Patent Publication Number: US-9903305-B2

Title: Control device for internal combustion engine

Description:
TECHNICAL FIELD 
     The present invention relates to a control device for a cylinder direct-injection internal combustion engine, and for example, relates to a control device for driving a fuel injection valve. 
     Background Art 
     There has been known a conventional internal combustion engine control device where in one combustion cycle in the combustion chamber for an internal combustion engine, a fuel is injected from a fuel injection control device having a fuel injection valve electromagnetically driven to a combustion chamber at a given timing. Applications for a large number of techniques for stably controlling the behavior of a valve body equipped within the fuel injection valve have been filed. For example, there has been disclosed a technique for intermittently supplying a drive voltage so as to minimize an impulsive force when the valve body provided within the fuel injection valve is opened or closed (for example, refer to Patent Literature 1). 
     Incidentally, in the fuel injection control device for the cylinder direct-injection internal combustion engine, it is general that as a drive voltage of the fuel injection valve, a high voltage boosted to a given voltage on the basis of a battery voltage is applied to the fuel injection valve. This is intended to rapidly open a valve body of the fuel injection valve by applying a high voltage under a condition where the valve body equipped within the fuel injection valve is pushed in a valve closing direction with the aid of a high fuel pressure. 
     Also, in the technique of Patent Literature 1, there is disclosed that a voltage supply when driving the fuel injection valve is performed under time control. In the fuel injection control device for the cylinder direct-injection internal combustion engine, a drive current of a fuel injection valve is detected, and control is performed on the basis of the detected drive current. 
     CITATION LIST 
     
         
         Patent Literature 1: Japanese Translation of PCT International Application Publication No. 2002-514281 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     However, because of a device difference variation in a circuit for boosting the battery voltage or a drive circuit for the fuel injection valve, a real drive current may be varied, or because of a variation in a circuit for detecting the drive current, a difference is likely to occur between a target drive current that is a control target and a real drive current that is detected by the control device. 
     Also, when a so-called multi-stage injection that plural injections are performed in one combustion cycle is performed, from a relationship of injection intervals of the cylinders (injection intervals between a first injection and a second injection, and between the second injection and a third injection), or injection timing of a present injection cylinder and a next injection cylinder, a possibility that the next injection is performed in a state where overall injection intervals are adjacent to each other, and the high voltage applied from the booster circuit does not reach a target high voltage is high. This leads to a risk that a variation in the fuel injection amount occurs because the valve body behavior of the fuel injection valve is different each time. 
     The present invention has been made in view of the above problems, and an object of the present invention is to provide a control device for an internal combustion engine which is capable of stabilizing the behavior when opening a fuel injection valve which is attributable to a variation in a device difference such as a drive circuit for the fuel injection valve, and reducing a variation in the fuel injection amount. 
     Solution to Problem 
     In order to achieve the above object, according to the present invention, there is provided a control device for an internal combustion engine, including a battery that applies a battery voltage to the internal combustion engine; a fuel injection valve that injects a fuel directly into a combustion chamber; high voltage generation means for boosting the battery voltage to a target high voltage to generate a desired high voltage; high voltage detection means for detecting a real high voltage generated by the high voltage generation means; fuel injection valve drive means for applying any one of the real high voltage detected by the high voltage detection means, and the battery voltage to the fuel injection valve at a desired timing to drive the fuel injection valve; and drive current detection means for detecting a drive current of the fuel injection valve, in which the control device includes high voltage difference detection means for obtaining a difference between a predetermined reference voltage and the real high voltage detected by the high voltage detection means, drive current difference storage means for storing the amount of device difference variation of the real drive current detected by the drive current detection means in advance, and drive control value correction means for correcting at least one of a target value of the drive current to the fuel injection valve and a target value of a drive time, on the basis of at least one result of the drive current difference storage means. 
     Advantageous Effects of Invention 
     According to the present invention, even if the device difference variation of the circuit that drives the fuel injection valve occurs or the variation occurs in the high voltage to be applied to the fuel injection valve, the behavior of the valve body equipped in the fuel injection valve can be stably controlled, and the variation in the fuel injection amount of the fuel injection valve can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an overall configuration diagram of an internal combustion engine system using a control device for an internal combustion engine. 
         FIG. 2  is a configuration diagram of a fuel injection valve control device in  FIG. 1 . 
         FIG. 3  is a configuration diagram of fuel injection valve drive means in  FIG. 2 . 
         FIG. 4  is a block diagram illustrating a configuration of a control unit in  FIG. 2 . 
         FIG. 5  is a timing chart 1 illustrating one example of a method for correcting high voltage generation means. 
         FIG. 6  is a timing chart 2 illustrating another example of the method for correcting the high voltage generation means. 
         FIG. 7  is a block diagram illustrating an example of a drive current correcting method. 
         FIG. 8  is a timing chart of an example of the drive current correcting method. 
         FIG. 9  is a flowchart of the drive current correcting method. 
         FIG. 10  is a timing chart 1 related to a conventional fuel injection valve drive. 
         FIG. 11  is a timing chart 2 related to the conventional fuel injection valve drive. 
         FIG. 12  is a timing chart 3 related to the conventional fuel injection valve drive. 
         FIG. 13  is a timing chart 4 related to the conventional fuel injection valve drive. 
         FIG. 14  is a flowchart related to a high voltage variation correction according to the present invention. 
         FIG. 15  is a timing chart related to the drive of the fuel injection valve according to the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a description will be given of a fuel injection control device for an internal combustion engine according to an embodiment of the present invention.  FIG. 1  illustrates a basic configuration of an internal combustion engine and a fuel injection control device for the internal combustion engine according to this embodiment. 
     Referring to  FIG. 1 , an air to be sucked into an internal combustion engine  101  passes through an air flow meter (ARM: Air flow meter)  120 , is sucked into a throttle valve  119  and a collector  115  in the stated order, and thereafter supplied to a combustion chamber  121  formed in an upper portion of a piston  102  through an intake pipe  110  and an intake valve  103  provided in each of cylinders. 
     On the other hand, a fuel is fed to a high pressure fuel pump  125  provided in the internal combustion engine  101  from a fuel tank  123  by the aid of a low pressure fuel pump  124 , and the high pressure fuel pump  125  regulates a fuel pressure to a desired pressure on the basis of a control command value from an ECU (engine control unit)  100 . As a result, the high pressure fuel is fed to a fuel injection valve  105  through a high pressure fuel pipe  128 , and the fuel injection valve  105  injects the fuel into the combustion chamber  121  on the basis of a command from a fuel injection valve control device  200  provided in the ECU  100 . 
     In order to control the high pressure fuel pump  125 , the internal combustion engine  101  is equipped with a fuel pressure sensor  126  that measures a pressure within a high pressure fuel pipe  128 . The ECU  100  generally performs so-called feedback control on the basis of the sensor value so that the fuel pressure within the high pressure fuel pipe  128  becomes a desired pressure. Further, the internal combustion engine  101  includes an ignition coil  107  and an ignition plug  106 , and is structured so that an energization control to the ignition coil  107  and an ignition control by the ignition plug  106  are conducted at a desired timing by the ECU  100 . 
     With the above configuration, the intake air and fuel are combusted by spark emitted from the ignition plug  106 , and move down the piston  102  within the cylinder. An exhaust gas generated by the combustion is exhausted into an exhaust pipe  111  through an exhaust valve  104 , and a three-way catalyst  112  for purifying the exhaust gas is disposed on the exhaust pipe  111 . 
     The ECU  100  incorporates the fuel injection valve control  200  described above, and receives signals from a crank angle sensor  116  that measures a crank shaft (not shown) angle of the internal combustion engine  101 , the AFM  120  indicative of the amount of intake air, an oxygen sensor  113  that detects an oxygen concentration in the exhaust gas, an accelerator opening sensor  122  indicative of the opening of an accelerator operated by a driver, and the fuel pressure sensor  126 . 
     The signals input from the respective sensors will be further described. The ECU  100  calculates a required torque of the internal combustion engine  101 , and also determines whether to be in an idle state, or not, according to the signal from the accelerator opening sensor  122 . Also, the ECU  100  is equipped with rotational speed detection means for calculating a rotational speed (hereinafter referred to as “engine rotational speed”) of the internal combustion engine according to the signal from the crank angle sensor  116 , and means for determining whether the three-way catalyst  112  is in a warm-up state, or not, according to a cooling temperature of the internal combustion engine  101  which is obtained from a water temperature sensor  108 , and an elapsed time after the internal combustion engine starts. 
     Also, the ECU  100  calculates the amount of intake air necessary for the internal combustion engine  101 , and outputs an opening signal commensurate with the amount of intake air to the throttle valve  119 . The fuel injection valve control device  200  calculates the amount of fuel corresponding to the amount of intake air, outputs a fuel injection signal to the fuel injection valve  105 , and outputs an ignition signal to the ignition coil  107 . 
       FIG. 2  illustrates one example of a basic configuration of the fuel injection valve control device according to the present invention. In this figure, a voltage  150  (hereinafter referred to as “low voltage”) applied from the battery is applied to the fuel injection valve control device  200  through a fuse  151  and a relay  152 . 
     The fuel injection valve control device  200  will be described. A high voltage generator circuit  201  is a circuit that generates a high supply voltage (hereinafter referred to as “high voltage”) necessary when a valve body provided within the fuel injection valve  105  opens on the basis of the low voltage applied from a battery (not shown), and the high voltage is boosted to a desired voltage on the basis of a command from a drive IC  203 . Also, a fuel injection valve drive circuit (Hi)  202   a  is configured to select any one of the high voltage and the low voltage as the supply voltage to be applied to the fuel injection valve  105 . 
     When the fuel injection valve  105  is opened from a closed state, the high voltage is first applied to the fuel injection valve  105 , and after a valve opening current required when the valve body provided within the fuel injection valve opens is supplied thereto, the voltage to be applied is switched to the low voltage, and a holding current is supplied thereto in order to maintain the valve body within the fuel injection valve  105  in an valve opening state. A fuel injection valve drive circuit (Lo)  202   b  is a drive circuit disposed downstream of the fuel injection valve  105  in order to supply a drive current to the fuel injection valve  105  as with the fuel injection valve drive circuit (Hi)  202   a.    
     The high voltage generator circuit  201 , the fuel injection valve drive circuit (Hi)  202   a , and the fuel injection valve drive circuit (Lo)  202   b  are controlled by the drive IC  203 , and applies/supplies a desired drive voltage and drive current to the fuel injection valve  105 . Also, a drive period (energization time of the fuel injection valve  105 ), a drive voltage value, and a drive current of the drive IC  203  are controlled on the basis of command values calculated by a fuel injection valve pulse width calculation block  204   a  and a fuel injection valve drive waveform command block  204   b  provided in a drive control block  204  within the fuel injection valve control device  200 . With the above operation, the drive control and the amount of fuel injection of the fuel injection valve  105 , which are necessary for combustion of the internal combustion engine  101 , are optimally controlled. 
       FIG. 3  illustrates one example of the drive circuit of the fuel injection valve illustrated in  FIG. 2 . As described in  FIG. 2 , the fuel injection valve drive circuit (Hi)  202   a  that supplies the drive current in order to hold the opening and closing states of the fuel injection valve  105  is disposed upstream of the fuel injection valve  105 . A current is applied to the fuel injection valve  105  from the high voltage generator circuit  201  in the figure through a diode  302  provided for the purpose of preventing a reverse current flow with the use of a TR_Hivboost  303  with the high voltage. On the other hand, after the fuel injection valve has been opened, power is supplied to the fuel injection valve  105  from a low voltage power supply circuit  304  for allowing a low current (the holding current) necessary to maintain (hold) a fuel injection valve open state to flow through a diode  305  for preventing the reverse current flow with the use of a circuit of a TR_Hivb  306  in the figure, as with the high voltage. 
     Subsequently, the above-described fuel injection valve drive circuit (Lo)  202   b  is disposed downstream of the fuel injection valve  105 , and when a drive circuit TR_Low  308  turns on, a current supplied from the upstream high voltage generator circuit  201  or the low voltage power supply circuit  304  can be supplied to the fuel injection valve  105 . Also, a current consumed by the fuel injection valve  105  is detected by a shunt resistor  309  disposed downstream of the fuel injection valve  105  to perform a desired fuel injection valve current control which will be described later. 
       FIG. 4  illustrates an example of a block diagram of a control unit  400  that corrects a drive control value (drive current or drive time) of the fuel injection valve  105  according to the present invention. Referring to  FIG. 4 , a high voltage generated by the high voltage generator circuit  201  is applied to fuel injection valve drive means  411 , which means that a high voltage is applied to the drive IC  203  from the high voltage generator circuit  201  in  FIG. 2 . High voltage detection means  402  is provided for the purpose of detecting the high voltage generated by the high voltage generator circuit  201 . High voltage difference detection means  404  calculates a difference between the real high voltage detected by the high voltage detection means  402 , and a reference voltage  403  which will be described later, and delivers the difference to drive control value correction means  409 . 
     On the other hand, since a variation in the drive current to be supplied to the fuel injection valve  105  is a device difference variation caused by components configuring the fuel injection valve control device  200 , the drive current variation cannot be detected directly within the control unit  400 . For that reason, the amount of device difference variation of the fuel injection valve control device  200  is detected as a current difference value  405 , and stored in drive current difference storage means  406  in advance (indicated by a dashed line). The drive control value correction means  409  calculates the amount of correction of a target control value (target drive current or a target drive time) on the basis of a detection result of the high voltage difference detection means  404 , and a current difference value recorded in the drive current difference storage means  406 , and delivers the amount of correction to the fuel injection valve drive means  411 . It is needless to say that because the current difference value  405  is detected as plus or minus with respect to the reference current value, the drive control value correction means  409  performs a correction of an increase/decrease corresponding to the plus or minus. 
     The fuel injection valve drive means  411  performs a control so that a drive current to the fuel injection valve  105  becomes a desired profile on the basis of a basic control value  410  calculated by the drive control block ( 204  in  FIG. 2 ), and a drive current value of drive current detection means  403  for detecting a drive current of de fuel injection valve  105 . When information from the drive control value correction means  409  is updated, the fuel injection valve drive means  411  reflects the information on a basic control value  410 , and drives the fuel injection valve  105 . The drive current detection means  408  is generally performed by a method using the shunt resistor  309  in  FIG. 3 . 
     Subsequently, the high voltage difference detection means  404  within the control unit  400  in  FIG. 4  will be described in detail with reference to  FIGS. 5 and 6 .  FIG. 5  illustrates the characteristic when the high voltage generator circuit  201  boosts a battery voltage to a desired target voltage  504 . 
     The high voltage generator circuit  201  boosts a battery voltage  503  to the target high voltage  504  on the basis of a boost command  501  from the drive IC  203 . In the figure, the boost command starts the boost from a time T 507  when the boost command changes from low to high. In association with this operation, boosted voltages ( 502   a ,  502   b ,  502   c ) are gradually boosted to the target high voltages  504 . However, because the boost characteristics of the high voltage generator circuit  201  are varied, boosted voltage behaviors ( 502   a ,  502   b ,  502   c ) are boosted in respective different manners. Further, because the voltage value at a time T 508  when the boosting operation stops falls within a given range  506  sandwiching the target high voltage  504  from the device difference variation of the high voltage generator circuit  201 , the real high voltage has an upper limit value ( 505   a ) and a lower limit value ( 505   b ) with respect to the target high voltage  504 . For that reason, the high voltage difference detection means ( 404  in  FIG. 4 ) sets, for example, the target high voltage  504  as a reference voltage ( 403  in  FIG. 4 ), and detects a difference between the target high voltage  504 , and the real high voltages ( 502   a ,  502   b ,  502   c  subsequent to T 508 ) detected by the high voltage detection means ( 402  in  FIG. 4 ) 
     Also, when the above-mentioned multi-stage injection is conducted, it is assumed that the high voltage (hereinafter referred to as “Vboost”) generated by the high voltage generator circuit ( 201  in  FIG. 4 ) is supplied to the fuel injection valve from a state in which the voltage is remarkably lower than the target high voltage. The details will be described with reference to  FIG. 6 . 
       FIG. 6  illustrates one example of the Vboost behavior under a multi-stage injection control. Referring to  FIG. 6 , a Vboost supply command signal  601  to the fuel injection valve n changes from low to high in a period from T 606  to T 607 , and during this period, a Vboost  603  is supplied to the fuel injection valve n. For that reason, The Vboost  603  is reduced to  603   a , and thereafter again boosted to a target high voltage  605  by a series of boost operation illustrated in  FIG. 5 . In the figure, the boosting behavior is illustrated with the inclusion of a dashed line from  603   a  to  604 . 
     In the conventional injection control that does not perform the multi-stage injection, it is assumed that the Vboost  603  is not reduced during the boosting operation. However, when the multi-stage injection is performed, because the above-mentioned injection interval becomes shorter, the Vboost  603  is not always limited to the vicinity of the target high voltage  605 . 
     For example, as illustrated in the figure, if the Vboost supply command signal  602  to the fuel injection valve N+1 is high from T 608  to T 609 , the Vboost  603  is supplied to the fuel injection valve n+1 from the Vboost  603   b  at a time T 608  during the boosting operation, and is reduced to Vboost  603   c  at a time T 609 . In the series of operation, there arises such a problem that the Vboost  603  to be supplied to the fuel injection valve n+1 becomes  603   b  remarkably apart from the target high voltage  605 . 
     For that reason, the high voltage difference detection means  404  in  FIG. 4  sets a reference boost characteristic  604  of the high voltage generator circuit ( 201  in  FIG. 4 ) in advance, and predicts, for example, a voltage value  603   a  at a time T 607  when the supply of the Vboost  603  to the fuel injection valve n stops, and a voltage  603   b  at a time T 608  when the Vboost  603  starts to be supplied to the fuel injection valve n+1 on the basis of an elapsed time from T 607  to T 608 , and the reference boost characteristic. Then, the high voltage difference detection means  404  corrects a variation of Vboost  603 . As an example of the predicting method, there is a method in which a relational expression is used assuming that  603   a  is an intercept, and the reference boost characteristic is an inclination. 
     Subsequently, the drive current difference storage means  406  in  FIG. 4  will be described with reference to  FIGS. 7 and 8 .  FIG. 7  illustrates an example for detecting the drive current variation of the fuel injection valve. Referring to  FIG. 7 , the fuel injection valve control device  200  includes the fuel injection valve drive means  411  and the drive current detection means  408  which have been described above, and the fuel injection valve drive means  411  supplies a drive current  704  on the basis of plural target control values ( 705   a ,  705   b ,  705   c ) illustrated in reference numeral  705 , and a real drive current  707  detected by the drive current detection means  408 . Supplementally, the control system shows not a specific configuration, but an original drive configuration. Also, apart from the above control system, a current measuring instrument  703  that detects the drive current  704  to the fuel injection valve  105  is connected in a manner illustrated in the figure, and a current value detected by the current measuring instrument  703  becomes a measurement result  706 . 
     This is a method in which in the original control system, the drive current  704  is switched and controlled depending on whether the drive current  707  detected by the drive current detection means  408  reaches the target control values ( 705   a ,  705   b ,  705   c ), or not. Because a variation in the real drive current  707  generated from the device difference variation such as the drive current detection means  408  cannot be grasped by the control system, all of the manufactured fuel injection valve control devices are measured independently. In this measurement, the device difference variation of the fuel injection valve control device  200  including the drive current detection means  408  is detected by the current measuring instrument  703  which is independent from the control system, and always stabilizes a measurement precision. 
     The result measured by the above method is illustrated in  FIG. 8 .  FIG. 8  is a diagram schematically illustrating a result  706  measured by the method illustrated in  FIG. 7 . Also, in the figure, the results measured by the different fuel injection valve control devices  200  are illustrated in three typical forms as  801 ,  802 , and  803 , respectively. 
     First, the measurement results of  801  are control led without any error, for the respective target control values that change as Ip ( 804 ), Ih1 ( 805 ), and Ih2 ( 806 ). This means that because the drive current detection means  408  in  FIG. 7  has a standard characteristic, no correction is required. In other words, the fuel injection valve of reference numeral  801  has a characteristic having no error. 
     On the other hand, the respective measurement results of reference numeral  802  are represented by  804   a ,  805   a , and  806   a , and currents higher than the respective target control values  804 ,  805 , and  806  are obtained. This means that the current value detected by the drive current detection means  408  having the measurement results of reference numeral  802  is dispersed at a higher side. Also, the respective measurement results of reference numeral  803  are represented by  804   b ,  805   b , and  806   b , and currents lower than the respective target control values  804 ,  805 , and  806  are obtained, and the current values are dispersed at a lower side. 
     From the above results, there is a risk that the drive currents  801 ,  802 , and  803  to the fuel injection valve  105  have different profiles from the device difference variation of the drive current detection means  408  in  FIG. 70 , and the behavior of the fuel injection valve  105  is dispersed. For that reason, in the present invention, the drive current variation is measured for each of the fuel injection valve control devices  200  (specifically, ECUs  100 ), and stored in the respective ECUs  100  to correct the drive current variation. 
     In detail, for example, differences between the original Ip ( 804 ) and the measurement results ( 804   a ,  804   b ) are measured in advance, through a procedure illustrated in  FIG. 9 . That is, the real drive current of the fuel injection valve  105  is measured (S 901 ), current difference values between the target control value Ip ( 403 ) as a reference value, and the measured real drive current values ( 804   a ,  804   b ) are calculated (S 902 ), and the results are written in the drive current difference storage means  406  (S 903 ). The fuel injection valve control device  200  corrects a target control value  804  of the fuel injection valve  105  on the basis of the current difference values written into the drive current difference storage means  406 . 
     Specifically, if the measurement result is higher than the reference value  804 , that is, in the ECU  100  where the measurement result is represented by reference numeral  804   a , the target current  804  of Ip is corrected to be lower by a difference therebetween. On the contrary, if the measurement result is lower than the reference value  804 , that is, in the ECU  100  where the measurement result is represented by reference numeral  804   b , the target current  804  of Ip is corrected to be higher by a difference therebetween. The target drive currents of Ih1 ( 805 ) and Ih2 ( 806 ) are subjected to the same procedure, thereby being capable of correcting the variation in the drive current. That is, the drive control value correction means  409  includes the current difference values set in the drive current difference storage means  406  in advance, and if the current difference value is higher than the reference voltage  403 , a target value of the drive current to the fuel injection valve  105  is corrected to be lower by a current difference value set in the drive current difference storage means  406  in advance. Alternatively, the target value of the drive time is corrected to be shorter. Also, if the current difference value set in the drive current difference storage means  406  in advance is lower than the reference voltage  403 , the target value of the drive current to the fuel injection valve  105  is corrected to be higher by the current difference value set in the drive current difference storage means  406  in advance, or the target value of the drive time is corrected to be longer. 
     Subsequently, the basic control operation of the fuel injection valve  105  will be described with reference to  FIG. 10 .  FIG. 10  illustrates one example showing the drive current when the drive time of the fuel injection valve  105  is relatively short. That is, this means that a time since the fuel injection on valve  105  is opened until the fuel injection valve  105  is closed is short. The basic control operation of the fuel injection valve  105  will be described. The supply of the drive current to the fuel injection valve starts from a time T 1006  when a drive pulse signal  1001  changes from low to high. In this situation, the target control value is so determined as to obtain a desired drive current profile. In this figure, the control is conducted according to whether the real drive current reaches the target control value, or not. 
     In detail, first, the current Ip ( 1002   a ) required to open the valve body installed within the fuel injection valve is set as a target current, and on the basis of the above operation, the drive current  1002  is supplied to the fuel injection valve  105 . As a result, when the drive current  1002  gradually increases, and soon reaches Ip ( 1002   a ), the target current is switched to the lh1 ( 403   b ), and control is made so that the drive current  1002  is attenuated to this value. In the configuration of this figure, because the drive pulse signal  1001  changes from high to low before a drive current  1002  reaches lh1 ( 1002   b ), a current supply to the fuel injection valve  105  from T 1007  stops. 
     This figure illustrates a case in which the drive time of the fuel injection valve  105  is relatively short. The original drive current  1002  is to be controlled to obtain a profile represented in  FIG. 8 . However, because the drive time of the fuel injection valve  105  is short, the operation of the fuel injection valve  105  stops without the use of the subsequent target control values (lh1 ( 805 ) and Lh2 ( 806 ). From this fact, the drive time of the fuel injection valve  105  is relatively short. Hence, it is needless to say that if the drive pulse signal  1002  is longer than that in this figure, even if the drive current reaches Ih1 ( 1002   b ), the control is executed according to a given target control value (Ih2 ( 806 )). 
     Subsequently, the valve body behavior provided within the fuel injection valve according to this control will be described. A valve body behavior  1003  is roughly classified into three states including starting valve opening operation  1005   a  on the basis of a drive current  1002  from T 1006 , thereafter a valve open holding state  1005   b , and valve closing operation  1005   c  from T 1007  when the supply of the drive current stops. 
     If the drive pulse signal  1001  is relatively long, a period of the valve open holding state  1005   b , but the valve opening operation  1005   a  and the valve open holding state  1005   b  are hardly changed. Therefore, since the amount of fuel injection injected from the fuel injection valve  105  is governed by a temporal length of the valve opening holding state, the amount of fuel injection is hardly affected by the valve opening operation  1005   a  and  1005   c  of the valve body. However, as with this configuration, if the drive pulse signal  1001  is shorter, the period  1005   b  during which the valve body is completely opened is short, a rate of the periods  1005   a  and  1005   c  during which the valve body is opened or closed is large. For that reason, the amount of fuel injection is extremely largely affected by the opening and closing behaviors ( 1005   a ,  1005   c ) of the valve body. 
     Also, the valve opening and closing behaviors ( 1005   a ,  1005   c ) are different every time the fuel injection valve  105  is driven due to the variation of the drive current  1002 . As a typical example, as illustrated in reference numeral  1004  in the figure, there is a bouncing that becomes unstable in the valve behavior by allowing the valve body to vigorously collide with a stopper in opening the valve body, and there arises a problem that the amount of fuel injection is different depending on the presence/absence of the bouncing, or the degree of bouncing. From the above facts, if the drive pulse signal  1001  is shorter, there is required that the fuel injection valve  105  is controlled with high precision, and the valve opening/closing behaviors ( 1005   a ,  1005   c ) of the valve body are stabilized every times. 
     Subsequently, a description will be given of a method of driving the fuel injection valve  105  which reduces the bouncing described above with reference to  FIG. 11 . In  FIG. 11 , a current switching signal Ihold 1  ( 1102 ) is added to a drive pulse signal  1101 . The drive pulse signal  1101  is a signal described above, and the Ihold 1  ( 1102 ) is a signal generated on the basis of the calculation result calculated by the fuel injection valve drive waveform command block  204   b  in  FIG. 2 . In the case of high level, the supply voltage to be applied to the fuel injection valve  105  is set as the high voltage generated by the high voltage generator circuit  201 , and in the case of low level, the supply voltage is set as the low voltage (battery voltage). 
     For convenience of description, in this drawing, a configuration in which the Ihold 1  ( 1102 ) is output directly to the fuel injection valve drive IC ( 203  in  FIG. 2 ) from the drive control unit ( 204  in  FIG. 2 ) will be described. The problem and advantages of the present invention are not limited to the above configuration, but likewise applied to, for example, a configuration in which information is transmitted on an annual basis by a serial communication when information related to the drive waveform calculated in the block  204   b  in  FIG. 2  is output to the fuel injection valve drive IC  203 . 
     A drive control method for the fuel injection valve  105  illustrated in  FIG. 11  will be described. A drive current  1103  is supplied to the fuel injection valve  105  from a time (T 1105 ) when both of the drive pulse signal  1101  and the above-mentioned Ihold 1  ( 1102 ) become high, on the basis of the drive pulse signal  1101  and the Ihold 1  ( 1102 ). With this operation, the drive current  1103  starts to gradually increase from T 1106  when a given period is elapsed from T 1105 , and reaches Ip ( 1103   a ) (T 1107 ). 
     In this situation, the fuel injection valve control device  200  switches the Ihold 1  ( 1102 ) from high to low, and cuts off the supply of the drive current  1103  while stopping the supply of the high voltage. For that reason, the drive current  1103  is decreased to a desired current ( 1103   b ). In this configuration, the desired current  1103   b  needs to be optimized according to the valve body characteristic or a fuel pressure of the fuel injection valve  105 , but for description, OA is assumed. Also, the desired current  1103   b  may be controlled according to an elapsed time from a T 1107  that reaches Ip ( 1003   a ). 
     When the drive current  1103  reaches the desired current  1103   b , the fuel injection valve control device  200  switches a next target control value to the Ih1 ( 1103   c ), and again starts the supply of the drive current  1103  to the fuel injection valve  105  (T 1108 ). As a result, the drive current  1103  increases to the vicinity of Ih1 ( 1103   b ) of the target current, and holds Ih1 till T 1109  when the drive pulse signal changes from high to low. 
     In the description of  FIG. 11 , a series of description has been made with the target control value as the drive current. Alternatively, the target control value may be set as the drive time. For example, a time from T 1105  when the drive current is supplied to the fuel injection valve  105  till T 1107  after a given time is elapsed from T 1105  may be dealt with as the target control value, the drive current  1102  may be cut off, and Ip ( 1103   a ) may be used instead. It is needless to say that in this method, Ih1 ( 1103   c ) is also replaced as the drive time from T 1108  to T 1109 . 
     Subsequently, a description will be given of the valve body behavior provided in the fuel injection valve according to the method of driving the fuel injection valve  105 . In the opening behavior of the valve body, the drive current  1103  is supplied from a time (T 1105 ) when the drive pulse signal  1101  becomes high, and the valve opening operation gradually starts after a given time is elapsed (T 1106 ). Thereafter, since the Ihold 1  ( 1102 ) becomes high, the drive current  1103  continues to be supplied to the fuel injection valve  105  by the above-mentioned high voltage. Therefore, the valve body moves in the valve opening direction while being accelerated. 
     Thereafter, since the Ihold 1  ( 1102 ) becomes low, and the supply of the drive current  1103  to the fuel injection valve  105  stops at T 1107  when the drive current reaches Ip ( 1103   a ), the valve opening operation is conducted by only an inertial force. Therefore, the acceleration of the valve body is reduced ( 1111 ) into a soft ending state. As a result, the valve body is suppressed to vigorously collide with the stopper, and secondary injection associated with bouncing can be suppressed. 
     Thereafter, the valve body is completed opened from a soft landing behavior (T 1108 ), and this state is held till T 1109  when the drive pulse signal  1101  changes from high to low. Thereafter the drive pulse signal  1101  becomes low at T 1109 , and the supply of the drive current  1103  stops, and therefore the valve opening behavior is performed at T 1110  as a start point. 
     When the control according to this embodiment is conducted, as compared with the conventional control (control where the multi-stage injection is not conducted), there is a need to drive the fuel injection valve  105  with high precision. In detail, when the soft landing is performed, there is a need to reduce the variation of the valve body behavior caused by at least disturbance. 
     Specifically, the device difference variation in the high voltage generator circuit  201 , and the drive circuits  202   a , and  202   b  in  FIG. 2 , or the shunt resistor  309  provided to detect the drive current of the fuel injection valve  105  in  FIG. 3  corresponds to the disturbance. That is, when those device difference variation occurs, a profile (a variation in she real drive current to she target current) is largely affected by the device difference variation, and due to this influence, the valve body behavior of the fuel injection valve  105  is also varied. For that reason, it is desirable to detect those device difference variations, and reflect the variations to the target control value of the drive current  1103 . For that reason, in the present invention, a variety of correction means described in  FIGS. 4 to 9  is provided. 
     The advantages obtained by correction of the high voltage according to the present invention will be described with reference to  FIGS. 12 to 15 .  FIG. 12  illustrates one example of a timing chart when the target control value of the fuel injection valve  105  is set as the drive time. From above in the figure, Vboost ( 1201   a ,  1201   b ,  1201   c ), drive currents ( 1202   a ,  1202   b ,  1202   c ) of the fuel injection valve  105 , and the valve body behaviors ( 1203   a ,  1203   b ,  1203   c ) provided in the fuel injection valve are illustrated. Alphabets attached to the respective ends thereof represent results of driving the fuel injection valve  105  in the different ECUs  100  (fuel injection valve control devices  200 ). 
     For convenience of description, it is assumed that the behaviors when the fuel injection valve  105  is driven by the ECU  100  having the high voltage generator circuit  201  with the standard (no variation) boost characteristics are  1201   a  (Vboost),  1202   a  (drive current), and  1203   a  (valve body behaviors). 
     First, the respective Vboost ( 120   a ,  1201   b ,  1201   c ) before a time (T 1205 ) when the drive of the fuel injection valve  105  starts represent difference voltages, and it is found that the variation occurs. This is attributable to the differences of the boost characteristics of the high voltage generator circuit  201  described with reference to  FIG. 5 , or an influence caused by the above-mentioned injection intervals. 
     Thereafter, in order that the drive of the fuel injection valve  105  starts from T 1205 , the respective Vboost ( 1201   a ,  1201   b ,  1201   c ) start to drop. Because the drive currents ( 1202   a ,  1202   b ,  1202   c ) are determined according to the Vboost ( 1201 ,  1201   b ,  1201   c ) at the time T 1205 , the drive currents start to increase with respective different current profiles, and on the basis of those profiles, descending behaviors of the Vboost ( 1201   a ,  1201   b ,  1201   c ) are also varied. 
     Also, because this control has a sequence of stopping the drive currents ( 1202   a ,  1202   b ,  1202   c ) of the fuel injection valve  105  at T 1206  when a given time is elapsed with T 1205  as a start point once, the respective drive currents ( 1204   a ,  1204   b ,  1204   c ) at the time T 1206  are different in value from each other. 
     In an ideal valve body behavior ( 1203   a ), because the drive current is cut off at an appropriate timing, soft landing can be performed. However, in the  1202   b  having the characteristic of the drive current lower than the ideal drive current ( 1202   a ), because the current is cut off before the valve body collides with the stopper, there is a risk that the valve body cannot be completely opened as in  1203   b.    
     On the other hand, in the  1202   c  having the characteristics of the drive current higher than the ideal drive current ( 1202   a ), because of a timing when the drive current ( 1202   c ) is cut off after the valve body has already collided with the stopper, bouncing is conducted as illustrated by  1203   c , and the advantages of the soft landing cannot be obtained. In this way, if the soft landing cannot be implemented at an appropriate timing, the advantages cannot be obtained. As a result, there is a need to correct a drive condition for converging the variation of the Vboost ( 1201   a ,  1201   h ,  1201   c ). 
     Subsequently, a case in which the target control value of the fuel injection valve  105  is set as the drive current will be described with reference to  FIG. 13 . In  FIG. 13 , it is assumed that the drive of the fuel injection valve  105  is also implemented by the respective ECUs  100  (fuel injection valve control devices  200 ) having the device difference variation of the high voltage generator circuit  201  in  FIG. 2 , and the respective behaviors caused by the ECU  100  provided with the high voltage generator circuit  201  having the ideal boost characteristics are set as  1301   a  (Vboost),  1302   a  (drive current), and  1303   a  (valve body behavior). 
     First, before a time (T 1305 ) when the drive of the fuel injection valve  105  starts (T 1305 ), Vboost ( 1301   a ,  1301   b ,  1301   c ) represent respective different voltages due to the device difference variation of the high voltage generator circuit  201  in  FIG. 2 , and it is found that the variation occurs. Thereafter, the drive current is supplied to the fuel injection valve  105  until drive currents ( 1302   a ,  1302   b ,  1302   c ) become Ip ( 1304 ). However, the drive current profiles are different ( 1302   a ,  1302   b ,  1302   c ) according to the supply Vboost ( 1301   a ,  1301   b ,  1301   c ) depending on the device difference variation of the above-described high voltage generator circuit  201 . 
     For example, the drive current ( 1302   b ) in the ECU  100  of the Vboost ( 1301   b ) lower than the Vboost ( 1301   a ,  1301   b ,  1301   c ) of the ECU  100  having the ideal boost characteristic is gentler in the rising of the drive drive current ( 1302   c ) in the ECU  100  of the Vboost ( 1301   c ) higher than the Vboost ( 1301   a ) of the ECU  100  having the ideal boost characteristic is quicker in the rising than the ideal drive current ( 1302   a ). For that reason, the valve body behaviors within the fuel injection valve are also affected, and different as indicated by  1303   a ,  1303   b , and  1303   c.    
     As a result, the original valve body behavior is to cut off the current immediately before the valve body collides with the stopper as indicated by  1303   a , but in the  1303   b  lower in the drive current, a response of the valve body is slow. On the other hand, because  1303   c  is higher in the drive current, the valve body collides with the stopper before reaching Ip ( 1304 ), and bouncing occurs. Because the soft landing is performed as described above, even if the stop condition of the drive current is set as Ip ( 1304 ), or the drive time (from T 1305  to T 1308 ), because the ideal valve body behavior is varied, there is a need to correct the variation. 
     Also, it is needless to say that the condition of again supplying the drive current to the fuel injection valve  105  also suffers from the same problem in both of  FIGS. 2 and 3 . That is, when the soft landing of the fuel injection valve  105  is conducted, there is a need to correct the target control value according to the device difference variation of the ECU  100 . 
     Under the circumstances, the present invention is characterized in that the target control value (target current or target drive time) is corrected on the basis of those variations. An embodiment of the present invention will be described with reference to  FIGS. 14 and 15 .  FIG. 14  is a flowchart of the fuel injection valve control device  200  according to the present invention. 
     In order to solve the above problem, it is first determined whether it is a timing for determining the high voltage, or not, in S 1401 . In this embodiment, it is assumed what the determination is conducted by an annual processing, and this condition is determined every 10 ms. (Really, it is desirable that the determination is performed just before the drive start timing of the fuel injection valve  105 .) If the condition in S 1401  is not met, the flow proceeds to Step of S 1405 . If the condition is met, the flow proceeds to S 1402 , and the real high voltage is detected by the high voltage detection means  402  in  FIG. 4 . The real high voltage means the real high voltage really detected as compared with the target high voltage to be generated by the high voltage generation unit. 
     In S 1403 , a difference between the real high voltage (real high voltage) detected in S 1402  and the reference value (in this example, the target high voltage) of the high voltage is detected. This step corresponds to the contents described in  FIGS. 5 and 6 . Thereafter, in S 1404 , the target control value (target current or the target drive time) of the fuel injection valve  105  is corrected according to the difference calculated in S 1403 . For example, if the target control value is set as the drive current as in  FIG. 13 , a relation of the voltage and the resistance may be used as an expression from the resistor of the fuel injection valve  105  to correct the current value. After the current correction amount for each of the differences is set in advance, the correction value may be referred to. Further, in the embodiment of  FIG. 12 , the advantages of the present invention can be obtained by applying the latter for correction. Therefore, in S 1405 , the drive of the fuel injection valve  105  is implemented, and the current control is executed, which corresponds to the contents described in the fuel injection valve drive means  411  in  FIG. 4 . 
     The above control will be described with reference to a timing chart of  FIG. 15 . In this drawings, it is assumed that the respective behaviors when the ECU  100  having the ideal characteristic without the need of correcting the target control value are  1501   a  (Vboost),  1502   a  (drive current), and  1503   a  (valve body behavior). 
     It is determined whether a condition of S 1401  in  FIG. 14  is met, or not, before the fuel injection valve  105  is driven (before T 1505 ). If the condition is met, values of the Vboost ( 1501   a ,  1501   b ,  1501   c ) are detected according to a step S 1402 , and the flow proceeds to a difference detection step of S 1403 . In S 1403 , a difference between the Vboost ( 1501   a ) of the reference voltage (target high voltage in this example), and  1501   b  or  1501   c  is detected, and the target control value (target current or target drive time) is corrected on the basis of the difference in S 1404 . 
     As a result, for example, if the target control value is the drive current, Ip that is a first target control value becomes  1504   a  ideally (when no correction is required). If the real drive current is lower than  1504   a  as the above correction, the drive current is corrected to be higher to increase the drive current ( 1504   b ). If the real drive current is higher than  1504   a , the drive current is corrected to be lower to decrease the drive current, to thereby provide  1504   c.    
     Also, even if the target control value is the drive time, the first target drive time is T 1507  ideally (if no correction is required). The shortage of the drive time, or the extension of the drive time is corrected by the above correction, to thereby provide T 1506  (reduction correction of the drive time) or T 1508  (extension correction of the drive time). As a result, the behavior when the valve body of the fuel injection valve  105  is opened which is attributable to the device difference variation such as the drive circuit of the fuel injection valve  105  is stabilized, thereby being capable of reducing the variation in the amount of fuel injection of the fuel injection valve  105 . 
     Also, it is needless to say that if the drive current in  FIGS. 7 and 8  is corrected at the same time, the fuel injection value is controlled with higher precision. As a result, the valve body behaviors also conduct the soft landing at an ideal timing, the bouncing can be reduced, and the fuel injection control suppressing the variation in the amount of fuel injection can be conducted. 
     In conducting the soft landing, since a target control value when the drive current is again supplied to the fuel injection valve  105  also requires the above correction, a control corresponding to this correction is performed. With those corrections, the target control values of the drive currents ( 1504   a ,  1504   b ,  1504   c ) or the drive times (T 1506 , T 1507 , T 1508 ) are made variable for each of the ECUs  100 , thereby stabilizing the opening behavior of the fuel injection valve  105 , and improving the linearity of a low flow rate range. 
     The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, but can be variously changed in design without departing from the spirit of the present invention described in the patent claims. For example, in the above-mentioned embodiments, in order to easily understand the present invention, the specific configurations are described. However, the present invention does not always provide all of the configurations described above. Also, a part of one configuration example can be replaced with another configuration example, and the configuration of one embodiment can be added with the configuration of another embodiment. Also, in a part of the respective configuration examples, another configuration can be added, deleted, or replaced. 
     Also, the control lines and the information lines necessary for description are illustrated, and all of the control lines and the information lines necessary for products are not illustrated. In fact, it may be conceivable that most of the configurations are connected to each other. In the above embodiments, the example in which both of the target control value (drive current or drive time) to the fuel injection valve  105  on the basis of at least one result of the high voltage difference detection means  404  and the drive current difference storage means  406  has been described, but only one of them may be corrected. 
     LIST OF REFERENCE SIGNS 
     
         
           100  . . . ECU 
           101  . . . internal combustion engine 
           105  . . . fuel injection valve 
           200  . . . control device (fuel injection valve control device) 
           201  . . . high voltage generator circuit (high voltage generation means) 
           400  . . . control unit 
           402  . . . high voltage detection means 
           403  . . . reference voltage 
           404  . . . high voltage difference detection means 
           405  . . . current difference value 
           406  . . . drive current difference storage means 
           408  . . . drive current detection means 
           409  . . . drive control value correction means 
           411  . . . fuel injection valve drive means 
           1501   a  . . . high voltage behavior by ECU of reference characteristics 
           1501   b  . . . high voltage behavior corrected by drive time extension or drive current increase of target control value 
           1501   c  . . . high voltage behavior corrected by drive time reduction or drive current decrease of target control value 
           1502   a  . . . fuel injection valve drive current by ECU of reference characteristics 
           1502   b  . . . fuel injection valve drive current corrected by drive time extension or drive current increase of target control value 
           1502   c  . . . fuel injection valve drive current corrected by drive time reduction or drive current decrease of target control value 
           1503   a  . . . valve body behavior by ECU of reference characteristics 
           1503   b  . . . valve body behavior corrected by drive time extension or drive current increase of target control value 
           1503   c  . . . valve body behavior corrected by drive time reduction or drive current decrease of target control value 
           1504   b  . . . target control value (current) corrected by drive time extension or drive current increase of target control value 
           1504   c  . . . target control value (current) corrected by drive time reduction or drive current decrease of target control value 
         T 1505  . . . fuel injection valve drive start timing 
         T 1506  . . . target control value (drive time) corrected by drive time reduction or drive current decrease of target control value 
         T 1507  . . . target control value (drive time) by ECU of reference characteristics 
         T 1508  . . . target control value (drive time) corrected by drive time extension or drive current increase of target control value