Abstract:
The objective of the present invention is to provide an engine with improved startability and stable operation regardless of the driving environment and usage conditions. The engine is equipped with a control means, which calculates a standard injection timing on the basis of the target rotational frequency of the engine and a standard injection amount, that is, the amount of fuel injected, and which corrects the standard injection timing using at least one correction amount. A fuel injection control unit calculates a cooling water correction amount on the basis of the target rotational frequency of the engine, the standard injection amount, and the cooling water temperature, and when the cooling water temperature is less than a first prescribed temperature the control unit corrects the standard injection timing using only the cooling water correction amount.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation application of U.S. patent application Ser. No. 14/655,532, filed on Jun. 25, 2015, the entire contents of which are incorporated herein by reference and priority to which is hereby claimed. application Ser. No. 14/655,532 is the U.S. national stage of Application No. PCT/JP2013/074322, filed on Sep. 10, 2013. Priority under 35 U.S.C. §119(a) and 35 U.S.C. §365(b) is claimed from Japanese Application No. 2012-281650, filed Dec. 25, 2012, and Japanese Application No. 2012-281651, filed Dec. 25, 2012, the disclosures of which are also incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to an engine and more particularly relates to an engine that includes a fuel injection control device. 
       BACKGROUND ART 
       [0003]    Conventionally, regarding diesel engines, there is a case where the vaporization of fuel is not facilitated at a cold start, and startability is reduced. Accordingly, there have been known fuel injection devices that correct a fuel injection time in such a manner as to intentionally advance the fuel injection time at the cold start. When the coolant temperature of the engine is lower than a predetermined temperature, correction is made in such a manner as to advance the fuel injection time until the coolant temperature reaches the predetermined temperature, which improves the startability of the engine. For example, Patent Literature 1 discloses the above-mentioned engine. 
         [0004]    The fuel injection control device disclosed in Patent Literature 1 makes correction (advance correction) in which, when the coolant temperature is equal to or lower than a predetermined temperature at the start of the engine, an injection time is advanced. Also, generally, there is a case where the injection time is advanced and corrected based on an indicator except for the coolant temperature for the purpose of suppressing the generation of black smoke and the like. Accordingly, in some operating environments of the engine, there is a possibility that the injection time is excessively advanced and corrected not only by the coolant temperature but also by a plurality of indicators, and the operating state of the engine becomes unstable, or engine stall is caused. 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         PTL 1: Japanese Unexamined Patent Application Publication No. 2007-32326 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0006]    The present invention has been achieved in view of the above-mentioned circumstances. It is an object of the present invention to provide an engine that improves startability and stabilizes operating states irrespective of operating environments and use modes. 
       Solution to Problem 
       [0007]    Regarding the present invention, an engine may be configured to include a control means that calculates a standard injection time based on a target number of revolutions and a fuel injection amount of the engine and corrects the standard injection time, fuel injection pressure, a fuel injection interval, or the fuel injection amount based on at least a correction amount, and the control means is configured to calculate a coolant correction amount based on the target number of revolutions, the fuel injection amount, and a coolant temperature of the engine, and when the coolant temperature is less than a first predetermined temperature, the control means is configured to correct the standard injection time, the fuel injection pressure, the fuel injection interval, or the fuel injection amount only based on the coolant correction amount. 
         [0008]    Regarding the present invention, when the coolant temperature is equal to or higher than a second predetermined temperature, the control means is configured to correct the standard injection time, the fuel injection pressure, the fuel injection interval, or the fuel injection amount based on at least the correction amount except for the coolant correction amount. 
         [0009]    Regarding the present invention, the control means may be configured to set the first predetermined temperature and the second predetermined temperature in response to an outside temperature. 
       Advantageous Effects of Invention 
       [0010]    As the effects of the present invention, the following advantageous effects are provided. 
         [0011]    According to one aspect of the present invention, under the condition in which the coolant temperature Tm is substantially affected, the correction based on the coolant correction amount Wc can be preferentially performed. Accordingly, the startability is improved, and operating states are stabilized irrespective of operating environments and use modes. 
         [0012]    According to another aspect of the present invention, under the condition in which the coolant temperature is slightly affected, the correction based on the coolant correction amount is not made. Accordingly, the startability is improved, and operating states are stabilized irrespective of operating environments and use modes. 
         [0013]    According to another aspect of the present invention, correction conditions based on the coolant temperature are changed based on the outside temperature at the start of the engine. Accordingly, the startability is improved, and operating states are stabilized irrespective of operating environments and use modes. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]      FIG. 1  is a schematic view illustrating the constitution of a fuel injection control device according to the present invention. 
           [0015]      FIG. 2  is a view illustrating a graph representing a relation of a coolant temperature and a correction amount of an injection time from the start of an engine. 
           [0016]      FIG. 3  is a view illustrating a flowchart representing the control mode of correcting the injection time of the first embodiment of the fuel injection control device according to the present invention. 
           [0017]      FIG. 4  is a view illustrating a flowchart representing the control mode of correcting the injection pressure of the first embodiment of the fuel injection control device according to the present invention. 
           [0018]      FIG. 5  is a view illustrating a flowchart representing the control mode of correcting the injection intervals of the first embodiment of the fuel injection control device according to the present invention. 
           [0019]      FIG. 6  is a view illustrating a flowchart representing the control mode of correcting the injection amount of the first embodiment of the fuel injection control device according to the present invention. 
           [0020]      FIG. 7  is a view illustrating a flowchart representing the control mode of correcting the injection time of the second embodiment of the fuel injection control device according to the present invention. 
           [0021]      FIG. 8  is a schematic view illustrating the constitution of the engine according to a third embodiment. 
           [0022]      FIG. 9  is a view illustrating the selective map of the engine according to the third embodiment. 
           [0023]      FIG. 10  is a view illustrating an effective passage cross-sectional area of an EGR device under predetermined conditions of the engine according to the third embodiment. 
           [0024]      FIG. 11  is a view illustrating a flowchart representing the control mode of calculating the effective passage cross-sectional area of the EGR device of the third embodiment of the engine. 
           [0025]      FIG. 12  is a view illustrating the effective passage cross-sectional area of the EGR device under each predetermined condition in a case where the different pressure in the engine is equal. 
           [0026]      FIG. 13  is a view illustrating the threshold value of the effective passage cross-sectional area of the EGR device of a fourth embodiment of the engine. 
           [0027]      FIG. 14  is a view illustrating a flowchart representing the control mode of calculating the effective passage cross-sectional area of the EGR device of the fourth embodiment of the engine. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0028]    Next, an engine  1  according to a first embodiment of the present invention will be described referring to  FIG. 1 . 
         [0029]    As illustrated in  FIG. 1 , the engine  1  is a diesel engine, and in the present embodiment, as illustrated in  FIG. 1 , the engine  1  is an inline four cylinder engine that includes four cylinders  3 . 
         [0030]    Regarding the engine  1 , outside air supplied via an intake pipe  2  and fuel supplied from fuel injection valves  4  are mixed in the interior of cylinders  3  and combusted, thereby drivingly rotating an output shaft. The engine  1  discharges exhaust gas generated by the combustion of the fuel to the outside via an exhaust pipe  5 . The engine  1  includes a fuel injection control device  10  that controls a fuel injection amount injected from the fuel injection valves  4  and an ECU  18  that controls the engine  1 . 
         [0031]    The fuel injection control device  10  serves to control fuel injection. The fuel injection control device  10  includes an engine revolution detecting unit  11  that detects the number of revolutions of the engine  1 , an operation amount detecting unit  12  that detects the operation amount S of an accelerator  7 , an atmospheric pressure/outside temperature detecting unit  13  that detects atmospheric pressure P and an outside temperature To, an intake flow amount detecting unit  14  that detects the flow amount of intake air, a coolant temperature detecting unit  15  that detects a coolant temperature Tm of the engine  1 , a fuel injection pressure detecting unit  16  that detects fuel injection pressure Fp, and a fuel injection control unit  17  that is a control means for controlling the fuel injection. 
         [0032]    The engine revolution detecting unit  11  serves to detect the number of revolutions N of the engine  1 . The engine revolution detecting unit  11  is constituted by a rotary encoder and provided on the output shat of the engine  1 . It is noted that, in the present embodiment, the engine revolution detecting unit  11  is constituted by the rotary encoder, but any may be applied as long as the number of revolutions N can be detected. 
         [0033]    The operation amount detecting unit  12  serves to detect the operation amount S of the accelerator  7 . The operation amount detecting unit  12  is constituted by a stroke sensor or an angle sensor and provided on the output lever of the accelerator  7 . It is noted that, in the present embodiment, the operation amount detecting unit  12  is constituted by the stroke sensor or the angle sensor, but any may be applied as long as the operation amount S can be detected. 
         [0034]    The atmospheric pressure/outside temperature detecting unit  13  serves to detect the atmospheric pressure P and the outside temperature To. The atmospheric pressure/outside temperature detecting unit  13  is constituted by an atmospheric pressure sensor, a temperature sensor, and the like and installed at a position where the atmospheric pressure P and the outside temperature To can be measured. 
         [0035]    The intake flow amount detecting unit  14  serves to detect the intake flow amount F of the engine  1 . The intake flow amount detecting unit  14  is constituted by a flow amount sensor and the like and installed in the intake pipe  2  of the engine  1 . 
         [0036]    The coolant temperature detecting unit  15  serves to detect the coolant temperature Tm of the engine  1 . The coolant temperature detecting unit  15  is constituted by a temperature sensor and arranged in a radiator  6  that performs the heat exchange of the coolant of the engine  1 . 
         [0037]    The fuel injection pressure detecting unit  16  serves to detect the fuel injection pressure Fp of the fuel injection valves  4 . The fuel injection pressure detecting unit  16  is constituted by a pressure sensor and the like and arranged in a fuel pipe, not illustrated, that supplies the fuel to the fuel injection valves  4 . 
         [0038]    The fuel injection control unit  17 , which is the control means, stores various programs for performing the control of fuel injection, a revolution map M 1  for calculating the target number of revolutions Nt of the engine  1  based on the operation amount S, a standard fuel injection amount map M 2  for calculating a standard injection amount Qs based on the target number of revolutions Nt and the coolant temperature Tm, a standard injection time map M 3  for calculating a standard injection time ITs of fuel based on the target number of revolutions Nt and the standard injection amount Qs, a coolant correction amount map M 4  for calculating a standard coolant correction amount Wcs based on the target number of revolutions Nt and the standard injection amount Qs, a coolant temperature correction map M 5  for calculating a coolant temperature correction coefficient Tmf based on the coolant temperature Tm, an atmospheric pressure correction amount map M 6  for calculating a standard atmospheric pressure correction amount Pcs based on the target number of revolutions Nt and the standard injection amount Qs, an atmospheric pressure correction map M 7  for calculating an atmospheric pressure correction coefficient Pf based on the atmospheric pressure P, a standard injection pressure map M 8  for calculating a standard injection pressure IPs of the fuel based on the target number of revolutions Nt and the standard injection amount Qs, a standard injection interval map M 9  for calculating a standard injection interval IIs of the fuel based on the target number of revolutions Nt and the standard injection amount Qs, a standard injection amount map M 10  for calculating a standard injection amount IVs of the fuel based on the target number of revolutions Nt and the standard injection amount Qs, and the like. 
         [0039]    The target number of revolutions Nt represents the number of revolutions of the engine  1  rotating at a constant speed in a no-load state in a case where the accelerator  7  is operated only by the operation amount S. 
         [0040]    The standard injection amount Qs represents a fuel injection amount that serves as a standard for the target number of revolutions Nt at the coolant temperature Tm, in order to suppress the occurrence of the black smoke from the engine  1 . 
         [0041]    The standard injection time ITs represents a fuel injection time that serves as a standard for the target number of revolutions Nt and the standard injection amount Qs, which improves the startability of the engine  1  (prevents the engine stall) and suppresses the occurrence of the black smoke. 
         [0042]    The standard coolant correction amount Wcs represents a correction amount that serves as a standard in a case where the coolant correction is made with respect to the target number of revolutions Nt and the standard injection amount Qs. 
         [0043]    The coolant temperature correction coefficient Tmf represents a correction coefficient for calculating a coolant correction amount Wc at the coolant temperature Tm. 
         [0044]    The standard atmospheric pressure correction amount Pcs represents a correction amount that serves as a standard in a case where atmospheric pressure is corrected with respect to the target number of revolutions Nt and the standard injection amount Qs. 
         [0045]    The atmospheric pressure correction coefficient Pf represents a correction coefficient for calculating an atmospheric pressure correction amount Pc at the atmospheric pressure P. 
         [0046]    The standard injection pressure IPs represents fuel injection pressure that serves as a standard for the target number of revolutions Nt and the standard injection amount Qs, which improves the startability of the engine  1  and suppresses the occurrence of the black smoke. 
         [0047]    The standard injection interval IIs represents a fuel injection interval that serves as a standard for the target number of revolutions Nt and the standard injection amount Qs, which improves the startability of the engine  1  and suppresses the occurrence of the black smoke. 
         [0048]    The standard injection amount IVs represents a fuel injection amount that serves as a standard for the target number of revolutions Nt and the standard injection amount Qs, which improves the startability of the engine  1  and suppresses the occurrence of the black smoke. 
         [0049]    A first predetermined temperature Tm 1  represents the threshold value of the coolant in a case where the correction of the standard injection time ITs is made only based on the correction for the coolant, in order to improve the startability of the engine  1  and suppress the occurrence of the black smoke. 
         [0050]    A second predetermined temperature Tm 2  represents the threshold value of the coolant in a case where the correction of the standard injection time ITs is made based on corrections except for the correction for the coolant, in order to improve the startability of the engine  1  and suppress the occurrence of the black smoke. 
         [0051]    The ECU  18  serves to control the engine  1 . In the ECU  18 , various programs and data used for controlling the engine  1  are stored. The ECU  18  may be configured such that a CPU, a ROM, a RAM, an HDD, and the like are connected via a bus, or configured to be made up of one-chip LSI and the like. The ECU  18  includes the fuel injection control unit  17 . 
         [0052]    The fuel injection control unit  17  (ECU  18 ) is connected to the fuel injection valves  4  and can control the fuel injection valves  4 . 
         [0053]    The fuel injection control unit  17  is connected to the engine revolution detecting unit  11  and can acquire the number of revolutions N detected by the engine revolution detecting unit  11 . 
         [0054]    The fuel injection control unit  17  is connected to the operation amount detecting unit  12  and can acquire the operation amount S detected by the operation amount detecting unit  12 . 
         [0055]    The fuel injection control unit  17  is connected to the atmospheric pressure/outside temperature detecting unit  13  and can acquire the atmospheric pressure P and the outside temperature To detected by the atmospheric pressure/outside temperature detecting unit  13 . 
         [0056]    The fuel injection control unit  17  is connected to the intake flow amount detecting unit  14  and can acquire the intake flow amount F detected by the intake flow amount detecting unit  14 . 
         [0057]    The fuel injection control unit  17  is connected to the coolant temperature detecting unit  15  and can acquire the coolant temperature Tm detected by the coolant temperature detecting unit  15 . 
         [0058]    The fuel injection control unit  17  is connected to the fuel injection pressure detecting unit  16  and can acquire the fuel injection pressure Fp detected by the fuel injection pressure detecting unit  16 . 
         [0059]    The fuel injection control unit  17  can calculate the target number of revolutions Nt from the revolution map M 1  based on the operation amount S acquired. 
         [0060]    The fuel injection control unit  17  can calculate an excess air ratio λ based on the intake flow amount F and the atmospheric pressure P acquired. 
         [0061]    The fuel injection control unit  17  can calculate the standard injection amount Qs from the standard fuel injection amount map M 2  based on the coolant temperature Tm acquired and the target number of revolutions Nt calculated. 
         [0062]    The fuel injection control unit  17  can calculate the standard injection time ITs from the standard injection time map M 3  based on the target number of revolutions Nt and the standard injection amount Qs calculated. 
         [0063]    The fuel injection control unit  17  can calculate the standard coolant correction amount Wcs from the coolant correction amount map M 4  based on the target number of revolutions Nt and the standard injection amount Qs calculated. 
         [0064]    The fuel injection control unit  17  can calculate the coolant temperature correction coefficient Tmf from the coolant temperature correction map M 5  based on the coolant temperature Tm acquired. 
         [0065]    The fuel injection control unit  17  can calculate the standard atmospheric pressure correction amount Pcs from the atmospheric pressure correction amount map M 6  based on the target number of revolutions Nt and the standard injection amount Qs calculated. 
         [0066]    The fuel injection control unit  17  can calculate the atmospheric pressure correction coefficient Pf from the atmospheric pressure correction map M 7  based on the atmospheric pressure P acquired. 
         [0067]    The fuel injection control unit  17  can calculate the standard injection pressure IPs from the standard injection pressure map M 8  based on the target number of revolutions Nt and the standard injection amount Qs calculated. 
         [0068]    The fuel injection control unit  17  can calculate the standard injection interval IIs from the standard injection interval map M 9  based on the target number of revolutions Nt and the standard injection amount Qs calculated. 
         [0069]    The fuel injection control unit  17  can calculate the standard injection amount IVs from the standard injection amount map M 10  based on the target number of revolutions Nt and the standard injection amount Qs calculated. 
         [0070]    The fuel injection control unit  17  can calculate the coolant correction amount Wc from the standard coolant correction amount Wcs and the coolant temperature correction coefficient Tmf calculated. 
         [0071]    The fuel injection control unit  17  can calculate the atmospheric pressure correction amount Pc from the standard atmospheric pressure correction amount Pcs and the atmospheric pressure correction coefficient Pf calculated. 
         [0072]    The fuel injection control unit  17  can advance and correct the standard injection time ITs, or delay and correct the standard injection time ITs at an appropriate injection time based on the coolant correction amount Wc and the atmospheric pressure correction amount Pc calculated. 
         [0073]    The ECU  18  can control the engine  1  based on the operation amount S, the number of revolutions N, the target number of revolutions Nt, the standard injection amount Qs, and the standard injection time ITs that are acquired via the fuel injection control unit  17 . 
         [0074]    Hereinafter, the control mode of correcting the injection time of the fuel injection control unit  17  after the start of the engine  1  according to the first embodiment of the present invention will be described referring to  FIGS. 2 and 3 . 
         [0075]    As illustrated in  FIG. 2 , the fuel injection control unit  17  controls in such a manner that the standard injection time ITs (see a line B in  FIG. 2 ) is advanced and corrected based on the coolant correction amount Wc until the coolant temperature Tm (see a line A in  FIG. 2 ) reaches the first predetermined temperature Tm 1  after the start of the engine  1 . Also, the fuel injection control unit  17  controls in such a manner that the standard injection time ITs is advanced and corrected based on the coolant correction amount Wc and the atmospheric pressure correction amount Pc until the coolant temperature Tm, which has reached the first predetermined temperature Tm 1  after the start of the engine  1 , reaches the second predetermined temperature Tm 2 . Then, when the coolant temperature Tm reaches the second predetermined temperature Tm 2  after the start of the engine  1 , the fuel injection control unit  17  controls in such a manner that the standard injection time ITs is advanced and corrected based on the atmospheric pressure correction amount Pc. It is noted that, in the present embodiment, the correction amount except for the coolant correction amount Wc is represented as the atmospheric pressure correction amount Pc, but not limited to this. 
         [0076]    Next, the control mode of correcting the injection time of the fuel injection control unit  17  will be specifically described referring to  FIG. 3 . 
         [0077]    As illustrated in  FIG. 3 , after the start of the engine  1 , at Step S 110 , the fuel injection control unit  17  of the fuel injection control device  10  acquires the operation amount S detected by the operation amount detecting unit  12 , the atmospheric pressure P and the outside temperature To detected by the atmospheric pressure/outside temperature detecting unit  13 , the intake flow amount F detected by the intake flow amount detecting unit  14 , and the coolant temperature Tm detected by the coolant temperature detecting unit  15  and allows the Step to transfer to Step S 120 . 
         [0078]    At the Step S 120 , the fuel injection control unit  17  calculates the target number of revolutions Nt from the revolution map M 1  based on the operation amount S acquired, calculates the standard injection amount Qs from the standard fuel injection amount map M 2  based on the coolant temperature Tm acquired and the target number of revolutions Nt calculated, and allows the Step to transfer to Step S 130 . 
         [0079]    At the Step S 130 , the fuel injection control unit  17  calculates the standard injection time ITs from the standard injection time map M 3  based on the target number of revolutions Nt and the standard injection amount Qs calculated, and allows the Step to transfer to Step S 140 . 
         [0080]    At the Step S 140 , the fuel injection control unit  17  calculates the standard coolant correction amount Wcs from the coolant correction amount map M 4  based on the target number of revolutions Nt and the standard injection amount Qs calculated, calculates the coolant temperature correction coefficient Tmf from the coolant temperature correction map M 5  based on the coolant temperature Tm, and allows the Step to transfer to Step S 150 . 
         [0081]    At the Step S 150 , the fuel injection control unit  17  calculates the standard atmospheric pressure correction amount Pcs from the atmospheric pressure correction amount map M 6  based on the target number of revolutions Nt and the standard injection amount Qs calculated, calculates the atmospheric pressure correction coefficient Pf from the atmospheric pressure correction map M 7  based on the atmospheric pressure P acquired, and allows the Step to transfer to Step S 160 . 
         [0082]    At the Step S 160 , the fuel injection control unit  17  calculates the coolant correction amount Wc based on the standard coolant correction amount Wcs and the coolant temperature correction coefficient Tmf calculated, calculates the atmospheric pressure correction amount Pc based on the standard atmospheric pressure correction amount Pcs and the atmospheric pressure correction coefficient Pf calculated, and allows the Step to transfer to Step S 170 . 
         [0083]    At the Step S 170 , the fuel injection control unit  17  determines whether or not the coolant temperature Tm acquired is equal to or higher than the first predetermined temperature Tm 1 . As a result, when it is determined that the coolant temperature Tm acquired is equal to or higher than the first predetermined temperature Tm 1 , the fuel injection control unit  17  allows the Step to transfer to Step S 180 . In contrast, when it is determined that the coolant temperature Tm acquired is less than the first predetermined temperature Tm 1 , the fuel injection control unit  17  allows the Step to transfer to Step S 280 . 
         [0084]    At the Step S 180 , the fuel injection control unit  17  determines whether or not the coolant temperature Tm acquired is equal to or higher than the second predetermined temperature Tm 2 . As a result, when it is determined that the coolant temperature Tm acquired is equal to or higher than the second predetermined temperature Tm 2 , the fuel injection control unit  17  allows the Step to transfer to Step S 190 . In contrast, when it is determined that the coolant temperature Tm acquired is less than the second predetermined temperature Tm 2 , the fuel injection control unit  17  allows the Step to transfer to Step S 390 . 
         [0085]    At the Step S 190 , the fuel injection control unit  17  corrects the standard injection time ITs calculated based on the atmospheric pressure correction amount Pc calculated and returns the Step to the Step S 110 . That is, the fuel injection control unit  17  does not use the coolant correction amount Wc for the correction of the standard injection time ITs. 
         [0086]    At the Step S 280 , the fuel injection control unit  17  corrects the standard injection time ITs calculated based on the coolant correction amount Wc and returns the Step to the Step S 110 . That is, the fuel injection control unit  17  does not use the atmospheric pressure correction amount Pc for the correction of the standard injection time ITs. 
         [0087]    At the Step S 390 , the fuel injection control unit  17  corrects the standard injection time ITs calculated based on the coolant correction amount Wc and the atmospheric pressure correction amount Pc and returns the Step to the Step S 110 . 
         [0088]    In this manner, regarding the engine  1 , when the coolant temperature Tm is less than the first predetermined temperature Tm 1 , at which the temperature is substantially affected by the startability of the engine  1  or the occurrence of the black smoke, the correction of the standard injection time ITs is made only based on the coolant correction amount Wc. As a result, the injection time is not excessively advanced and corrected due to the addition of the coolant correction amount Wc and the atmospheric pressure correction amount Pc. 
         [0089]    Also, regarding the engine  1 , when the coolant temperature Tm is equal to or higher than the first predetermined temperature Tm 1  at which the temperature is substantially affected by the startability of the engine  1  or the occurrence of the black smoke, and less than the second predetermined temperature Tm 2  at which the atmospheric pressure is substantially affected by the startability of the engine  1  or the occurrence of the black smoke, the correction of the standard injection time ITs is made based on the coolant correction amount Wc and the atmospheric pressure correction amount Pc. As a result, the injection time is appropriately advanced and corrected based on the coolant correction amount Wc and the atmospheric pressure correction amount Pc. 
         [0090]    Also, regarding the engine  1 , when the coolant temperature Tm is equal to or higher than the second predetermined temperature Tm 2 , at which the atmospheric pressure is substantially affected by the startability of the engine  1  or the occurrence of the black smoke, the correction of the standard injection time ITs is made based on the atmospheric pressure correction amount Pc. As a result, the injection time is not excessively advanced and corrected due to the addition of the coolant correction amount Wc and the atmospheric pressure correction amount Pc. In the present embodiment, when the coolant temperature Tm is equal to or higher than the second predetermined temperature Tm 2 , the correction of the standard injection time ITs is made based on the atmospheric pressure correction amount Pc, but not limited to this. At least a correction amount (for example, an outside air temperature, a lubricant temperature, and an elapsed time from the start of the engine  1 ) except for the atmospheric pressure correction amount Pc may be applied. 
         [0091]    Hereinafter, the control mode of correcting the injection pressure of the fuel injection control unit  17  after the start of the engine  1  according to the first embodiment of the present invention will be described referring to  FIG. 4 . It is noted that, in the embodiment described below, regarding the same matters of the embodiments that have been already described, their specific descriptions are omitted, and the following description focuses on the different matters. 
         [0092]    The same control described above is performed from the Steps S 110  to S 120 . 
         [0093]    At Step S 131 , the fuel injection control unit  17  calculates the standard injection pressure IPs from the standard injection pressure map M 8  based on the target number of revolutions Nt and the standard injection amount Qs calculated and allows the Step to transfer to the Step S 140 . 
         [0094]    The same control described above is performed from the Steps S 140  to S 180 . 
         [0095]    At Step S 191 , the fuel injection control unit  17  corrects the standard injection pressure IPs calculated, based on the atmospheric pressure correction amount Pc calculated and returns the Step to the Step S 110 . That is, the fuel injection control unit  17  does not use the coolant correction amount Wc for the correction of the standard injection pressure IPs. 
         [0096]    At Step S 281 , the fuel injection control unit  17  corrects the standard injection pressure IPs calculated, based on the coolant correction amount Wc and returns the Step to the Step S 110 . That is, the fuel injection control unit  17  does not use the atmospheric pressure correction amount Pc for the correction of the standard injection pressure IPs. 
         [0097]    At Step S 391 , the fuel injection control unit  17  corrects the standard injection pressure IPs calculated, based on the coolant correction amount Wc and the atmospheric pressure correction amount Pc and returns the Step to the Step S 110 . 
         [0098]    Hereinafter, the control mode of correcting the injection intervals of the fuel injection control unit  17  after the start of the engine  1  according to the first embodiment of the present invention will be described referring to  FIG. 5 . It is noted that, in the embodiment described below, regarding the same matters of the embodiments that have been already described, their specific descriptions are omitted, and the following description focuses on the different matters. 
         [0099]    The same control described above is performed from the Steps S 110  to S 120 . 
         [0100]    At Step S 132 , the fuel injection control unit  17  calculates the standard injection interval IIs from the standard injection interval map M 9  based on the target number of revolutions Nt and the standard injection amount Qs calculated and allows the Step to transfer to the Step S 140 . 
         [0101]    The same control described above is performed from the Steps S 140  to S 180 . 
         [0102]    At Step S 192 , the fuel injection control unit  17  corrects the standard injection interval IIs calculated, based on the atmospheric pressure correction amount Pc calculated and returns the Step to the Step S 110 . That is, the fuel injection control unit  17  does not use the coolant correction amount Wc for the correction of the standard injection interval IIs. 
         [0103]    At Step S 282 , the fuel injection control unit  17  corrects the standard injection interval IIs calculated, based on the coolant correction amount Wc and returns the Step to the Step S 110 . That is, the fuel injection control unit  17  does not use the atmospheric pressure correction amount Pc for the correction of the standard injection interval IIs. 
         [0104]    At Step S 392 , the fuel injection control unit  17  corrects the standard injection interval IIs calculated, based on the coolant correction amount Wc and the atmospheric pressure correction amount Pc and returns the Step to the Step S 110 . 
         [0105]    Hereinafter, the control mode of correcting the injection amount of the fuel injection control unit  17  after the start of the engine  1  according to the first embodiment of the present invention will be described referring to  FIG. 6 . It is noted that, in the embodiment described below, regarding the same matters of the embodiments that have been already described, their specific descriptions are omitted, and the following description focuses on the different matters. 
         [0106]    The same control described above is performed from the Steps S 110  to S 120 . 
         [0107]    At the Step S 133 , the fuel injection control unit  17  calculates the standard injection amount IVs from the standard injection amount map M 10  based on the target number of revolutions Nt and the standard injection amount Qs calculated and allows the Step to transfer to the Step S 140 . 
         [0108]    The same control described above is performed from the Steps S 140  to S 180 . 
         [0109]    At the Step S 193 , the fuel injection control unit  17  corrects the standard injection amount IVs calculated, based on the atmospheric pressure correction amount Pc calculated and returns the Step to the Step S 110 . That is, the fuel injection control unit  17  does not use the coolant correction amount Wc for the correction of the standard injection amount IVs. 
         [0110]    At the Step S 283 , the fuel injection control unit  17  corrects the standard injection amount IVs calculated, based on the coolant correction amount Wc and returns the Step to the Step S 110 . That is, the fuel injection control unit  17  does not use the atmospheric pressure correction amount Pc for the correction of the standard injection amount IVs. 
         [0111]    At the Step S 393 , the fuel injection control unit  17  corrects the standard injection amount IVs calculated, based on the coolant correction amount Wc and the atmospheric pressure correction amount Pc and returns the Step to the Step S 110 . 
         [0112]    As described above, the engine  1  according to the first embodiment of the present invention includes the fuel injection control device  10  including the fuel injection control unit  17 , which is the control means that calculates the standard injection time ITs based on the target number of revolutions Nt of the engine  1  and the standard injection amount Qs, which is the fuel injection amount, and that corrects the standard injection time ITs, the standard injection pressure IPs, the standard injection interval IIs, or the standard injection amount IVs based on at least a correction amount, and the fuel injection control unit  17  calculates the coolant correction amount Wc based on the target number of revolutions Nt, the standard injection amount Qs, and the coolant temperature Tm of the engine  1 , and when the coolant temperature Tm is less than the first predetermined temperature Tm 1 , the fuel injection control unit  17  corrects the standard injection time ITs, the standard injection pressure IPs, the standard injection interval IIs, or the standard injection amount IVs only based on the coolant correction amount Wc. 
         [0113]    With this constitution, under the condition in which the coolant temperature Tm is substantially affected, the correction based on the coolant correction amount Wc can be preferentially performed. Accordingly, the startability is improved, and operating states are stabilized irrespective of operating environments and use modes. 
         [0114]    Also, when the coolant temperature Tm is equal to or higher than the second predetermined temperature Tm 2 , the fuel injection control unit  17  corrects the standard injection time ITs based on the atmospheric pressure correction amount Pc, which is one of correction coefficients except for the coolant correction amount Wc. 
         [0115]    With this constitution, under the condition in which the coolant temperature Tm is slightly affected, the correction based on the coolant correction amount Wc is not made. Accordingly, the startability is improved, and operating states are stabilized irrespective of operating environments and use modes. 
         [0116]    Next, the engine  1  of a second embodiment of the engine according to the present invention will be described referring to  FIGS. 1 and 7 . The engine  1  includes a fuel injection control device  19 . The fuel injection control device  19  includes a fuel injection control unit  20  and calculates the first predetermined temperature Tm 1  and the second predetermined temperature Tm 2  in accordance with the outside temperature To. It is noted that the standard injection time will be described in the following embodiment, out of control modes of the standard injection time, the fuel injection pressure, the fuel injection interval, or the fuel injection amount of the fuel injection control unit  17 . It is noted that, regarding the same matters of the embodiments that have been already described, their specific descriptions are omitted, and the following description focuses on the different matters. 
         [0117]    As illustrated in  FIG. 1 , the fuel injection control unit  20  stores a predetermined temperature calculating map M 11  for calculating the first predetermined temperature Tm 1  and the second predetermined temperature Tm 2  from the outside temperature To. The fuel injection control unit  20  performs a predetermined calculation in accordance with these programs and the like and stores the results of the calculation. 
         [0118]    The fuel injection control unit  20  can calculate the first predetermined temperature Tm 1  and the second predetermined temperature Tm 2  from the predetermined temperature calculating map M 11  based on the outside temperature To acquired. 
         [0119]    Hereinafter, the mode of fuel injection control after the start of the engine  1  of the fuel injection control device  19  according to the second embodiment of the present invention will be described referring to  FIG. 7 . 
         [0120]    As illustrated in  FIG. 7 , at Step S 135 , the fuel injection control unit  20  calculates the first predetermined temperature Tm 1  and the second predetermined temperature Tm 2  from the predetermined temperature calculating map M 11  based on the outside temperature To acquired and allows the Step to transfer to the Step S 140 . It is noted that, in the present embodiment, any one of the first predetermined temperature Tm 1  and the second predetermined temperature Tm 2  may be regarded as a calculated value based on the outside temperature To. 
         [0121]    As described above, regarding the engine  1  according to the second embodiment of the present invention, the fuel injection control unit  20 , which is a control means, sets the first predetermined temperature Tm 1  and the second predetermined temperature Tm 2  in accordance with the outside temperature To. 
         [0122]    With this constitution, correction conditions based on the coolant temperature Tm are changed based on the outside temperature To at the start of the engine  1 . Accordingly, the startability is improved, and operating states are stabilized irrespective of operating environments and use modes. 
         [0123]    Hereinafter, an engine  21  according to a third embodiment will be described referring to  FIG. 8 . 
         [0124]    As illustrated in  FIG. 8 , the engine  21  is a diesel engine  21 , and in the present embodiment, an inline four cylinder engine  21  that includes four cylinders  23 . 
         [0125]    Regarding the engine  21 , intake air supplied to the interior of the cylinders  23  via an intake pipe  22  and fuel supplied from fuel injection valves  24  to the interior of the cylinders  23  are mixed in the interior of cylinders  23  and combusted, thereby drivingly rotating an output shaft. The engine  21  discharges exhaust gas generated by the combustion of the fuel to the outside via an exhaust pipe  25 . 
         [0126]    The engine  21  includes an engine revolution detecting sensor  26 , an injection amount detecting sensor  27  of the fuel injection valves  24 , an EGR device  28 , and an ECU  35 , which is a control device. 
         [0127]    The engine revolution detecting sensor  26  serves to detects the number of revolutions N of the engine  21 . The engine revolution detecting sensor  26  is constituted by a sensor and a pulsar and provided on the output shaft of the engine  21 . It is noted that, in the present embodiment, the engine revolution detecting sensor  26  is constituted by the sensor and the pulsar, but any may be applied as long as the number of revolutions N can be detected. 
         [0128]    The injection amount detecting sensor  27  serves to detect an injection amount f of fuel injected from the fuel injection valves  24 . The injection amount detecting sensor  27  is provided in a midway portion of a fuel supply pipe not illustrated. The injection amount detecting sensor  27  is constituted by a flow amount sensor. It is noted that, in the present embodiment, the injection amount detecting sensor  27  is constituted by the flow amount sensor, but not limited to this, and any may be applied as long as the injection amount f of fuel can be detected. 
         [0129]    The EGR device  28  recirculates part of the exhaust gas into the intake air. The EGR device  28  includes an EGR pipe  29 , an EGR valve  30 , an intake pressure detecting sensor  31 , an exhaust pressure detecting sensor  32 , an EGR gas temperature detecting sensor  33 , an opening degree detecting sensor  34 , and an ECU  35 , which is an EGR control unit. 
         [0130]    The EGR pipe  29  is a pipe that guides the exhaust gas to the intake pipe  22 . The EGR pipe  29  is provided in such a manner that the intake pipe  22  and the exhaust pipe  25  are communicated. Accordingly, part of the exhaust gas passing through the exhaust pipe  25  is guided to the intake pipe  22  via the EGR pipe  29 . That is, it is configured such that part of the exhaust gas can be recirculated into the intake air as the EGR gas (hereinafter, merely referred to as “EGR gas”). 
         [0131]    The EGR valve  30  serves to limit the flow amount of the EGR gas passing through the EGR pipe  29 . The EGR valve  30  is constituted by the electromagnetic flow control valve of a normal closed-type. The EGR valve  30  is provided in the midway portion of the EGR pipe  29 . The EGR valve  30  can acquire a signal from the ECU  35  described later and change the opening degrees of the EGR valve  30 . It is noted that, in the present embodiment, the EGR valve  30  is constituted by the electromagnetic flow control valve of a normal closed-type, but any may be applied as long as the flow amount of the EGR gas can be limited. 
         [0132]    The intake pressure detecting sensor  31  constituting a differential pressure detecting means serves to detect intake pressure P 1 . The intake pressure detecting sensor  31  is provided in the midway portion of the intake pipe  22  that can detect the intake pressure P 1 . Similarly, the exhaust pressure detecting sensor  32  constituting the differential pressure detecting means serves to detect exhaust pressure P 2 . The exhaust pressure detecting sensor  32  is provided in the midway portion of the exhaust pipe  25  that can detect the exhaust pressure P 2 . 
         [0133]    The EGR gas temperature detecting sensor  33  serves to detect an EGR gas temperature Tegr. The EGR gas temperature detecting sensor  33  is constituted by a thermocouple. The EGR gas temperature detecting sensor  33  is provided in the midway portion of the EGR pipe  29  that can detect the EGR gas temperature Tegr. It is noted that, in the present embodiment, the EGR gas temperature detecting sensor  33  is constituted by the thermocouple, but any may be applied as long as the EGR gas temperature Tegr can be detected. 
         [0134]    The opening degree detecting sensor  34  serves to detect an EGR-valve opening degree G. The opening degree detecting sensor  34  is constituted by a position detecting sensor. The opening degree detecting sensor  34  is provided in the EGR valve  30 . It is noted that, in the present embodiment, the opening degree detecting sensor  34  is constituted by the position detecting sensor, but any may be applied as long as the EGR-valve opening degree G can be detected. 
         [0135]    The ECU  35  serves to control the engine  21 . Specifically, the ECU  35  controls the main body of the engine  21  and the EGR device  28 . The ECU  35  stores various programs and data used for performing the control of the engine  21 . The ECU  35  may be configured such that a CPU, a ROM, a RAM, an HDD, and the like are connected via a bus, or configured to be made up of one-chip LSI and the like. 
         [0136]    The ECU  35  is connected to the fuel injection valves  24  and can control the fuel injection valves  24 . 
         [0137]    The ECU  35  is connected to the engine revolution detecting sensor  26  and can acquire the number of revolutions N detected by the engine revolution detecting sensor  26 . 
         [0138]    The ECU  35  is connected to the injection amount detecting sensor  27  and can acquire the injection amount f detected by the injection amount detecting sensor  27 . 
         [0139]    The ECU  35  is connected to the EGR valve  30  and can control the opening and closing of the EGR valve  30 . 
         [0140]    The ECU  35  is connected to the intake pressure detecting sensor  31  and the exhaust pressure detecting sensor  32 , each of which is a differential pressure detecting means, and can acquire the intake pressure P 1  detected by the intake pressure detecting sensor  31  and the exhaust pressure P 2  detected by the exhaust pressure detecting sensor  32  and calculate an EGR differential pressure ΔP and an intake-and-exhaust pressure ratio π. 
         [0141]    The ECU  35  is connected to the EGR gas temperature detecting sensor  33  and can acquire the EGR gas temperature Tegr detected by the EGR gas temperature detecting sensor  33 . 
         [0142]    The ECU  35  is connected to the opening degree detecting sensor  34  and can acquire the EGR-valve opening degree G detected by the opening degree detecting sensor  34 . 
         [0143]    The ECU  35  stores effective passage cross-sectional area maps R 1 , R 2 , . . . Rn (in the present embodiment, effective passage cross-sectional area maps R 1 , R 2 , R 3 , and R 4 ) for calculating the effective passage cross-sectional area Ared of the EGR device  28  based on the EGR-valve opening degree G and the EGR differential pressure ΔP. Also, the ECU  35  stores a selective map Ry for selecting one effective passage cross-sectional area map Rx out of the effective passage cross-sectional area maps R 1 , R 2 , R 3 , and R 4  based on the number of revolutions N and the injection amount f. 
         [0144]    The ECU  35  can select one effective passage cross-sectional area map Rx from the selective map Ry based on the number of revolutions N and the injection amount f acquired. The ECU  35  can calculate the effective passage cross-sectional area Ared from one effective passage cross-sectional area map Rx selected based on the intake pressure P 1 , the exhaust pressure P 2 , the EGR gas temperature Tegr, and the EGR-valve opening degree G and control the opening and closing of the EGR valve  30 . 
         [0145]    Hereinafter, the control mode of calculating EGR gas weight Megr in the EGR device  28  of the engine  21  according to the third embodiment will be described referring to  FIGS. 9 to 11 . 
         [0146]    The ECU  35  calculates the EGR differential pressure ΔP represented by Expression 1 below based on the intake pressure P 1  and the exhaust pressure P 2  acquired and calculates the intake-and-exhaust pressure ratio π represented by Expression 2 below. Subsequently, as illustrated in  FIG. 9 , the ECU  35  selects the effective passage cross-sectional area map Rx from the selective map Ry based on the number of revolutions N and the injection amount f acquired. Furthermore, as illustrated in  FIG. 10 , the ECU  35  calculates the effective passage cross-sectional area Ared from the effective passage cross-sectional area map Rx selected based on the EGR differential pressure ΔP calculated and the EGR-valve opening degree G acquired. Then, the ECU  35  calculates the EGR gas weight Megr represented by Expression 3 below based on the exhaust pressure P 2  and the EGR gas temperature Tegr acquired, the intake-and-exhaust pressure ratio π and the effective passage cross-sectional area Ared calculated, an exhaust specific heat ratio κ, which is a constant, and a gas constant R. 
         [0000]    
       
         
           
             
               
                 
                   
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         [0147]    Next, the control mode of calculating the EGR gas weight Megr in the EGR device  28  of the engine  21  will be specifically described. 
         [0148]    As illustrated in  FIG. 11 , at Step S 410 , the ECU  35  acquires the number of revolutions N detected by the engine revolution detecting sensor  26 , the injection amount f detected by the injection amount detecting sensor  27 , the EGR-valve opening degree G detected by the opening degree detecting sensor  34 , the intake pressure P 1  detected by the intake pressure detecting sensor  31 , the exhaust pressure P 2  detected by the exhaust pressure detecting sensor  32 , and the EGR gas temperature Tegr detected by the EGR gas temperature detecting sensor  33  and allows the Step to transfer to Step S 420 . 
         [0149]    At the Step S 420 , the ECU  35  calculates the EGR differential pressure ΔP and the intake-and-exhaust pressure ratio π from the intake pressure P 1  and the exhaust pressure P 2  acquired and allows the Step to transfer to Step S 430 . 
         [0150]    At the Step S 430 , the ECU  35  selects one effective passage cross-sectional area map Rx from the selective map Ry based on the number of revolutions N and the injection amount f acquired and allows the Step to transfer to Step S 440 . 
         [0151]    At the Step S 440 , the ECU  35  calculates the effective passage cross-sectional area Ared from the effective passage cross-sectional area map Rx based on the EGR differential pressure ΔP calculated and the EGR-valve opening degree G acquired and allows the Step to transfer to Step S 450 . 
         [0152]    At the Step S 450 , the ECU  35  calculates the EGR gas weight Megr from the intake pressure P 2  and the EGR gas temperature Tegr acquired, the intake-and-exhaust pressure ratio π and the effective passage cross-sectional area Ared calculated, the exhaust specific heat ratio κ, which is a constant, and the gas constant R and controls the EGR-valve opening degree G based on the EGR gas weight Megr calculated. The ECU  35  allows the Step to transfer to the Step S 410 . 
         [0153]    That is, as illustrated in  FIG. 12 , regarding the EGR device  28 , when the states of the number of revolutions N and the injection amount f of the engine  21  are different, there is a case where, even when the EGR differential pressure ΔP and the EGR-valve opening degree G are identical, the values of the effective passage cross-sectional area Ared are different. Accordingly, the ECU  35  controls in such a manner as to select the optimal effective passage cross-sectional area map Rx based on the states of the number of revolutions N and the injection amount f (see  FIG. 9 ). 
         [0154]    Accordingly, even when the operating states of the engine  21  are different, the EGR gas weight Megr is calculated based on the EGR differential pressure ΔP and the EGR-valve opening degree G Consequently, the effect of suppressing the generation of nitrogen oxide by means of the EGR device  28  is appropriately given. 
         [0155]    As descried above, regarding the engine  21  according to the third embodiment, the engine  21  includes the EGR device  28  that recirculates part of the exhaust gas into the intake air as the EGR gas, and the engine  21  further includes the EGR valve  30  that limits the EGR gas weight Megr, the intake pressure detecting sensor  31  and the exhaust pressure detecting sensor  32  that are a differential pressure detecting means for detecting differential pressure between the intake pressure P 1  and the exhaust pressure P 2 , the ECU  35 , which is a control device, that changes the EGR-valve opening degree G of the EGR valve  30  and adjusts the EGR gas weight Megr, and the ECU  35  includes the plurality of effective passage cross-sectional area maps Rx for calculating the effective passage cross-sectional area Ared of the EGR device  28  from the EGR-valve opening degree G and the EGR differential pressure ΔP and calculates the effective passage cross-sectional area Ared from one effective passage cross-sectional area map Rx selected from the plurality of effective passage cross-sectional area maps R 1 , R 2 , R 3 , and R 4 . 
         [0156]    Also, the ECU  35  selects one effective passage cross-sectional area map Rx from the plurality of effective passage cross-sectional area maps R 1 , R 2 , R 3 , and R 4  based on the number of revolutions N and the injection amount f of the engine  21 . 
         [0157]    With this constitution, the effective passage cross-sectional area map Rx in accordance with the operating states of the engine  21  is selected from among the plurality of effective passage cross-sectional area maps R 1 , R 2 , R 3 , and R 4 . Accordingly, the EGR gas weight Megr based on the operating states can be calculated. 
         [0158]    Next, the engine  21  of a fourth embodiment of the engine  21  according to the present invention will be described referring to  FIGS. 8, 13, and 14 . It is noted that, in the embodiment described below, regarding the same matters of the embodiments that have been already described, their specific descriptions are omitted, and the following description focuses on the different matters. 
         [0159]    As illustrated in  FIG. 8 , the ECU  35  can select one effective passage cross-sectional area map Rx, out of the effective passage cross-sectional area maps R 1 , R 2 , . . . Rn (in the present embodiment, the effective passage cross-sectional area maps R 1 , R 2 , R 3 , and R 4 ) for calculating the effective passage cross-sectional area Ared of the EGR device  28  based on the exhaust pressure P 2  and the intake-and-exhaust pressure ratio π. 
         [0160]    Hereinafter, the control mode of calculating the EGR gas weight Megr in the EGR device  28  of the engine  21  according to the third embodiment will be described. 
         [0161]    As illustrated in  FIG. 13 , the ECU  35  selects the effective passage cross-sectional area map Rx suitable for calculating the effective passage cross-sectional area Ared of the EGR device  28  based on the exhaust pressure P 2  acquired and the intake-and-exhaust pressure ratio π calculated. Specifically, when the intake-and-exhaust pressure ratio π is higher than a predetermined value X, and the exhaust pressure P 2  is higher than a predetermined value Y (an area D in  FIG. 13 ), the ECU  35  selects the effective passage cross-sectional area map R 4 . Also, when the intake-and-exhaust pressure ratio π is higher than the predetermined value X, and the exhaust pressure P 2  is equal to or lower than the predetermined value Y (an area C in  FIG. 13 ), the ECU  35  selects the effective passage cross-sectional area map R 3 . Also, when the intake-and-exhaust pressure ratio π is equal to or lower than the predetermined value X, and the exhaust pressure P 2  is higher than the predetermined value Y (an area B in  FIG. 13 ), the ECU  35  selects the effective passage cross-sectional area map R 2 . Also, when the intake-and-exhaust pressure ratio π is equal to or lower than the predetermined value X, and the exhaust pressure P 2  is equal to or lower than the predetermined value Y (an area A in  FIG. 13 ), the ECU  35  selects the effective passage cross-sectional area map R 1 . 
         [0162]    Next, the control mode of calculating the EGR gas weight Megr in the EGR device  28  of the engine  21  will be specifically described. 
         [0163]    The ECU  35  performs the same control as the aforementioned control from the Step S 410  to the Step S 420 . 
         [0164]    At Step S 431 , the ECU  35  determines whether or not the intake-and-exhaust pressure ratio π is higher than the predetermined value X. As a result, when the ECU  35  determines that the intake-and-exhaust pressure ratio π is higher than the predetermined value X, the ECU  35  allows the Step to transfer to Step S 432 . In contrast, when the ECU  35  determines that the intake-and-exhaust pressure ratio π is lower than the predetermined value X, the ECU  35  allows the Step to transfer to Step S 532 . 
         [0165]    At the Step S 432 , the ECU  35  determines whether or not the exhaust pressure P 2  is higher than the predetermined value Y. As a result, when the ECU  35  determines that the exhaust pressure P 2  is higher than the predetermined value Y, the ECU  35  allows the Step to transfer to Step S 433 . In contrast, when the ECU  35  determines that the exhaust pressure P 2  is lower than the predetermined value Y, the ECU  35  allows the Step to transfer to Step S 733 . 
         [0166]    At the Step S 433 , the ECU  35  selects the effective passage cross-sectional area map R 4  and allows the Step to transfer to the Step S 440 . 
         [0167]    The ECU  35  performs the same control as the aforementioned control from the Step S 440  to the Step S 450 . 
         [0168]    At the Step S 532 , the ECU  35  determines whether or not the exhaust pressure P 2  is higher than the predetermined value Y. As a result, when the ECU  35  determines that the exhaust pressure P 2  is higher than the predetermined value Y, the ECU  35  allows the Step to transfer to Step S 533 . In contrast, when the ECU  35  determines that the exhaust pressure P 2  is lower than the predetermined value Y, the ECU  35  allows the Step to transfer to Step S 633 . 
         [0169]    At the step S 533 , the ECU  35  selects the effective passage cross-sectional area map R 2  and allows the Step to transfer to the Step S 440 . 
         [0170]    At the step S 633 , the ECU  35  selects the effective passage cross-sectional area map R 1  and allows the Step to transfer to the Step S 440 . 
         [0171]    At the step S 733 , the ECU  35  selects the effective passage cross-sectional area map R 3  and allows the Step to transfer to the Step S 440 . 
         [0172]    As described above, regarding the engine  21  according to the fourth embodiment, the ECU  35  selects one effective passage cross-sectional area map Rx out of the plurality of effective passage cross-sectional area maps R 1 , R 2 , R 3 , and R 4  based on the intake-and-exhaust pressure ratio π between the intake pressure P 1  and the exhaust pressure P 2 , and the exhaust pressure P 2 . With this constitution, the effective passage cross-sectional area map Rx in accordance with the operating states of the engine  21  is selected from among the plurality of effective passage cross-sectional area maps R 1 , R 2 , R 3 , and R 4 . Accordingly, the EGR gas weight Megr based on the operating states can be calculated. 
       INDUSTRIAL APPLICABILITY 
       [0173]    The present invention can be utilized for an engine that includes a fuel injection control device. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1  Engine 
           10  Fuel injection control device 
           16  Fuel injection detecting unit 
         Nt Target number of revolutions 
         P Atmospheric pressure 
         Tm Coolant temperature 
         Qs Standard injection amount 
         ITs Standard injection time 
         Wc Coolant correction amount 
         Tm 1  First predetermined temperature 
           21  Engine 
           28  EGR device 
           30  EGR valve 
           31  Intake pressure detecting sensor 
           32  Exhaust pressure detecting sensor 
           35  ECU 
         Megr EGR gas weight 
         G EGR-valve opening degree 
         ΔP EGR differential pressure 
         Ared Effective passage cross-sectional area 
         Rx Effective passage cross-sectional area map