Patent Publication Number: US-9890733-B2

Title: Control device for internal combustion engine

Description:
BACKGROUND 
     Field of the Disclosure 
     The present disclosure relates to a control device for an internal combustion engine having a fuel injection valve and an accelerator opening degree sensor, 
     Background Art 
     Conventionally, an electronically controlled throttle device having an accelerator opening degree sensor has been known. As an example of an electronically controlled throttle device of this kind, the electronically controlled throttle device described in JP 2005-233088 A may be cited, for example. 
     In the electronically controlled throttle device described in JP 2005-233088 A, a torque limiter is operated when the change amount of accelerator request torque is large, and a target torque is limited. As a result, worsening of response and occurrence of shock due to a torque level difference are restrained. 
     Further, JP 2015-017571 A discloses that a target acceleration characteristic is set in advance based on an accelerator opening degree and a vehicle speed, and that as the vehicle speed is lower, a larger target acceleration is set. 
     SUMMARY OF THE DISCLOSURE 
     Although JP 2005-233088 A describes the feature in which the target torque is limited, JP 2005-233088 A does not describe a constraint under which an acceleration does not increase even when a driver increases the accelerator opening degree. 
     Examples of the constraint under which the acceleration does not increase even when the driver increases the accelerator opening degree include a torque constraint under which torque that is actually outputted does not increase even when a request torque is increased, a smoke emission amount constraint under which a fuel injection amount does not increase even when the driver increases the accelerator opening degree to avoid the smoke emission amount reaching a predetermined value or more, and the like. 
     When the present operating state is close to the constraint, and the driver increases the accelerator opening degree, if any countermeasure for preventing the driving state from reaching the constraint is not performed, a target acceleration increase amount of a large value is set, as a result which, the driving state reaches the constraint, and the acceleration is unlikely to increase even when the driver increases the accelerator opening degree. 
     In the light of the aforementioned problem, an object of the present disclosure is to provide a control device for an internal combustion engine capable of reducing a fear that an acceleration does not increase even when a driver increases an accelerator opening degree. 
     According to a first aspect of an embodiment of the present disclosure, there is provided a control device for an internal combustion engine including a fuel injection valve, and an accelerator opening degree sensor, 
     the control device including 
     a basic accelerator request torque calculating section calculating a basic accelerator request torque based on an accelerator opening degree detected by the accelerator opening degree sensor, and 
     a target acceleration increase amount calculating section calculating a target acceleration increase amount based on a relation of the target acceleration increase amount and an accelerator opening degree increase amount, 
     wherein the control device calculates a torque increase amount correction amount based on the target acceleration increase amount, calculates a request engine torque based on the basic accelerator request torque and the torque increase amount correction amount, calculates a request injection amount based on the request engine torque, and controls the fuel injection valve based on the request injection amount, and 
     the relation of the target acceleration increase amount and the accelerator opening degree increase amount, which is used in calculation of the target acceleration increase amount, is such that as a present operating state is closer to a constraint, a ratio of the target acceleration increase amount and the accelerator opening degree increase amount becomes smaller. 
     That is, in the control device for an internal combustion engine according to the first aspect discussed above, in order to calculate the target acceleration increase amount, the relations of the target acceleration increase amount and the accelerator opening degree increase amount, with ratios of the target acceleration increase amount and the accelerator opening degree increase amount differing from one another, are used in accordance with whether or not the present operating state is close to the constraint. 
     When the present operating state is not close to the constraint, even if the acceleration is increased quickly, the operating state is unlikely to reach the constraint. 
     In the light of this point, in the control device for an internal combustion engine according to the first aspect discussed above, in the case where the present operating state is not close to the constraint, the relation of the target acceleration increase amount and the accelerator opening degree increase amount, with the ratio of the target acceleration increase amount and the accelerator opening degree increase amount being large is used. Consequently, when the driver increases the accelerator opening degree, the target acceleration increase amount of a large value is calculated. As a result, the acceleration can be increased quickly in accordance with the acceleration request by the driver. 
     Meanwhile, if the acceleration is increased quickly when the present operating state is close to the constraint, the operating state is likely to reach the constraint. When the operating state reaches the constraint, the acceleration does not increase even when the driver increases the accelerator opening degree. 
     In the light of the above point, in the control device for an internal combustion engine according to the first aspect discussed above, the relation of the target acceleration increase amount and the accelerator opening degree increase amount, with the ratio of the target acceleration increase amount and the accelerator opening degree increase amount being small, is used when the present operating state is close to the constraint. Consequently, when the driver increases the accelerator opening degree, the target acceleration increase amount of a small value is calculated. As a result, the acceleration can be gradually increased, whereby in the time period of acceleration request by the driver, the acceleration can be continuously increased without causing the operating state to reach the constraint. 
     That is, the control device for an internal combustion engine according to the first aspect discussed above can reduce the fear that the acceleration does not increase even when the driver increases the accelerator opening degree as the operating state reaches the constraint. 
     In other words, the control device for an internal combustion engine according to the first aspect discussed above can realize increase of the acceleration that satisfies the acceleration request by the driver even when the present operating state is close to the constraint. 
     By the earnest study of the present inventor, it has been found out that responsiveness of the acceleration increase, which is realized to the accelerator opening degree increase operation by the driver is enhanced when the relation of the target acceleration increase amount and the accelerator opening degree increase amount is set based on the relation in which the ratio of the accelerator opening degree increase amount and the accelerator opening degree is proportional to the ratio of the target acceleration increase amount and the target acceleration. 
     In the light of the above point, according to a second aspect of an embodiment of the present disclosure, there is provided the control device for an internal combustion engine according to the first aspect discussed above wherein the relation of the target acceleration increase amount and the accelerator opening degree increase amount is set based on a relation in which a ratio of the accelerator opening degree increase amount and the accelerator opening degree is proportional to a ratio of the target acceleration increase amount and a target acceleration. 
     Consequently, in the control device for an internal combustion engine according to the second aspect discussed above, responsiveness of the acceleration increase which is realized to the accelerator opening degree increase operation by the driver can be enhanced more than in the case where the relation of the target acceleration increase amount and the accelerator opening degree increase amount is set based on the relation in which the ratio of the accelerator opening degree increase amount and the accelerator opening degree is not proportional to the ratio of the target acceleration increase amount and the target acceleration. 
     According to a third aspect of an embodiment of the present disclosure, there is provided the control device for an internal combustion engine according to the first aspect discussed above, wherein an increase amount per accelerator opening degree increase amount, of the request injection amount calculated by the control device at a time of accelerator opening degree increase becomes smaller as the present operating state is closer to the constraint. 
     That is, in the control device for an internal combustion engine according to the third aspect discussed above, the request injection amount with the increase amount per accelerator opening degree increase amount being small is calculated at the time of accelerator opening degree increase when the present operating state is close to the constraint. 
     Consequently, in the control device for an internal combustion engine according to the third aspect discussed above, the fuel injection amount can be reduced more, and fuel efficiency can be enhanced more than in the case where the request injection amount with the increase amount per accelerator opening degree increase amount being large is calculated at the time of accelerator opening degree increase and the operating state reaches the constraint. 
     According to the first aspect discussed above, the possibility that the acceleration does not increase even when the driver increases the accelerator opening degree can be reduced. 
     According to the second aspect discussed above, the responsiveness of the acceleration increase, which is realized to the accelerator opening degree increase operation by the driver can be enhanced. 
     According to the third aspect discussed above, the fuel injection amount is reduced, and fuel efficiency can be enhanced. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic block diagram of an engine system to which a control device for an internal combustion engine of a first embodiment is applied; 
         FIG. 2  is a flowchart for explaining control of a fuel injection valve  30  and the like, which is executed at a time of accelerator opening degree increase in the engine system illustrated in  FIG. 1 ; 
         FIG. 3  is a diagram illustrating a relation of a basic accelerator request torque, an engine speed NE and a gear position; 
         FIG. 4  is a diagram illustrating a relation of relations RL 1 , RL 2  and RL 3  between a target acceleration increase amount ΔG [m/s 2 ] and an accelerator opening degree increase amount ΔPa [%]; 
         FIG. 5  is a time chart for explaining control at the time of accelerator opening degree increase in a case where a present operating state in the engine system to which the control device for an internal combustion engine of the first embodiment is applied is not close to a constraint; 
         FIG. 6  is a time chart for explaining control at the time of accelerator opening degree increase in a case where the present operating state in the engine system to which the control device for an internal combustion engine of the first embodiment is applied is close to the constraint; and 
         FIG. 7  is a time chart for explaining control at the time of accelerator opening degree increase in a case where a present operating state in another example of the engine system to which the control device for an internal combustion engine of the first embodiment is applied is close to a constraint. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, a first embodiment of a control device for an internal combustion engine of the present disclosure will be described.  FIG. 1  is a schematic block diagram of an engine system to which the control device for an internal combustion engine of the first embodiment is applied. 
     In an example illustrated in  FIG. 1  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, a crank angle sensor  20 , a gear position sensor  21 , an accelerator opening degree sensor  22 , a vehicle speed sensor  23 , a control device (ECU)  10 , a fuel injection valve  30 , an EGR device  31 , a turbocharger  32  and a throttle valve  33  are provided. 
     The control device  10  is provided with a basic accelerator request torque calculating section  10   a  calculating a basic accelerator request torque [Nm], a target acceleration increase amount calculating section  10   b  calculating a target acceleration increase amount ΔG [m/s 2 ], and a vehicle model  10   c  calculating a target torque increase amount [Nm]. Further, in a request state quantity calculating section  10   d  provided in the control device  10 , a request injection amount [mm3/st], a request turbocharging pressure [kPa], a request EGR rate [−] and a request throttle opening degree [%] are calculated. 
       FIG. 2  is a flowchart for explaining control of the fuel injection valve  30  and the like, which is executed at a time of accelerator opening degree increase in the engine system illustrated in  FIG. 1 . A routine illustrated in  FIG. 2  is executed at predetermined time intervals. 
     When the routine illustrated in  FIG. 2  is started, first of all in step S 100 , the engine speed NE [rpm] calculated based on an output signal of the crank angle sensor  20  (refer to  FIG. 1 ) is acquired, and is inputted to the basic accelerator request torque calculating section  10   a  (refer to  FIG. 1 ). Further, a gear position detected by the gear position sensor  21  (refer to  FIG. 1 ) is acquired, and is inputted to the basic accelerator request torque calculating section  10   a  and the vehicle model  10   c.    
     In the example illustrated in  FIG. 1  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the gear position detected by the gear position sensor  21  is inputted to the basic accelerator request torque calculating section  10   a  and the vehicle model  10   c,  whereas in another example, instead, a gear position estimated based on a gear ratio calculated from the engine speed NE and a vehicle speed [km/h] can be inputted to the basic accelerator request torque calculating section  10   a  and the vehicle model  10   c.    
     As illustrated in  FIG. 2 , in step S 100 , an accelerator opening degree Pa [%] calculated based on en output signal of the accelerator opening degree sensor  22  (refer to  FIG. 1 ) is further acquired, and is inputted to the basic accelerator request torque calculating section  10   a  (refer to  FIG. 1 ). Further, an accelerator opening degree increase amount (a difference between the accelerator opening degree Pa that is acquired when the routine illustrated in  FIG. 2  is executed this time, and the accelerator opening degree Pa that is acquired when the routine illustrated in  FIG. 2  is executed a previous time, for example) that is calculated based on the accelerator opening degree Pa is acquired, and inputted to the target acceleration increase amount calculating section  10   b  (refer to  FIG. 1 ). 
     Further, in step S 100 , a constraint under which an acceleration G [m/s 2 ] does not increase even when the driver increases the accelerator opening degree Pa is acquired, and is inputted to the target acceleration increase amount calculating section  10   b.    
     In the example illustrated in  FIGS. 1 and 2  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, a torque constraint TR (refer to  FIGS. 5B and 6B ) under which a torque that is actually outputted does not increase even when a request torque is increased is used, as a constraint inputted to the target acceleration increase amount calculating section  10   b.    
     As illustrated in  FIG. 2 , in step S 100 , a present operating state is further acquired, and is inputted to the target acceleration increase amount calculating section  10   b  (refer to  FIG. 1 ). 
     In the example illustrated in  FIGS. 1 and 2  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, as the present operating state which is inputted to the target acceleration increase amount calculating section  10   b,  a request engine torque (refer to  FIG. 1 ,  FIG. 5H  and  FIG. 6H ) is used, for example. 
     As illustrated in  FIG. 2 , in step S 100 , the vehicle speed [km/h] calculated based on an output signal of the vehicle speed sensor  23  (refer to  FIG. 1 ) is further acquired, and is inputted to the vehicle model  10   c  (refer to  FIG. 1 ). Further, a vehicle weight [kg], a differential ratio [−], and a tire diameter [m] are inputted to the vehicle model  10   c.    
     Next, in step S 101 , the basic accelerator request torque is calculated based on the engine speed NE, the gear position and the accelerator opening degree Pa by the basic accelerator request torque calculating section  10   a  (refer to  FIG. 1 ). 
       FIG. 3  is a diagram illustrating a relation of the basic accelerator request torque, the engine speed NE and the gear position. As illustrated in  FIG. 3 , as the engine speed NE is higher, a value of the basic accelerator request torque calculated by the basic accelerator request torque calculating section  10   a  becomes smaller. Further, as the gear position is higher, a change amount of the basic accelerator request torque per unit change amount of the engine speed NE becomes smaller per unit change amount. 
     Further, as the accelerator opening degree Pa is larger, the value of the basic accelerator request torque calculated by the basic accelerator request torque calculating section  10   a  becomes larger. 
       FIG. 4  is a diagram illustrating a relation of relations RL 1 , RL 2  and RL 3  of the target acceleration increase amount ΔG [m/s 2 ] and the accelerator opening degree increase amount ΔPa [%]. 
     In an example illustrated in  FIG. 4  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the relation RL 1  in which a ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is large, the relation RL 2  in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is smaller than in the relation RL 1 , and the relation RL 3  in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is smaller than in the relation RL 2  are selectively used. As illustrated in  FIG. 4 , the relations RL 1 , RL 2  and RL 3  are set so that when a value of the accelerator opening degree increase amount ΔPa is zero, a value of the target acceleration increase amount ΔG becomes zero. 
     In the example illustrated in  FIG. 2  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, in step S 102 , one of the three relations RL 1 , RL 2  and RL 3  illustrated in  FIG. 4  is selected based on the present operating state (the request engine torque) and the constraint (the torque constraint). 
     More specifically, in the example illustrated in  FIGS. 1 to 4  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the relation RL 1  in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is large is selected in step S 102 , when the present operating state (the request engine torque (refer to  FIG. 5H )) is not close to the constraint (the torque constraint TR (refer to  FIG. 5H )). 
     When the present operating state (the request engine torque (refer to  FIG. 6H )) is close to the constraint (the torque constraint TR (refer to  FIG. 6H )), the relation RL 3  in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is small is selected in step S 102 . 
     When the present operating state (the request engine torque) is relatively close to the constraint (the torque constraint) although the present operating state is not so close to the constraint as in the case where the relation RL 3  is selected, and the operating state (the request engine torque) is likely to reach the constraint (the torque constraint) if the acceleration is increased quickly, the relation RL 2  in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is smaller than in the relation RL 1  is selected. 
     In the example illustrated in  FIG. 4  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the three relations RL 1 , RL 2  and RL 3  are selectively used, whereas in another example, a plurality of optional relations other than the three relations can be also used selectively instead. 
     As illustrated in  FIG. 2 , next in step S 103 , the target acceleration increase amount ΔG [m/s 2 ] is calculated by the target acceleration increase amount calculating section  10   b  (refer to  FIG. 1 ) based on one of the three relations RL 1 , RL 2  and RL 3  that is selected in step S 102 , and the accelerator opening degree increase amount ΔPa. 
     Next, in step S 104 , the target torque increase amount [Nm] is calculated by the vehicle model  10   c  (refer to  FIG. 1 ). 
     As the target acceleration increase amount ΔG is larger, the target torque increase amount calculated by the vehicle model  10   c  becomes larger. As the vehicle speed is larger, friction becomes larger, and thus the value of the target torque increase amount becomes larger. As the gear position is higher, the gear ratio becomes smaller in general, and thus the value of the target torque increase amount becomes large. Further, the value of the target torque increase amount calculated by the vehicle model  10   c  becomes larger as the vehicle weight is larger, becomes larger as the differential ratio is larger, and becomes larger as the tire diameter is larger. 
     Next, in step S 105 , a basic accelerator request torque increase amount [Nm] that is a difference between the basic accelerator request torque [Nm] calculated in step S 101  when the routine illustrated in  FIG. 2  is executed this time, and a basic accelerator request torque previous value [Nm] calculated in step S 101  when the routine illustrated in  FIG. 2  is executed the previous time is calculated. 
     Next, in step S 106 , a torque increase amount correction amount [Nm] is calculated by subtracting the basic accelerator request torque increase amount calculated in step S 105  from the target torque increase amount calculated in step S 104 . A value of the torque increase amount correction amount calculated in step S 106  is zero or less. 
     As illustrated in  FIG. 2 , subsequently in step S 107 , a request engine torque that is a total sum of the basic accelerator request torque calculated in step S 101  and the torque increase amount correction amount calculated in step S 106  is calculated. 
     Next, in step S 108 , the request injection amount [mm 3 /st] is calculated by the request state quantity calculating section  10   d  (refer to  FIG. 1 ). 
     Next, in step S 109 , the fuel injection valve  30  is controlled by the control device  10  based on the request injection amount calculated in step S 108 . 
       FIG. 5  is a time chart for explaining control at a time of accelerator opening degree increase in the case where the present operating state in the engine system to which the control device for an internal combustion engine of the first embodiment is applied is not close to the constraint. 
     In an example illustrated in  FIG. 5 , as illustrated in  FIG. 5A , in a time period from a time t 1  to a time t 2 , the accelerator opening degree Pa increases from a value Pa 1  to a value Pa 2 . As a result, as illustrated in  FIG. 5B , the basic accelerator request torque calculated by the basic accelerator request torque calculating section  10   a  (refer to  FIG. 1 ) increases from a value TI to a value T 2  in the time period from the time t 1  to the time t 2 . 
     In the example illustrated in  FIG. 5 , as illustrated in  FIG. 5H , at a time point of the time t 1 , the present operating state (a value T 1  of the request engine torque) is not close to the constraint (the torque constraint TR). Consequently, even if an acceleration G (refer to  FIG. 5J ) is increased quickly, the operating state (the request engine torque) is unlikely to reach the constraint (the torque constraint TR). In the light of this point, in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the relation RL 1  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is large is selected in step S 102  (refer to  FIG. 4 ). 
     Consequently, as illustrated in  FIG. 5D , the target acceleration increase amount ΔG calculated based on the relation RL 1  and a value ΔPa 1  (refer to  FIG. 5C ) of the accelerator opening degree increase amount ΔPa becomes a large value ΔG 1  when the driver increases the accelerator opening degree Pa (the time t 1 ). 
     In the example illustrated in  FIG. 5 , the value ΔG 1  of the target acceleration increase amount ΔG is large, and thus, as illustrated in  FIG. 5E , the target torque increase amount calculated by the vehicle model  10   c  (refer to  FIG. 1 ) at the time point of the time t 1  becomes a large value ΔTT 1 . 
     In the example illustrated in  FIG. 5 , as illustrated in  FIG. 5E  and  FIG. 5F , at the time point of the time t 1 , the value ΔTT 1  of the target torque increase amount becomes equal to a value ΔRT 1  of the basic accelerator request torque increase amount that is the difference between the basic accelerator request torque calculated when the routine illustrated in  FIG. 2  is executed this time, and the basic accelerator request torque previous value calculated when the routine illustrated in  FIG. 2  is executed the previous time. 
     As a result, as illustrated in  FIG. 5G , the value of the torque increase amount correction amount calculated by subtracting the value ΔRT 1  of the basic accelerator request torque increase amount from the value ΔTT 1  of the target torque increase amount becomes zero. 
     The values illustrated in  FIG. 5C ,  FIG. 5D ,  FIG. 5E ,  FIG. 5F  and  FIG. 5G  are differences between the values calculated when the routine illustrated in  FIG. 2  is executed this time, and the values calculated when the routine illustrated in  FIG. 2  is executed the previous time. 
     Since in the example illustrated in  FIG. 5 , the value of the torque increase amount correction amount (refer to  FIG. 5G ) is zero, the value T 1  of the request engine torque at the time point of the time t 1  is equal to the value T 1  of the basic accelerator request torque (refer to  FIG. 5B ) at the time point of the time t 1 , and the value T 2  of the request engine torque at the time point of the time t 2  is equal to the value T 2  of the basic accelerator request torque at the time point of the time t 2 , as illustrated in  FIG. 5H . 
     Consequently, as illustrated in  FIG. 5I , in the time period from the time t 1  to the time t 2 , the request injection amount quickly increases from a value Q 1  to a value Q 2 . As a result, in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, as illustrated in  FIG. 5J , in the time period from the time t 1  to the time t 2 , the acceleration G can be quickly increased from a value G 1  to a value G 2 . 
       FIG. 6  is a time chart for explaining control at a time of accelerator opening degree increase in the case where the present operating state in the engine system to which the control device for an internal combustion engine of the first embodiment is applied is close to the constraint. 
     In an example illustrated in  FIG. 6 , as illustrated in  FIG. 6A , in a time period from a time t 11  to a time t 13 , the accelerator opening degree Pa increases from a value Pa 3  to a value Pa 4 . As a result, as illustrated in  FIG. 6B , the basic accelerator request torque calculated by the basic accelerator request torque calculating section  10   a  (refer to  FIG. 1 ) increases from a value T 3  to a value T 4  in the time period from the time t 11  to the time t 13 . 
     In the example illustrated in  FIG. 6 , as illustrated in  FIG. 6H , at a time point of the time t 11 , the present operating state (a value T 3  of the request engine torque) is close to the constraint (the torque constraint TR). Consequently, if the acceleration G (refer to  FIG. 5J ) is increased quickly as in the example illustrated in  FIG. 5 , the operating state (the request engine torque) is likely to reach the constraint (the torque constraint TR). In the light of this point, in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the relation RL 3  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is small is selected in step S 102  (refer to  FIG. 2 ). 
     Consequently, as illustrated in  FIG. 6D , the target acceleration increase amount ΔG calculated based on the relation RL 3  and a value ΔPa 2  (refer to  FIG. 6C ) of the accelerator opening degree increase amount ΔPa becomes a small value ΔG 2  when the driver increases the accelerator opening degree Pa (the time t 11 ). (If the value ΔPa 1  (refer to  FIG. 5C ) and the value ΔPa 2  (refer to  FIG. 6C ) are equal to each other, the value ΔG 2  (refer to  FIG. 6D ) becomes smaller than the value ΔG 1  (refer to  FIG. 5C ).) 
     In the example illustrated in  FIG. 6 , the value ΔG 2  of the target acceleration increase amount ΔG is small, and thus, as illustrated in  FIG. 6E , the target torque increase amount calculated by the vehicle model  10   c  (refer to  FIG. 1 ) at the time point of the time t 11  becomes a small value ΔTT 2 . 
     In the example illustrated in  FIG. 6 , as illustrated in  FIG. 6E  and  FIG. 6F , at the time point of the time t 11 , the value ΔTT 2  of the target torque increase amount becomes smaller than a value ΔRT 2  of the basic accelerator request torque increase amount that is the difference between the basic accelerator request torque calculated when the routine illustrated in  FIG. 2  is executed this time and the basic accelerator request torque previous value calculated when the routine illustrated in  FIG. 2  is executed the previous time. 
     As a result, as illustrated in  FIG. 6G , the torque increase amount correction amount calculated by subtracting the value ΔRT 2  of the basic accelerator request torque increase amount from the value ΔTT 2  of the target torque increase amount becomes a negative value ΔTC 2 . 
     The values illustrated in  FIG. 6C ,  FIG. 6D ,  FIG. 6E ,  FIG. 6F  and  FIG. 6G  are differences between the values calculated when the routine illustrated in  FIG. 2  is executed this time, and the values calculated when the routine illustrated in  FIG. 2  is executed the previous time. 
     Since in the example illustrated in  FIG. 6 , the torque increase amount correction amount (refer to  FIG. 6G ) becomes the negative value ΔTC 2  after the time t 11 , the value of the request engine torque at the time point after the time t 11  becomes smaller than the value of the basic accelerator request torque (refer to  FIG. 6B ) at the time point after the time t 11 , as illustrated in  FIG. 6H . In more detail, a value T 5  (≦the torque constraint TR) of the request engine torque at the time point of the time t 13  becomes smaller than a value T 4  (&gt;the torque constraint TR) of the basic accelerator request torque at the time point of the time t 13 . 
     Consequently, as illustrated in  FIG. 61 , in the time period from the time t 11  to the time t 13 , the request injection amount gradually increases from a value Q 3  to a value Q 4 . As a result, in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, as illustrated in  FIG. 6J , in the time period from the time t 11  to the time t 13 , the acceleration G can be gradually increased from a value G 3  to a value  34 . 
     Thereby, in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, as illustrated in  FIG. 6H  and  FIG. 6J , in an acceleration request time period (in the time period from the time t 11  to the time t 13 ) by the driver, the acceleration G can be increased continuously without causing the operating state (the request engine torque (refer to  FIG. 6H )) to reach the constraint (the torque constraint TR). 
     That is, in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, increase of the acceleration G that satisfies the acceleration request by the driver can be realized even when the present operating state (the value T 3  of the request engine torque at the time point of the time t 11 ) is close to the constraint (the torque constraint TR). 
     Next, control at a time of accelerator opening degree increase in a case where a present operating state is close to the constraint in an engine system of a comparative example will be described. 
     In the engine system of the comparative example, as in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the accelerator opening degree Pa increases from the value Pa 3  to the value Pa 4 , in the time period from the time t 11  to the time t 13 , as illustrated in  FIG. 6A . As a result, as illustrated in  FIG. 6B , the basic accelerator request torque calculated by the basic accelerator request torque calculating section  10   a  (refer to  FIG. 1 ) increases from the value T 3  to the value T 4  in the time period from the time t 11  to the time t 13 . 
     In the engine system of the comparative example, the relations RL 2  and RL 3  (refer to  FIG. 4 ) in each of which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is small are not included in the target acceleration increase amount calculating section  10   b  (refer to  FIG. 1 ), but only the relation RL 1  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is large is included in the target acceleration increase amount calculating section  10   b.    
     Consequently, in the engine system of the comparative example, the relation RL 1  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is large is selected in step S 102  (refer to  FIG. 2 ), although at the time point of the time t 11 , the present operating state (the value T 3  of the request engine torque) is close to the constraint (the torque constraint TR) as illustrated in  FIG. 6H , and if the acceleration G (refer to  FIG. 6J ) is increased quickly, the operating state (the request engine torque) is likely to reach the constraint (the torque constraint TR). 
     As a result, as illustrated in  FIG. 6D  by the broken line, the target acceleration increase amount ΔG calculated based on the relation RL 1  and the value ΔPa 2  (refer to  FIG. 6C ) of the accelerator opening degree increase amount ΔPa becomes a large value ΔG 3  when the driver increases the accelerator opening degree Pa (the time t 11 ). (If the value ΔPa 1  (refer to FIG.  5 C) and the value ΔPa 2  (refer to  FIG. 6C ) are equal to each other, the value ΔG 3  (refer to  FIG. 6D ) becomes equal to the value ΔG 1  (refer to  FIG. 5D .)) 
     In the engine system of the comparative example, the value ΔG 3  of the target acceleration increase amount ΔG at the time point of the time t 11  is large, and thus, as illustrated in  FIG. 6E  by the broken line, the target torque increase amount calculated by the vehicle model  10   c  (refer to  FIG. 1 ) at the time point of the time t 11  also becomes a large value ΔTT 3 . 
     In the engine system of the comparative example, as illustrated in  FIG. 6E  by the broken line, at the time point of the time t 11 , the value ΔTT 3  of the target torque increase amount becomes equal to a value ΔRT 2  (refer to  FIG. 6F ) of the basic accelerator request torque increase amount that is the difference between the basic accelerator request torque calculated when the routine illustrated in  FIG. 2  is executed this time and the basic accelerator request torque previous value calculated when the routine illustrated in  FIG. 2  is executed the previous time. 
     As a result, as illustrated in  FIG. 6G  by the broken line, at the time point of the time t 11 , the value of the torque increase amount correction amount calculated by subtracting the value ΔRT 2  of the basic accelerator request torque increase amount from the value ΔTT 3  of the target torque increase amount becomes zero, 
     The values illustrated by the broken lines in  FIG. 6D ,  FIG. 6E  and  FIG. 6G  are differences between the values calculated when the routine illustrated in  FIG. 2  is executed this time, and the values calculated when the routine illustrated in  FIG. 2  is executed the previous time. 
     Since in the engine system of the comparative example, the value of the torque increase amount correction amount (refer to  FIG. 6G ) at the time point of the time t 11  becomes zero, the value T 3  of the request engine torque at the time point of the time t 11  becomes equal to the value T 3  of the basic accelerator request torque (refer to  FIG. 6B ) at the time point of the time t 11 , as illustrated by the broken line in  FIG. 6H . 
     Further, in the engine system of the comparative example, the value of the torque increase amount correction amount (refer to  FIG. 6G ) in the time period from the time t 11  to a time t 12  also becomes zero, and therefore, as shown in  FIG. 6H  by the broken line, a value T 5  of the request engine torque at the time point of the time t 12  becomes equal to the value T 5  of the basic accelerator request torque (refer to  FIG. 6B ) at the time point of the time t 12 . 
     Consequently, in the time period from the time t 11  to the time t 12 , the request injection amount increases quickly from a value Q 3  to a value Q 4  as illustrated by the broken line in  FIG. 6I , and the acceleration G increases quickly from a value G 3  to a value G 4 , as illustrated by the broken line in  FIG. 6J . 
     However, in the engine system of the comparative example, the operating state (the request engine torque) reaches the constraint (the torque constraint TR) at the time t 12  before the time t 13 , and the request engine torque does not increase as illustrated by the broken line in  FIG. 6H , although the driver increases the accelerator opening degree Pa and issues an acceleration request in the time period from the time t 11  to the time t 13  as shown in  FIG. 6A  and  FIG. 6C . 
     That is, in the engine system of the comparative example, the request engine torque (refer to  FIG. 6H ) is limited to the fixed value T 5  (=the torque constraint TR) by the constraint (the torque constraint TR) inputted to the target acceleration increase amount calculating section  10   b  (refer to  FIG. 1 ), although the accelerator opening degree Pa (refer to  FIG. 6A ) also increases, and with this, the basic accelerator request torque (refer to  FIG. 6B ) increases in the time period from the time t 12  to the time t 13 . 
     As a result, in the engine system of the comparative example, the acceleration G is limited to the fixed value G 4  as illustrated by the broken line in  FIG. 6J  although the driver issues the acceleration request in the time period from the time t 12  to the time t 13 , and the increase of the acceleration G which satisfies the acceleration request of the driver cannot be realized. 
     In more detail, in the engine system of the comparative example, the value of the target acceleration increase amount ΔG (refer to  FIG. 6D ) is limited to zero in the time period from the time t 12  to the time t 13  by the constraint (the torque constraint TR) inputted to the target acceleration increase amount calculating section  10   b  (refer to  FIG. 1 ). As a result, the value of the target torque increase amount (refer to  FIG. 6E ) becomes zero, and the torque increase amount correction amount (refer to the broken line in  FIG. 6G ) calculated by subtracting the value ΔRT 2  of the basic accelerator request torque increase amount (refer to  FIG. 6F ) from the value (zero) of the target torque increase amount becomes the negative value ΔTC 3 . 
     In other words, in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the relation RL 3  (refer to  FIG. 4 ) of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa, in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is small, which is selected in step S 102  (refer to  FIG. 2 ) is used in step S 103  (refer to  FIG. 2 ), when the present operating state (the request engine torque (refer to  FIG. 6H )) is close to the constraint (the torque constraint TR (refer to  FIG. 6H )). Consequently, when the driver increases the accelerator opening degree (the time t 11  (refer to  FIG. 6 )), the target acceleration increase amount. ΔG (refer to  FIG. 6D ) of the small value ΔG 2  is calculated. As a result, the acceleration G (refer to  FIG. 6J ) can be gradually increased, whereby during an acceleration request time period by the driver (during the time period from the time t 11  to the time t 13 ), the acceleration G can be continuously increased without causing the operating state (the request engine torque (refer to  FIG. 6H )) to reach the constraint (the torque constraint TR). 
     That is, the engine system to which the control device for an internal combustion engine of the first embodiment is applied can reduce the possibility that the acceleration G (refer to  FIG. 6J ) does not increase even if the driver increases the accelerator opening degree Pa (refer to  FIG. 6A ) with the operating state (the request engine torque (refer to  FIG. 6H )) reaching the constraint (the torque constraint TR) as in the time period from the time t 12  to the time t 13  in the comparative example illustrated by the broken lines in  FIG. 6 . 
     That is, the engine system to which the control device for an internal combustion engine of the first embodiment is applied can realize increase of the acceleration G (refer to  FIG. 6J ) that satisfies the acceleration request by the driver, as in the time period from the time t 11  to the time t 13  in the example illustrated by the solid line in  FIG. 6 , even when the present operating state (the request engine torque (refer to  FIG. 6H )) is close to the constraint (the torque constraint TR (refer to  FIG. 6H )). 
     By the earnest study of the present inventor, it has been found out that responsiveness of the acceleration increase that is realized to an accelerator opening degree increasing operation by the driver is enhanced, when the relations RL 1 , RL 2  and RL 3  (refer to  FIG. 4 ) of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa are set, based on a relation ((ΔPa/Pa) ∝ (ΔG/G)) in which the ratio (ΔPa/Pa) of the accelerator opening degree increase amount ΔPa (refer to  FIG. 4 ,  FIG. 5C  and  FIG. 6C ) and the accelerator opening degree Pa (refer to  FIG. 5A  and  FIG. 6A ) is proportional to the ratio (ΔG/G) of the target acceleration increase amount ΔG (refer to  FIG. 4 ,  FIG. 5D  and  FIG. 6D ) and the target acceleration G (refer to  FIG. 5J  and  FIG. 6J ). 
     In the light of the above point, in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the relations RL 1 , RL 2  and RL 3  of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa are set, based on the relation ((ΔPa/Pa) ∝ (ΔG/G)) in which the ratio (ΔPa/Pa) of the accelerator opening degree increase amount ΔPa and the accelerator opening degree Pa is proportional to the ratio (ΔG/G) of the target acceleration increase amount ΔG and the target acceleration G. 
     Consequently in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, responsiveness of the acceleration increase, which is realized to the accelerator opening degree increasing operation by the driver can be enhanced more than in a case where the relation of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is set, based on a relation in which the ratio (ΔPa/Pa) of the accelerator opening degree increase amount ΔPa and the accelerator opening degree Pa is not proportional to the ratio (ΔG/G) of the target acceleration increase amount ΔG and the target acceleration G. 
     As described above, in the example illustrated in  FIG. 5  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the present operating state (the value T 1  of the request engine torque (refer to  FIG. 5H )) is not close to the constraint (the torque constraint TR) at the time point of the time T 1 . Therefore, by using the relation RL 1  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is large in step S 103  (refer to  FIG. 2 ), at the time of accelerator opening degree increase from the time t 1  to the time t 2 , the target acceleration increase amount ΔG with an increase amount per accelerator opening degree increase amount ΔPa being large is calculated. Further, the torque increase amount correction amount (the value is zero) is calculated in step S 106  (refer to  FIG. 2 ) based on the target acceleration increase amount ΔG calculated in step S 103 . Further, the request engine torque (the value is equal to the value of the basic accelerator request torque) is calculated in step S 107  (refer to  FIG. 2 ), based on the basic accelerator request torque calculated in step S 101  (refer to  FIG. 2 ) and the torque increase amount correction amount calculated in step S 106 . Further, based on the request engine torque calculated in step S 107 , the request injection amount (refer to  FIG. 5I ) with an increase amount per accelerator opening degree increase amount ΔPa being large is calculated in step S 108  (refer to  FIG. 2 ). 
     Meanwhile, in the example illustrated by the solid lines in  FIG. 6  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the present operating state (the value T 3  of the request engine torque (refer to  FIG. 6H )) is close to the constraint (the torque constraint TR) at the time point of the time t 11 . Consequently, by using the relation RL 3  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is small in step S 103  at the time of accelerator opening degree increase from the time t 11  to the time t 13 , the target acceleration increase amount ΔG with the increase amount per accelerator opening degree increase amount ΔPa being small is calculated. Further, based on the target acceleration increase amount ΔG calculated in step S 103 , the torque increase amount correction amount (the value is a negative value) is calculated in step S 106 . Further, the request engine torque (the value is smaller than the value of the basic accelerator request torque) is calculated in step S 107 , based on the basic accelerator request torque calculated in step S 101 , and the torque increase amount correction amount calculated in step S 106 . Further, based on the request engine torque calculated in step S 107 , the request injection amount (refer to  FIG. 6I ) with the increase amount per accelerator opening degree increase amount ΔPa is calculated in step S 108 . 
     In the comparative example illustrated by the broken lines in  FIG. 6 , the relation RL 1  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is large is used at the time of accelerator opening degree increase, although the present operating state (the value T 3  of the request engine torque (refer to  FIG. 6H )) is close to the constraint (the torque constraint TR) at the time point of the time t 11 . Consequently, the request injection amount (refer to  FIG. 6I ) with the increase amount per accelerator opening degree increase amount ΔPa being large is calculated in the time period from the time t 11  to the time t 12 , and as a result, the operating state (the request engine torque (refer to  FIG. 6H )) reaches the constraint (the torque constraint TR) at the time t 12 . 
     In other words, in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the request injection amount (refer to  FIG. 6I ) with the increase amount per accelerator opening degree increase amount being small is calculated at the time of accelerator opening degree increase (in the time period from the time t 11  to the time t 13 ) when the present operating state (the value T 3  of the request engine torque (refer to  FIG. 6H )) is close to the constraint (the torque constraint TR), as shown by the solid lines in  FIG. 6 . 
     That is, in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the increase amount per accelerator opening degree increase amount of the request injection amount (refer to  FIG. 5I  and  FIG. 6I ) calculated by the control device  10  (refer to  FIG. 1 ) at the time of accelerator opening degree increase (in the time period from the time t 1  to the time t 2  in  FIG. 5 , and in the time period from the time t 11  to the time t 13  in  FIG. 6 ) is smaller as the present operating state (the request engine torque (refer to  FIG. 5H  and  FIG. 6H )) is closer to the constraint (the torque constraint TR). 
     Consequently, in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the fuel injection amount can be reduced by the amount illustrated by hatching in  FIG. 6I , and fuel efficiency can be enhanced more than in the comparative example illustrated by the broken lines in  FIG. 6  in which the request injection amount (refer to the broken line in  FIG. 6I ) with the increase amount per accelerator opening degree increase amount being large is calculated at the time of accelerator opening degree increase (in the time period from the time t 11  to the time t 12  in  FIG. 6 ) and the operating state (the request engine torque (refer to the broken line in  FIG. 6H )) reaches the constraint (the torque constraint TR). 
     In the example illustrated in  FIGS. 1 and 6 , the control device for an internal combustion engine of the first embodiment is applied to the engine system having the turbocharger  32 , but in another example, the control device for an internal combustion engine of the first embodiment can be also applied to an engine system that does not have the turbocharger  32 , instead. 
       FIG. 7  is a time chart for explaining control at the time of accelerator opening degree increase in a case where a present operating state is close to the constraint in another example of the engine system to which the control device for an internal combustion engine of the first embodiment is applied. 
     In the example illustrated in  FIG. 7  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, at the time of accelerator opening degree increase in the case of the present operating state (the request engine torque) being close to the constraint (the torque constraint), in order to increase the acceleration G (refer to  FIG. 7F ) gradually from the value G 3  to the value G 4 , the request injection amount (refer to  FIG. 7A ) is gradually increased from a value Q 9  to a value Q 10 , a request EGR rate (refer to  FIG. 7C ) is gradually decreased from a value R 6  to a value R 5 , a request turbocharging pressure (refer to  FIG. 7D ) is gradually increased from a value P 3  to a value P 4 , and a request throttle opening degree (refer to  FIG. 7E ) is gradually increased from a value TA 1  to a value TA 2 . Further, an air amount (refer to  FIG. 7B ) is gradually increased from a value M 5  to a value M 6 . 
     More specifically, in the example illustrated in  FIG. 7  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, in step S 108  (refer to  FIG. 2 ), the request state quantity calculating section  10   d  (refer to  FIG. 1 ) calculates the request injection amount [mm 3 /st] (refer to  FIG. 1  and  FIG. 7A ), the request EGR rate [−] (refer to  FIG. 1  and  FIG. 7C ), the request turbocharging pressure [kPa] (refer to  FIG. 1  and  FIG. 7D ), and a request throttle opening degree [%] (refer to  FIG. 1  and  FIG. 7E ). 
     In more detail, in the example illustrated in  FIG. 7  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, at the time of accelerator opening degree increase (in the time period from the time t 11  to the time t 13 ) in the case where the present operating state (the request engine torque) is close to the constraint (the torque constraint), the target acceleration increase amount ΔG (refer to  FIG. 1 ) calculated by using the relation RL 3  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is small is used in calculation of the request injection amount, the request EGR rate, the request turbocharging pressure and the request throttle opening degree. 
     Further, in step S 109  (refer to  FIG. 2 ), based on the request injection amount calculated in step S 108 , the fuel injection valve  30  (refer to  FIG. 1 ) is controlled by the control device  10  (refer to  FIG. 1 ). Further, in step S 109 , the control device  10  controls an EGR valve (not illustrated) of the EGR device  31  (refer to  FIG. 1 ), a wastegate valve (not illustrated) of the turbocharger  32  (refer to  FIG. 1 ) and the throttle valve  33  (refer to  FIG. 1 ), based on the request EGR rate, the request turbocharging pressure and the request throttle opening degree which are calculated in step S 108 . 
     If the target acceleration increase amount ΔG (refer to  FIG. 1 ) calculated by using the relation RL 1  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is large is used in calculation of the request injection amount (refer to  FIG. 1  and  FIG. 7A ), the request EGR rate (refer to  FIG. 1  and  FIG. 7C ), the request turbocharging pressure (refer to  FIG. 1  and  FIG. 7D ) and the request throttle opening degree (refer to  FIG. 1  and  FIG. 7E ), in the example illustrated in  FIG. 7 , in the time period from the time t 11  to the time t 12 , the request injection amount increases from the value Q 9  to the value Q 10  as illustrated by a broken line in  FIG. 7A , the air amount increases from the value M 5  to the value M 6  as illustrated by a broken line in  FIG. 7B , the request EGR rate decreases from the value R 6  to the value R 5  as illustrated by a broken line in  FIG. 7C , the request turbocharging pressure increases from the value P 3  to the value P 4  as illustrated by a broken line in  FIG. 7D , the request throttle opening degree increases from the value TA 1  to the value TA 2  as shown by a broken line in  FIG. 7E , and the acceleration G increases from the value G 3  to the value G 4  as shown by a broken line in  FIG. 7F , in the time period from the time t 11  to the time t 12 . 
     As described above, in the example illustrated by the solid lines in  FIG. 6  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, at the time of accelerator opening degree increase (in the time period from the time t 11  to the time t 13 ) in the case where the present operating state (the request engine torque) is close to the constraint (the torque constraint), the target acceleration increase amount ΔG (refer to  FIG. 1  and  FIG. 6D ) calculated by using the relation RL 3  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is small is used in calculation of the request injection amount (refer to  FIG. 6I ). 
     Further, as described above, in the example illustrated in  FIG. 7  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, at the time of accelerator opening degree increase (in the time period from the time t 11  to the time t 13 ) in the case where the present operating state (the request engine torque) is close to the constraint (the torque constraint), the target acceleration increase amount ΔG (refer to  FIG. 1  and  FIG. 6D ) calculated by using the relation RL 3  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is small is used in calculation of the request injection amount (refer to  FIG. 7A ), the request EGR rate (refer to  FIG. 7C ), the request turbocharging pressure (refer to  FIG. 7D ) and the request throttle opening degree (refer to  FIG. 7E ). 
     Meanwhile, in another example (not illustrated) of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, at the time of accelerator opening degree increase in the case where the present operating state (the request engine torque) is close to the constraint (the torque constraint), the target acceleration increase amount ΔG (refer to  FIG. 1  and  FIG. 6D ) calculated by using the relation RL 3  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is small is used in calculation of the request injection amount, and can be also used in calculation of arbitrary one or two of the request EGR rate, the request turbocharging pressure and the request throttle opening degree, instead. 
     In the example illustrated in  FIG. 1  of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the target torque increase amount [Nm] is calculated by the vehicle model  10   c  based on the target acceleration increase amount ΔG [m/s 2 ], and the torque increase amount correction amount [Nm] is calculated based on the target torque increase amount [Nm] next, whereas in another example (not illustrated) of the engine system to which the control device for an internal combustion engine of the first embodiment is applied, the torque increase amount correction amount [Nm] can be also calculated based on the target acceleration increase amount ΔG [m/s 2 ] via arbitrary means (not illustrated) other than the vehicle model  10   c,  instead. 
     Hereinafter, a second embodiment of the control device for an internal combustion engine of the present disclosure will be described. 
     An engine system to which the control device for an internal combustion engine of the second embodiment is applied is configured substantially similarly to the engine system to which the control device for an internal combustion engine of the first embodiment described above is applied, except for a point that will be described later. Consequently, according to the engine system to which the control device for an internal combustion engine of the second embodiment is applied, a substantially similar effect to the aforementioned engine system to which the control device for an internal combustion engine of the first embodiment described above is applied can be provided, except for a point that will be described later. 
     As described above, in the engine system to which the control device for an internal combustion engine of the first embodiment is applied, as the constraint under which the acceleration G does not increase even when the driver increases the accelerator opening degree Pa, the torque constraint TR (refer to  FIG. 5B  and  FIG. 6B ) under which even when the request torque is increased, the torque actually outputted does not increase is used, and is inputted to the target acceleration increase amount calculating section  10   b  (refer to  FIG. 1 ). 
     In the engine system to which the control device for an internal combustion engine of the second embodiment is applied, instead of the above, a smoke emission amount constraint under which the request injection amount (the fuel injection amount) (refer to  FIG. 1 ) does not increase even when the driver increases the accelerator opening degree Pa is used as the constraint in which the acceleration C does not increase even when the driver increases the accelerator opening degree Pa, and is inputted to the target acceleration increase amount calculating section  10   b.  By setting the smoke emission amount constraint, the smoke emission amount can be prevented from being a predetermined value or more. 
     In the engine system to which the control device for an internal combustion engine of the second embodiment is applied, in step S 102  (refer to  FIG. 2 ), one of the three relations RL 1 , RL 2  and RL 3  illustrated in  FIG. 4  is selected based on the present operating state (the smoke emission amount) and the constraint (the smoke emission amount constraint). 
     More specifically, the engine system to which the control device for an internal combustion engine of the second embodiment is applied, the relation RL 1  in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is large is selected in step S 102 , when the present operating state (the smoke emission amount) is not close to the constraint (the smoke emission amount constraint). 
     When the present operating state (the smoke emission amount) is close to the constraint (the smoke emission amount constraint), the relation RL 3  in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is small is selected in step S 102 . 
     When the present operating state (the smoke emission amount) is relatively close to the constraint (the smoke emission amount constraint) although the present operating state is not so close to the constraint as in the case where the relation RL 3  is selected, and the operating state (the smoke emission amount) is likely to reach the constraint (the smoke emission amount constraint) if the acceleration is quickly increased, the relation RL 2  in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is smaller than in the relation RL 1  is selected. 
     In the engine system to which the control device for an internal combustion engine of the second embodiment is applied, the request injection amount (refer to  FIG. 6I ) can be gradually increased from the value Q 3  to the value Q 4  in the acceleration request time period (in the time period from the time t 11  to the time t 13  in  FIG. 6 ) by the driver by using the relation RL 3  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is small, when the present operating state (the smoke emission amount) is close to the constraint (the smoke emission amount constraint), whereby the acceleration G (refer to  FIG. 6J ) can be gradually increased from the value G 3  to the value G 4 . 
     That is, in the engine system to which the control device for an internal combustion engine of the second embodiment is applied, in the acceleration request time period (in the time period from the time t 11  to the time t 13  in  FIG. 6 ) by the driver, the acceleration G can be continuously increased without causing the operating state (the smoke emission amount) to reach the constraint (the smoke emission amount constraint). 
     That is, in the engine system to which the control device for an internal combustion engine of the second embodiment is applied, increase of the acceleration G that satisfies the acceleration request by the driver can be realized even when the present operating state (the smoke emission amount at the time point of the time t 11  in  FIG. 6 ) is close to the constraint (the smoke emission amount constraint). 
     Hereinafter, a third embodiment of the control device for an internal combustion engine of the present disclosure will be described. 
     The engine system to which the control device for an internal combustion engine of the third embodiment is applied is configured to be substantially similar to the engine system to which the control device for an internal combustion engine of the first embodiment described above is applied, except for a point that will be described later. Consequently, according to the engine system to which the control device for an internal combustion engine of the third embodiment is applied, a substantially similar effect to the engine system to which the control device for an internal combustion engine of the first embodiment described above is applied can be provided, except for a point that will be described later. 
     In the engine system to which the control device for an internal combustion engine of the third embodiment is applied, an emission purifying catalyst temperature constraint under which the request injection amount (the fuel injection amount) (refer to  FIG. 1 ) does not increase even when the driver increases the accelerator opening degree Pa is used as the constraint in which the acceleration G does not increase even when the driver increases the accelerator opening degree Pa, and is inputted to the target acceleration increase amount calculating section  10   b  (refer to  FIG. 1 ). By setting the emission purifying catalyst temperature constraint, a possibility of emission being worsened as the temperature of an emission purifying catalyst (not illustrated) becomes a predetermined value or more can be restrained. 
     In the engine system to which the control device for an internal combustion engine of the third embodiment is applied, in step S 102  (refer to  FIG. 2 ), one of the three relations RL 1 , RL 2  and RL 3  illustrated in  FIG. 4  is selected based on the present operating state (the emission purifying catalyst temperature) and the constraint (the emission purifying catalyst temperature constraint). 
     More specifically, in the engine system to which the control device for an internal combustion engine of the third embodiment is applied, the relation RL 1  in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is large is selected in step S 102 , when the present operating state (the emission purifying catalyst temperature) is not close to the constraint (the emission purifying catalyst temperature constraint). 
     When the present operating state (the emission purifying catalyst temperature) is close to the constraint (the emission purifying catalyst temperature constraint), the relation RL 3  in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is small is selected in step S 102 . 
     When the present operating state (the emission purifying catalyst temperature) is relatively close to the constraint (the emission purifying catalyst temperature constraint) although the present operating state is not so close to the constraint as in the case where the relation RL 3  is selected, and the operating state (the emission purifying catalyst temperature) is likely to reach the constraint (the emission purifying catalyst temperature constraint) if the acceleration is quickly increased, the relation RL 2  is selected, in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is smaller than in the relation RL 1 . 
     In the engine system to which the control device for an internal combustion engine of the third embodiment is applied, the request injection amount (refer to  FIG. 6I ) can be gradually increased from the value Q 3  to the value Q 4  in the acceleration request time period (in the time period from the time t 11  to the time t 13  in  FIG. 6 ) by the driver by using the relation RL 3  (refer to  FIG. 4 ) in which the ratio of the target acceleration increase amount ΔG and the accelerator opening degree increase amount ΔPa is small, when the present operating state (the emission purifying catalyst temperature) is close to the constraint (the emission purifying catalyst temperature constraint), whereby the acceleration G (refer to  FIG. 6J ) can be gradually increased from the value G 3  to the value G 4 . 
     That is, in the engine system to which the control device for an internal combustion engine of the third embodiment is applied, in the acceleration request time period (the time period from the time t 11  to the time t 13  in  FIG. 6 ) by the driver, the acceleration G can be continuously increased without causing the operating state (the emission purifying catalyst temperature) to reach the constraint (the emission purifying catalyst temperature constraint). 
     That is, in the engine system to which the control device for an internal combustion engine of the third embodiment is applied, increase of the acceleration G that satisfies the acceleration request by the driver can be realized even when the present operating state (the emission purifying catalyst temperature at the time point of the time t 11  in  FIG. 6 ) is close to the constraint (the emission purifying catalyst temperature constraint). 
     Parameters that should be restrained to be less than predetermined values in a vehicle that is loaded with an engine system include NV (noise, and vibration). 
     In the engine system to which a control device for an internal combustion engine of a fourth embodiment is applied, as the constraint under which the acceleration G does not increase even when the driver increases the accelerator opening degree Pa, an NV constraint under which the request injection amount (the fuel injection amount) (refer to  FIG. 1 ) does not increase even when the driver increases the accelerator opening degree Pa is used. By setting the NV constraint, NV can be restrained from being a predetermined value or more. NV is calculated by using a transmission output shaft rotational speed, for example. 
     Parameters that should be restrained to be less than predetermined values in the engine system having the turbocharger  32  (refer to  FIG. 1 ) include a turbo rotational speed. 
     In an engine system to which a control device for an internal combustion engine of a fifth embodiment is applied, as the constraint under which the acceleration G does not increase even when the driver increases the accelerator opening degree Pa, a turbo rotational speed constraint under which the request injection amount (the fuel injection amount) (refer to  FIG. 1 ) does not increase even when the driver increases the accelerator opening degree Pa is used. By setting the turbo rotational speed constraint, a turbo rotational speed can be restrained from being a predetermined value or more. The turbo rotational speed is acquired by using a turbo rotational speed sensor (not illustrated), for example. 
     Parameters that should be restrained to be less than predetermined values in the engine system having the turbocharger  32  (refer to  FIG. 1 ) include a turbocharging pressure. 
     In an engine system to which a control device for an internal combustion engine of a sixth embodiment is applied, as the constraint under which the acceleration G does not increase even when the driver increases the accelerator opening degree Pa, a turbocharging pressure constraint under which the request injection amount (the fuel injection amount) (refer to  FIG. 1 ) does not increase even when the driver increases the accelerator opening degree Pa is used. By setting the turbocharging pressure constraint, the turbocharging pressure can be restrained from being a predetermined value or more. The turbocharging pressure is acquired by using a turbocharging pressure sensor (not illustrated), for example. 
     In an engine system to which a control device for an internal combustion engine of a seventh embodiment is applied, the constrains that are set in the engine systems to which the control devices for an internal combustion engine of the first to the sixth embodiments described above are applied also can be properly combined. 
     In an eighth embodiment, the first to the seventh embodiments and the respective examples described above also can be properly combined.