that executes S150 and S160) that calculates the evaporative gas supply amount (purge gas concentration RB1) based on the second sensor output S2, the evaporative gas supply amount Can be properly detected, and the detection error of the evaporation gas supply amount can be reduced.

Note that the second sensor output S2 also changes according to the concentration change of the EGR gas, so that it can be used not only for the evaporative gas supply amount but also for calculating the EGR gas supply amount.
Next, the internal combustion engine 11 is configured such that the EGR gas supply unit 12a is provided on the intake passage 12 upstream of the purge gas supply unit 12b.

  The ECU 2 of the fuel evaporative gas detection device 1 receives the first sensor output S1 of the first intake oxygen sensor 4 by executing S140 and S160. The first sensor output S1 is a signal (intermediate oxygen concentration signal) corresponding to the oxygen concentration in the intake passage 12 between the EGR gas supply unit 12a and the purge gas supply unit 12b.

  The ECU 2 is configured to determine whether the exhaust gas recirculation process (EGR process) in which the exhaust gas (EGR gas) is supplied to the intake passage 12 (EGR process) is being performed by executing S120. The ECU 2 is configured to determine whether or not the purge process (fuel evaporative gas) is being supplied to the intake passage 12 during the execution of the purge process by executing S130.

  After the internal combustion engine 11 is started, the ECU 2 executes S140 and S150 when it is determined in S120 that the exhaust gas recirculation process is stopped and in S130 it is determined that the purge process is stopped. The reference concentration (the first atmospheric oxygen concentration CA1 and the second atmospheric oxygen concentration CA2) of the intake passage 12 is calculated based on the sensor output S1 and the second sensor output S2.

  The ECU 2 executes S160, S170 and S180 to generate the reference concentration (first atmospheric oxygen concentration CA1, second atmospheric oxygen concentration CA2), the oxygen concentration signal (second sensor output S2), and the intermediate oxygen concentration signal (second oxygen concentration signal). Based on the first sensor output S1), the evaporative gas supply amount (purge gas concentration RB1) is calculated.

  The fuel evaporation gas detection apparatus 1 having such a configuration uses the first sensor output S1 in addition to the second sensor output S2 to reduce the influence of the EGR gas while performing the EGR process while reducing the amount of evaporative gas supplied (purge gas The concentration RB1) can be detected.

  Thereby, the fuel evaporative gas detection device 1 can reduce the influence of the EGR gas by using the first sensor output S1 during the EGR process, and the detection error of the evaporative gas supply amount (purge gas concentration RB1) It can be reduced.

[1-5. Correspondence of wording]
Here, the correspondence relationship of words is demonstrated.
The fuel evaporative gas detection device 1 corresponds to a fuel evaporative gas detection device, the intake passage 12 corresponds to an intake pipe, the EGR gas corresponds to an exhaust gas for exhaust gas recirculation, and the purge gas corresponds to a fuel evaporative gas. The two-sensor output S2 corresponds to the oxygen concentration signal, and the purge gas concentration RB1 corresponds to the evaporation gas supply amount. The EGR gas supply unit 12a corresponds to an exhaust gas supply unit, and the purge gas supply unit 12b corresponds to a fuel evaporative gas supply unit. The ECU 2 that executes S140 or S160 to acquire the second sensor output S2 corresponds to a signal reception unit, the ECU 2 that executes S120 corresponds to a recirculation determination unit, and the ECU 2 that executes S130 corresponds to a purge determination unit. The ECU 2 that executes S170 and S180 corresponds to the supply amount calculation unit. S140 or S160 corresponds to the signal reception step, S120 corresponds to the recirculation determination step, S130 corresponds to the purge determination step, and S170 and S180 correspond to the supply amount calculation step.

  The first sensor output S1 corresponds to the intermediate oxygen concentration signal, and the ECU 2 that executes S140 or S160 to acquire the first sensor output S1 corresponds to the intermediate signal reception unit, and the ECU 2 that executes S140 and S150 calculates the reference concentration It corresponds to the department.

[2. Second embodiment]
[2-1. Fuel evaporative gas detection processing]
As a second embodiment, a fuel evaporative gas detection device 1 for detecting an evaporative gas supply amount (purge gas concentration) using the second sensor output S2 of the second intake oxygen sensor 5 will be described.

  The fuel evaporative gas detection apparatus 1 according to the second embodiment does not use the first sensor output S1 of the first intake oxygen sensor 4 as compared with the first embodiment, but uses the second sensor output S2 of the second intake oxygen sensor 5 The difference is that the amount of evaporative gas supplied (purge gas concentration) is detected using this method. The same contents as those of the first embodiment in the second embodiment will be described using the same reference numerals, or the description thereof will be omitted.

  The fuel evaporative gas detection device 1 according to the second embodiment differs from the first embodiment in the contents of the fuel evaporative gas detection process executed by the ECU 2. The fuel evaporative gas detection process of the second embodiment will be described based on the flowchart of FIG.

  When the fuel evaporation gas detection process is started, the ECU 2 first determines in S310 (S represents a step) whether the atmospheric oxygen concentration (second atmospheric oxygen concentration CA2) has been calculated or not, An affirmative determination is made in Step S360, and the process proceeds to Step S360. If not calculated, a negative determination is made in Step S320, and the process proceeds to Step S320.

  When the ECU 2 makes a negative determination in S310 and proceeds to S320, it determines whether or not the EGR valve 23 is in the open state, and when making a positive determination (when it is in the open state), the same step is repeatedly executed to make a negative determination. In the case (in the closed state), the process proceeds to S330.

  When the ECU 2 makes a negative determination in S320 and proceeds to S330, it determines whether or not the purge valve 18 is in the open state, and proceeds to S320 when making a positive determination (when open), making a negative determination (closed When it is in the state), the process proceeds to S340.

  When the ECU 2 makes a negative determination in S330 and proceeds to S340, the sensor output (second sensor output S2) of the second intake oxygen sensor 5 is acquired. At this time, since both the EGR valve 23 and the purge valve 18 are in the closed state, the exhaust gas and the fuel evaporative gas (purge gas) are not supplied to the intake passage 12, and only the atmosphere passes through. Therefore, the second sensor output S2 at this time indicates a value corresponding to the oxygen concentration of the air passing through the intake passage 12.

  At the next S350, the ECU 2 calculates the oxygen concentration of the atmosphere based on the sensor output acquired at S340. In the second embodiment, the ECU 2 calculates a second atmospheric oxygen concentration CA2 based on the second sensor output S2.

When the process in S350 is completed, the process proceeds to S310 again.
When the ECU 2 makes an affirmative determination in S310 and shifts to S360, it determines whether or not the EGR valve 23 is in the open state, and when making an affirmative determination (when in the open state), proceeds to S430, making a negative determination ( If it is in the closed state), the process proceeds to S370. The ECU 2 is configured to determine whether the exhaust gas recirculation process (EGR process) is being performed or stopped by executing S360.

  When the ECU 2 makes a negative determination in S360 and proceeds to S370, the ECU 2 obtains the second sensor output S2 of the second intake oxygen sensor 5 and calculates the oxygen concentration (second oxygen concentration CS) based on the second sensor output S2. Do.

  At this time, the state (open state, closed state) of the purge valve 18 is indefinite, but the second sensor output S2 at this time is the state of the EGR valve 23 and the state of the purge valve 18 (in other words, to the intake path 12 It changes according to the supply amount of purge gas.

  The ECU 2 calculates the concentration (purge gas concentration RB2 [%]) of the purge gas supplied to the intake passage 12 based on [Equation 3] in the next S380.

  CA2 is the second atmospheric oxygen concentration CA2 calculated in S350, CS is the second oxygen concentration CS calculated in S370, and K1 is a predetermined coefficient. The coefficient K1 is a proportionality constant determined in accordance with the characteristics of the second intake oxygen sensor 5.

The ECU 2 detects the amount of fresh air flow FL1 flowing through the intake passage 12 in the next S390. The ECU 2 detects the amount of fresh air flow FL1 based on a flow signal from a mass flow sensor (not shown in FIG. 1) provided downstream of the air cleaner in the upstream region of the intake path 12. The fresh air flow amount FL1 detected at this time is the flow rate per unit time, and the unit is [m ³ / s].

The ECU 2 calculates the flow rate of the purge gas (purge flow rate FL2 [m ³ / s]) flowing through the purge valve 18 in the purge gas path 17 in the next S400 based on [Equation 4]. The purge flow rate FL2 can be calculated by a general calculation method using a pressure difference (differential pressure) before and after the valve based on Bernoulli's theorem. The purge flow rate FL2 calculated in the present embodiment is a flow rate per unit time, and the unit is [m ³ / s].

Cd is a predetermined coefficient, Apg is a valve cross section [m ² ] of the purge valve 18, Pin is a purge valve inlet pressure [Pa], Pout is a purge valve outlet pressure [Pa], 、 pg is a purge gas Density [kg / m ³ ].

The ECU 2 calculates the ratio (flow rate ratio Rf (= FL2 / FL1)) between the new air flow amount FL1 and the purge flow rate FL2 in the next S410.
The ECU 2 calculates the integrated flow rate (purge integrated flow rate Qf) of the purge gas supplied to the intake passage 12 using the map shown in FIG. 5 in the next S420. For example, in the case where the flow rate ratio Rf = 2.5 [%] and the purge gas concentration RB2 = 1.75 [%], the purge integrated flow rate Qf = 5 [L] (== 0) corresponding to these values. 005 [m ³ ]) is used as the calculation result.

  When the ECU 2 makes an affirmative determination in S360 and proceeds to S430, it determines whether or not the purge integrated flow rate Qf has been calculated, and in the case where it has been calculated, it makes an affirmative determination and proceeds to S440. A negative determination is made, and the process moves to S360 again. In S430, it is determined whether or not the calculation processing of the purge integrated flow rate Qf in S420 has been executed. Further, in S430, when the purge integrated flow rate Qf is reset in S500, it is determined that the arithmetic processing of the purge integrated flow rate Qf in S420 is not executed, and when S420 is executed thereafter, the calculation of the purge integrated flow rate Qf It is determined that the process has been executed.

When the ECU 2 makes an affirmative determination in S430 and proceeds to S440, it detects a new air flow amount FL1 flowing through the throttle valve 15 in the intake passage 12 as in S390.
The ECU 2 calculates the flow rate of the purge gas (purge flow rate FL2 [m ³ / s]) flowing through the purge valve 18 in the purge gas path 17 based on [Equation 4] as in S400 in the next S450.

The ECU 2 calculates the ratio (flow rate ratio Rf (= FL2 / FL1)) between the new air flow amount FL1 and the purge flow rate FL2 in the following S460, as in S410.
The ECU 2 calculates the purge integrated flow rate Qf based on [Equation 5] in the next S470. Here, ta is a unit time (interval time ta) in which the purge valve 18 is in the open state, and in other words, represents a time in which the purge gas is supplied. The execution cycle of S470 that is repeatedly executed corresponds to the interval time ta. “FL2 · ta” in [Equation 5] corresponds to an increase in the integrated purge flow rate Qf when the interval time ta has elapsed.

  The ECU 2 calculates the purge gas concentration RB2 using the map shown in FIG. 5 in the next S480. For example, when the flow rate ratio Rf is 7.5 [%] and the purge integrated flow rate Qf is 10.0 [L], the purge gas concentration RB2 = 3.75 [%] corresponding to these numerical values is calculated. It is used as a result.

  When S420 or S480 ends, the ECU 2 shifts to S490, and determines whether the time during which the purge valve 18 is closed (hereinafter also referred to as purge close time Tpc) is greater than a predetermined determination time THTI. When the determination is affirmative, the process proceeds to S500, and when the determination is negative, the process proceeds to S510. In the second embodiment, the determination time THTI is set to 1.0 [min]. The determination time THTI is not limited to a fixed value, and may be a variable value set according to the atmospheric temperature. In that case, for example, the determination time THTI may be set shorter as the ambient temperature rises, and the determination time THTI may be set longer as the ambient temperature decreases.

When the ECU 2 makes an affirmative determination in S490 and proceeds to S500, it resets the purge integrated flow rate Qf. Specifically, the purge integrated flow rate Qf is set to 0.
When the closed state of the purge valve 18 is continued for a long time, the purge gas (fuel) accumulated in the canister 16 increases and the purge gas concentration RB2 becomes high. In this case, there is a possibility that an error may occur between the numerical value of the purge gas concentration RB2 obtained by calculating cumulatively and the actual purge gas concentration RB2. Therefore, when the closed state of the purge valve 18 exceeds a predetermined time, the occurrence of an error with the actual purge gas concentration RB2 can be suppressed by resetting the cumulatively calculated purge gas concentration RB2.

  When the ECU 2 makes a negative determination in S490 or ends S500 and proceeds to S510, it determines whether detection of the purge gas concentration RB2 has ended, and in the case of making a positive determination, the fuel evaporative gas detection processing ends, and negative If it is determined, the process proceeds to S360 again. In S510 of the present embodiment, it is determined that the detection is completed, for example, at the end of the operation of the internal combustion engine, at the occurrence of an abnormality of the internal combustion engine, or at the occurrence of an abnormality of the fuel evaporative gas detection device 1.

  As described above, in the fuel evaporative gas detection process of the second embodiment, calculation of the second atmospheric oxygen concentration CA2 is executed (affirmative determination in S310) and the EGR valve 23 is in the closed state (No in S360) In the determination), the purge gas concentration RB2 is calculated using the second sensor output S2 (S370, S380). In the fuel evaporative gas detection process of the second embodiment, calculation of the second atmospheric oxygen concentration CA2 is executed (affirmative determination in S310) and the EGR valve 23 is in the open state (affirmative determination in S360) The purge gas concentration RB2 is calculated using the purge integrated flow rate Qf (S480).

  Further, the ECU 2 also executes an EGR rate calculation process for calculating the EGR rate, as a process different from the fuel evaporative gas detection process. Here, the details of the EGR rate calculation process will be omitted. A step of calculating the EGR rate may be added to the fuel evaporative gas detection process. For example, an EGR ratio calculation step may be added after an affirmative determination is made in S360 (in other words, before S430 is performed) or immediately after S480.

[2-2. Change state of each part]
Next, the change state of each part in the internal combustion engine 11 of the second embodiment will be described using the time chart shown in FIG.

  In the time chart shown in FIG. 6, the internal combustion engine 11 is started at time t10, and the purge permission flag Fp is turned on at time t11 when the operating state of the internal combustion engine 11 (cooling water temperature, lubricating oil temperature, etc.) satisfies predetermined conditions. It is set to the state.

  After starting the internal combustion engine 11, the ECU 2 executes the above-described S340 and S350 during the period in which the purge permission flag Fp is set to the OFF state (during the period from time t10 to time t11 in FIG. 6). , The second atmospheric oxygen concentration CA2 is calculated.

  When the purge permission flag Fp is set to the ON state, the ECU 2 executes a purge valve control process to control the state (opened state, closed state) of the purge valve 18. In FIG. 6, the purge valve 18 is set to the open state three times during the period from time t11 to time t12, and along with this, the second oxygen concentration CS fluctuates, and according to the calculation result in S380. The purge gas concentration RB2 fluctuates.

  When the EGR permission flag Fe is set to the ON state, the ECU 2 executes the EGR control process to control the state (opened state, closed state) of the EGR valve 23. In FIG. 6, after time t12, the purge valve 18 is set to the open state once, and the EGR valve 23 is set to the open state twice. Along with this, the second oxygen concentration CS fluctuates, and the purge gas concentration RB2 fluctuates according to the calculation result in S480.

The ECU 2 calculates the total value (final value) of the purge gas concentration RB2 by summing up the respective calculation results (waveforms) at S380 and S480.
[2-3. effect]
As described above, the fuel evaporative gas detection device 1 according to the second embodiment supplies the amount of purge gas supplied to the intake passage 12 (purge gas concentration) in the internal combustion engine 11 configured to supply the EGR gas and the purge gas to the intake passage 12. It is configured to detect RB2).

The fuel evaporative gas detection device 1 includes an ECU 2 that executes a fuel evaporative gas detection process.
The ECU 2 acquires the second sensor output S2 of the second intake oxygen sensor 5 by executing S340 and S370 of the fuel evaporation gas detection process. The second sensor output S2 corresponds to an oxygen concentration signal corresponding to the oxygen concentration in the portion downstream of the EGR gas supply unit 12a and the purge gas supply unit 12b in the intake passage 12.

  The ECU 2 executes the steps S350 and S380 of the fuel evaporation gas detection process to calculate the second atmospheric oxygen concentration CA2 and the second oxygen concentration CS based on the second sensor output S2.

  Since the oxygen concentration in the portion downstream of the EGR gas supply unit 12a and the purge gas supply unit 12b in the intake passage 12 changes at least in accordance with the evaporative gas supply amount (purge gas concentration), the ECU 2 outputs the second sensor output S2. The evaporative gas supply amount can be calculated based on that.

  Since the fuel evaporative gas detection device 1 includes the ECU 2 (specifically, the ECU 2 executing S350 and S380) that calculates the evaporative gas supply amount (purge gas concentration) based on the second sensor output S2, the evaporative gas supply amount is The detection can be properly performed, and the detection error of the evaporative gas supply amount can be reduced.

  Next, the ECU 2 is configured to execute S320 to determine whether the exhaust gas recirculation process (EGR process) in which the exhaust gas (EGR gas) is supplied to the intake passage 12 is being executed. ing. The ECU 2 is configured to determine whether or not the purge process (fuel evaporative gas) is being supplied to the intake passage 12 during the execution of the purge process by executing S330.

  After the internal combustion engine 11 is started, the ECU 2 executes S340 and S350 when it is determined that the exhaust gas recirculation processing is stopped in S320 and when it is determined that the purge processing is stopped in S330. The reference concentration (second atmospheric oxygen concentration CA2) of the intake passage 12 is calculated based on the sensor output S2.

  The ECU 2 executes S370 and S380 during the recirculation stop period in which the EGR processing is determined to be stopped (during the period determined to be negative in S360), the reference concentration (second atmospheric oxygen concentration CA2). The evaporation gas supply amount (purge gas concentration RB2) is calculated based on the oxygen concentration signal (second sensor output S2).

  Since the oxygen concentration in the intake passage 12 is not affected by the exhaust gas (EGR gas) during the recirculation stop period (in other words, during the stop of the exhaust gas recirculation process), the influence of the fuel evaporative gas (purge gas) Change is likely to occur. For this reason, the fuel evaporative gas detection device 1 of the second embodiment is based on the second atmospheric oxygen concentration CA2 and the second sensor output S2 during the stop of the exhaust gas recirculation processing (during the period of negative determination in S360). Since the influence of the exhaust gas (EGR gas) can be suppressed by computing the purge gas concentration RB2, the purge gas concentration RB2 can be detected with high accuracy.

  Next, the ECU 2 is configured to acquire the new air flow amount FL1, which is the flow rate of the air supplied to the intake passage 12, by executing S390 and S440. The ECU 2 is configured to calculate an evaporative gas flow rate (purge flow rate FL2) which is a flow rate of the purge gas supply unit 12b in the intake passage 12 by executing S400 and S450.

  The ECU 2 executes the processes from S440 to S480 during the recirculation process that is determined to be in the exhaust gas recirculation process (affirmative determination in S360), and thereby the purge integrated flow rate based on the new air flow amount FL1 and the purge flow rate FL2. It is configured to determine Qf. Further, the ECU 2 performs the second oxygen concentration CS, the fresh air flow amount FL1, and the purge flow rate by executing S370 to S420 during the recirculation stop period determined to be in the recirculation stop (negative determination in S360). The purge integrated flow rate Qf is determined on the basis of FL2.

  During the recirculation process (affirmative determination in S360), the ECU 2 executes S480 to estimate the purge gas concentration RB2 by estimating the change state of the purge gas concentration RB2 based on the new air flow amount FL1 and the purge flow rate FL2. It is configured to ask for.

  The fuel evaporative gas detection device 1 according to the second embodiment executes the process of S480 without using the second sensor output S2 affected by the EGR gas during the recirculation process, whereby the fresh air flow amount FL1 and the purge integration are integrated. The purge gas concentration RB2 can be determined by estimation based on the flow rate Qf.

Thus, the fuel evaporative gas detection device 1 can reduce the influence of the EGR gas during the recirculation process, and can reduce the detection error of the purge gas concentration RB2.
[2-4. Correspondence of wording]
Here, the correspondence relationship of words is demonstrated.

  The ECU 2 that executes S340 or S370 to acquire the second sensor output S2 corresponds to a signal reception unit, the ECU 2 that executes S320 corresponds to a recirculation determination unit, and the ECU 2 that executes S330 corresponds to a purge determination unit. The ECU 2 that executes S370, S380, and S480 corresponds to the supply amount calculation unit. The ECU 2 that executes S340 and S350 corresponds to a reference concentration calculation unit.

  S340 or S370 corresponds to the signal reception step, S320 corresponds to the recirculation determination step, S330 corresponds to the purge determination step, and S370, S380 and S480 correspond to the supply amount calculation step.

  The new air flow amount FL1 corresponds to the new air flow amount information, the ECU 2 executing S390 and S440 corresponds to the new air flow amount information acquiring unit, the purge flow rate FL2 corresponds to the evaporative gas flow rate, and the ECU 2 executing S400 and S450 The purge integrated flow rate Qf corresponds to the evaporative gas integrated amount, and the ECU 2 that executes S420 and S470 corresponds to the integrated amount calculating unit.

[3. Third embodiment]
[3-1. Fuel evaporative gas detection processing]
As a third embodiment, a fuel evaporative gas detection device 1 that detects the evaporative gas supply amount (purge gas concentration) using the second sensor output S2 of the second intake oxygen sensor 5 will be described.

  The fuel evaporative gas detection device 1 of the third embodiment does not use the first sensor output S1 of the first intake oxygen sensor 4 as compared to the first embodiment, but uses the second sensor output S2 of the second intake oxygen sensor 5 The difference is that the amount of evaporative gas supplied (purge gas concentration) is detected using this method. The contents similar to those of the first embodiment in the third embodiment will be described using the same reference numerals, or the descriptions thereof will be omitted.

  The fuel evaporative gas detection device 1 according to the third embodiment differs from the first embodiment in the contents of the fuel evaporative gas detection process executed by the ECU 2. The fuel evaporative gas detection process of the third embodiment will be described based on the flowchart of FIG. 7.

  When the fuel evaporation gas detection process is started, the ECU 2 first determines in S610 (S represents a step) whether or not the oxygen concentration in the atmosphere (the second atmospheric oxygen concentration CA2) has been calculated, and the calculation is completed. An affirmative determination is made in which the process proceeds to S660, and a negative determination is made in the case where the calculation is not performed, and the process proceeds to S620.

  When the ECU 2 makes a negative determination in S610 and proceeds to S620, it determines whether or not the purge valve 18 is in the open state, and in the case of making a positive determination (in the open state), the same step is repeatedly executed, and when the negative determination is made. In the case of the closed state, the process proceeds to step S630.

  When the ECU 2 makes a negative determination in S620 and proceeds to S630, it determines whether or not the EGR valve 23 is in the open state, and proceeds to S620 when making a positive determination (when in the open state), making a negative determination ( If it is in the closed state), the process proceeds to S640.

  When the ECU 2 makes a negative determination in S630 and proceeds to S640, it acquires a sensor output (second sensor output S2) of the second intake oxygen sensor 5. At this time, since both the EGR valve 23 and the purge valve 18 are in the closed state, the exhaust gas and the fuel evaporative gas (purge gas) are not supplied to the intake passage 12, and only the atmosphere passes through. Therefore, the second sensor output S2 at this time indicates a value corresponding to the oxygen concentration of the air passing through the intake passage 12.

  At the next S650, the ECU 2 calculates the oxygen concentration of the atmosphere based on the sensor output acquired at S640. In the third embodiment, the ECU 2 calculates a second atmospheric oxygen concentration CA2 based on the second sensor output S2.

When the process in S650 is completed, the process returns to S610.
When the ECU 2 makes an affirmative determination in S610 and shifts to S655, it determines whether the purge valve 18 is in the open state or not, and when making the affirmative determination (in the open state), proceeds to S660, makes the negative determination (closed If it is in the state), the process proceeds to S656.

  When the ECU 2 makes a negative determination in S610 and shifts to S656, the ECU 2 obtains the second sensor output S2 of the second intake oxygen sensor 5 and calculates the oxygen concentration (second oxygen concentration CS) based on the second sensor output S2. Do.

  The ECU 2 calculates an EGR rate RA2 [%] (sensor) based on the difference between the second atmospheric oxygen concentration CA2 and the second oxygen concentration CS in the next S657. The EGR rate RA2 is a volume ratio of the EGR gas contained in the gas flowing to the intake passage 12. The EGR rate RA2 (sensor) means a value calculated using the second sensor output S2 in the EGR rate RA2.

  When the ECU 2 makes an affirmative determination in S655 and shifts to S660, it determines whether the EGR valve 23 is in the open state or not, and when making the affirmative determination (in the open state), proceeds to S690, makes the negative determination ( If it is in the closed state), the process proceeds to S670. The ECU 2 is configured to determine whether the exhaust gas recirculation process (EGR process) is being performed or is being stopped by executing S660.

  When the ECU 2 makes a negative determination in S660 and shifts to S670, the ECU 2 obtains the second sensor output S2 of the second intake oxygen sensor 5 and calculates the oxygen concentration (second oxygen concentration CS) based on the second sensor output S2. Do.

  At this time, the state (open state, closed state) of the purge valve 18 is indefinite, but the second sensor output S2 at this time is the state of the EGR valve 23 and the state of the purge valve 18 (in other words, to the intake path 12 It changes according to the supply amount of purge gas.

  The ECU 2 calculates the concentration of the purge gas (purge gas concentration RB3 [%]) supplied to the intake passage 12 based on the above [Equation 3] in the next S680, as in S380 of the second embodiment.

When the ECU 2 makes an affirmative determination in S660 and proceeds to S690, it calculates the flow rate of the EGR gas (EGR flow rate FL3 [m ³ / s]) flowing through the EGR valve 23 in the EGR gas path 21 The flow rate (fresh air flow amount FL4) of fresh air (atmosphere) flowing in the region upstream of the supply unit 12a is detected, and the EGR rate RA2 [%] (model) is calculated based on [Equation 6]. The EGR rate RA2 is a volume ratio of the EGR gas contained in the gas flowing to the intake passage 12. The EGR rate RA2 (model) means a value calculated using the EGR flow rate FL3 and the fresh air flow rate FL4 in the EGR rate RA2.

FL3 is the EGR flow rate, and FL4 is the fresh air flow rate. The EGR flow rate FL3 and the new air flow rate FL4 detected at this time are volumetric flow rates (volumes of gas flowing per unit time), and the unit is [m ³ / s].

  Although not shown in FIG. 1, the internal combustion engine 11 is provided with a mass flow sensor on the downstream side of the air cleaner in the upstream region of the intake passage 12. The ECU 2 detects the fresh air flow amount FL4 based on the flow rate signal from the mass flow sensor.

  The ECU 2 calculates the EGR flow rate FL3 used in [Equation 6] based on [Equation 7]. The EGR flow rate FL3 can be calculated by a general calculation method using a pressure difference (differential pressure) before and after the valve based on Bernoulli's theorem. In the present embodiment, the EGR flow rate FL3 is calculated based on [Equation 7].

Cd is a predetermined coefficient, Aeg is a cross-sectional area [m ² ] of the EGR valve 23, Pin is an EGR valve inlet pressure [Pa], Pout is an EGR valve outlet pressure [Pa], ρeg is the density [kg / m ³ ] of the purge gas.

  The ECU 2 calculates the purge gas concentration RB3 [%] based on [Equation 8] in the next S700.

  CA2 is the second atmospheric oxygen concentration CA2 calculated in S650, CS is the second oxygen concentration CS calculated in S670, and K1 is a predetermined coefficient. The coefficient K1 is a proportionality constant determined in accordance with the characteristics of the second intake oxygen sensor 5.

  When S680 or S700 is completed, the ECU 2 proceeds to S710 to determine whether the detection of the purge gas concentration RB3 is completed. When the determination is affirmative, the fuel evaporative gas detection process is ended, and when it is determined negative. It transfers to S660 again. In S710 of the present embodiment, it is determined that the detection is completed, for example, at the end of the operation of the internal combustion engine, at the occurrence of an abnormality of the internal combustion engine, or at the occurrence of an abnormality of the fuel evaporative gas detection device 1.

  As described above, in the fuel evaporative gas detection process of the third embodiment, calculation of the second atmospheric oxygen concentration CA2 is executed (affirmative determination in S610) and the EGR valve 23 is closed (No in S660) In the determination), the purge gas concentration RB3 is calculated using the second sensor output S2 (S670, S680). In the fuel evaporative gas detection process of the third embodiment, calculation of the second atmospheric oxygen concentration CA2 is executed (affirmative determination in S610) and the EGR valve 23 is in the open state (affirmative determination in S660) The purge gas concentration RB3 is calculated using the EGR rate RA2 (S690, S700).

[3-2. Change state of each part]
Next, the change state of each part in the internal combustion engine 11 of the third embodiment will be described using the time chart shown in FIG.

  In the time chart shown in FIG. 8, the internal combustion engine 11 is started at time t20, and the purge permission flag Fp is turned on at time t21 when the operating condition of the internal combustion engine 11 (cooling water temperature, lubricating oil temperature, etc.) satisfies predetermined conditions. It is set to the state.

  After starting the internal combustion engine 11, the ECU 2 executes the above-described S640 and S650 during the period in which the purge permission flag Fp is set to the OFF state (during the period from time t20 to time t21 in FIG. 8). , The second atmospheric oxygen concentration CA2 is calculated.

  When the purge permission flag Fp is set to the ON state, the ECU 2 executes a purge valve control process to control the state (opened state, closed state) of the purge valve 18. In FIG. 8, the purge valve 18 is set to the open state three times during the period from time t21 to time t22, and along with this, the second oxygen concentration CS fluctuates, and according to the calculation result in S680. The purge gas concentration RB3 fluctuates.

  When the EGR permission flag Fe is set to the ON state, the ECU 2 executes the EGR control process to control the state (opened state, closed state) of the EGR valve 23. In FIG. 8, after time t22, the purge valve 18 is set to the open state once, and the EGR valve 23 is set to the open state twice. Along with this, the second oxygen concentration CS fluctuates, and the purge gas concentration RB3 fluctuates according to the calculation result in S700.

The ECU 2 calculates the total value (final value) of the purge gas concentration RB3 by summing up the respective calculation results (waveforms) at S680 and S700.
[3-3. effect]
As described above, the fuel evaporative gas detection device 1 according to the third embodiment supplies the amount of purge gas supplied to the intake passage 12 (purge gas concentration) in the internal combustion engine 11 configured to supply the EGR gas and the purge gas to the intake passage 12. It is configured to detect RB3).

The fuel evaporative gas detection device 1 includes an ECU 2 that executes a fuel evaporative gas detection process.
The ECU 2 acquires the second sensor output S2 of the second intake oxygen sensor 5 by executing S640 and S670 of the fuel evaporation gas detection process. The second sensor output S2 corresponds to an oxygen concentration signal corresponding to the oxygen concentration in the portion downstream of the EGR gas supply unit 12a and the purge gas supply unit 12b in the intake passage 12.

  The ECU 2 executes S650 and S670 of the fuel evaporation gas detection process to calculate the second atmospheric oxygen concentration CA2 and the second oxygen concentration CS based on the second sensor output S2.

  Since the oxygen concentration in the portion downstream of the EGR gas supply unit 12a and the purge gas supply unit 12b in the intake passage 12 changes at least in accordance with the evaporative gas supply amount (purge gas concentration), the ECU 2 outputs the second sensor output S2. The evaporative gas supply amount can be calculated based on the above.

  Since the fuel evaporative gas detection device 1 includes the ECU 2 (specifically, the ECU 2 that executes S650 and S670) that calculates the evaporative gas supply amount (purge gas concentration) based on the second sensor output S2, the evaporative gas supply amount is The detection can be properly performed, and the detection error of the evaporation gas supply amount can be reduced.

  Next, the ECU 2 is configured to determine whether or not the exhaust gas recirculation process (EGR process) in which the exhaust gas (EGR gas) is supplied to the intake passage 12 is being executed by executing S620. ing. The ECU 2 is configured to determine whether or not the purge process (fuel evaporative gas) is being supplied to the intake passage 12 is being performed by executing S630.

  After the internal combustion engine 11 is started, the ECU 2 executes S640 and S650 when it is determined in S620 that the exhaust gas recirculation process is stopped and in S630 it is determined that the purge process is stopped. The reference concentration (second atmospheric oxygen concentration CA2) of the intake passage 12 is calculated based on the sensor output S2.

  The ECU 2 executes S 670 and S 680 during the recirculation stop period in which it is determined that the EGR processing is stopped (during the period determined to be negative in S 660), the reference concentration (second atmospheric oxygen concentration CA 2) The evaporation gas supply amount (purge gas concentration RB3) is calculated based on the oxygen concentration signal (second sensor output S2).

  Since the oxygen concentration in the intake passage 12 is not affected by the exhaust gas (EGR gas) during the recirculation stop period (in other words, during the stop of the exhaust gas recirculation process), the influence of the fuel evaporative gas (purge gas) Change is likely to occur. For this reason, the fuel evaporative gas detection device 1 of the third embodiment is based on the second atmospheric oxygen concentration CA2 and the second sensor output S2 during the stop of the exhaust gas recirculation processing (during the period of negative determination in S660). By calculating the purge gas concentration RB3, the influence of the exhaust gas (EGR gas) can be suppressed, so the purge gas concentration RB3 can be detected with high accuracy.

  Next, the ECU 2 executes S690 to obtain the EGR rate RA2 (exhaust gas supply rate) based on the new air flow amount FL4 and the EGR flow rate FL3. The ECU 2 is configured to calculate the purge gas concentration RB3 based on the EGR rate RA2 and the second oxygen concentration CS by executing S700 during execution of the EGR process (affirmative determination in S660).

  Since the fuel evaporation gas detection device 1 uses the EGR rate RA2 in the calculation of the purge gas concentration RB3 during the EGR process, the fuel evaporative gas detection device 1 calculates the purge gas concentration RB3 so as to reduce the influence of the EGR gas in the second oxygen concentration CS. be able to. Thus, the fuel evaporative gas detection device 1 can reduce the influence of the EGR gas during the EGR process, and can reduce the detection error of the purge gas concentration RB3.

[3-4. Correspondence of wording]
Here, the correspondence relationship of words is demonstrated.
The ECU 2 that executes S640 or S670 to acquire the second sensor output S2 corresponds to the signal reception unit, the ECU 2 that executes S620 corresponds to the recirculation determination unit, and the ECU 2 that executes S630 corresponds to the purge determination unit. The ECU 2 that executes S670, S680, S690 and S700 corresponds to the supply amount calculation unit. The ECU 2 that executes S640 and S650 corresponds to a reference concentration calculation unit.

  S640 or S670 corresponds to the signal reception step, S620 corresponds to the recirculation determination step, S630 corresponds to the purge determination step, and S670, S680, S690 and S700 correspond to the supply amount calculation step.

  The new air flow FL4 corresponds to the new air flow information, the ECU 2 that executes S690 to acquire the new air flow FL4 corresponds to the new air flow information acquisition unit, the EGR flow FL3 corresponds to the exhaust gas flow, and S690 is The ECU 2 that executes the operation to acquire the EGR flow rate FL3 corresponds to the exhaust gas flow rate calculation unit.

[4. Other embodiments]
As mentioned above, although embodiment of this indication was described, this indication is not limited to the above-mentioned embodiment, It is possible in the range which does not deviate from the gist of this indication to carry out in various modes.

  For example, in the second and third embodiments, the installation of the first intake oxygen sensor 4 in the internal combustion engine 11 is omitted, and only the second intake oxygen sensor 5 is provided as an oxygen sensor in the intake passage 12. It is also good.

  Further, each numerical value in the map shown in FIG. 5 is an example, and is not limited to these numerical values, and other numerical values may be adopted according to the configuration of the internal combustion engine. The coefficient K1 is not limited to a predetermined fixed value, and may be a variable value. For example, the learning process may be performed based on various state quantities in an actual usage environment, and the value of the coefficient K1 may be changed according to the learning result.

  Next, the function of one component in the above embodiment may be shared by a plurality of components or the function of a plurality of components may be performed by one component. Further, part of the configuration of the above embodiment may be omitted. In addition, at least a part of the configuration of the above-described embodiment may be added to or replaced with the configuration of the other above-described embodiment. In addition, all the aspects contained in the technical thought specified from the wording as described in a claim are an embodiment of this indication.

  In addition to the computer system described above, a host system having the computer system as a component, a program for causing the computer to function as the computer system, a non-transient actual recording medium such as a semiconductor memory storing the program, and a concentration calculation method The present disclosure can also be implemented in various forms.

  DESCRIPTION OF SYMBOLS 1 ... Fuel evaporative gas detection apparatus, 2 ... Electronic control unit (ECU), 4 ... 1st intake oxygen sensor, 5 ... 2nd intake oxygen sensor, 8 ... Exhaust oxygen sensor, 9 ... Three-way catalyst, 11 ... Internal combustion engine, 12: Intake path, 12a: EGR gas supply portion, 12b: Purge gas supply portion, 13: Exhaust path, 14: Fuel injection valve (injector), 15: Throttle valve, 16: Canister, 17: Purge gas path, 18: Purge valve, 21 ... EGR gas path, 23 ... EGR valve.

Claims (6)

In an internal combustion engine having a construction in which exhaust gas for exhaust gas recirculation and fuel evaporation gas of a fuel tank are supplied to an intake pipe, fuel evaporation detecting an evaporation gas supply amount which is a supply amount of the fuel evaporation gas to the intake pipe A gas detector,
An exhaust gas supply unit to which the exhaust gas is supplied, and a signal reception unit which receives an oxygen concentration signal according to an oxygen concentration in a portion downstream of the fuel evaporation gas supply unit to which the fuel evaporation gas is supplied. When,
A recirculation determination unit that determines whether the exhaust gas recirculation process, in which the exhaust gas is supplied to the intake pipe, is being performed;
A purge determination unit that determines whether a purge process in which the fuel vapor is supplied to the intake pipe is in progress;
A supply amount calculation unit that calculates the evaporation gas supply amount based on the determination result by the recirculation determination unit, the determination result by the purge determination unit, and the oxygen concentration signal;
A fuel evaporative gas detector comprising: The fuel evaporative gas detection device according to claim 1, wherein
When the recirculation determination unit determines that the exhaust gas recirculation process is stopped and the purge determination unit determines that the purge process is stopped, the reference of the intake pipe based on the oxygen concentration signal A reference density calculation unit that calculates the density;
Equipped with
The supply amount calculation unit is configured to calculate the oxygen concentration signal after the calculation of the reference concentration and during a recirculation stop period determined by the recirculation determination unit to be in the cessation of the exhaust gas recirculation processing. Calculating the evaporative gas supply amount based on the reference concentration;
Fuel evaporative gas detector. The fuel evaporative gas detection device according to claim 2,
A new air flow information acquisition unit for acquiring new air flow information that is the flow rate of the atmosphere supplied to the intake pipe;
An evaporative gas flow rate calculating unit which calculates an evaporative gas flow rate which is a flow rate of the fuel evaporative gas supply unit;
During recirculation processing in which it is determined that the exhaust gas recirculation processing is being performed by the recirculation judgment unit, the accumulated evaporation amount is calculated based on the new air flow rate information and the evaporation gas flow rate, and the recirculation is stopped. During the period, an integrated amount calculation unit for calculating an evaporative gas integrated amount based on the oxygen concentration signal, the new air flow amount information, and the evaporative gas flow rate;
Have
The supply amount calculation unit determines the supply amount of the evaporation gas by estimating a change state of the supply amount of the evaporation gas based on the accumulated amount of evaporation gas and the information on the amount of fresh air flow during the recirculation process. ,
Fuel evaporative gas detector. The fuel evaporative gas detection device according to claim 2,
A new air flow information acquisition unit for acquiring new air flow information that is the flow rate of the atmosphere supplied to the intake pipe;
An exhaust gas flow rate calculating unit which calculates an exhaust gas flow rate which is a flow rate of the exhaust gas supply unit;
Have
The supply amount calculation unit determines an exhaust gas supply rate based on the new air flow amount information and the exhaust gas flow rate, and the recirculation determination unit is determining that the exhaust gas recirculation process is being performed. Calculating the evaporative gas supply amount based on the exhaust gas supply rate and the oxygen concentration signal.
Fuel evaporative gas detector. The fuel evaporative gas detection device according to claim 1, wherein
The exhaust gas supply unit is provided upstream of the fuel evaporative gas supply unit in the intake pipe,
The fuel evaporative gas detection device
An intermediate signal receiving unit for receiving an intermediate oxygen concentration signal corresponding to an oxygen concentration between the exhaust gas supply unit and the fuel evaporation gas supply unit in the intake pipe;
When the recirculation determination unit determines that the exhaust gas recirculation process is stopped and the purge determination unit determines that the purge process is stopped, the reference of the intake pipe based on the oxygen concentration signal A reference density calculation unit that calculates the density;
Equipped with
The supply amount calculation unit calculates the evaporation gas supply amount based on the reference concentration, the oxygen concentration signal, and the intermediate oxygen concentration signal.
Fuel evaporative gas detector. In an internal combustion engine having a construction in which exhaust gas for exhaust gas recirculation and fuel evaporation gas of a fuel tank are supplied to an intake pipe, fuel evaporation detecting an evaporation gas supply amount which is a supply amount of the fuel evaporation gas to the intake pipe A gas detection method,
A signal receiving step of receiving an oxygen concentration signal corresponding to an oxygen concentration in a portion downstream of the exhaust gas supply unit to which the exhaust gas is supplied and the fuel evaporation gas supply unit to which the fuel evaporation gas is supplied in the intake pipe; When,
A recirculation determination step of determining whether an exhaust gas recirculation process is being performed in which the exhaust gas is supplied to the intake pipe;
A purge determination step of determining whether a purge process in which the fuel evaporative gas is supplied to the intake pipe is in progress; a determination result of the recirculation determination step; a determination result of the purge determination step; A supply amount calculation step of calculating the evaporation gas supply amount based on a signal;
A fuel evaporative gas detection method comprising:

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