阅读说明：本技术 催化器劣化诊断方法及催化器劣化诊断系统 (Catalyst deterioration diagnosis method and catalyst deterioration diagnosis system ) 是由 冈本拓 中曾根修 门奈广祐 于 2019-09-02 设计创作，主要内容包括：本发明提供一种催化器劣化诊断方法及催化器劣化诊断系统。该催化器劣化诊断方法能够基于通过催化器后的废气中的NOx浓度高精度地进行催化器劣化诊断。催化器劣化诊断方法用于包括气体传感器(702)的系统,该气体传感器(702)测定从催化器(601)通过的废气的空燃比及氮氧化物浓度,且具有氨干扰性。当通过气体传感器(702)最新得到的空燃比大于预先确定的比理论空燃比大的临界空燃比的情况下,燃料喷射装置(501)在燃料切断后恢复燃料喷射时,开始监测由气体传感器(702)检测出的氮氧化物浓度的暂时增大,由此取得氮氧化物浓度的暂时增大量。判定暂时增大量是否大于临界量。(The invention provides a catalyst deterioration diagnosis method and a catalyst deterioration diagnosis system. The catalyst deterioration diagnosis method can perform the catalyst deterioration diagnosis with high accuracy based on the NOx concentration in the exhaust gas after passing through the catalyst. A catalyst deterioration diagnosis method is used for a system including a gas sensor (702), and the gas sensor (702) measures the air-fuel ratio and the nitrogen oxide concentration of exhaust gas passing through a catalyst (601) and has ammonia interference. When the air-fuel ratio newly obtained by the gas sensor (702) is larger than a predetermined critical air-fuel ratio larger than the theoretical air-fuel ratio, the fuel injection device (501) starts monitoring the temporary increase in the concentration of nitrogen oxides detected by the gas sensor (702) when the fuel injection is resumed after the fuel cut, thereby obtaining the temporary increase in the concentration of nitrogen oxides. It is determined whether the temporary increase amount is larger than the threshold amount.)

1. A catalyst deterioration diagnosis method that is a catalyst deterioration diagnosis method for a system that includes: an internal combustion engine having a fuel injection device; a catalyst into which exhaust gas from the internal combustion engine is introduced; and a gas sensor that measures an air-fuel ratio and a nitrogen oxide concentration of the exhaust gas passing through the catalyst and has ammonia interference,

the catalyst deterioration diagnosis method is characterized by comprising the following steps:

a step of starting monitoring a temporary increase in the concentration of nitrogen oxides detected by the gas sensor when the fuel injection device resumes fuel injection after fuel cut when an air-fuel ratio newly obtained by the gas sensor is larger than a predetermined critical air-fuel ratio larger than a theoretical air-fuel ratio, thereby obtaining a temporary increase amount of the concentration of nitrogen oxides; and

and a step of determining whether or not the temporary increase amount is larger than a threshold amount.

2. The catalyst degradation diagnostic method according to claim 1,

the catalyst is a three-way catalyst.

3. The catalyst degradation diagnostic method according to claim 1 or 2,

the critical air-fuel ratio is greater than 50.

4. The catalyst degradation diagnostic method according to any one of claims 1 to 3,

the temporary increase in the concentration of nitrogen oxides detected by the gas sensor is monitored only during a period in which the air-fuel ratio obtained by the gas sensor is lean with respect to stoichiometry.

5. The catalyst degradation diagnostic method according to any one of claims 1 to 4,

the system is a vehicle comprising a step-variable transmission or a continuously variable transmission connected to the internal combustion engine,

when the air-fuel ratio newly obtained by the gas sensor is larger than the threshold air-fuel ratio, the fuel injection device starts monitoring a temporary increase in the concentration of nitrogen oxides detected by the gas sensor when fuel injection is resumed after a fuel cut, following a downshift of the stepped transmission or a simulated downshift of the continuously variable transmission during deceleration of the vehicle.

6. The catalyst degradation diagnostic method according to any one of claims 1 to 5,

the system is a vehicle, and the catalyst degradation diagnosis method further includes: and a step of setting the threshold amount based on a state of the vehicle when the step of obtaining the temporary increase amount is performed.

7. The catalyst degradation diagnostic method according to any one of claims 1 to 6,

the system is a vehicle, and starts monitoring of a temporary increase in the concentration of nitrogen oxides detected by the gas sensor only when the state of the vehicle is included in a predetermined range.

8. A catalyst deterioration diagnosis system diagnoses a degree of deterioration of a catalyst into which exhaust gas from an internal combustion engine having a fuel injection device is introduced,

the catalyst deterioration diagnosis system is characterized by comprising:

a gas sensor capable of measuring an air-fuel ratio and a nitrogen oxide concentration of the exhaust gas passing through the catalyst and having ammonia interference; and

a control device that operates the internal combustion engine,

the control device includes:

a fuel injection control unit that controls an operation of the fuel injection device;

an air-fuel ratio determination unit that determines whether or not an air-fuel ratio obtained by the gas sensor is greater than a predetermined critical air-fuel ratio that is greater than a theoretical air-fuel ratio;

a monitoring unit that starts monitoring a temporary increase in the concentration of nitrogen oxide detected by the gas sensor when the fuel injection control unit instructs the fuel injection device to resume fuel injection after fuel cut if the latest determination result obtained by the air-fuel ratio determination unit as to whether the air-fuel ratio obtained by the gas sensor is greater than the threshold air-fuel ratio is that the air-fuel ratio obtained by the gas sensor is greater than the threshold air-fuel ratio; and

an increase amount determination unit that determines whether or not the temporary increase amount acquired by the monitoring unit is greater than a threshold amount.

9. The catalyst degradation diagnostic system according to claim 8,

the catalyst is a three-way catalyst.

10. The catalyst degradation diagnostic system according to claim 8 or 9,

the critical air-fuel ratio is greater than 50.

11. The catalyst degradation diagnosis system according to any one of claims 8 to 10,

the monitoring unit monitors a temporary increase in the concentration of nitrogen oxide detected by the gas sensor only during a period in which the air-fuel ratio obtained by the gas sensor is lean with respect to the stoichiometric ratio.

12. The catalyst degradation diagnosis system according to any one of claims 8 to 11,

the catalyst deterioration diagnosis system is used for a vehicle having a stepped transmission or a continuously variable transmission,

the monitoring portion starts monitoring a temporary increase in the concentration of nitrogen oxides when the fuel injection device resumes fuel injection after a fuel cut in accordance with a downshift of the stepped transmission or a simulated downshift of the continuously variable transmission during deceleration of the vehicle when the latest determination result obtained by the air-fuel ratio determination portion as to whether the air-fuel ratio obtained by the gas sensor is greater than the threshold air-fuel ratio is that the air-fuel ratio obtained by the gas sensor is greater than the threshold air-fuel ratio.

13. The catalyst degradation diagnosis system according to any one of claims 8 to 12,

the catalyst deterioration diagnosis system is used for a vehicle,

the control device includes a threshold amount setting unit that sets the threshold amount based on a state of the vehicle when the monitoring unit acquires the temporary increase amount.

14. The catalyst degradation diagnosis system according to any one of claims 8 to 13,

the catalyst deterioration diagnosis system is used for a vehicle,

the monitoring unit operates only when the state of the vehicle is included in a predetermined range.

Technical Field

The present invention relates to a catalyst deterioration diagnosis method and a catalyst deterioration diagnosis system, and more particularly to a catalyst deterioration diagnosis method and a catalyst deterioration diagnosis system for a catalyst into which exhaust gas from an internal combustion engine is introduced.

Background

Exhaust gas containing harmful substances, namely, NOx (nitrogen oxides), THC (total hydrocarbons) and CO (carbon monoxide), is discharged from a gasoline engine. A Three-Way Catalyst (TWC) which is a Catalyst in which these 3 kinds of substances are removed together is mounted on many gasoline-powered vehicles. The three-way catalyst has a honeycomb body. The honeycomb body mainly has: containing CeO₂A ceramic portion of (ceria), and a portion containing a noble metal such as Pt (platinum), Pd (palladium), and Rh (rhodium). Pt and Pd are mainly used for converting HC and CO into CO by oxidation₂(carbon dioxide) and H₂O (water). Rh is mainly used to reduce NOx. Use of cerium oxide for reacting O₂(oxygen) adsorption or desorption.

TWCs for gasoline engines need to accumulate oxygen required for oxidation of HC and CO when the oxygen content in exhaust gas is high. This is because: gasoline engines operate on a stoichiometric center, so the exhaust gas from a gasoline engine is generally of a lower oxygen content than the exhaust gas from a diesel engine.

The stoichiometric operation means that the Air-Fuel ratio, i.e., a/F (Air/Fuel: Air/Fuel) is about 14.6. In this case, the amount of air introduced into the cylinder is set on the assumption that the fuel introduced into the cylinder of the engine is completely combusted. Specifically, the amount of air introduced into the cylinder is set assuming that C (carbon) and H (hydrogen) are completely oxidized by complete combustion. In actual operation, a/F was finely adjusted around 14.6. The state of relatively high a/F is referred to as lean, and the exhaust gas from the engine contains relatively much oxygen. The opposite state is called over-rich. In a gasoline engine, a lean state and an over-rich state are precisely controlled around a stoichiometric state.

The NOx purification performance of the TWC is relatively high in the rich operation (reducing atmosphere) and relatively low in the lean operation (oxygen-excess atmosphere). This is because: during the rich operation, the oxygen content in the exhaust gas is low, and therefore NOx is easily reduced. On the other hand, the purification performance of the TWC for HC and CO is relatively high in the lean operation and relatively low in the over-rich operation. This is because: during lean operation, HC and CO are easily oxidized because the oxygen content in the exhaust gas is high. There are various cases where the purifying performance of the TWC deteriorates, and the main deterioration modes are: the overall purification efficiency decreases in the case of over-concentration and under-concentration, the purification efficiency decreases in the case of over-concentration, and the like.

In recent years, in vehicles (typically automobiles), OBD (On-Board Diagnostics) is sometimes performed in accordance with the requirements of laws and regulations. According to the OBD, a failure diagnosis is performed using a function provided to the vehicle itself. In case a malfunction is detected, the driver may be warned.

OBD of TWC can be performed by, for example, OSC method (Oxygen Storage Capacity). In the OSC method, O provided on the upstream side and the downstream side of the TWC is used₂The sensor indirectly measures the specific surface area of the ceria in the TWC. On the upstream side of the TWC, in other words, between the engine and the TWC, a limiting current type a/F (Air/Fuel) sensor, which is a kind of O, is generally provided in order to measure the Air-Fuel ratio₂A sensor. On the downstream side of the TWC, in other words, between the TWC and the exhaust port, O of a voltage type is usually provided₂A sensor.

In the OSC method, a change from the stoichiometric state to each of the lean state and the over-rich state is made larger than usual. If the engine is in a lean state, the oxygen concentration in the exhaust gas rises, and the concentration change starts to pass through O on the upstream side of the TWC₂The sensor detects it immediately. At this time, O on the downstream side of TWC₂The sensor still detects a stoichiometric condition or an over-rich condition. This is because: ceria in TWC adsorbs oxygen in the exhaust gas. Since the amount of oxygen that can be adsorbed by ceria is limited, if the lean state of the engine continues for a whileO on the downstream side of TWC₂The sensor also begins to detect a lean condition. Then, if the engine is in an over-rich state, the change is passed through O on the upstream side of the TWC₂The sensor detects the signal immediately. At this time, O on the downstream side of TWC₂The sensor still detects a lean condition. This is because: ceria in TWC releases oxygen. Since the amount of oxygen released from ceria is limited, if the rich condition of the engine continues for a while, O on the downstream side of TWC₂The sensor also begins to detect an over-rich condition. Then, the engine is in a lean state again. In such an engine, while the state of the engine is repeatedly changed between the lean state and the over-rich state, O on the upstream side is detected₂Sensor and downstream side O₂The detection result of over-rich/lean differs between the sensors. From this time and the gas flow rate, the maximum value of the oxygen storage amount of ceria is estimated. Based on this estimation, it is determined whether the OSC of ceria has deteriorated. When it is determined that the OSC of ceria is deteriorated, the OBD obtains a diagnosis result that the TWC is deteriorated.

In TWC, deterioration of the ceria portion and deterioration of the noble metal portion do not necessarily occur to the same extent. Ceria is a promoter and the purification of harmful substances (particularly NOx) is mainly performed by noble metals, and therefore, in order to perform the deterioration diagnosis of TWC with high accuracy, it is desired to evaluate the deterioration of noble metal portions more accurately. According to the OSC method described above, the measurement is performed with respect to the ceria portion, but not with respect to the noble metal portion. Thereby, the error of the estimation of the performance of the TWC, particularly the NOx purification rate, is likely to increase.

In addition, the OSC method is susceptible to O on the upstream side and the downstream side of the TWC₂The influence of measurement errors due to the deterioration of the sensor. In particular, O on the downstream side of the TWC₂When the sensor is of a voltage type, hydrogen or the like adheres to the sensor electrode, and thus the determination of rich/lean may vary. This deviation is easily affected by the composition of gasoline or engine oil, and therefore it is difficult to cope with the deviation by correction. The determination error of over-rich/lean directly causes the diagnosis error of the OSC methodAnd (4) poor. Further, due to the influence of hydrogen or the like generated in the TWC, O may be generated on the downstream side₂The sensor makes a determination that the bias toward over-rich is present. In addition, if the engine is stopped for a long period of time, a large amount of CO is generated₂Adsorption to for O₂The site of (1). After engine start, if with the CO₂The diagnosis is started in a state where the deviation is insufficient, and the diagnosis error increases. Further, when the intake air amount of the engine is increased, the proportion of oxygen in the intake air that is not adsorbed by ceria increases, and therefore there is a possibility that the estimation error of the OSC increases. This situation is particularly problematic when EGR (Exhaust Gas Recirculation) is used. O is₂The adsorption ratio reduction of (b) is also affected by the exhaust gas temperature, which may also cause an estimation error of the OSC.

In the OSC method, there is a limited chance of satisfying conditions suitable for diagnosis (for example, the intake air amount, the temperature of the exhaust gas, and the engine speed). Specifically, if a state in which the engine speed is high to some extent and the speed is substantially constant (for example, 60km/h to 90km/h) does not continue for some extent, the diagnosis cannot be performed with sufficient accuracy. On the other hand, for example, IUPR (In Use Monitor performance: ratios) is sometimes recommended, that is, when 10 runs are performed, diagnosis is appropriately performed In 3 or more runs. The OSC method may not satisfy the required IUPR.

As a method for solving the above problems, a method of more directly evaluating the purification performance is considered. Specifically, it is considered to estimate the degree of purification of NOx by measuring the amount of NOx on the downstream side of the TWC.

According to japanese patent application laid-open No. 2010-1781 (patent document 1), the valve overlap is changed in order to change the NOx concentration in the exhaust gas supplied to the TWC. Then, deterioration of the catalyst is determined based on the overlap amount at the time when the output from the sensor on the downstream side of the TWC reaches the predetermined value. Thus, in this method, engine control for OBD is executed separately from the driving operation of the driver. In other words, active OBD is performed. From the viewpoint of drivability, active OBD is not preferable. In addition, the operating state (intake air amount, exhaust gas temperature, engine speed, and the like) to which the active OBD can be applied is considerably limited, and thus, the opportunity to perform diagnosis is also considerably limited. Thus, other OBD methods are desirable.

According to japanese patent laid-open No. 2012-219740 (patent document 2), a purification performance evaluation method of a catalyst is disclosed. Specifically, when the air-fuel ratio of the atmosphere in which the catalyst is placed is lean and the catalyst is in a predetermined temperature range in which the catalytic activity is exhibited, the engine is operated so as to supply exhaust gas whose air-fuel ratio is excessively rich to the catalyst. In this state, the NOx purification rate, which is the time rate of change of the NOx concentration decrease amount on the downstream side of the catalyst, is determined. Further, an integrated value of the NOx concentration decrease amount in a predetermined period, that is, an NOx purification amount is obtained. The deterioration of the catalyst was evaluated based on the NOx purification rate and the NOx purification amount. In this method, the NOx concentration is detected by a NOx sensor.

Japanese patent application laid-open No. 2004-138486 (patent document 3) discloses an NOx sensor capable of detecting an air-fuel ratio in addition to an NOx concentration. The NOx sensor has a laminated structure including zirconia as a solid electrolyte having oxygen ion conductivity. The laminated structure is provided with a first chamber and a second chamber disposed on the downstream side of the first chamber. A pump electrode having low reducibility against NOx is formed on a surface facing the first chamber so as to remove O₂And the air-fuel ratio is detected. The air-fuel ratio is calculated based on the pumped oxygen amount of the electrode. A pump electrode having high reducibility against NOx is formed on a surface facing the second chamber so as to detect NOx.

Disclosure of Invention

The NOx sensor widely used in automobiles described in the above-mentioned Japanese patent application laid-open No. 2004-138486 is usually NH₃And (4) interference. Typically: in the first chamber of the sensor, NH₃The NOx concentration becomes NO and the NO is detected in the second chamber of the sensor, whereby the NOx concentration is detected excessively high. In catalysts for purifying exhaust gases, in particular three-way catalysts (TWC), it is known that NH may be generated₃(Ammonia). Thus, in the catalyst performance evaluation method described in japanese patent application laid-open No. 2012-219740, there is a possibility that NH may be mixed into the exhaust gas after passing through the catalyst₃. NH is mixed in the NOx sensor pair₃In the case of detecting the NOx concentration of the exhaust gas, NH is generated by the NOx sensor₃The noise may reduce the detection accuracy of the NOx concentration. Thus, it is difficult to evaluate the performance degradation caused by the deterioration of the catalyst with high accuracy.

The present invention has been made to solve the above-described problems, and an object thereof is to provide a catalyst deterioration diagnosis method and a catalyst deterioration diagnosis system that can perform a catalyst deterioration diagnosis with high accuracy based on the NOx concentration in the exhaust gas after passing through the catalyst.

The catalyst deterioration diagnosis method of the present invention is applied to a system including: an internal combustion engine having a fuel injection device; a catalyst into which exhaust gas from the internal combustion engine is introduced; and a gas sensor that measures an air-fuel ratio and a nitrogen oxide concentration of the exhaust gas passing through the catalyst and has ammonia interference. The catalyst deterioration diagnosis method includes the following steps. When the air-fuel ratio newly obtained by the gas sensor is larger than a predetermined critical air-fuel ratio larger than the stoichiometric air-fuel ratio, the fuel injection device starts monitoring the temporary increase in the concentration of nitrogen oxide detected by the gas sensor when the fuel injection is resumed after the fuel cut, thereby acquiring the temporary increase in the concentration of nitrogen oxide. It is determined whether the temporary increase amount is larger than the threshold amount.

The catalyst deterioration diagnosis system of the present invention is used for diagnosing the degree of deterioration of a catalyst into which exhaust gas from an internal combustion engine having a fuel injection device is introduced. The catalyst deterioration diagnosis system includes: a gas sensor and a control device. The gas sensor can measure the air-fuel ratio and the nitrogen oxide concentration of the exhaust gas passing through the catalyst, and has ammonia interference. The control device operates the internal combustion engine. The control device has: an air-fuel ratio determination unit, a fuel injection control unit, a monitoring unit, and an increase amount determination unit. The fuel injection control unit controls the operation of the fuel injection device. The air-fuel ratio determination unit determines whether or not the air-fuel ratio obtained by the gas sensor is greater than a predetermined critical air-fuel ratio that is greater than the stoichiometric air-fuel ratio. When the latest determination result as to whether or not the air-fuel ratio obtained by the gas sensor is greater than the critical air-fuel ratio is obtained by the air-fuel ratio determination unit, and the air-fuel ratio obtained by the gas sensor is greater than the critical air-fuel ratio, the fuel injection control unit instructs the fuel injection device to resume fuel injection after fuel cut, and the monitoring unit starts monitoring the temporary increase in the concentration of nitrogen oxides detected by the gas sensor, thereby obtaining the temporary increase in the concentration of nitrogen oxides. The increase amount determination unit determines whether or not the temporary increase amount acquired by the monitoring unit is larger than a threshold amount.

Effects of the invention

According to the present invention, the catalyst deterioration diagnosis can be performed with high accuracy based on the NOx concentration in the exhaust gas after passing through the catalyst. The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

Drawings

Fig. 1 is a diagram schematically showing a configuration of a vehicle according to an embodiment of the present invention.

Fig. 2 is a flowchart schematically showing a catalyst deterioration diagnosis method of the embodiment of the invention.

Fig. 3 is a flowchart schematically showing a step of acquiring a temporary increase amount of the NOx concentration in the catalyst deterioration diagnosis method according to the embodiment of the present invention.

FIG. 4 is a graph showing, for the first period, the speed, the rotation speed, the actual NOx discharge amount, the air-fuel ratio, and the actual NH in the experiment in which the vehicle was used₃Graph of the measurement result of the discharge amount.

FIG. 5 shows the speed, the number of revolutions, the actual NOx emission amount, and the NOx emission amount in the second period in the experiment in which the vehicle was used,Air-fuel ratio, and actual NH₃Graph of the measurement result of the discharge amount.

FIG. 6 shows the speed, the rotation speed, the actual NOx discharge amount, the air-fuel ratio, and the actual NH in an experiment in which the vehicle was used for the third period₃Graph of the measurement result of the discharge amount.

Fig. 7 is a graph showing the correlation between the actual NOx discharge amount and the aging time of the catalyst in an experiment in which the vehicle was used.

Description of the symbols

An ECU (control device) 100 …, a 110 … air-fuel ratio determining portion, a 120 … fuel injection control portion, a 130 … monitoring portion, a 140 … shift control portion, a 150 … increase amount determining portion, a 160 … threshold amount setting portion, a 170 … storage portion, a 180 … diagnosing portion, a 190 … vehicle state detecting portion, a 200 … display portion, a 300 … accelerator pedal, a 400 … stepped transmission, a 500 … gasoline engine (internal combustion engine), a 501 … fuel injection device, a 601 … c (catalyst), a 602 tw 602 … additional catalyst, a 701 … air-fuel ratio sensor, a 702 … gas sensor, and a 800 … acceleration detector.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(constitution)

Fig. 1 is a diagram schematically showing a configuration of a vehicle (system) according to the present embodiment. In the present embodiment, the vehicle is an automobile driven by the driver DR. The automobile is provided with: a gasoline engine 500 (internal combustion engine) having a fuel injection device 501, a step-variable transmission 400 connected to the gasoline engine 500, a TWC601 (catalyst), and a catalyst deterioration diagnosis system described later.

The vehicle may further include: an accelerator pedal 300 (driving operation device) operated by a driver DR, an additional catalyst 602, an air-fuel ratio sensor 701, and an acceleration detector 800. The accelerator pedal 300 is operated by a driver DR to operate the vehicle. The additional catalyst 602 is disposed downstream of the TWC 601. The additional catalyst 602 is: such as TWC, GPF (Gasoline Particulate Filter) or SCR (Selective catalytic reduction). The air-fuel ratio sensor 701 is disposed between the gasoline engine 500 and the TWC 601. The air-fuel ratio sensor 701 is mainly used to control the gasoline engine 500. The acceleration detector 800 is a device for detecting the acceleration of the vehicle. The acceleration detector 800 is an arbitrary device that measures a physical quantity by which the acceleration can be finally calculated. Note that this calculation process may be performed outside the acceleration detector 800 or may be performed in the catalyst deterioration diagnosis system. Preferably, the acceleration detector 800 is an acceleration sensor that can detect a value corresponding to the acceleration by itself.

The catalyst deterioration diagnosis system is used to diagnose the degree of deterioration of the TWC601 into which exhaust gas from the gasoline engine 500 is introduced. The catalyst deterioration diagnosis system includes: an ECU (Electronic Control Unit)100 (Control device), and a gas sensor 702. The catalyst deterioration diagnosis system may further have a display portion 200. The display section 200 is: such as a lamp or a display device.

The gas sensor 702 can measure the air-fuel ratio and NOx concentration of the exhaust gas passing through the TWC 601. Gas sensor 702 has NH for NOx concentration determination₃Interference. Specifically, if NH is mixed in the gas detected by gas sensor 702₃The detection value of the NOx concentration is mistaken for a larger value. Having NH₃The interference may be due to NH₃To NOx (typically NO) by oxidation reactions within the sensor. This oxidation reaction may occur particularly in an electrode containing a noble metal (e.g., Pt) in the gas sensor 702.

As a typical example, the gas sensor 702 has a laminated structure including zirconia as a solid electrolyte having oxygen ion conductivity. The laminated structure is provided with a first chamber and a second chamber disposed on the downstream side of the first chamber. A first pump electrode (e.g., an electrode containing Pt) having low reducibility with respect to NOx is provided on a surface facing the first chamber so as to remove O₂And the air-fuel ratio is detected. The air-fuel ratio is calculated based on the pumping oxygen amount of the first pump electrode. A second pump having high reducibility against NOx is provided on a surface facing the second chamberAn electrode (e.g., an electrode containing Rh). The NOx concentration is detected based on the pumping oxygen amount of the second pump electrode. The second pump electrode has a higher reducibility against NOx than the first pump electrode. In addition, O in the second chamber may be added to the surface facing the second chamber₂An auxiliary pump electrode (e.g., a Pt-containing electrode) with a reduced concentration.

In the above example, the gas sensor 702 is an amperometric sensor. The current NOx sensor is less susceptible to adsorption of poisoning substances, and particularly suppresses the influence of sulfur poisoning by performing a high-temperature operation. In contrast, for example, electromotive O₂The sensor is prone to errors caused by adsorption of poisoning substances.

The ECU100 operates the gasoline engine 500. The ECU100 has: air-fuel ratio determination unit 110, fuel injection control unit 120, monitoring unit 130, shift control unit 140, increase amount determination unit 150, threshold amount setting unit 160, result storage unit 170, and diagnosis unit 180. In addition, the ECU100 may include a vehicle state detection portion 190.

The ECU100 is constituted by a circuit including at least 1 IC (integrated circuit). The circuit includes at least 1 processor (not shown). Each function of the ECU100 may be realized by a processor executing software. The software is described as a program and stored in a memory (not shown). A memory for storing a program may be included in the ECU100, for example, a nonvolatile or volatile semiconductor memory.

The fuel injection control unit 120 controls the operation of the fuel injection device 501. The shift control unit 140 controls the operation of the stepped transmission 400. The stepped transmission 400 is: and a power transmission mechanism that changes a speed ratio discontinuously.

Air-fuel ratio determination unit 110 determines whether or not the air-fuel ratio obtained by gas sensor 702 is greater than a threshold air-fuel ratio. The critical air-fuel ratio may be a predetermined ratio. The critical air-fuel ratio is larger than the stoichiometric air-fuel ratio (about 14.6 in the present embodiment), and preferably larger than 50. Hereinafter, a state in which the air-fuel ratio is larger than the critical air-fuel ratio is also referred to as a strongly lean state.

The monitoring portion 130 refers to the latest determination result obtained by the air-fuel ratio determination portion 110 as to whether or not the air-fuel ratio obtained by the gas sensor 702 is greater than the threshold air-fuel ratio. When the latest result is that the air-fuel ratio obtained by the gas sensor 702 is larger than the threshold air-fuel ratio, the monitoring unit 130 starts monitoring the temporary increase in the NOx concentration detected by the gas sensor 702 when the fuel injection control unit 120 instructs the fuel injection device 501 to resume the fuel injection after the fuel cut. Thus, the monitoring unit 130 obtains the temporary increase amount of the NOx concentration. The temporary increase amount is, for example, a maximum value (peak value) of the NOx concentration obtained after the start of monitoring.

Preferably, when the latest determination result obtained by air-fuel ratio determination unit 110 is that the air-fuel ratio obtained by gas sensor 702 is greater than the threshold air-fuel ratio, monitoring unit 130 starts monitoring the temporary increase in NOx concentration when fuel injection from fuel injection device 501 is resumed after a fuel cut, following a downshift of stepped transmission 400 during deceleration of the vehicle. Whether or not deceleration is in progress may be determined based on the detection result of the acceleration detector 800.

The monitoring unit 130 may be configured to: the operation is performed only when the state of the vehicle is included in a predetermined range. The vehicle state is acquired by the vehicle state detection unit 190.

Increase amount determination unit 150 determines whether or not the temporary increase amount obtained by monitoring unit 130 is larger than the threshold amount set by threshold amount setting unit 160. The determination result is stored in the result storage unit 170.

The threshold amount setting unit 160 sets the threshold amount used by the increase amount determination unit 150 as described above. Threshold amount setting unit 160 may set the threshold amount by selecting one of a plurality of predetermined amounts. This selection may be performed based on the state of the vehicle when the monitoring unit 130 acquires the temporary increase amount. The vehicle state is acquired by the vehicle state detection unit 190. For example, the larger the fuel injection amount, the higher the threshold amount may be set. In this case, the selection as described above is not necessary, and the threshold amount setting unit 160 may be a memory (storage unit) that holds only one value.

The result storage unit 170 is a memory (storage unit) that stores the determination result obtained by the increase amount determination unit 150. The diagnosis unit 180 diagnoses whether or not the TWC601 is deteriorated beyond the limit based on the determination result stored in the result storage unit 170. In this case, the diagnosis unit 180 may perform statistical processing on the stored determination results as necessary. For example, when the temporary increase amount of the determination results of the predetermined number of times is larger than the threshold amount is equal to or larger than a predetermined ratio, the diagnostic unit 180 diagnoses that the TWC601 is deteriorated beyond the limit.

The vehicle state detection unit 190 is a unit that detects the state of the vehicle. The state of the vehicle may include the state of the gasoline engine 500 such as an intake air amount, a fuel injection amount, an engine speed, an EGR rate, a supercharging pressure (in the case of a turbo engine). Additionally, the vehicle state may include a gear selection state of the step-variable transmission 400. The above state can be detected by a sensor or the like. Alternatively, the above state may be detected with reference to the content of a command generated inside the ECU100, for example, the fuel injection amount may be referred to the output of the fuel injection control portion 120, and the shift position selection state may be referred to the output of the shift control portion 140. The state of the vehicle detected by the vehicle state detecting unit 190 may include states other than those described above, and may include, for example, a speed, an acceleration, a temperature of the TWC601, and the like. The vehicle speed may be detected by a speed detector (not shown). The temperature can be detected by a thermometer (not shown).

(diagnostic method)

Fig. 2 is a flowchart schematically showing a catalyst deterioration diagnosis method using the above catalyst deterioration diagnosis system in the present embodiment.

In step S100, monitoring unit 130 acquires the temporary increase amount of the NOx concentration. Hereinafter, the details of step S100 will be described with reference to fig. 3.

In step S200, threshold amount setting unit 160 sets the threshold amount. Threshold amount setting unit 160 may set the threshold amount by selecting one of a plurality of predetermined amounts. This selection may be performed based on the state of the vehicle when the monitoring unit 130 acquires the temporary increase amount of the NOx concentration. For example, the larger the fuel injection amount, the higher the threshold amount may be set. It should be noted that the threshold amount may be fixed to a value, in which case the selection as described above is not necessary.

In step S300, the increase amount determination unit 150 determines whether or not the temporary increase amount is larger than the threshold amount. In step S400, the result storage unit 170 stores the determination result.

In step S500, the diagnosis unit 180 diagnoses whether or not the TWC601 is deteriorated beyond the limit based on the determination result stored in the result storage unit 170. In this case, the diagnosis unit 180 may perform statistical processing on the stored determination results as necessary. If the number of stored determination results is too small, the process returns from step S500 to step S100, whereby a further determination result can be obtained. The diagnosis result is preferably displayed on the display unit 200 and notified to the driver DR.

In step S100, when the air-fuel ratio newly obtained by the gas sensor 702 is larger than the critical air-fuel ratio, the fuel injection device 501 starts monitoring the temporary increase in the NOx concentration detected by the gas sensor 702 when the fuel injection is resumed after the fuel cut. This results in a temporary increase in the NOx concentration. Fig. 3 is a flowchart schematically showing a process for executing step S100 (fig. 2).

In step S110, the monitoring unit 130 determines whether or not the fuel injection device 501 has performed a fuel cut. In other words, the monitoring portion 130 determines whether the fuel injection control portion 120 instructs a fuel cut. In the case where the fuel cut is not performed, the process returns to step S110. If the fuel cut is performed, the process proceeds to step S120.

In step S120, monitoring unit 130 determines whether fuel injection from fuel injection device 501 is resumed. In other words, the monitoring portion 130 determines whether the fuel injection control portion 120 has resumed the instruction of fuel injection. In the case where the fuel injection is not resumed, the process returns to step S120 itself. In the case where the fuel injection is resumed, the process proceeds to step S130.

In step S130, the monitoring unit 130 causes the air-fuel ratio determination unit 110 to determine whether or not the air-fuel ratio newly obtained by the gas sensor 702 is in a strongly lean state. Thus, monitoring unit 130 determines whether the air-fuel ratio is in a strongly lean state when fuel injection of fuel injection device 501 is resumed. Although the air-fuel ratio changes toward the rich side by the recovery of the fuel injection, it is possible to grasp the air-fuel ratio that is hardly affected by the recovery of the fuel injection by paying attention to whether or not the air-fuel ratio that is newly obtained at the time when the fuel injection is recovered is in a strongly lean state. In the case where the grasped air-fuel ratio is not in a strongly lean state, the process returns to step S110. In the case where the grasped air-fuel ratio is in a strongly lean state, the process proceeds to step S140.

In step S140, the monitoring unit 130 starts monitoring the temporary increase in the NOx concentration detected by the gas sensor 702. Specifically, the monitoring portion 130 is in a state of waiting for a temporary increase in the NOx concentration to occur.

In step S150, the monitoring unit 130 acquires the temporary increase amount of the NOx concentration. The temporary increase was: for example, the maximum value (peak value) of the NOx concentration obtained first after the NOx concentration has temporarily increased is started to wait in step S140.

Preferably limited to: the resumption of fuel injection in step S120 described above is performed in accordance with the downshift of the stepped transmission 400 in deceleration of the vehicle. In this case, when the air-fuel ratio newly obtained by gas sensor 702 is larger than the critical air-fuel ratio, fuel injection device 501 executes step S140 described above when fuel injection is resumed after a fuel cut in accordance with a downshift of stepped transmission 400 during deceleration of the vehicle. Downshifting of the stepped transmission 400 during deceleration of the vehicle is usually accompanied by a fuel cut and recovery of fuel injection after the fuel cut in order to adjust the rotation speed. This makes it easy to obtain a high frequency opportunity to execute step S140 even in a normal operation which is not an operation for the purpose of diagnosis itself.

The step S140 may be executed only when the state of the vehicle is included in a predetermined range. When the state of the vehicle is not included in the prescribed range, the process may return to step S110.

In step S150 described above, the monitoring unit 130 preferably monitors the temporary increase in the NOx concentration detected by the gas sensor 702 only during a period in which the air-fuel ratio obtained by the gas sensor 702 is lean with respect to the stoichiometric value. If the temporary increase amount of the NOx concentration is not obtained during this period, the process may return to step S110.

(experimenting and investigating)

FIGS. 4 to 6 show the speed, the engine speed, the NOx emission amount, the air-fuel ratio, and the NH measured in a running test (bench test) of a vehicle having a TWC601 (FIG. 1)₃A graph showing the temporal change of the discharge amount in the first to third periods. The sampling period of each measurement data is 1 second (half of the horizontal scale), and the obtained data points are connected by a straight line in the graph.

Shown NOx emission and NH₃The discharge amount is obtained not by the gas sensor 702 (fig. 1), but by a gas analyzer provided on the downstream side of the gas sensor 702 for the purpose of experiment. Gas analyzer, unlike gas sensor 702, does not have NH₃Interference. Thus, the gas analyzer can always detect the actual NOx emission amount and the actual NH₃And discharging the amount. It should be noted that NH is not contained in the above₃A disturbing gas analyzer is a measurement device for experiments, and is generally difficult to mount on a general automobile.

4 TWCs 601 subjected to hydrothermal aging treatment for 0h (hour: hour), 2h, 4h, and 10h were prepared, and running experiments were performed on them. For the hydrothermal aging treatment, an electric furnace was used, and 2% of O was mixed in an inert gas₂And 10% of H₂And performing hydrothermal aging treatment at 1000 ℃ in the atmosphere of O. As a vehicle having the TWC601 (fig. 1), an automobile having a 1.4-liter gasoline engine and a 6-speed automatic transmission, that is, "Golf 7", manufactured by the public automobile company in 2014 was used. The TWC601 also uses "Golf 7" certified products. As a driving pattern for driving test, FTP-75 (Federal test procedure-75) by EPA (United states Environmental Protection Agency) was used.

In the curves in the middle of each of fig. 4 to 6, the range between 14.6 (stoichiometry) and about 50 indicates the value of the air-fuel ratio detected by the gas sensor 702. Referring to the middle of fig. 4 to 6, arrows AF1, AF5, and AF11 indicate timings at which the air-fuel ratio increases to 50 or more. Further, the arrow AF2, the arrow AF6, and the arrow AF12 indicate timings at which the air-fuel ratio decreases to less than 50. Further, arrows AF3, AF7, and AF9 indicate timings at which the air-fuel ratio decreases to 14.6 (stoichiometry) or less. Further, the arrows AF4, AF8, and AF10 indicate timings at which the air-fuel ratio exceeds 14.6 (stoichiometry).

Referring to the middle of fig. 4 and 6, timings NE1 to NE4 correspond to: with the downshift in vehicle deceleration, fuel injection device 501 (fig. 1) is at a timing just after the fuel injection is resumed after the fuel cut and before the change to the over-rich state (air-fuel ratio < 14.6). At timings NE1 to NE4, a temporary increase in NOx emission amount is detected. Fig. 7 is a graph showing the correlation between the aging time and the NOx emission amount at each of the timings NE1 to NE 4. From these results, it can be seen that: the peak value of the NOx emission amount is approximately proportional to the aging time at each of the timings NE1 to NE 4.

Referring again to the lower part of FIGS. 4 and 6, NH is applied to each of timings NE1 to NE4₃The discharge amount is substantially zero. Thus, at timings NE 1-NE 4, NH is present even though₃The interfering gas sensor 702 (fig. 1) is not interfered, and can detect an accurate value similar to that of the gas analyzer. Given in the following table: the detection values (ppm) obtained by the gas analyzer at timings NE1 to NE4, and the detection signal (V) from the gas sensor 702 (fig. 1).

TABLE 1

From the above results, it can be seen that: by detecting the NOx emission amount at any of the timings NE1 to NE4 with the gas sensor 702 (fig. 1), a measurement value proportional to the aging time can be obtained. Timings NE1 to NE4 are: with the downshift in vehicle deceleration, fuel injection device 501 (fig. 1) is at a timing just after the fuel injection is resumed after the fuel cut and before the change to the over-rich state (air-fuel ratio < 14.6). Thus, in order to obtain the NOx emissions at the timings NE1 to NE4, the temporary increase in the NOx concentration may be monitored at the timing when the fuel injection from the fuel injection device 501 is resumed after the fuel cut in accordance with the downshift during deceleration of the vehicle. Timings at which the NOx discharge amount reaches the maximum value after the start of monitoring correspond to timings NE1 to NE 4.

After the timing NE3, the air-fuel ratio changes from the lean state to the rich state as indicated by an arrow AF7, and NH is observed as indicated by a bracket HE1 at the lower part of fig. 4₃Is discharged. Thus, in order to use with NH₃The interfering gas sensor 702 detects the NOx concentration with high accuracy, and preferably monitors a temporary increase in the NOx concentration only during the lean state.

Referring to fig. 5, timings Q1 to Q3 also correspond to: the fuel injection device resumes the timing immediately after fuel injection after fuel cut with a downshift in deceleration of the vehicle. The more the proportional relationship between the peak value of the NOx emission amount and the aging time at the timings Q1 through Q3, the less clearly visible at the timings NE1 through NE 4. The reason is considered to be: since the period of fuel cut immediately before the timings Q1 to Q3 is short, the air-fuel ratio is not so large or the time for which the air-fuel ratio is large is short immediately before the timings Q1 to Q3. When the air-fuel ratio is not too large or the time during which the air-fuel ratio is large is short, it is estimated that: in the TWC601 (fig. 1), oxygen is not sufficiently adsorbed in the ceria portion, which results in the decrease in the proportional relationship as described above. From this, it is considered that, in order to improve the proportional relationship between the peak value of the NOx discharge amount and the aging time, the peak value of the NOx discharge amount may be acquired only after a sufficiently large air-fuel ratio is detected. The change in the air-fuel ratio is not instantaneously generated but is continuously generated to some extent, and therefore, it is considered that: if the critical air-fuel ratio is made sufficiently large, oxygen storage will proceed sufficiently even if the time for which the air-fuel ratio is equal to or greater than the critical air-fuel ratio is short. According to the study of the inventors of the present invention, if the critical air-fuel ratio is made larger than 50, the proportional relationship can be significantly improved.

Note that the air-fuel ratio immediately before the timing NE2 (fig. 4) is smaller than the air-fuel ratio immediately before the timings Q1 to Q3 and the like, but the above proportional relationship can be sufficiently obtained at the timing NE 2. The reason is considered to be: the state in which the air-fuel ratio is high immediately before the timing NE2 continues for a certain long time (about 2 seconds). In view of these circumstances, the process of starting monitoring the temporary increase in NOx concentration when the fuel injection is resumed after the fuel cut may be performed in a case where a state where the air-fuel ratio obtained by the gas sensor 702 is greater than the critical air-fuel ratio continues for a predetermined time or longer (for example, about 2 seconds). Consider that: in this case, the critical air-fuel ratio can be set lower while maintaining the diagnostic accuracy.

(Effect)

According to the present embodiment, when the air-fuel ratio newly obtained by the gas sensor 702 is larger than the critical air-fuel ratio, the fuel injection device 501 starts monitoring the temporary increase in the NOx concentration detected by the gas sensor 702 when the fuel injection is resumed after the fuel cut. Then, a temporary increase in the NOx concentration is obtained. This temporary increase amount has a correlation with the deterioration of the TWC 601. Further, by setting the timing to acquire the temporary increase amount of the NOx concentration as described above, the timing to acquire the temporary increase amount of the NOx concentration is deviated from the timing to generate a large amount of NH by the TWC601₃The timing of (1). Thereby, due to NH₃The disturbance of the NOx concentration measurement becomes small, so the NOx concentration can be measured more accurately. Thus, the catalyst deterioration diagnosis can be performed with high accuracy based on the NOx concentration in the exhaust gas after passing through the TWC 601.

In general, fuel cut is often performed during deceleration operation of a vehicle, and a strong lean atmosphere is generated. When the fuel cut is stopped (in other words, when the fuel injection is resumed), control from a strongly lean atmosphere to an excessively rich atmosphere is usually performed. The reason for this control is that: in a state where the catalyst stores oxygen to the maximum extent due to a strong lean atmosphere, NOx purification performance cannot be ensured. By using an excessively rich atmosphere to release oxygen to some extent, NOx purification performance can be ensured. During normal operation, a fuel cut operation is stopped a plurality of times. In particular, when a downshift is performed in accordance with a deceleration operation, the fuel injection after the fuel cut is resumed for the purpose of adjusting the engine speed. Thus, the state of the vehicle suitable for the OBD of the present embodiment is obtained at a high frequency, and it is not necessary to specially perform engine control for the purpose of the OBD. Thus, the OBD according to the present embodiment is suitable for use as an OBD in which engine control is not intentionally performed for the purpose of the OBD, that is, a passive OBD.

Compared to the OSC method described above, the diagnosis in the present embodiment is performed based on the NOx concentration, and therefore, a diagnosis result reflecting the purification performance of NOx more directly can be obtained. The diagnosis in the present embodiment can be performed in a shorter time (typically, 1 second or less) than the OSC method.

In the case where the critical air-fuel ratio is larger than 50, the correlation between the temporary increase amount of the NOx concentration and the degree of deterioration of the gas sensor 702 becomes higher. This can further improve the accuracy of the catalyst deterioration diagnosis. Note that if the fuel cut is continued for a certain period of time, a state occurs in which the air-fuel ratio is greater than 50, and therefore this state can frequently occur during normal operation. Thus, even if the critical air-fuel ratio is made larger than 50, the chance of OBD is not significantly impaired.

Preferably, when the air-fuel ratio newly obtained by gas sensor 702 is larger than the critical air-fuel ratio, fuel injection device 501 starts monitoring the temporary increase in NOx concentration detected by gas sensor 702 when fuel injection is resumed after a fuel cut, following the downshift of stepped transmission 400 during deceleration of the vehicle. Downshifting of the stepped transmission 400 accompanied by deceleration of the vehicle is frequently performed during normal running of the vehicle. Thus, by starting monitoring the temporary increase in NOx concentration at the time of this downshift, it is possible to perform the catalyst degradation diagnosis at a high frequency. In addition, at the time of downshift, a fuel cut and a subsequent resumption of fuel injection are generally performed. Thus, it is not necessary to perform a fuel cut and recovery of subsequent fuel injection only for the purpose of performing catalyst degradation diagnosis. Thus, the catalyst deterioration diagnosis can be performed in the form of passive OBD. Further, at the time of downshift during deceleration, a state in which the state of the vehicle is close to a predetermined state is easily obtained. In particular, in an automatic transmission vehicle, a downshift during deceleration may be performed by a processor of the ECU100 executing a specific program. This reduces variation in the vehicle state during OBD. Accordingly, it is possible to suppress the occurrence of a deviation in the correlation coefficient between the temporary increase amount of the NOx concentration and the degree of deterioration of the gas sensor 702 due to a difference in the state of the vehicle. This can further improve the accuracy of the catalyst deterioration diagnosis.

The threshold amount to be compared with the temporary increase amount in the increase amount determination unit 150 may be set based on the state of the vehicle when the temporary increase amount of the NOx concentration is obtained. Thereby, it is possible to correct the difference in the correlation coefficient between the temporary increase amount of the NOx concentration and the degree of deterioration of the gas sensor 702, which is caused by the difference in the state of the vehicle. Thus, the accuracy of the catalyst deterioration diagnosis can be further improved.

Monitoring of the temporary increase in the NOx concentration detected by the gas sensor 702 may be started only when the state of the vehicle is included in a predetermined range determined in advance. In this case, it is possible to suppress the occurrence of a deviation in the correlation coefficient between the temporary increase amount of the NOx concentration and the degree of deterioration of the gas sensor 702 due to a difference in the vehicle state. This can further improve the accuracy of the catalyst deterioration diagnosis.

Preferably, the temporary increase in the NOx concentration detected by the gas sensor 702 is detected only during a period in which the air-fuel ratio obtained by the gas sensor 702 is lean from the stoichiometric value. In this case, NH generated after the air-fuel ratio obtained by gas sensor 702 changes from lean to over-rich can be more reliably suppressed₃The effect on the gas sensor 702. This can further improve the accuracy of the catalyst deterioration diagnosis.

(modification of Transmission)

A Continuously Variable Transmission (CVT) may be used instead of the stepped Transmission 400 (fig. 1). The CVT is a power transmission mechanism capable of continuously changing the gear ratio, unlike the stepped transmission 400. In a vehicle having a CVT, the ECU may control the CVT to simulate discrete gear ratio changes similar to the shifting of the stepped transmission 400. In this specification, the downshift simulated by this method is referred to as simulated downshift. In particular, in a vehicle having a shift paddle, a simulated downshift may be performed in correspondence with an operation of the shift paddle by the driver DR (fig. 1).

In the present modification, when the air-fuel ratio obtained by gas sensor 702 is greater than the critical air-fuel ratio as a result of the latest determination by air-fuel ratio determination unit 110, monitoring unit 130 starts monitoring the temporary increase in NOx concentration when fuel injection from fuel injection device 501 is resumed after a fuel cut in accordance with a simulated downshift of the CVT during deceleration of the vehicle. Thus, when the air-fuel ratio newly obtained by gas sensor 702 (fig. 1) is larger than the threshold air-fuel ratio, fuel injection device 501 (fig. 1) starts monitoring the temporary increase in NOx concentration detected by gas sensor 702 when fuel injection is resumed after a fuel cut, following a simulated downshift during vehicle deceleration.

According to the present modification, when the air-fuel ratio newly obtained by gas sensor 702 is larger than the critical air-fuel ratio, fuel injection device 501 starts monitoring the temporary increase in NOx concentration detected by gas sensor 702 when fuel injection is resumed after a fuel cut, following a simulated downshift during vehicle deceleration. In the simulated downshift, a fuel cut and a subsequent resumption of fuel injection are generally performed. Thus, it is not necessary to perform the fuel cut and the subsequent recovery of the fuel injection only for the purpose of executing the catalyst degradation diagnosis method. Thus, the catalyst deterioration diagnosis method may be performed in the form of passive OBD.

(other modification example)

In the above embodiment, the catalyst deterioration diagnosis of the TWC601 (fig. 1) is performed, but in addition to this, the catalyst deterioration diagnosis of the additional catalyst 602 may be performed by the same method as in the above embodiment, or alternatively, the catalyst deterioration diagnosis of the additional catalyst 602 may be performed by the same method as in the above embodiment.

Although the gas sensor 702 capable of measuring both the air-fuel ratio and the NOx concentration has been described in the above embodiment, the gas sensor may be formed of an air-fuel ratio sensor element formed independently of each other and having NH₃Interfering NOx elements.

In the above embodiment, the description has been given of the case where the vehicle is driven by the driver DR, but the vehicle may be automatically operated. In this case, the display portion 200 may be provided to display the passenger (not the driver DR), or the display portion 200 may be omitted. In addition, in the case of the automatic operation of the vehicle, the accelerator pedal 300 may be omitted.

Although the present invention has been described in detail, the above description is an example in all aspects, and the present invention is not limited thereto. Can be explained as follows: numerous variations not illustrated may be assumed without departing from the scope of the invention.