Patent Publication Number: US-2023135414-A1

Title: Engine controller and engine controlling method

Description:
BACKGROUND 
     1. Field 
     The present disclosure relates to an engine controller and an engine controlling method that control an engine mounted on a vehicle. Particularly, the present disclosure relates to an engine controller and an engine controlling method for an engine equipped with a liquid-cooled turbocharger that performs cooling with cooling water supplied by an electric pump. 
     2. Description of Related Art 
     If an engine is stopped immediately after a high-load operation, the turbocharger may be overheated after the engine is stopped. In order to prevent overheating of the turbocharger after the engine is stopped, an electric pump is driven to supply cooling water to the turbocharger after the engine is stopped in some cases, as described in Japanese Laid-Open Patent Publication No. 2016-079935. 
     If the electric pump is driven after the engine is stopped, the amount of charge of the battery decreases. This may lead to battery exhaustion. Aside from driving of the electric pump during stoppage of the engine, there are multiple possible causes of battery exhaustion. It is thus difficult to identify the causes of battery exhaustion. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     In one general aspect, an engine controller is configured to control an engine. The engine is mounted on a vehicle and includes a turbocharger and an electric pump that supplies a cooling water to the turbocharger. The engine controller includes a processor and a storage. The processor is configured to execute: a determination process that determines whether the cooling water needs to be supplied to the turbocharger after the engine is stopped; a post-stoppage pump driving process that drives the electric pump after the engine is stopped if the determination process determines that the cooling water needs to be supplied; and a recording process that records, in the storage, a number of times of execution of the post-stoppage pump driving process. 
     The above-described engine controller records, in the storage, a number of times of execution of the post-stoppage pump driving process, which is one of the causes of battery exhaustion. Referring to the recorded number of times of execution facilitates the determination of whether the cause of battery exhaustion is the post-stoppage pump driving process or other. This allows the cause of the battery exhaustion to be identified easily. 
     In the above-described engine controller, the post-stoppage pump driving process may include varying of driving time of the electric pump after stoppage of the engine depending on a temperature state of the turbocharger at the stoppage of the engine. The recording process may include recording of information of the driving time together with the number of times of execution. The processor may be configured to divide a set range of the driving time into time sections, and record the number of times of execution of the post-stoppage pump driving process for each of the time sections. 
     In the above-described engine controller, the vehicle may perform automatic stopping and automatic restarting of the engine in accordance with a traveling condition of the vehicle. The recording process does not record the number of times of execution of the post-stoppage pump driving process if the post-stoppage pump driving process is executed in response to the automatic stopping. 
     In the above-described engine controller, if the post-stoppage pump driving process is executed repeatedly due to repeated stopping and restarting of the engine, the recording process may record, as one time, the number of times of execution of the post-stoppage pump driving process. 
     In another general aspect, an engine controlling method configured to control an engine is provided. The engine is mounted on a vehicle and includes a turbocharger and an electric pump that supplies a cooling water to the turbocharger. The engine controlling method includes: determining whether the cooling water needs to be supplied to the turbocharger after the engine is stopped; executing a post-stoppage pump driving process that drives the electric pump after the engine is stopped if it is determined that the cooling water needs to be supplied; and recording, in a storage, a number of times of execution of the post-stoppage pump driving process. 
     Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram showing an engine controller according to one embodiment. 
         FIG.  2    is a flowchart of a stopped state process executed by the engine controller. 
         FIG.  3    is a flowchart of a post-stoppage process executed by the engine controller. 
     
    
    
     Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience. 
     DETAILED DESCRIPTION 
     This description provides a comprehensive understanding of the methods, apparatuses, and/or systems described. Modifications and equivalents of the methods, apparatuses, and/or systems described are apparent to one of ordinary skill in the art. Sequences of operations are exemplary, and may be changed as apparent to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Descriptions of functions and constructions that are well known to one of ordinary skill in the art may be omitted. 
     Exemplary embodiments may have different forms, and are not limited to the examples described. However, the examples described are thorough and complete, and convey the full scope of the disclosure to one of ordinary skill in the art. 
     In this specification, “at least one of A and B” should be understood to mean “only A, only B, or both A and B.” 
     An engine controller according to one embodiment will be described with reference to  FIGS.  1  to  3   . The engine controller according to the present embodiment is employed in an engine  10  mounted on a vehicle. 
     &lt;Configuration of Engine Controller&gt; 
     First, the configuration of the engine controller according to the present embodiment will be described with reference to  FIG.  1   . As shown in  FIG.  1   , the engine  10  is provided with an intake passage  11  and an exhaust passage  12 . The engine  10  is also provided with an oil pump  13 , which is driven by rotation of the engine  10 . 
     The engine  10  is provided with a turbocharger  20 . The turbocharger  20  includes a turbine housing  21 , which is provided on the exhaust passage  12  of the engine  10 , and a compressor housing  22 , which is provided on the intake passage  11  of the engine  10 . The turbine housing  21  and the compressor housing  22  are coupled to each other by a journal housing  23 . The turbine housing  21  incorporates a turbine wheel  24 , which is rotated by receiving flow of exhaust gas flowing through the exhaust passage  12 . The compressor housing  22  incorporates a compressor wheel  25 , which rotates to compress intake air flowing through the intake passage  11 . The journal housing  23  receives a turbine shaft  26 , which couples the turbine wheel  24  and the compressor wheel  25  to each other. The turbine shaft  26  is supported by a floating bearing  27  so as to be rotatable with respect to the journal housing  23 . A seal ring  28  is attached to a section of the turbine shaft  26  that is close to the section coupled to the turbine wheel  24  to restrict inflow of exhaust gas from the turbine housing  21  into the journal housing  23 . 
     An oil passage  29  is formed in the journal housing  23  to cause oil to flow through the floating bearing  27 . The oil passage  29  is supplied with some of the oil discharged by the oil pump  13 . Also, a water jacket  30  is formed in the journal housing  23 . The water jacket  30  is a passage through which cooling water flows. The water jacket  30  is supplied with cooling water by an electric pump  31 , which is located outside the turbocharger  20 . The electric pump  31  is driven by power supplied by a battery  14  mounted on the vehicle. The vehicle is also equipped with an alternator  15 , which generates power when rotated by the engine  10 . The battery  14  is charged with the power generated by the alternator  15 . 
     The vehicle in which the engine  10  is mounted is equipped with an engine control module (ECM)  40 . The ECM  40  includes a processing device  41 , which executes various types of processes to control the engine, and a storage  42 , which stores programs and data for controlling the engine. The ECM  40  receives detection signals of state quantities indicating the traveling state of the vehicle, such as a vehicle speed V, an engine rotation speed NE, an accelerator pedal depression amount ACC, a boost pressure PB, an intake air flow rate GA, an intake air temperature THA, and an outside air temperature THO. The ECM  40  also receives an IG signal, which indicates an operating state of an ignition switch  43 . Based on the received signals, the ECM  40  controls, for example, a throttle opening degree TA, a fuel injection amount QINJ, and an ignition timing AOP of the engine  10 . 
     During the operation of the engine  10 , the ECM  40  estimates a housing temperature TH1, which is the temperature of the turbine housing  21 , and temperatures of generation sites P 1  to P 3  of oil coke. The generation site P 1  is a section in the oil passage  29  that is close to the seal ring  28 . The occurrence site P 2  is a section in the oil passage  29  that is close to the floating bearing  27 . The generation site P 3  is an oil drain portion, which is a section of the oil passage  29  that is on the downstream side of the floating bearing  27 . In the following description, the temperature of the generation site P 1  will be referred to as a seal ring temperature TH2, the temperature of the generation site P 2  will be referred to as a bearing temperature TH3, and the temperature of the generation site P 3  will be referred to as an oil drain temperature TH4. 
     The ECM  40  estimates the housing temperature TH1, the seal ring temperature TH2, the bearing temperature TH3, and the oil drain temperature TH4 based on various state quantities that represent the traveling condition of the vehicle. The state quantities used to estimate the temperatures include the vehicle speed V, the engine rotation speed NE, the accelerator pedal depression amount ACC, the fuel injection amount QINJ, the boost pressure PB, the intake air flow rate GA, the intake air temperature THA, and the outside air temperature THO. The temperatures are estimated, for example, by a neural network that has been trained through machine learning. 
     The vehicle on which the engine  10  is mounted performs automatic stopping and automatic restarting of the engine  10  in accordance with the traveling condition of the vehicle. The automatic stopping and the automatic restarting of the engine  10  are performed only when the amount of charge of the battery  14  is greater than or equal to a certain level. In the following description, the stopping of the engine  10  that is not the automatic stopping but is performed by turning off the ignition switch  43  will be referred to as manual stopping of the engine  10 . 
     &lt;Post-Stoppage Pump Driving Process&gt; 
     When the engine  10  is stopped, the ECM  40  determines whether the turbocharger  20  needs to be cooled based on the housing temperature TH1, the seal ring temperature TH2, the bearing temperature TH3, and the oil drain temperature TH4. When determining that such cooling is needed, the ECM  40  executes a post-stoppage pump driving process, which drives the electric pump  31  after the engine  10  is stopped, thereby supplying cooling water to cool the turbocharger  20 . 
       FIG.  2    shows the flowchart of a stopped state process. When the engine  10  is stopped, the ECM  40  executes the stopped state process in order to execute the post-stoppage pump driving process. The stopped state process is executed both at the automatic stopping and the manual stopping of the engine  10 . 
     When starting the stopped state process in response to stoppage of the engine  10 , the ECM  40  obtains, in step S 100 , the current values of the housing temperature TH1, the seal ring temperature TH2, the bearing temperature TH3, and the oil drain temperature TH4. These temperatures indicate the temperature state of the turbocharger  20  when the engine  10  is stopped. 
     Subsequently, the ECM  40  calculates a first request driving time TM1, a second request driving time TM2, a third request driving time TM3, and a fourth request driving time TM4 in step S 110 . The first request driving time TM1 is calculated based on the housing temperature TH1, which has been obtained in step S 100 , using a first calculation map MAP 1 . The first request driving time TM1 represents driving time of the electric pump  31  required to lower the housing temperature TH1 to an appropriate temperature. The second request driving time TM2 is calculated based on the seal ring temperature TH2, which has been obtained in step S 100 , using a second calculation map MAP 2 . The second request driving time TM2 represents driving time of the electric pump  31  required to lower the seal ring temperature TH2 to an appropriate temperature that reduces the formation of oil coke. The third request driving time TM3 is calculated based on the bearing temperature TH3, which has been obtained in step S 100 , using a third calculation map MAP 3 . The third request driving time TM3 represents driving time of the electric pump  31  required to lower the bearing temperature TH3 to an appropriate temperature that reduces the formation of oil coke. The fourth request driving time TM4 is calculated based on the oil drain temperature TH4, which has been obtained in step S 100 , using a fourth calculation map MAP 4 . The fourth request driving time TM4 represents driving time of the electric pump  31  required to lower the oil drain temperature TH4 to an appropriate temperature that reduces the formation of oil coke. The first to fourth calculation maps MAP 1  to MAP 4  are each designed to set the value of the request driving time to 0 when the temperature of the corresponding site is lower than a certain value of the temperature. Also, the first to fourth calculation maps MAP 1  to MAP 4  are each designed to increase the value of the request driving time as the temperature of the site increases, when the temperature of the corresponding site is higher than or equal to the certain value of the temperature. The certain value is different for each of the first to fourth calculation maps MAP 1  to MAP 4 . In the subsequent step S 120 , the ECM  40  sets the value of a request driving time TMR to the greatest value of the first to fourth request driving times TM1 to TM4. 
     Next, in step S 130 , the ECM  40  determines whether the request driving time TMR has been set to a value greater than 0. If the request driving time TMR has been set to 0 (NO), the cooling water does not need to be supplied to the turbocharger  20  after the engine  10  is stopped. In this case, the ECM  40  ends the stopped state process at the current stoppage of the engine  10 . If the request driving time TMR has been set to a value greater than 0 (YES), the cooling water needs to be supplied to the turbocharger  20  after the engine  10  is stopped. In this case, the ECM  40  advances the process to step S 140 . In the present embodiment, step S 130  corresponds to a determination process that determines whether the cooling water needs to be supplied to the turbocharger  20  after the engine  10  is stopped. 
     When advancing the process to step S 140 , the ECM  40  determines whether a recording completion flag is set in step S 140 . If the recording completion flag is set (YES), the ECM  40  advances the process to step S 180 . If the recording completion flag is not set (NO), the ECM  40  advances the process to step S 150 . 
     In step S 150 , the ECM  40  determines whether the current stoppage of the engine  10  has been caused by the automatic stopping. If the stoppage has been caused by the automatic stopping (YES), the ECM  40  advances the process to step S 180 . If the current stoppage has not been caused by the automatic stopping (NO), that is, if the current stoppage of the engine  10  has been caused by the manual stopping in response to an off operation of the ignition switch  43 , the ECM  40  advances the process to step S 160 . 
     In step S 160 , the ECM  40  increments an execution counter, which is stored in the storage  42 . In the present embodiment, the set range of the request driving time TMR is divided into multiple time sections, and an execution counter is prepared for each of the time sections. In step S 160 , the ECM  40  increments the execution counter for the time section that corresponds to the current set value of the request driving time TMR. The values of the execution counters in the storage  42  are retained even after power supply to the ECM  40  is stopped. In the subsequent step S 170 , the ECM  40  sets the recording completion flag and advances the process to step S 180 . In a case in which the recording completion flag is already set when the stopped state process is started as described above (S 140 : YES), and in a case of the automatic stopping (S 150 : YES), the ECM  40  advances the process to step S 180  without incrementing the execution counter. In the present embodiment, step S 160  corresponds to a recording process that records, in the storage  42 , the number of times the post-stoppage pump driving process has been executed. 
     When advancing the process to step S 180 , the ECM  40  resets the value of a driving time counter TMC to 0 in step S 180 . After starting to drive the electric pump  31  in step S 190 , the ECM  40  ends the stopped state process at the current stoppage of the engine  10 . 
     In a case in which the electric pump  31  is operating after the engine  10  is stopped, the ECM  40  executes a post-stoppage process shown in  FIG.  3    at each predefined control cycle. When starting the post-stoppage process, the ECM  40  increments the driving time counter TMC in step S 200 . In step S 210 , the ECM  40  determines whether the value of the driving time counter TMC is greater than or equal to the value of the request driving time TMR. If the value of the driving time counter TMC is less than the value of the request driving time TMR (NO), the ECM  40  ends the post-stoppage process in the current control cycle. If the value of the driving time counter TMC is greater than or equal to the request driving time TMR (YES), the ECM  40  stops driving the electric pump  31  in step S 220 . After clearing the recording completion flag in step S 230 , the ECM  40  ends the post-stoppage process in the current control cycle. 
     In the present embodiment, the post-stoppage pump driving process is executed through the above-described stopped state process and the post-stoppage process. The post-stoppage pump driving process is completed when the electric pump  31  is driven for a time that corresponds to the value of the request driving time TMR. At the same time as the completion of the post-stoppage pump driving process, the recording completion flag is cleared. 
     If the engine  10  is restarted before the time corresponding to the value of the request driving time TMR elapses after the post-stoppage pump driving process is started, the post-stoppage pump driving process is suspended. In this case, the recording completion flag remains set. 
     If the temperature of the turbocharger  20  is relatively high after the engine  10  is restated, the ECM  40  drives the electric pump  31  to cool the turbocharger  20 . The ECM  40  clears the recording completion flag when the turbocharger  20  is cooled so that the electric pump  31  is stopped. 
     &lt;Operation and Advantages of Embodiment&gt; 
     Operation and advantages of the present embodiment will now be described. 
     During high-load operation of the engine  10 , high-temperature exhaust gas flows into the turbine housing  21 , so that the temperature of the turbocharger  20  is relatively high. This can carbonize oil in the turbocharger  20 , so that oil coke may be accumulated in the oil passage  29 . During the operation of the engine  10 , the electric pump  31  is driven to supply the cooling water to cool the turbocharger  20 . In the present embodiment, in a case in which the engine  10  is stopped with the turbocharger  20  at a relatively high temperature, for example, immediately after a high-load operation, the post-stoppage pump driving process continues to drive the electric pump  31  even after the engine  10  is stopped. This cools the turbocharger  20  and thus reduces the formation and accumulation of oil coke. 
     When the engine  10  stopped, the alternator  15  stops generating power, so that the battery  14  stops being charged. Accordingly, if the post-stoppage pump driving process is executed to drive the electric pump  31  after the engine  10  is stopped, the amount of charge of the battery  14  decreases due to power consumption by the electric pump  31 . If the operation of the electric pump  31  is performed frequently for an extended period of time by the post-stoppage pump driving process after the stoppage of the engine  10 , the charging capability of the battery  14  is reduced. In other words, battery exhaustion may occur. 
     A vehicle may be brought to a car dealer when battery exhaustion occurs. In such a case, the car dealer identifies the cause of the battery exhaustion and performs necessary maintenance. Aside from the electric pump  31  having been driven after stoppage of the engine  10 , a failure in the vehicle electrical system such as the alternator  15  may cause battery exhaustion. 
     In this regard, the number of times the post-stoppage pump driving process has been executed is stored in the storage  42  in the present embodiment. The number of times the post-stoppage pump driving process has been executed, which is stored in the storage  42 , can be checked using a scanning tool at an auto repair shop such as a car dealer. This allows the cause of the battery exhaustion to be identified easily. 
     The engine controller of the present embodiment has the following advantages. 
     (1) The number of times the post-stoppage pump driving process has been executed is stored in the storage  42 . This allows the cause of battery exhaustion to be identified easily. 
     (2) In the present embodiment, the driving time of the electric pump  31  in the post-stoppage pump driving process is varied depending on the temperature state of the turbocharger  20  at the stoppage of the engine  10 . The operation of the electric pump  31  caused by the post-stoppage pump driving process affects the charging capability of the battery  14  more when the driving time is relatively long than when the driving time is relatively short. In the present embodiment, the number of times the post-stoppage pump driving process has been executed is recorded for each of the time sections of the driving time. It is thus easy to determine whether the cause of battery exhaustion is the operation of the electric pump  31  in the post-stoppage pump driving process. 
     (3) When the amount of charge of the battery  14  is relatively low, the automatic stopping of the engine  10  is not performed. Also, the battery  14  restarts to be charged by the restarting of the engine  10  after the automatic stopping. Thus, the post-stoppage pump driving process at the automatic stopping is unlikely to cause reduction in the charging capability of the battery  14 . In this regard, the execution of the post-stoppage pump driving process at the automatic stopping is not included in the number of times of execution in the present embodiment. It is thus easy to reliably determine whether the cause of battery exhaustion is the operation of the electric pump  31  in the post-stoppage pump driving process. 
     (4) If stopping and restarting of the engine  10  are repeated, the post-stoppage pump driving process may be executed each time the engine  10  is stopped. In such a case, the operation of the electric pump  31  in the post-stoppage pump driving process is discontinued after a short period of time. The charging capability of the battery  14  is thus not easily reduced. If the number of times the post-stoppage pump driving process has been executed is recorded faithfully, it may be difficult to identify the cause of battery exhaustion from the number of times of the execution. In this regard, in the present embodiment, when the post-stoppage pump driving process is executed repeatedly due to repeated stopping and restarting of the engine  10 , the number of times the post-stoppage pump driving process has been executed is recorded as one time. It is thus easy to reliably determine whether the cause of battery exhaustion is the operation of the electric pump  31  in the post-stoppage pump driving process. 
     The above-described embodiment may be modified as follows. The above-described embodiment and the following modifications can be combined as long as the combined modifications remain technically consistent with each other. 
     The recorded number of times the post-stoppage pump driving process has been executed may include the number of times the process has been executed at the automatic stopping of the engine  10  and the number of times the process has been executed when stopping and restarting of the engine  10  are repeated. 
     In the above-described embodiment, the number of times the post-stoppage pump driving process has been executed is recorded for each of the time sections of the driving time. This allows the driving time of the electric pump  31  in the process to be determined with a certain level of accuracy. Information of the driving time of the electric pump  31  can be recorded by a method other than recording the number of times the post-stoppage pump driving process has been executed for each of the time sections of the driving time of the electric pump  31 . For example, a method may be employed that records the total driving time or an average driving time of the electric pump  31  in the post-stoppage pump driving process. In any case, if information of the driving time of the electric pump  31  in the post-stoppage pump driving process is recorded together with the number of times the process has been executed, such information is useful to identify the cause of battery exhaustion. 
     For example, in a case in which the driving time of the electric pump  31  in the post-stoppage pump driving process is fixed, only the number of times of the process has been executed may be recorded. 
     The ECM  40  or the processing device  41  may include one or more processors that perform various processes according to computer programs (software). The ECM  40  or the processing device  41  may be circuitry including one or more dedicated hardware circuits such as application specific integrated circuits (ASICs) that execute at least part of various processes, or a combination thereof. The processor includes a CPU and a memory such as a RAM and a ROM. The memory stores program code or instructions configured to cause the CPU to execute processes. The memory, which is a computer-readable medium, includes any type of media that are accessible by general-purpose computers and dedicated computers. 
     Various changes in form and details may be made to the examples above without departing from the spirit and scope of the claims and their equivalents. The examples are for the sake of description only, and not for purposes of limitation. Descriptions of features in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if sequences are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined differently, and/or replaced or supplemented by other components or their equivalents. The scope of the disclosure is not defined by the detailed description, but by the claims and their equivalents. All variations within the scope of the claims and their equivalents are included in the disclosure.