阅读说明：本技术 一种后处理系统硫中毒确定方法、装置、车辆及介质 (Method, device, vehicle and medium for determining sulfur poisoning of aftertreatment system ) 是由 赵德财 孙善良 于 2021-09-29 设计创作，主要内容包括：本发明实施例公开了一种后处理系统硫中毒确定方法、装置、车辆及介质。该后处理系统硫中毒确定方法包括：在确定后处理系统同时满足第一监控放行条件和第二监控放行条件后,获取上游NOx传感器测量得到的发动机排气中的上游NOx值、下游NOx传感器测量得到的发动机排气中的下游NOx值以及DPF压差传感器测量得到的DPF压差值；根据所述上游NOx值和所述下游NOx值确定SCR转化效率监控状态,并根据所述DPF压差值确定DPF压差监控状态；基于所述SCR转化效率监控状态和所述DPF压差监控状态确定所述后处理系统是否出现硫中毒故障。本发明实施例的技术方案,以实现有效准确对后处理系统的硫中毒故障进行监控。(The embodiment of the invention discloses a method, a device, a vehicle and a medium for determining sulfur poisoning of an aftertreatment system. The aftertreatment system sulfur poisoning determination method includes: after the aftertreatment system is determined to simultaneously meet the first monitoring release condition and the second monitoring release condition, acquiring an upstream NOx value in engine exhaust measured by an upstream NOx sensor, a downstream NOx value in engine exhaust measured by a downstream NOx sensor and a DPF differential pressure value measured by a DPF differential pressure sensor; determining an SCR conversion efficiency monitoring state according to the upstream NOx value and the downstream NOx value, and determining a DPF pressure difference monitoring state according to the DPF pressure difference value; determining whether a sulfur poisoning fault has occurred in the aftertreatment system based on the SCR conversion efficiency monitoring state and the DPF pressure differential monitoring state. The technical scheme of the embodiment of the invention can effectively and accurately monitor the sulfur poisoning fault of the post-processing system.)

1. An aftertreatment system sulfur poisoning determination method, comprising:

after the aftertreatment system is determined to simultaneously meet the first monitoring release condition and the second monitoring release condition, acquiring an upstream NOx value in engine exhaust measured by an upstream NOx sensor, a downstream NOx value in engine exhaust measured by a downstream NOx sensor and a DPF differential pressure value measured by a DPF differential pressure sensor;

determining an SCR conversion efficiency monitoring state according to the upstream NOx value and the downstream NOx value, and determining a DPF pressure difference monitoring state according to the DPF pressure difference value;

determining whether a sulfur poisoning fault has occurred in the aftertreatment system based on the SCR conversion efficiency monitoring state and the DPF pressure differential monitoring state.

2. The aftertreatment system sulfur poisoning determination method of claim 1, further comprising, prior to determining that the aftertreatment system satisfies both the first monitoring release condition and the second monitoring release condition:

and acquiring the mass flow of the engine exhaust of the aftertreatment system, an SCR upstream temperature value measured by an SCR upstream temperature sensor and a DOC upstream temperature value measured by a DOC upstream temperature sensor.

3. The aftertreatment system sulfur poisoning determination method of claim 2, wherein the first monitored release condition is that a temperature rate of change of the SCR upstream temperature value over a preset time period is less than a nominal temperature rate of change limit, and that no ammonia slip fault, no fault in the upstream NOx sensor, no fault in the downstream NOx sensor, and no fault in the SCR upstream temperature sensor are determined by a vehicle OBD system;

the second monitoring release condition is that the engine exhaust mass flow is in the preset exhaust mass flow range, the DOC upstream temperature value is in the preset DOC upstream temperature range, and the vehicle OBD system determines that the DPF differential pressure sensor has no fault.

4. The aftertreatment system sulfur poisoning determination method of claim 1, wherein determining an SCR conversion efficiency monitoring state based on the upstream NOx value and the downstream NOx value comprises:

determining an SCR conversion efficiency value according to the upstream NOx value and the downstream NOx value, and determining an SCR conversion efficiency deviation according to the SCR conversion efficiency value;

and if the number of times of the accumulated efficiency deviation overrun times that the SCR conversion efficiency deviation is greater than the preset conversion efficiency deviation limit value is detected and the number of times of the calibrated efficiency deviation overrun times is reached, determining that the SCR conversion efficiency monitoring state is SCR conversion efficiency deterioration.

5. The aftertreatment system sulfur poisoning determination method of claim 4, wherein determining a DPF pressure differential monitoring condition based on the DPF pressure differential value comprises:

determining DPF pressure difference deviation according to the DPF pressure difference value, and if the accumulated pressure difference deviation overrun times that the DPF pressure difference deviation is greater than a preset pressure difference deviation limit value is detected, and the calibrated pressure difference deviation overrun times are reached, determining that the DPF pressure difference monitoring state is DPF pressure difference deterioration;

determining whether a sulfur poisoning fault has occurred in the aftertreatment system based on the SCR conversion efficiency monitoring state and the DPF pressure differential monitoring state, including:

determining that a sulfur poisoning fault has occurred in the aftertreatment system after confirming that the SCR conversion efficiency is degraded and the DPF pressure differential is degraded.

6. The aftertreatment system sulfur poisoning determination method of claim 1, further comprising:

generating a regeneration detoxification request upon determining that the aftertreatment system has a sulfur poisoning failure;

in response to the regeneration detoxification request, acquiring the current sulfur poisoning driving mileage or the current sulfur poisoning driving time of the vehicle, and determining the sulfur content of the fuel currently used by the vehicle according to the current sulfur poisoning driving mileage or the current sulfur poisoning driving time;

and determining the regeneration detoxification mode of the vehicle according to the sulfur content of the fuel.

7. The aftertreatment system sulfur poisoning determination method of claim 6, further comprising, after generating the regeneration detoxification request:

and if the current sulfur poisoning driving mileage or the current sulfur poisoning driving time is less than a set lower limit detoxification threshold value, or the regeneration detoxification times are greater than a set regeneration detoxification times limit value, not responding to the regeneration detoxification request.

8. An aftertreatment system sulfur poisoning determination device, comprising:

the data acquisition module is used for acquiring an upstream NOx value in the engine exhaust measured by an upstream NOx sensor, a downstream NOx value in the engine exhaust measured by a downstream NOx sensor and a DPF pressure difference value measured by a DPF pressure difference sensor after the aftertreatment system is determined to simultaneously meet a first monitoring release condition and a second monitoring release condition;

the monitoring state determining module is used for determining an SCR conversion efficiency monitoring state according to the upstream NOx value and the downstream NOx value and determining a DPF pressure difference monitoring state according to the DPF pressure difference value;

a sulfur poisoning fault determination module to determine whether a sulfur poisoning fault has occurred in the aftertreatment system based on the SCR conversion efficiency monitoring state and the DPF pressure differential monitoring state.

9. A vehicle, characterized in that the vehicle comprises:

one or more processors;

storage means for storing one or more programs;

when executed by the one or more processors, cause the one or more processors to implement the aftertreatment system sulfur poisoning determination method of any of claims 1-7.

10. A computer-readable storage medium, on which a computer program is stored, which program, when being executed by a processor, is adapted to carry out the method for determining sulfur poisoning of an aftertreatment system according to any one of claims 1-7.

Technical Field

The embodiment of the invention relates to the technical field of aftertreatment control, in particular to a method, a device, a vehicle and a medium for determining sulfur poisoning of an aftertreatment system.

Background

The diesel engines of the fifth country or the sixth country have higher requirements on oil products, but the oil products in domestic markets have different sulfur contents, and some users still use inferior fuel oil with the third country and the fourth country or even with extremely high sulfur content in order to save cost in the actual use process.

The Diesel engine uses high-sulfur fuel oil to cause a large amount of sulfides in tail gas, serious pollution is caused to an after-treatment system, especially, pollution is caused to DOC (Diesel Oxidation Catalyst) and SCR (Selective Catalytic Reduction) of the after-treatment system of the Diesel engine, the Catalyst is poisoned by sulfur, the conversion efficiency of the DOC to NO is reduced after poisoning, and then the passive regeneration effect of the DPF (Diesel Particulate Filter) is weakened, and meanwhile, the conversion efficiency of the SCR to the tail gas of nitrogen oxides is also reduced, so that the emission is over standard. The after-treatment system can cause irreversible failure after long-time poisoning, and the after-treatment failure caused by sulfur poisoning frequently occurs in the market, so that certain loss is brought to customers and enterprises.

Disclosure of Invention

The embodiment of the invention provides a method, a device, a vehicle and a medium for determining sulfur poisoning of an aftertreatment system, so as to effectively and accurately monitor sulfur poisoning faults of the aftertreatment system.

In a first aspect, an embodiment of the present invention provides an aftertreatment system sulfur poisoning determination method, including:

after the aftertreatment system is determined to simultaneously meet the first monitoring release condition and the second monitoring release condition, acquiring an upstream NOx value in engine exhaust measured by an upstream NOx sensor, a downstream NOx value in engine exhaust measured by a downstream NOx sensor and a DPF differential pressure value measured by a DPF differential pressure sensor;

determining an SCR conversion efficiency monitoring state according to the upstream NOx value and the downstream NOx value, and determining a DPF pressure difference monitoring state according to the DPF pressure difference value;

determining whether a sulfur poisoning fault has occurred in the aftertreatment system based on the SCR conversion efficiency monitoring state and the DPF pressure differential monitoring state.

Optionally, before determining that the post-processing system simultaneously satisfies the first monitoring release condition and the second monitoring release condition, the method further includes:

and acquiring the mass flow of the engine exhaust of the aftertreatment system, an SCR upstream temperature value measured by an SCR upstream temperature sensor and a DOC upstream temperature value measured by a DOC upstream temperature sensor.

Optionally, the first monitoring release condition is that the temperature change rate of the SCR upstream temperature value in a preset time period is smaller than a standard temperature change rate limit value, and it is determined by a vehicle OBD system that there is no ammonia leakage fault, no fault in the upstream NOx sensor, no fault in the downstream NOx sensor, and no fault in the SCR upstream temperature sensor;

the second monitoring release condition is that the engine exhaust mass flow is in the preset exhaust mass flow range, the DOC upstream temperature value is in the preset DOC upstream temperature range, and the vehicle OBD system determines that the DPF differential pressure sensor has no fault.

Optionally, determining the SCR conversion efficiency monitoring state according to the upstream NOx value and the downstream NOx value includes:

determining an SCR conversion efficiency value according to the upstream NOx value and the downstream NOx value, and determining an SCR conversion efficiency deviation according to the SCR conversion efficiency value;

and if the number of times of the accumulated efficiency deviation overrun times that the SCR conversion efficiency deviation is greater than the preset conversion efficiency deviation limit value is detected and the number of times of the calibrated efficiency deviation overrun times is reached, determining that the SCR conversion efficiency monitoring state is SCR conversion efficiency deterioration.

Optionally, determining a DPF pressure difference monitoring state according to the DPF pressure difference value includes:

determining DPF pressure difference deviation according to the DPF pressure difference value, and if the accumulated pressure difference deviation overrun times that the DPF pressure difference deviation is greater than a preset pressure difference deviation limit value is detected, and the calibrated pressure difference deviation overrun times are reached, determining that the DPF pressure difference monitoring state is DPF pressure difference deterioration;

determining whether a sulfur poisoning fault has occurred in the aftertreatment system based on the SCR conversion efficiency monitoring state and the DPF pressure differential monitoring state, including:

determining that a sulfur poisoning fault has occurred in the aftertreatment system after confirming that the SCR conversion efficiency is degraded and the DPF pressure differential is degraded.

Optionally, the method for determining sulfur poisoning of an aftertreatment system further comprises:

generating a regeneration detoxification request upon determining that the aftertreatment system has a sulfur poisoning failure;

in response to the regeneration detoxification request, acquiring the current sulfur poisoning driving mileage or the current sulfur poisoning driving time of the vehicle, and determining the sulfur content of the fuel currently used by the vehicle according to the current sulfur poisoning driving mileage or the current sulfur poisoning driving time;

and determining the regeneration detoxification mode of the vehicle according to the sulfur content of the fuel.

Optionally, after generating the request for regenerative detoxification, the method further comprises:

and if the current sulfur poisoning driving mileage or the current sulfur poisoning driving time is less than a set lower limit detoxification threshold value, or the regeneration detoxification times are greater than a set regeneration detoxification times limit value, not responding to the regeneration detoxification request.

In a second aspect, an embodiment of the present invention also provides an aftertreatment system sulfur poisoning determination device, including:

the data acquisition module is used for acquiring an upstream NOx value in the engine exhaust measured by an upstream NOx sensor, a downstream NOx value in the engine exhaust measured by a downstream NOx sensor and a DPF pressure difference value measured by a DPF pressure difference sensor after the aftertreatment system is determined to simultaneously meet a first monitoring release condition and a second monitoring release condition;

the monitoring state determining module is used for determining an SCR conversion efficiency monitoring state according to the upstream NOx value and the downstream NOx value and determining a DPF pressure difference monitoring state according to the DPF pressure difference value;

a sulfur poisoning fault determination module to determine whether a sulfur poisoning fault has occurred in the aftertreatment system based on the SCR conversion efficiency monitoring state and the DPF pressure differential monitoring state.

In a third aspect, an embodiment of the present invention further provides a vehicle, including:

one or more processors;

a storage device for storing a plurality of programs,

when at least one of the plurality of programs is executed by the one or more processors, the one or more processors are caused to implement a method for determining sulfur poisoning of an aftertreatment system according to an embodiment of the first aspect of the invention.

In a fourth aspect, embodiments of the present invention further provide a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements a method for determining sulfur poisoning of an aftertreatment system according to embodiments of the first aspect of the present invention.

According to the technical scheme of the embodiment of the invention, after the aftertreatment system is determined to simultaneously meet the first monitoring release condition and the second monitoring release condition, the upstream NOx value in the engine exhaust measured by the upstream NOx sensor, the downstream NOx value in the engine exhaust measured by the downstream NOx sensor and the DPF pressure difference value measured by the DPF pressure difference sensor are obtained; determining an SCR conversion efficiency monitoring state according to the upstream NOx value and the downstream NOx value, and determining a DPF pressure difference monitoring state according to the DPF pressure difference value; determining whether a sulfur poisoning fault has occurred in the aftertreatment system based on the SCR conversion efficiency monitoring state and the DPF pressure differential monitoring state. The problem of current aftertreatment system sulfur poisoning judge through former row carbon loading mass flow and the carbon loading mass flow in the DPF carry out the comparison, all use the calculated value as the basis, the error is great, and only monitor to single factor and have the wrong risk of reporting is solved to realize effectively accurately monitoring aftertreatment system's sulfur poisoning trouble.

Drawings

FIG. 1 is a flow chart of a method for determining sulfur poisoning in an aftertreatment system according to an embodiment of the invention;

FIG. 2 is a schematic structural diagram of a diesel aftertreatment system provided in accordance with an embodiment of the invention;

FIG. 3 is a flowchart illustrating a method for determining sulfur poisoning in an aftertreatment system according to a second embodiment of the invention;

FIG. 4 is a block diagram of an apparatus for determining sulfur poisoning in an aftertreatment system according to a third embodiment of the present invention;

fig. 5 is a schematic hardware structure diagram of a vehicle according to a fourth embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in further detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention.

It should be further noted that, for the convenience of description, only some but not all of the relevant aspects of the present invention are shown in the drawings. Before discussing exemplary embodiments in more detail, it should be noted that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although a flowchart may describe the operations (or steps) as a sequential process, many of the operations can be performed in parallel, concurrently or simultaneously. In addition, the order of the operations may be re-arranged. The process may be terminated when its operations are completed, but may have additional steps not included in the figure. The processes may correspond to methods, functions, procedures, subroutines, and the like.

Example one

Fig. 1 is a flowchart of an after-treatment system sulfur poisoning determination method according to an embodiment of the present invention, which may be applied to the determination, alarm, and regeneration detoxification of the after-treatment system sulfur poisoning of the diesel engine. The method for determining the sulfur poisoning of the aftertreatment system specifically comprises the following steps:

and S110, acquiring an upstream NOx value in the engine exhaust measured by an upstream NOx sensor, a downstream NOx value in the engine exhaust measured by a downstream NOx sensor and a DPF pressure difference value measured by a DPF pressure difference sensor after the aftertreatment system is determined to simultaneously meet a first monitoring release condition and a second monitoring release condition.

Fig. 2 is a schematic structural diagram of a Diesel engine aftertreatment system according to an embodiment of the present invention, referring to fig. 2, engine exhaust sequentially passes through a DOC (Diesel Oxidation Catalyst), a DPF (Diesel Particulate Filter), and an SCR (Selective Catalytic Reduction), where reference numeral 1 is a DOC upstream temperature sensor, reference numeral 2 is a DPF upstream temperature sensor, reference numeral 3 is an SCR upstream temperature sensor, reference numeral 4 is an upstream NOx sensor, reference numeral 5 is a downstream NOx sensor, reference numeral 6 is a DPF differential pressure sensor, reference numeral 7 is an engine control unit ECU, and the engine control unit ECU is configured to complete acquisition and storage of parameters of the sensors, and storage and transmission of limits corresponding to the parameters.

Wherein the upstream NOx sensor is located upstream of the SCR for removing nitrogen oxides from the exhaust of the engine, and the upstream NOx sensor is for measuring an upstream NOx value in the exhaust of the engine.

A downstream NOx sensor is located downstream of the SCR for measuring a downstream NOx value in the engine exhaust.

The DPF differential pressure sensor is arranged between the upstream and the downstream of the DPF and used for collecting the differential pressure between the upstream and the downstream of the DPF. It can be understood that, because the transient variation of the differential pressure measurement value is relatively large, the embodiment performs filtering processing on the differential pressure measurement value measured by the DPF differential pressure sensor to obtain the DPF differential pressure value.

With continued reference to fig. 2, specifically, upon determining that the aftertreatment system satisfies both the first monitor release condition and the second monitor release condition, an upstream NOx value in the engine exhaust flowing into the aftertreatment system is measured by an upstream NOx sensor, a downstream NOx value in the engine exhaust flowing into the aftertreatment system is measured by a downstream NOx sensor, a DPF differential pressure value at the DPF of the engine exhaust flowing into the aftertreatment system is measured by a DPF differential pressure sensor, and the engine control unit ECU obtains the upstream NOx value measured by the upstream NOx sensor, the downstream NOx value measured by the downstream NOx sensor, and the DPF differential pressure value measured by the DPF differential pressure sensor.

On the basis of the above embodiment, before determining that the post-processing system simultaneously satisfies the first monitoring release condition and the second monitoring release condition, the method further includes: and acquiring the mass flow of the engine exhaust of the aftertreatment system, an SCR upstream temperature value measured by an SCR upstream temperature sensor and a DOC upstream temperature value measured by a DOC upstream temperature sensor.

With reference to fig. 2, specifically, before it is determined that the aftertreatment system simultaneously satisfies the first monitoring release condition and the second monitoring release condition, the engine control unit ECU obtains the engine exhaust mass flow of the aftertreatment system, the SCR upstream temperature value measured by the SCR upstream temperature sensor, and the DOC upstream temperature value measured by the DOC upstream temperature sensor, so as to determine whether the aftertreatment system satisfies the first monitoring release condition and the second monitoring release condition according to the parameters.

Further, on the basis, in order to perform more accurate sulfur poisoning diagnosis on the aftertreatment system, other factors which may cause low SCR conversion efficiency need to be eliminated, in this embodiment, before performing sulfur poisoning diagnosis on the aftertreatment system, a first monitoring release condition is determined, where the first monitoring release condition is that a temperature change rate of the SCR upstream temperature value in a preset time period is smaller than a standard temperature change rate limit value, and it is determined by a vehicle OBD system that there is no ammonia leakage fault, no fault in the upstream NOx sensor, no fault in the downstream NOx sensor, and no fault in the SCR upstream temperature sensor;

simultaneously, monitor DPF pressure differential, confirm the second control condition of releasing, the second control condition of releasing does engine exhaust mass flow is in predetermineeing exhaust mass flow within range, just DOC upstream temperature value is in predetermineeing DOC upstream temperature within range, and passes through vehicle OBD system confirms DPF pressure differential sensor does not have the trouble.

The vehicle OBD system is a vehicle-mounted diagnosis system and is used for monitoring the running condition of the engine and whether the tail gas exceeds the standard or not and giving out a warning.

In this embodiment, the vehicle OBD system is used to determine no ammonia slip fault, no upstream NOx sensor fault, no downstream NOx sensor fault, no SCR upstream temperature sensor fault, and no DPF differential pressure sensor fault.

S120, determining an SCR conversion efficiency monitoring state according to the upstream NOx value and the downstream NOx value, and determining a DPF pressure difference monitoring state according to the DPF pressure difference value.

On the basis of the above embodiment, determining the SCR conversion efficiency monitoring state based on the upstream NOx value and the downstream NOx value includes: determining an SCR conversion efficiency value according to the upstream NOx value and the downstream NOx value, and determining an SCR conversion efficiency deviation according to the SCR conversion efficiency value; and if the number of times of the accumulated efficiency deviation overrun times that the SCR conversion efficiency deviation is greater than the preset conversion efficiency deviation limit value is detected and the number of times of the calibrated efficiency deviation overrun times is reached, determining that the SCR conversion efficiency monitoring state is SCR conversion efficiency deterioration.

The SCR conversion efficiency value is determined by an upstream NOx value and a downstream NOx value, and in order to eliminate the influence of transient load change of the engine and consider that sulfur poisoning is a process which generates influence after continuous action, the SCR conversion efficiency is monitored in an integral mode.

The preset conversion efficiency deviation limit value can be formulated according to the working condition of the engine, and tests show that after sulfur poisoning of the post-treatment system, the SCR conversion efficiency is degraded in different working conditions according to different rules, for example, the working condition of a vehicle on a road in an urban area is low in engine exhaust temperature, the SCR conversion efficiency is rapidly degraded, and the degradation amplitude is large; when the vehicle is in a high-speed working condition, the engine has high exhaust temperature and certain detoxification capability, and the SCR conversion efficiency is slowly degraded. Therefore, different preset conversion efficiency deviation limits Δ Ef _ max are set under different working conditions, deviation limit curve calibration at different temperatures is required, the higher the temperature is, the smaller the preset conversion efficiency deviation limit for SCR conversion efficiency diagnosis is, for example, when the engine exhaust temperature is 250 ℃, the deviation of the preset conversion efficiency is greater than 10%, the SCR conversion efficiency is considered to be deteriorated, the engine exhaust temperature is 350 ℃, the deviation of the preset conversion efficiency is greater than 5%, the SCR conversion efficiency is considered to be deteriorated, wherein the calibration of the temperature curve mainly considers the generation and decomposition temperature of the sulfide substances and the conversion efficiency characteristic of the SCR catalyst, and finally the speed of the SCR conversion efficiency deterioration is influenced.

Specifically, an SCR conversion efficiency value is determined according to the upstream NOx value and the downstream NOx value, and the SCR conversion efficiency value is different from a set SCR conversion efficiency model value to obtain SCR conversion efficiency deviation. If the SCR conversion efficiency deviation is greater than the preset conversion efficiency deviation limit value, the SCR conversion efficiency is considered to be degraded, and the aftertreatment system may be poisoned by sulfur. And when the accumulated efficiency deviation overrun times reach the calibrated efficiency deviation overrun times, confirming that the SCR conversion efficiency monitoring state is SCR conversion efficiency deterioration.

On the basis of the above embodiment, determining the DPF pressure difference monitoring state according to the DPF pressure difference value includes: and determining the DPF pressure difference deviation according to the DPF pressure difference value, and if the accumulated pressure difference deviation overrun times that the DPF pressure difference deviation is greater than a preset pressure difference deviation limit value is detected, and the calibrated pressure difference deviation overrun times are reached, determining that the DPF pressure difference monitoring state is DPF pressure difference deterioration.

The preset differential pressure deviation limit value delta Pmax is set by considering the change of the running working condition of the vehicle, the passive regeneration effect of the DPF is poor under the low-temperature working condition (for example, the temperature is 250-300 ℃), and the differential pressure of the DPF is increased, so that the preset differential pressure deviation limit value delta Pmax is larger under the relatively low-temperature working condition to eliminate the influence of the working condition on the differential pressure deviation and increase the accuracy of sulfur poisoning diagnosis; under the high-temperature working condition (for example, the temperature is 300-.

Specifically, the DPF pressure difference value and a deviation integral value of the calibrated pressure difference are used for obtaining the DPF pressure difference deviation, if the DPF pressure difference deviation is larger than a preset pressure difference deviation limit value, the DPF pressure difference is considered to be degraded, and when the accumulated pressure difference deviation overrun times reach the calibrated pressure difference deviation overrun times, the DPF pressure difference monitoring state is confirmed to be the DPF pressure difference degradation.

S130, determining whether the after-treatment system has a sulfur poisoning fault or not based on the SCR conversion efficiency monitoring state and the DPF pressure difference monitoring state.

On the basis of the above, determining whether the aftertreatment system has a sulfur poisoning fault based on the SCR conversion efficiency monitoring state and the DPF differential pressure monitoring state includes: determining that a sulfur poisoning fault has occurred in the aftertreatment system after confirming that the SCR conversion efficiency is degraded and the DPF pressure differential is degraded.

Further, it can be understood that when the sulfur poisoning fault of the post-processing system is confirmed, the corresponding fault code is reported through the ECU, and the fault lamp of the vehicle reminds the user of timely processing.

On the basis of the above embodiment, the method for determining sulfur poisoning of an aftertreatment system further includes: generating a regeneration detoxification request upon determining that the aftertreatment system has a sulfur poisoning failure; in response to the regeneration detoxification request, acquiring the current sulfur poisoning driving mileage or the current sulfur poisoning driving time of the vehicle, and determining the sulfur content of the fuel currently used by the vehicle according to the current sulfur poisoning driving mileage or the current sulfur poisoning driving time; and determining the regeneration detoxification mode of the vehicle according to the sulfur content of the fuel.

The ECU judges and reports that the post-treatment system has sulfur poisoning faults, and automatically enters regeneration detoxification in response to the regeneration detoxification requests to perform high-temperature detoxification.

Specifically, in response to the regeneration detoxification request, obtaining a current sulfur poisoning driving distance or a current sulfur poisoning driving time of the vehicle, and when the current sulfur poisoning driving distance is smaller than a set first detoxification distance threshold (for example, the set first detoxification distance threshold is 1000km), or the current sulfur poisoning driving time is smaller than a set first detoxification time threshold (for example, the set first detoxification time threshold is 20h), determining that the sulfur content of the fuel used by the current vehicle is high, resulting in faster sulfur poisoning, and selecting the regeneration detoxification mode as a regeneration detoxification mode aiming at high sulfur content; when the current sulfur poisoning driving mileage is greater than a set first detoxification mileage threshold (for example, a set lower detoxification mileage threshold is 1000km), or the current sulfur poisoning driving time is greater than a set first detoxification time threshold (for example, a set first detoxification time threshold is 20h), the sulfur content of the fuel currently used by the vehicle is considered to be low, and the selected regeneration detoxification mode is a regeneration detoxification mode aiming at the low sulfur content, so that good economy and detoxification effect are ensured.

On the basis of the above, the first detoxification mileage threshold value and the first detoxification time threshold value are set as the lower detoxification limit value for determining whether the selected regeneration detoxification manner is the regeneration detoxification manner for high sulfur content or the regeneration detoxification manner for low sulfur content in response to the regeneration detoxification request, and the setting of the first detoxification mileage threshold value and the setting of the first detoxification time threshold value may be set by those skilled in the art according to actual needs, and the present embodiment does not set any limit to the specific values thereof.

It is appreciated that when an aftertreatment system sulfur poisoning failure is reported, high temperature regeneration is used to detoxify the aftertreatment system. Considering that the high-sulfur-content fuel oil and the low-sulfur-content fuel oil have different effects on the regeneration detoxification of the aftertreatment system, namely the aftertreatment system is faster in high-sulfur poisoning and slow in low-sulfur poisoning, and the detoxification of the aftertreatment system after the high-sulfur poisoning needs higher temperature and time to be better recovered, according to the law, different regeneration schemes are respectively designed according to the high-low-sulfur-content fuel oil.

For example, the regeneration temperature is set to 600 ℃ and the regeneration time is 30 minutes for the high-sulfur-content regeneration detoxification mode, and the regeneration temperature is set to 550 ℃ and the regeneration time is 20 minutes for the low-sulfur-content regeneration detoxification mode. Therefore, a plurality of different sulfur contents can be selected for division, and a plurality of different regeneration detoxification manners can be obtained correspondingly.

Further, after generating the request for regeneration detoxification, the method further comprises: and if the current sulfur poisoning driving mileage or the current sulfur poisoning driving time is less than a set lower limit detoxification threshold value, or the regeneration detoxification times are greater than a set regeneration detoxification times limit value, not responding to the regeneration detoxification request.

Wherein the lower detoxification threshold is set as a second detoxification mileage threshold or a second detoxification time threshold.

Specifically, if the vehicle uses high-sulfur fuel for a long time, frequent regeneration may be caused, which may shorten the life of the aftertreatment system, so the regeneration detoxification frequency limit is set, that is, when the current sulfur poisoning driving mileage is less than the set second detoxification mileage threshold (for example, the set second detoxification mileage threshold is 500km), or the current sulfur poisoning driving time is less than the set second detoxification time threshold (for example, the set second detoxification time threshold is 10h), or the regeneration detoxification frequency is greater than the set regeneration detoxification frequency limit (for example, the set regeneration detoxification frequency limit is not more than 5 times within 1 kilometer of the vehicle driving mileage), the ECU generates the regeneration detoxification request at this time, but does not enter the regeneration detoxification temporarily until the current sulfur poisoning driving mileage or the current sulfur poisoning driving time is greater than the set second detoxification threshold.

On the basis of the above, the setting of the second detoxification mileage threshold and the setting of the second detoxification time threshold are lower detoxification threshold values that determine whether to immediately enter the regenerative detoxification in response to the request for regenerative detoxification, and the setting of the second detoxification mileage threshold and the setting of the second detoxification time threshold may be set by those skilled in the art according to actual needs, and the specific values are not limited in any way in this embodiment.

According to the technical scheme of the embodiment of the invention, after the aftertreatment system is determined to simultaneously meet the first monitoring release condition and the second monitoring release condition, the upstream NOx value in the engine exhaust measured by the upstream NOx sensor, the downstream NOx value in the engine exhaust measured by the downstream NOx sensor and the DPF pressure difference value measured by the DPF pressure difference sensor are obtained; determining an SCR conversion efficiency monitoring state according to the upstream NOx value and the downstream NOx value, and determining a DPF pressure difference monitoring state according to the DPF pressure difference value; determining whether a sulfur poisoning fault has occurred in the aftertreatment system based on the SCR conversion efficiency monitoring state and the DPF pressure differential monitoring state. The problem of current aftertreatment system sulfur poisoning judge through former row carbon loading mass flow and the carbon loading mass flow in the DPF carry out the comparison, all use the calculated value as the basis, the error is great, and only monitor to single factor and have the wrong risk of reporting is solved to realize effectively accurately monitoring aftertreatment system's sulfur poisoning trouble.

Example two

Fig. 3 is a flowchart of a method for determining sulfur poisoning of an aftertreatment system according to a second embodiment of the invention, which is optimized based on the second embodiment.

Correspondingly, the method of the embodiment specifically includes:

s310, starting the engine, and simultaneously executing the step S320 and the step S330.

S320, determining that the aftertreatment system meets a first monitoring release condition, and acquiring an upstream NOx value in the engine exhaust measured by the upstream NOx sensor and a downstream NOx value in the engine exhaust measured by the downstream NOx sensor.

Specifically, the mass flow of the engine exhaust of the aftertreatment system, an SCR upstream temperature value measured by an SCR upstream temperature sensor, and a DOC upstream temperature value measured by a DOC upstream temperature sensor are obtained.

The first monitoring release condition is that the temperature change rate of the SCR upstream temperature value in a preset time period is smaller than a standard temperature change rate limit value, and an ammonia leakage fault, a fault-free upstream NOx sensor, a fault-free downstream NOx sensor and a fault-free SCR upstream temperature sensor are determined by a vehicle OBD system;

on the basis of the above, it is known from the ammonia storage characteristics of the SCR catalyst that a large amount of ammonia stored in the catalyst escapes when the temperature suddenly increases, which increases the measured value of the downstream NOx sensor, and the calculated SCR conversion efficiency value Ef _ act decreases, thereby affecting the diagnosis of sulfur poisoning. In the embodiment, when the post-treatment system is monitored for sulfur poisoning, the first monitoring release condition includes that the temperature change rate Δ T of the SCR upstream temperature value in the preset time period should be smaller than the standard temperature change rate limit value Δ T _ max.

The preset time period can be selected and set by a person skilled in the art according to actual conditions, and can be a time length of 5 seconds, 10 seconds, and the like, and the specific SCR upstream temperature value acquisition time length is not limited in any way in this embodiment.

The first monitoring release condition includes determining no ammonia leak fault by the vehicle OBD system, diagnosing and monitoring ammonia leak by the vehicle OBD system, and not performing sulfur poisoning diagnosis of the aftertreatment system when the ammonia leak fault is reported.

The first monitored release condition includes a determination by the vehicle OBD system that the upstream NOx sensor is not faulty, the downstream NOx sensor is not faulty, and the SCR upstream temperature sensor is not faulty, and if any of the sensors is faulty, no sulfur poisoning diagnosis should be performed.

S321, determining an SCR conversion efficiency value according to the upstream NOx value and the downstream NOx value, and determining an SCR conversion efficiency deviation according to the SCR conversion efficiency value.

And when the mass flow of the upstream NOx is integrated to a calibration limit value Mnox, carrying out SCR conversion efficiency calculation once to obtain an SCR conversion efficiency value Ef _ act. In order to realize more accurate diagnosis of sulfur poisoning of the aftertreatment system, the calibration limit value Mnox is set according to different working conditions by considering different temperatures and power under different loads and different degradation rules of the catalyst conversion efficiency, the lower value of the calibration limit value Mnox is set under the low-load working condition, such as the working condition that the engine exhaust temperature is less than 350 ℃, and the higher value of the Mnox is set under the high-load working condition, such as the working condition that the engine exhaust temperature is greater than 350 ℃.

The SCR conversion efficiency value Ef _ act is calculated according to the following formula:

wherein NOxup is the upstream NOx value; NOxdw is the downstream NOx value.

S322, judging whether the SCR conversion efficiency deviation is larger than a preset conversion efficiency deviation limit value or not, if so, controlling the number m of the efficiency deviation overrun times to be added with 1, executing the step S323, otherwise, resetting the integrator, and returning to execute the step S321.

S323, judging whether the accumulated efficiency deviation overrun number m reaches the calibrated efficiency deviation overrun number Mmax, if so, executing the step S324, otherwise, returning to execute the step S321.

S324, confirming that the SCR conversion efficiency monitoring state is SCR conversion efficiency deterioration, and executing step S340.

S330, determining that the post-processing system meets a second monitoring release condition, and acquiring a DPF pressure difference value measured by the DPF pressure difference sensor.

Wherein, should be based on the power window of engine, for example the power integration reaches calibration limit value W _ P and is a window, each window calculates a difference integral value of actual DPF pressure difference filter value and calibration pressure difference, obtains DPF pressure difference value delta P.

Specifically, the mass flow of the engine exhaust of the aftertreatment system, an SCR upstream temperature value measured by an SCR upstream temperature sensor, and a DOC upstream temperature value measured by a DOC upstream temperature sensor are obtained.

The second control condition of releasing does engine exhaust mass flow is in predetermineeing exhaust mass flow within range, just DOC upstream temperature value is in predetermineeing DOC upstream temperature within range, and passes through vehicle OBD system confirms DPF differential pressure sensor does not have the trouble.

The mass flow rate of the engine exhaust gas is within a preset exhaust gas mass flow rate range, for example, the mass flow rate of the engine exhaust gas is 200kg/h-1000kg/h, and the measurement accuracy of the DPF differential pressure sensor is higher in the preset exhaust gas mass flow rate range.

The DOC upstream temperature value is within a preset DOC upstream temperature range, for example, the DOC upstream temperature value is within 250-350 ℃, and the DPF passive regeneration effect is obvious within the preset DOC upstream temperature range.

And S331, judging whether the pressure difference value delta P of the DPF is larger than a preset pressure difference deviation limit value delta Pmax, if so, controlling the pressure difference deviation overrun number n to be added with 1, executing step S332, otherwise, resetting the integrator, and returning to execute step S330.

It should be noted that, while the DPF differential pressure value Δ P is determined, the determination of the DPF carbon loading model value change rate can be assisted, that is, it is determined whether the DPF differential pressure value Δ P is greater than the preset differential pressure deviation limit Δ Pmax and whether the DPF carbon loading model value change rate is greater than the preset change rate limit, so as to obtain the determination result.

S332, judging whether the accumulated pressure difference deviation overrun number n reaches the calibrated pressure difference deviation overrun number Nmax, if so, executing a step S333, otherwise, returning to execute the step S330.

Step S333, confirming that the DPF differential pressure monitoring state is DPF differential pressure degradation, and executing step S340.

And S340, determining that the sulfur poisoning fault occurs in the after-treatment system after confirming that the SCR conversion efficiency is degraded and the DPF pressure difference is degraded.

And S350, reporting a corresponding fault code through the ECU, and reminding a user to process in time through a fault lamp of the vehicle.

And S360, generating a regeneration detoxification request after determining that the sulfur poisoning fault occurs in the aftertreatment system.

On the basis, after the regeneration detoxification request is generated, the method further comprises the following steps: and if the current sulfur poisoning driving mileage or the current sulfur poisoning driving time is less than a set lower limit detoxification threshold value, or the regeneration detoxification times are greater than a set regeneration detoxification times limit value, not responding to the regeneration detoxification request.

And S370, responding to the regeneration detoxification request, acquiring the current sulfur poisoning driving mileage or the current sulfur poisoning driving time of the vehicle, and determining the sulfur content of the fuel currently used by the vehicle according to the current sulfur poisoning driving mileage or the current sulfur poisoning driving time.

And S380, determining a regeneration detoxification mode of the vehicle according to the sulfur content of the fuel oil.

According to the technical scheme of the embodiment of the invention, the influence on the DOC, the SCR and the DPF after the sulfur poisoning of the aftertreatment system is considered, namely the DOC reduces the conversion efficiency of NO, so that the passive regeneration effect is weakened, the pressure difference of the DPF is increased, the pressure difference deviation is integrated on the basis of a power integration window, different pressure difference deviation limit values are set for different working conditions, and if the pressure difference deviation limit values exceed the limit values, the pressure difference degradation is confirmed; after sulfur poisoning, SCR conversion efficiency is reduced, on the basis of an upstream NOx mass flow integral window, the SCR conversion efficiency deviation is monitored, the SCR efficiency degradation rules under different working conditions are considered, and different efficiency deviation limit values are set. The sulfur poisoning monitoring is comprehensively carried out by monitoring the SCR efficiency and the DPF pressure difference. The monitoring of the two modules is set with a monitoring release condition, so that the sulfur poisoning fault of the post-processing system can be more effectively and accurately monitored, and meanwhile, the sulfur poisoning fault can be monitored in the post-processing system which is currently and practically applied without additional hardware. On the other hand, after the sulfur poisoning fault of the aftertreatment system is determined, a proper regeneration detoxification mode can be selected according to the poisoning mileage and the fuel oil sulfur content, so that a good regeneration detoxification effect and economy are ensured, the oil consumption in the regeneration process is saved, and the adaptability and the robustness of the method for determining the sulfur poisoning of the aftertreatment system are improved.

EXAMPLE III

Fig. 4 is a structural diagram of a device for determining sulfur poisoning of an aftertreatment system according to a third embodiment of the present invention, which is applicable to determining, alarming, and regenerating and detoxifying sulfur poisoning of an aftertreatment system of a diesel engine.

As shown in fig. 4, the post-treatment system sulfur poisoning determination device includes: a data acquisition module 410, a monitoring status determination module 420, and a sulfur poisoning failure determination module 430, wherein:

a data acquisition module 410, configured to acquire an upstream NOx value in the engine exhaust measured by the upstream NOx sensor, a downstream NOx value in the engine exhaust measured by the downstream NOx sensor, and a DPF differential pressure value measured by the DPF differential pressure sensor after determining that the aftertreatment system simultaneously satisfies the first monitoring release condition and the second monitoring release condition;

a monitoring state determination module 420 for determining an SCR conversion efficiency monitoring state according to the upstream NOx value and the downstream NOx value, and determining a DPF differential pressure monitoring state according to the DPF differential pressure value;

a sulfur poisoning fault determination module 430 that determines whether a sulfur poisoning fault has occurred in the aftertreatment system based on the SCR conversion efficiency monitoring status and the DPF pressure differential monitoring status.

The device for determining sulfur poisoning of the aftertreatment system of the embodiment acquires an upstream NOx value in the engine exhaust measured by an upstream NOx sensor, a downstream NOx value in the engine exhaust measured by a downstream NOx sensor, and a DPF differential pressure value measured by a DPF differential pressure sensor after determining that the aftertreatment system simultaneously satisfies a first monitoring release condition and a second monitoring release condition; determining an SCR conversion efficiency monitoring state according to the upstream NOx value and the downstream NOx value, and determining a DPF pressure difference monitoring state according to the DPF pressure difference value; determining whether a sulfur poisoning fault has occurred in the aftertreatment system based on the SCR conversion efficiency monitoring state and the DPF pressure differential monitoring state. The problem of current aftertreatment system sulfur poisoning judge through former row carbon loading mass flow and the carbon loading mass flow in the DPF carry out the comparison, all use the calculated value as the basis, the error is great, and only monitor to single factor and have the wrong risk of reporting is solved to realize effectively accurately monitoring aftertreatment system's sulfur poisoning trouble.

On the basis of the above embodiments, the post-treatment system sulfur poisoning determination device further includes:

and the temperature value acquisition module is used for acquiring the mass flow of the engine exhaust of the aftertreatment system, an SCR upstream temperature value measured by the SCR upstream temperature sensor and a DOC upstream temperature value measured by the DOC upstream temperature sensor.

On the basis of the above embodiments, the first monitoring release condition is that the temperature change rate of the SCR upstream temperature value in a preset time period is smaller than a standard temperature change rate limit value, and it is determined by a vehicle OBD system that there is no ammonia slip fault, no fault in the upstream NOx sensor, no fault in the downstream NOx sensor, and no fault in the SCR upstream temperature sensor;

the second monitoring release condition is that the engine exhaust mass flow is in the preset exhaust mass flow range, the DOC upstream temperature value is in the preset DOC upstream temperature range, and the vehicle OBD system determines that the DPF differential pressure sensor has no fault.

On the basis of the above embodiments, determining the SCR conversion efficiency monitoring state according to the upstream NOx value and the downstream NOx value includes:

determining an SCR conversion efficiency value according to the upstream NOx value and the downstream NOx value, and determining an SCR conversion efficiency deviation according to the SCR conversion efficiency value;

and if the number of times of the accumulated efficiency deviation overrun times that the SCR conversion efficiency deviation is greater than the preset conversion efficiency deviation limit value is detected and the number of times of the calibrated efficiency deviation overrun times is reached, determining that the SCR conversion efficiency monitoring state is SCR conversion efficiency deterioration.

On the basis of the above embodiments, determining the DPF pressure difference monitoring state according to the DPF pressure difference value includes:

determining DPF pressure difference deviation according to the DPF pressure difference value, and if the accumulated pressure difference deviation overrun times that the DPF pressure difference deviation is greater than a preset pressure difference deviation limit value is detected, and the calibrated pressure difference deviation overrun times are reached, determining that the DPF pressure difference monitoring state is DPF pressure difference deterioration;

determining whether a sulfur poisoning fault has occurred in the aftertreatment system based on the SCR conversion efficiency monitoring state and the DPF pressure differential monitoring state, including:

determining that a sulfur poisoning fault has occurred in the aftertreatment system after confirming that the SCR conversion efficiency is degraded and the DPF pressure differential is degraded.

On the basis of the above embodiments, the post-treatment system sulfur poisoning determination device further includes:

a generate regeneration detoxification request module for generating a regeneration detoxification request upon determining that the aftertreatment system has a sulfur poisoning failure;

the fuel sulfur content determination module is used for responding to the regeneration detoxification request, obtaining the current sulfur poisoning driving mileage or the current sulfur poisoning driving time of the vehicle, and determining the fuel sulfur content currently used by the vehicle according to the current sulfur poisoning driving mileage or the current sulfur poisoning driving time;

and the regeneration detoxification mode determination module is used for determining the regeneration detoxification mode of the vehicle according to the sulfur content of the fuel oil.

On the basis of the above embodiments, after generating the request for regeneration detoxification, the method further includes:

and if the current sulfur poisoning driving mileage or the current sulfur poisoning driving time is less than a set lower limit detoxification threshold value, or the regeneration detoxification times are greater than a set regeneration detoxification times limit value, not responding to the regeneration detoxification request.

The device for determining sulfur poisoning of an aftertreatment system provided in each of the above embodiments may perform the method for determining sulfur poisoning of an aftertreatment system provided in any of the embodiments of the present invention, and has functional modules and advantageous effects corresponding to the method for determining sulfur poisoning of an aftertreatment system.

Example four

Fig. 5 is a schematic structural diagram of a vehicle according to a fourth embodiment of the present invention, as shown in fig. 5, the vehicle includes a processor 510, a memory 520, an input device 530, and an output device 540; the number of processors 510 in the vehicle may be one or more, and one processor 510 is taken as an example in fig. 5; the processor 510, memory 520, input device 530, and output device 540 in the vehicle may be connected by a bus or other means, as exemplified by the bus connection in fig. 5.

The memory 520 may be used as a computer-readable storage medium for storing software programs, computer-executable programs, and modules, such as program instructions/modules corresponding to the sulfur poisoning determination method of the aftertreatment system in the embodiment of the present invention (e.g., the data acquisition module 410, the monitoring state determination module 420, and the sulfur poisoning failure determination module 430 in the sulfur poisoning determination device). The processor 510 executes various functional applications and data processing of the vehicle, i.e., implements the above-described aftertreatment system sulfur poisoning determination method, by executing software programs, instructions, and modules stored in the memory 520.

The memory 520 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application program required for at least one function; the storage data area may store data created according to the use of the terminal, and the like. Further, the memory 520 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid state storage device. In some examples, the memory 520 may further include memory located remotely from the processor 510, which may be connected to the vehicle over a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.

The input device 530 may be used to receive input numeric or character information and generate key signal inputs related to user settings and function control of the vehicle. The output device 540 may include a display device such as a display screen.

EXAMPLE five

Embodiments of the present invention also provide a storage medium containing computer-executable instructions, which when executed by a computer processor, perform a method for determining sulfur poisoning of an aftertreatment system, the method comprising:

after the aftertreatment system is determined to simultaneously meet the first monitoring release condition and the second monitoring release condition, acquiring an upstream NOx value in engine exhaust measured by an upstream NOx sensor, a downstream NOx value in engine exhaust measured by a downstream NOx sensor and a DPF differential pressure value measured by a DPF differential pressure sensor;

determining an SCR conversion efficiency monitoring state according to the upstream NOx value and the downstream NOx value, and determining a DPF pressure difference monitoring state according to the DPF pressure difference value;

determining whether a sulfur poisoning fault has occurred in the aftertreatment system based on the SCR conversion efficiency monitoring state and the DPF pressure differential monitoring state.

Of course, the storage medium containing the computer-executable instructions provided by the embodiments of the present invention is not limited to the method operations described above, and may also perform related operations in the method for determining sulfur poisoning of an aftertreatment system provided by any embodiment of the present invention.

From the above description of the embodiments, it is obvious for those skilled in the art that the present invention can be implemented by software and necessary general hardware, and certainly, can also be implemented by hardware, but the former is a better embodiment in many cases. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which can be stored in a computer-readable storage medium, such as a floppy disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a FLASH Memory (FLASH), a hard disk or an optical disk of a computer, and includes several instructions for enabling a computer device (which may be a personal computer, a server, or a network device) to execute the methods according to the embodiments of the present invention.

It should be noted that, in the embodiment of the sulfur poisoning determination device of the aftertreatment system, the included units and modules are only divided according to the functional logic, but are not limited to the above division as long as the corresponding functions can be realized; in addition, specific names of the functional units are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present invention.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.