Patent Publication Number: US-2023141389-A1

Title: Diagnosis device and diagnosis method

Description:
TECHNICAL FIELD 
     The present disclosure relates to a diagnosis device and a diagnosis method. 
     BACKGROUND ART 
     Some vehicles are provided with a purification device that purifies exhaust gas in an exhaust passage of an internal combustion engine. The purification device includes a diesel oxidation catalyst (DOC), which is an oxidation catalyst, and a catalyzed soot filter (CSF), raises a temperature of the exhaust gas, and burns and removes particulate matter (PM) in the exhaust gas (so-called regeneration control). 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: JP-A-2018-193953 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     For example, when the purification device is provided upstream in the exhaust passage, the particulate matter (for example, soot) in the exhaust gas may adhere to the DOC and block the DOC. When the DOC is blocked, a flow of the exhaust gas deteriorates, and the above-described regeneration control is not smoothly executed. Therefore, it is required to appropriately estimate a degree of damage to the purification device and perform maintenance or the like. 
     The present disclosure has been made in view of these points, and an object of the present disclosure is to appropriately estimate a degree of damage to a purification device. 
     Solution to Problem 
     A first aspect of the present disclosure provides a diagnosis device. The diagnosis device includes: an acquisition unit configured to acquire, from a plurality of internal combustion engine devices, cumulative data for each parameter related to stress acting on a purification device configured to purify exhaust gas of an internal combustion engine and an exhaust gas temperature of the exhaust gas raised for purification; a damage degree identification unit configured to identify a degree of damage to the purification device based on the acquired cumulative data; a relationship identification unit configured to identify a relational expression indicating a relationship between the identified degree of damage and the exhaust gas temperature; an exhaust gas temperature acquisition unit configured to acquire an exhaust gas temperature of exhaust gas raised for purification performed by the purification device from a target device which is an internal combustion engine device to be diagnosed; and an estimation unit configured to estimate a degree of damage to the purification device of the target device based on the exhaust gas temperature of the target device acquired by the exhaust gas temperature acquisition unit and the relational expression identified by the relationship identification unit. 
     The estimation unit may estimate a degree of damage to an oxidation catalyst for purifying particulate matter as the degree of damage to the purification device. 
     The exhaust gas temperature acquisition unit may acquire a first temperature which is an upstream exhaust gas temperature of the oxidation catalyst, and a second temperature which is a downstream exhaust gas temperature of the oxidation catalyst, and the estimation unit may estimate the degree of damage to the oxidation catalyst based on a temperature difference between the first temperature and the second temperature and the relational expression. 
     The damage degree identification unit may identify the degree of damage according to cumulative data of each of a plurality of stress factors deteriorating the purification device. 
     A second aspect of the present disclosure provides a diagnosis method. The diagnosis method includes: a step of acquiring, from a plurality of internal combustion engine devices, cumulative data for each parameter related to stress acting on a purification device configured to purify exhaust gas of an internal combustion engine and an exhaust gas temperature of the exhaust gas raised for purification; a step of identifying a degree of damage to the purification device based on the acquired cumulative data; a step of identifying a relational expression indicating a relationship between the identified degree of damage and the exhaust gas temperature; a step of acquiring an exhaust gas temperature of exhaust gas raised for purification performed by the purification device from a target device which is an internal combustion engine device to be diagnosed; and a step of estimating a degree of damage to the purification device of the target device based on the acquired exhaust gas temperature of the target device and the identified relational expression. 
     Advantageous Effects of Invention 
     According to the present disclosure, it is possible to appropriately estimate a degree of damage to a purification device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic diagram showing an overview of a vehicle management system S. 
         FIG.  2    is a schematic diagram showing a configuration of a vehicle  1 . 
         FIG.  3    is a block diagram showing a configuration of a management device  100 . 
         FIG.  4    is a schematic diagram showing a relational expression. 
         FIG.  5    is a flowchart showing a flow for identifying the relational expression. 
         FIG.  6    is a flowchart showing estimation processing of a degree of damage to a diagnosis target. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     &lt;Overview of Vehicle Management System&gt; 
     An overview of a vehicle management system according to an embodiment will be described with reference to  FIG.  1   . 
       FIG.  1    is a schematic diagram showing an overview of a vehicle management system S. The vehicle management system S is a system configured to manage states of a plurality of vehicles  1   a ,  1   b , . . . ,  1   n  (hereinafter, also collectively referred to as “vehicles  1 ”) by operating a management device  100  and the vehicles  1  in cooperation with each other. 
     The plurality of vehicles  1  are, for example, trucks. The vehicle  1  corresponds to an internal combustion engine device including an engine which is an internal combustion engine. The vehicle  1  is provided with a sensor or the like configured to measure a state of the own vehicle, and transmits measured data to the management device  100 . 
     The management device  100  is a vehicle management device capable of communicating with the plurality of vehicles  1  and configured to manage the vehicles  1 . The management device  100  is, for example, a server provided in a management center. The management device  100  receives data (such as cumulative data to be described later) from each vehicle  1 . The management device  100  diagnoses the state of the vehicle  1  using the received data. For example, the management device  100  determines whether maintenance is necessary based on a diagnosis result. 
     &lt;Configuration of Vehicle&gt; 
     Configurations of the plurality of vehicles  1   a ,  1   b , . . . ,  1   n  shown in  FIG.  1    are the same. The configuration of the vehicle  1  will be described with reference to  FIG.  2   . Hereinafter, a configuration related to the diagnosis of the vehicle  1  will be described. 
       FIG.  2    is a schematic diagram showing the configuration of the vehicle  1 . As shown in  FIG.  2   , the vehicle  1  includes an engine  10 , an intake passage  20 , an exhaust passage  30 , a diesel particulate defuser (DPD)  32 , an injection unit  38 , and a selective catalytic reduction (SCR)  39 . 
     The engine  10  burns and expands an air-fuel mixture of fuel and intake air injected into a cylinder (a combustion chamber) to generate power. In the engine  10 , the intake air is suctioned into the cylinder, and exhaust gas after combustion is discharged from the cylinder. 
     The intake passage  20  is a passage through which the intake air flows toward the engine  10 . The intake passage  20  is provided with a supercharger configured to supercharge the intake air. 
     The exhaust passage  30  is a passage through which the exhaust gas from the engine  10  flows. The exhaust passage  30  is provided with a DPD  32 , the injection unit  38 , and an SCR  39 . 
     The DPD  32  is a purification device configured to remove particulate matter (for example, soot) in the exhaust gas. When a predetermined amount of particulate matter is accumulated in the filter, the DPD  32  performs regeneration (combustion) processing to remove the particulate matter. The DPD  32  includes a DOC  33 , a CSF  34 , and temperature sensors  35 ,  36 . 
     The DOC  33  is a diesel oxidation catalyst, and efficiently oxidizes hydrocarbon of the exhaust gas to raise a temperature of the exhaust gas. When the temperature of the exhaust gas rises, the combustion of the particulate matter during the regeneration processing is promoted. The DOC  33  has a so-called honeycomb structure. 
     The CSF  34  is a filter configured to collect the particulate matter in the exhaust gas. 
     The temperature sensor  35  is provided on a front surface  33   a  side of the DOC  33 , and is configured to detect the temperature of the exhaust gas before flowing into the DOC  33 . 
     The temperature sensor  36  is provided on a rear surface  33   b  side of the DOC  33 , and is configured to detect the temperature of the exhaust gas flowing out of the DOC  33 . 
     The injection unit  38  injects urea water, which is a precursor of ammonia, into the exhaust gas in the exhaust passage  30 . 
     The SCR  39  is a purification device configured to reduce NOx in the exhaust gas. The SCR  39  causes NOx and ammonia to react with each other to reduce NOx and ammonia to harmless nitrogen and water. 
     The particulate matter (for example, soot) in the exhaust gas may adhere to a front surface  33   a  of the DOC  33  and block the DOC  33 . When a degree of blockage (a degree of damage) of the DOC  33  is large, the flow of the exhaust gas deteriorates, and the regeneration processing cannot be performed smoothly. When the DOC  33  is blocked, a temperature inside the CSF  34  may also rise, and the CSF  34  may deteriorate. 
     On the other hand, the management device  100  acquires cumulative data indicating operation states from the plurality of vehicles  1 , and obtains a relational expression between the degree of damage to the DOC  33  and a characteristic value (specifically, the temperature of the exhaust gas) for identifying the damage. Then, the management device  100  estimates the degree of damage to the DOC  33  of the vehicle  1  to be diagnosed based on the relational expression obtained in advance and an exhaust gas temperature acquired from the vehicle  1  to be diagnosed. Accordingly, it is possible to appropriately estimate the degree of damage to the DOC  33  of the vehicle  1  to be diagnosed. 
     &lt;Configuration of Management Device&gt; 
     A configuration of the management device  100  that functions as a diagnosis device will be described with reference to  FIG.  3   . 
       FIG.  3    is a block diagram showing the configuration of the management device  100 . The management device  100  is operated by an administrator of the management center. As shown in  FIG.  3   , the management device  100  includes a communication unit  110 , a storage unit  112 , and a control unit  120 . 
     The communication unit  110  is configured to communicate with the vehicle  1  ( FIG.  1   ). The communication unit  110  is configured to transmit and receive data to and from the vehicle  1 . For example, the communication unit  110  receives the cumulative data indicating the operation state of the vehicle  1  from the vehicle  1 . 
     The storage unit  112  includes, for example, a read only memory (ROM) and a random access memory (RAM). The storage unit  112  is configured to store a program to be executed by the control unit  120  and various types of data. For example, the storage unit  112  stores the cumulative data acquired from each of the plurality of vehicles  1 . Further, the storage unit  112  is configured to store information on the relational expression of the degree of damage to the DOC  33 . 
     The control unit  120  is, for example, a central processing unit (CPU). The control unit  120  is configured to diagnose the vehicle  1  by executing the program stored in the storage unit  112 . In the present embodiment, the control unit  120  functions as a data acquisition unit  122 , a damage degree identification unit  123 , a relationship identification unit  124 , a target information acquisition unit  125 , and a diagnosis unit  126 . 
     The data acquisition unit  122  is configured to acquire data of the vehicle  1  from the plurality of vehicles  1 . In the present embodiment, the data acquisition unit  122  acquires cumulative data for each parameter related to stress acting on the DPD  32  (here, the DOC  33 ) from the plurality of vehicles  1 . By using the cumulative data, it is possible to diagnose the degree of damage to the DOC  33  that has deteriorated due to the complex stress. The data acquisition unit  122  periodically (for example, once per month) acquires the cumulative data. The data acquisition unit  122  stores the acquired cumulative data in the storage unit  112 . 
     There are a plurality of parameters of stress factors acting on the DOC  33 . For example, the parameters of stress factors are use in an operating region in which soot is likely to be generated, use in a state in which the exhaust gas is at a low temperature, use in a state in which a flow rate of the exhaust gas is low, and the like. The cumulative data indicates a frequency of each parameter. 
     The data acquisition unit  122  acquires the exhaust gas temperature of the exhaust gas raised for purification together with the cumulative data from the plurality of vehicles  1 . That is, the data acquisition unit  122  acquires the exhaust gas temperature during the regeneration processing. Here, the data acquisition unit  122  acquires the exhaust gas temperature detected by the temperature sensors  35 ,  36  during the regeneration processing. The exhaust gas temperature of the exhaust gas is a characteristic value capable of identifying the degree of damage to the deteriorated DOC  33 . Normally, when the exhaust gas temperature is high, the degree of damage to the DOC  33  tends to be small, and when the exhaust gas temperature is low, the degree of damage to the DOC  33  tends to be large. 
     The damage degree identification unit  123  is configured to identify the degree of damage to the DPD  32  (here, the DOC  33 ) of the vehicle  1 . The damage degree identification unit  123  identifies the degree of damage to the DOC  33  of each vehicle  1  based on the cumulative data acquired from the plurality of vehicles  1 . That is, the damage degree identification unit  123  identifies a degree of clogging of the front surface of the DOC  33  due to a plurality of stress factors. 
     The damage degree identification unit  123  identifies the degree of damage according to the cumulative data of each of the plurality of stress factors deteriorating the DOC  33 . At this time, the damage degree identification unit  123  multiplies a weighting coefficient for each stress factor. Accordingly, it is possible to identify the degree of damage reflecting the plurality of stress factors. 
     The relationship identification unit  124  is configured to identify a relational expression indicating a relationship between the degree of damage to the DOC  33  and a characteristic value for identifying the damage. That is, the relationship identification unit  124  is configured to identify a relational expression indicating the relationship between the degree of damage to the DOC  33  identified by the damage degree identification unit  123  and the exhaust gas temperature during the regeneration processing for identifying the damage. The relationship identification unit  124  stores the identified relational expression in the storage unit  112 . 
       FIG.  4    is a schematic diagram showing the relational expression. In a graph in  FIG.  4   , a horizontal axis represents the degree of damage to the DOC  33 , and a vertical axis represents the exhaust gas temperature which is the characteristic value. In the graph, the correspondence relationship between the degree of damage and the characteristic value based on the data periodically acquired from the one vehicle  1 , which is a failed vehicle, is plotted as a x mark. A curve on the graph is an approximate line of plotted data, and indicates the relational expression. The relationship identification unit  124  may identify the relational expression by averaging the approximate lines obtained for each of the plurality of vehicles  1 . 
     The relationship identification unit  124  may update the relational expression by machine learning. That is, the relationship is updated using the cumulative data and the exhaust gas temperature that are periodically acquired from the vehicle  1 . Accordingly, it is possible to identify the relational expression with higher accuracy. 
     The target information acquisition unit  125  is configured to acquire, from the vehicle  1  to be diagnosed, information on the characteristic value (here, the exhaust gas temperature) for identifying the degree of damage to the DOC  33 . That is, the target information acquisition unit  125  functions as an exhaust gas temperature acquisition unit configured to acquire the exhaust gas temperature of the exhaust gas raised for the regeneration processing. When the device to be diagnosed is the vehicle  1   a  shown in  FIG.  1   , the target information acquisition unit  125  acquires the exhaust gas temperature from the vehicle  1   a.    
     The target information acquisition unit  125  acquires an upstream temperature which is the upstream exhaust gas temperature of the DOC  33 , and a downstream temperature which is the downstream exhaust gas temperature of the DOC  33 . The upstream exhaust gas temperature is the temperature detected by the temperature sensor  35  ( FIG.  2   ), and the downstream exhaust gas temperature is the temperature detected by the temperature sensor  36 . The target information acquisition unit  125  obtains a temperature difference between the upstream exhaust gas temperature and the downstream exhaust gas temperature. The target information acquisition unit  125  outputs information on the obtained temperature difference to the diagnosis unit  126 . 
     The diagnosis unit  126  is configured to diagnose the vehicle  1  to be diagnosed. The diagnosis unit  126  functions as an estimation unit configured to estimate the degree of damage to the DOC  33  to be diagnosed based on the exhaust gas temperature acquired by the target information acquisition unit  125  and the relational expression identified by the relationship identification unit  124 . Specifically, the diagnosis unit  126  estimates the degree of damage to the DOC  33  to be diagnosed by applying the exhaust gas temperature during the regeneration processing to the relational expression. Accordingly, if the temperature difference during the regeneration processing is known, the diagnosis unit  126  can accurately estimate the degree of damage (the degree of clogging of the front surface of the DOC  33 ) to the DOC  33  that deteriorates due to the plurality of stress factors. 
     The diagnosis unit  126  estimates the degree of damage to the DOC  33  based on the temperature difference between the upstream temperature and the downstream temperature of the DOC  33  and the relational expression. For example, as shown in  FIG.  4   , when the temperature difference is T 1 , the diagnosis unit  126  estimates that the degree of damage is D 1 . The diagnosis unit  126  may predict a life of the DOC  33  based on the estimated degree of damage to the DOC  33 . 
     &lt;Flow of Processing Executed by Management Device&gt; 
     A flow of the diagnosis processing executed by the management device  100  will be described with reference to  FIGS.  5  and  6   . 
       FIG.  5    is a flowchart showing the flow for identifying the relational expression. 
     The data acquisition unit  122  of the management device  100  acquires the cumulative data and the exhaust gas temperature from the plurality of vehicles  1  (for example, the vehicles  1   a  to  1   n  in  FIG.  1   ) (step S 102 ). The data acquisition unit  122  periodically (for example, once per month) acquires the cumulative data and the exhaust gas temperature. 
     Next, the damage degree identification unit  123  identifies the degree of damage to the DOC  33  of each vehicle  1  based on the acquired cumulative data (step S 104 ). That is, the damage degree identification unit  123  identifies the degree of damage to the DOC  33  that deteriorates due to the plurality of stress factors. 
     Next, the relationship identification unit  124  identifies the relational expression indicating the relationship between the identified degree of damage and the exhaust gas temperature (step S 106 ). For example, the relationship identification unit  124  identifies the relational expression indicated by an approximate expression shown in  FIG.  4   . 
     Next, the relationship identification unit  124  stores the identified relational expression in the storage unit  112  (step S 108 ). By repeating the above-described processing, the relational expression stored in the storage unit  112  is updated. The relational expression with high accuracy can be stored. 
       FIG.  6    is a flowchart showing estimation processing of the degree of damage to a diagnosis target. 
     Here, the target information acquisition unit  125  of the management device  100  starts from the acquisition of the exhaust gas temperature from the vehicle  1  to be diagnosed (step S 122 ). The target information acquisition unit  125  acquires, as the exhaust gas temperature, the temperature difference between the upstream temperature and the downstream temperature of the DOC  33 . 
     Next, the diagnosis unit  126  estimates the degree of damage to the DOC  33  of the vehicle  1  to be diagnosed based on the exhaust gas temperature acquired in step S 122  and the relational expression stored in advance in the storage unit  112  (step S 124 ). For example, the diagnosis unit  126  can accurately estimate the degree of damage to the DOC  33  by obtaining the degree of damage corresponding to the exhaust gas temperature based on the relational expression shown in  FIG.  4   . 
     Next, the management device  100  transmits the information on the estimated degree of damage (step S 126 ). For example, the management device  100  transmits the information on the degree of damage to a maintenance factory. 
     &lt;Effects According to Present Embodiment&gt; 
     The management device  100  according to the above-described embodiment identifies the relational expression between the degree of damage to the DOC  33  and the exhaust gas temperature using the cumulative data acquired from the plurality of vehicles  1 . When the management device  100  acquires the exhaust gas temperature from the vehicle  1  to be diagnosed, the management device  100  estimates the degree of damage to the DOC  33  of the vehicle  1  to be diagnosed based on the correspondence relationship with the relational expression identified in advance. 
     Accordingly, by applying the exhaust gas temperature of the DOC  33  to be diagnosed to the relational expression, it is possible to appropriately estimate the degree of damage (specifically, the clogging of the front surface of the DOC  33 ) to the DOC  33  that deteriorates due to the plurality of stress factors. As a result, it is possible to appropriately perform maintenance of the DOC  33  or the like by providing the information on the estimated degree of damage to the maintenance factory. 
     Although the present disclosure has been described above using the embodiment, the technical scope of the present disclosure is not limited to the scope described in the above-described embodiment, and various modifications and changes can be made within the scope of the gist of the present disclosure. For example, all or a part of the devices can be functionally or physically distributed or integrated in any unit. Further, a new embodiment generated by any combination of a plurality of embodiments is also contained in the embodiment of the present disclosure. Effects according to the new embodiment obtained by the combination include effects according to the original embodiments. 
     The present application is based on the Japanese Patent Application No. 2020-033206 filed on Feb. 28, 2020, and contents thereof are incorporated herein as reference. 
     INDUSTRIAL APPLICABILITY 
     The diagnosis device and the diagnosis method according to the present disclosure are useful in that the degree of damage to the purification device can be appropriately estimated. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  vehicle 
               32  DPD 
               33  DOC 
               100  management device (diagnosis device) 
               122  data acquisition unit 
               123  damage degree identification unit 
               124  relationship identification unit 
               125  target information acquisition unit 
               126  diagnosis unit