Patent Publication Number: US-9410497-B2

Title: Electrical control unit

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is based on and claims the benefit of priority of Japanese Patent Application No. 2013-098730, filed on May 8, 2013, the disclosure of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure generally relates to an electrical control unit (ECU) for controlling an operation of a fuel injection device. 
     BACKGROUND 
     A Japanese patent document 1 (i.e., Japanese Patent Laid-Open No. 2011-247185) discloses a fuel injection control device for controlling each of the injectors installed in the cylinders of an internal-combustion engine. The fuel injection control device has a capacitor which supplies a high voltage to an electromagnetic valve and a booster circuit which boosts the battery voltage and charges a capacitor. Further, the fuel injection control device has a discharge switch that is installed in an electric current path which electrically connects the capacitor and the electromagnetic valve. The discharge switch is implemented as a MOSFET. The booster circuit has a first electric current path which connects the battery and the capacitor, and a second electric current path which branches from the first electric current path to lead to a ground. The first electric current path has a booster coil, and the second electric current path has a booster switching element. By switching the booster switching element ON and OFF, the battery voltage is boosted by the booster coil, and the boosted voltage is applied to the capacitor, and the capacitor is charged by the boosted voltage. The boosted voltage or a high voltage charged in the capacitor is applied to the electromagnetic valve of the injector by the turning ON of the discharge switch. Thereby, the electromagnetic valve opens and injection of the fuel is started. After the fuel injection is started, the battery voltage is applied to the electromagnetic valve at a predetermined apply timing (i.e., not from the capacitor but from the other path), for maintaining an open state of the electromagnetic valve and for continuing the fuel injection. Then, after the stoppage of the application of the battery voltage, the electromagnetic valve is closed and the fuel injection is stopped. 
     In the fuel injection control device disclosed in the patent document 1, in case that a circuit element provided in the electric current path that connects the ground and a boosted voltage path, which is a path for applying the boosted battery voltage to the electromagnetic valve, is short-circuited, an output voltage from the boosted voltage path to the electromagnetic valve becomes substantially the same as a ground voltage. The circuit element in the above case may be, for example, the capacitor of the fuel injection control device or the switching element in the patent document 1. As a result, even when an ON signal is input to the gate of MOSFET which is a discharge switch for the valve opening, MOSFET will not be turned ON and the voltage from the boosted voltage path will not be applied to the electromagnetic valve. In such case, at the predetermined apply timing, the battery voltage is applied from the other path and the electromagnetic valve starts to open at such timing. Therefore, in comparison to a non-short-circuited case, the start of the valve opening is delayed, thereby delaying the start of the fuel injection, which may result in that a preset amount of fuel cannot be injected within a predetermined period. 
     SUMMARY 
     It is an object of the present disclosure to provide an electrical control unit which prevents a delay of a fuel injection start timing, which may be observed in an above-mentioned situation. 
     In an aspect of the present disclosure, an electrical control unit for controlling an operation of a fuel injector includes a constant voltage supply unit supplying a preset voltage to the fuel injector, a boosted voltage supply unit supplying, to the fuel injector, a boosted voltage that is higher than the preset voltage, and a control unit controlling a supply timing of the constant voltage supply unit and a supply timing of the boosted voltage supply unit. The boosted voltage supply unit includes a booster circuit having an input of a power supply voltage, generating the boosted voltage by boosting the power supply voltage, and outputting the boosted voltage, and a discharge unit electrically connecting the booster circuit and the fuel injector when turned ON, and electrically interrupting the booster circuit and the fuel injector when turned OFF. The booster circuit includes a coil disposed in a first current path to which the power supply voltage is input on one end of the coil and from which the boosted voltage is output, a switching element (i) disposed in a second current path that leads from an other end of the coil to a reference voltage that is lower than the power supply voltage and (ii) supplying electric current to the coil when turned ON, a capacitor (i) disposed in a third current path that leads from a junction of the first current path and the second current path and leads to the reference voltage and (ii) charged by a counter electromotive force that is generated in the coil due to the turning ON and OFF of the switching element, and an interrupter (i) disposed in at least one of the second current path or the third current path, (ii) connected in series with the switching element or the capacitor, and (iii) interrupting electric current flowing through the interrupter when the switching element or the capacitor is short-circuited. The control unit includes a detector detecting whether the interrupter is interrupted, and at a fuel injection start time of the fuel injector, the control unit controls the discharge unit and the constant voltage supply unit to (i) supply the boosted voltage to start the fuel injection, (ii) supply the preset voltage to continue the fuel injection when the detector detects that the interrupter is not interrupted, and (iii) advance an interrupted power supply start timing relative to a non-interrupted power supply start timing when the detector detects that the interrupter is interrupted. 
     Thus, according to the present disclosure, when the switching element or the capacitor which is connected in series to the interrupter becomes short-circuited, the interrupter interrupts the electric current flowing in the second or the third current path in which the short-circuited switching element or capacitor is disposed. That is, the first current path is not short-circuited to the reference voltage. Therefore, the booster circuit is enabled to output a voltage that is higher than a voltage at a “first-current-path short-circuited” time (i.e., when the first current path is short-circuited to the reference voltage). 
     Here, when the switching element or the capacitor is short-circuited, the booster circuit will lose a booster function which raises the battery voltage, and the output voltage of the booster circuit becomes lower than the boosted voltage. Therefore, when the interrupter is interrupted, an applied voltage that is applied to the fuel injector becomes lower than the boosted voltage that is applied thereto when not short-circuited, and a time from a voltage application to the start of the fuel injection becomes longer. Therefore, in the conventional configuration, the fuel injection start timing is delayed. 
     In contrast, in the present disclosure, the detector detects whether the interrupter is interrupted. When an interruption of the interrupter is detected, the control unit controls the discharge unit and the constant voltage supply unit advances an Interrupted power supply start timing (i.e., to an earlier timing) relative a non-interrupted power supply start timing (i.e., a power supply start timing when short-circuiting has not occurred). 
     In the above, reference numbers are used to show an example correspondence between the description and the configuration in the embodiment that is mentioned later, for the ease of understanding of the present disclosure. However, what is meant by such reference numbers is not restricting/limiting the range of the present disclosure at all. Further, the features of the present disclosure other than the ones mentioned above will become apparent from the explanation and accompanying drawings of the embodiment described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Objects, features, and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings, in which: 
         FIG. 1  is an illustration of a configuration of an electrical control unit (ECU) in a first embodiment of the present disclosure and an internal-combustion engine to which the ECU is applied; 
         FIG. 2  is a block diagram of the ECU in  FIG. 1 ; 
         FIG. 3  is a flowchart of a process performed by the ECU in  FIG. 1 ; 
         FIG. 4  is a time chart of an operation of each of the components at a normal operation time of the ECU in  FIG. 1 ; 
         FIG. 5  is a time chart of an operation of each of the components at a short-circuit problem time of the ECU in  FIG. 1 ; and 
         FIG. 6  is a time chart of an operation of each of the components when the ECU in  FIG. 1  is applied to a four-cylinder internal-combustion engine. 
     
    
    
     DETAILED DESCRIPTION 
     Hereafter, an embodiment of the invention is described based on the drawing. 
     First Embodiment 
     First, the whole picture of an electrical control unit (ECU)  100  concerning the present embodiment and the internal-combustion engine  500  to which the ECU  100  is applied is explained. As shown in  FIG. 1 , the ECU  100  is a device which controls the fuel injection of an injector  502  which injects fuel directly into a combustion chamber  501  of each of the plural cylinders of the internal-combustion engine  500 . The injector  502  is equivalent to a fuel injector in the claims. 
     The fuel stored in a fuel tank  601  is supplied to the injector  502  via a low pressure fuel pump  602  and a high pressure fuel pump  603 . The fuel stored in the fuel tank  601  is specifically supplied to a high pressure fuel pump  603  in a low pressure by the low pressure fuel pump  602 , and the high pressure fuel pump  603  receiving the low pressure fuel raises the low fuel pressure to a high fuel pressure, for supplying it to the injector  502 . The injector  502  injects the supplied fuel directly into the combustion chamber  501  according to the voltage applied from the ECU  100 . 
     The outputs of a cam angle sensor  503  and a crank angle sensor  504  provided in the internal-combustion engine  500  are input into the ECU  100 , and, based on such outputs, the ECU  100  detects a fuel injection timing, and applies a voltage to the injector  502 . Then, by such application of a certain voltage, the fuel is injected from the injector  502 . To the ECU  100 , a battery voltage VB is supplied from a battery  505 . 
     In  FIG. 1 , although only one cylinder is shown, the injector  502  is provided for every cylinder, and the ECU  100  applies a voltage to each of four cylinders, in case that the internal-combustion engine  500  is a 4-cylinder engine, for example. 
     Although the ECU  100  is described as controlling the injector  502  in one of plural cylinders in the following description, the same applies to the controlling of the injector  502  in each of two or more cylinders respectively. 
     Based on  FIG. 2 , the ECU  100  which controls the injector  502  concerning the present embodiment are described. 
     The injector  502  has an electromagnetic valve and a magnet coil  502   a  which opens and closes the electromagnetic valve. A voltage is applied to the magnet coil  502   a  of the injector  502  from the ECU  100 . By supplying an electric power to the magnet coil  502   a , a valve body, which is not illustrated, moves to a valve opening position, and a fuel injection is performed. Then, when a power supply to the magnet coil  502   a  is interrupted, the valve body returns to an original valve closing position, and the fuel injection is stopped. 
     The ECU  100  has a +B terminal to which a battery voltage VB is applied, and has a constant current path Ll which electrically connects the +B terminal and an upstream side terminal of the injector  502 . A constant current switch  11  is disposed in the constant current path Ll (Ll: L+l). 
     The ECU  100  has a booster path Lh which is another path for electrically connecting the +B terminal and the upstream side terminal of the injector  502 . The booster circuit  20  which generates a boosted voltage applied to the injector  502  is disposed in the booster path Lh, and a discharge switch  12  is disposed at a position between the booster circuit  20  and the injector  502 . 
     The ECU  100  has a downstream path Lg which electrically connects a downstream side terminal of the injector  502  and a ground, and a downstream switch  13  is disposed in the downstream path Lg. 
     Thus, the ECU  100  has the constant current switch  11 , the discharge switch  12 , the downstream switch  13 , and the booster circuit  20 . 
     The ECU  100  has a microcomputer  30  which performs a booster control of the booster circuit  20 , and a turning ON and OFF control of the constant current switch  11 , the discharge switch  12 , and the downstream switch  13 . 
     The constant current switch  11 , when it is turned ON, electrically connects the +B terminal and the upstream side terminal of the injector  502 , and, when it is turned OFF, electrically interrupts a connection between them. The discharge switch  12 , when it is turned ON, electrically connects an output terminal of the booster circuit  20  and the upstream side terminal of the injector  502 , and, when it is turned OFF, electrically interrupts a connection between them. The downstream switch  13 , when it is turned ON, electrically connects the downstream side terminal of the injector  502  and the ground, and, when it is turned OFF, electrically interrupts a connection between them. 
     Therefore, when the constant current switch  11  and the downstream switch  13  are turned ON, the battery voltage VB is applied to the injector  502 , and electric current flows accordingly. When the discharge switch  12  and the downstream switch  13  are turned ON, the output voltage of the booster circuit  10  is applied to the injector  502 , and electric current flows accordingly. As the constant current switch  11 , the discharge switch  12 , and the downstream switch  13 , MOSFET may be used, for example. 
     The booster circuit  20  has a first current path  21  to which the battery voltage is input and which outputs the boosted voltage that is a boosted voltage of the battery voltage VB and a second current path  22  and a third current path  23  that respectively branch from the first current path  21  to lead to the ground. 
     A coil  24  to which the battery voltage VB is applied on one end is disposed in the first current path  21 , and the other end of the coil  24  is electrically connected to the second current path  22 . In the second current path  22 , a charge switch  25  is disposed, which flows electric current through the coil  24  when it is turned ON. The turning ON and OFF control of the charge switch  25  is performed by an instruction of the microcomputer  30 . By the turning ON and OFF of the charge switch  25 , a counter electromotive force is generated in the coil  24 . MOSFET may be used as the charge switch  25 , for example. 
     In the first current path  21 , a diode  26  for preventing a reverse flow is disposed at a junction point of the first current path  21  and the second current path  22 , to which an anode of the diode  26  is connected. A cathode of the diode  26  is electrically connected to the third current path  23 . In the third current path  23 , a capacitor  27  is disposed, which is charged by the counter electromotive force generated in the coil  24 . In the ECU  100 , although a ceramic multilayer capacitor is used as the capacitor  27 , other type of capacitors, such as an electrolytic capacitor or the like, may also be used. 
     Further, as a feature of the present disclosure, in the second current path  22 , a first interrupter wiring  28  is disposed in series to the charge switch  25  at a position between the charge switch  25  and the ground. Further, in the third current path  23 , a second interrupter wiring  29  is disposed in series to the capacitor  27  at a position between the capacitor  27  and the ground. Each of the interrupter wirings  28  and  29  generates heat according to the electric current flowing therein, and, when a predetermined fusing temperature is exceeded, respectively, the wirings  28  and  29  are fused, for interrupting the electric current flowing therein. 
     The fusing temperature of each of the interrupter wirings  28  and  29  is set to have a value so that the interrupter wirings  28  and  29  are fused before the temperature of the coil  24  exceeds a preset temperature by a self-generated heat that is caused by the electric current following therein. 
     The microcomputer  30  is electrically connected to and controls the switching of (i.e., for the turning ON and OFF) each of the constant current switch  11 , the discharge switch  12 , the downstream switch  13 , and charge switch  25 , and sends instructions to them for the switching of them. The microcomputer  30  has an injection instruction part  31  which generates an injection signal according to a combustion cycle of the internal-combustion engine  500  and a switch instruction part  32  which instructs the turning ON and OFF of the constant current switch  11 , the discharge switch  12 , the downstream switch  13 , and the charge switch  25  according to the injection signal. 
     The injection instruction part  31  generates the injection signal which instructs a start and a stop of fuel injection based on the output of the cam angle sensor  503  and the crank angle sensor  504  which are input to the microcomputer  30 . The injection signal is input to the switch instruction part  32 , and the switch instruction part  32  outputs the control signal for switching between the turning ON and OFF to the constant current switch  11 , the discharge switch  12 , the downstream switch  13 , and the charge switch  25  based on the injection signal. 
     Further, the microcomputer  30  is electrically connected at a position between the charge switch  25  and the first interrupter wiring  28  in the second current path  22 , and has a monitor part  33  which monitors a first monitor potential V1 which is a potential junction point to the second current path  22 . The microcomputer  30  also is electrically connected to a position between the capacitor  27  and the second interrupter wiring  29  in the third current path  23 , and the monitor part  33  also monitors a second monitor potential V2 which is a potential of a junction point to the third current path  23 . 
     Next, an operation of the ECU  100  concerning the present embodiment is explained. 
     First, how a boosted voltage is generated by the booster circuit  20  is explained. When the charge switch  25  is turned ON according to an instruction of the microcomputer  30 , the battery voltage VB is applied to the coil  24 , and electric current flows into the coil  24 . Then, according to an instruction of the microcomputer  30 , when the charge switch  25  is turned OFF, a counter electromotive force occurs in the coil  24 , and the capacitor  27  is charged. The turning ON and OFF of the charge switch  25  is repeatedly performed until the charge voltage of the capacitor  27  reaches a predetermined boosted voltage, and, as a result, the boosted voltage is generated. 
     Next, a detection of the short-circuit of the charge switch  25  and the capacitor  27  in the booster circuit  20  is explained. When the charge switch  25  and the capacitor  27  have not short-circuited, the first monitor potential V1 and the second monitor potential V2 is equated to the ground potential. On the other hand, when the charge switch  25  is short-circuited, a surge current flows into the second current path  22 , the first interrupter wiring  28  generates heat and is fused, and the first monitor potential V1 is equated to the battery voltage VB. Therefore, when the potential of the first monitor potential V1 currently monitored is equated to the ground potential, the monitor part  33  of the microcomputer  30  determines that a short-circuit has not occurred in the charge switch  25 , and, when the potential of the first monitor potential V1 is equated to a potential that is higher than the ground potential, it determines that a short-circuit has occurred in the charge switch  25 . 
     The same determination is made when the capacitor  27  is short-circuited. That is, in such a case, a surge current flows into the third current path  23 , and the second interrupter wiring  29  generates heat and is fused, and the second monitor potential V2 is equated to the battery voltage VB. Therefore, the monitor part  33  of the microcomputer  30  determines that a short-circuit has not occurred in the capacitor  27  when the potential of the second monitor potential V2 currently monitored is equated to the ground potential, and, when the potential of the second monitor potential V2 is equated to a potential that is higher than the ground potential, it determines that a short-circuit has occurred in the capacitor  27 . 
     Next, a control of the voltage applied to the injector  502  is explained.  FIG. 3  is a flowchart with which a process performed by the microcomputer  30  for the control of the voltage that is applied to the injector  502  is shown.  FIGS. 4 and 5  are time charts which show an example of the operation of each of the components at a time of performing the flowchart process.  FIG. 4  is a time chart of a normal case, that is, when the charge switch  25  and the capacitor  27  have not short-circuited.  FIG. 5  is a time chart of a short circuit case, that is, when the charge switch  25  and the capacitor  27  are short-circuited. With reference to these time charts, the flowchart in  FIG. 3  is explained. 
     First, the microcomputer  30  sets up an injection amount of the fuel (S 101 ). Next, the monitor part  33  of the microcomputer  30  detects the potentials, i.e., the first monitor potential V1 and the second monitor potential V2 (S 102 ). Then, the monitor part  33  determines whether the detected first monitor potential V1 is higher than the potential VG, i.e., the ground potential (S 103 ), and, when it determines that the detected potential is higher, the monitor part  33  sets a predetermined flag in the microcomputer  30  to “1” (S 104 ). This flag shows that the charge switch  25  or the capacitor  27  is short-circuited, that is, when the flag is 1, the flag shows that a short-circuit has occurred, and, when the flag is 0, the flag shows that a short-circuiting has not occurred. Therefore, when a flag is set to 1 in S 104 , the flag shows that a short-circuit has occurred in the charge switch  25  or the capacitor  27 . 
     On the other hand, when it is determined that the first monitor potential V1 is not higher than the ground potential VG in S 103 , the monitor part  33  determines whether the detected second monitor potential V2 is higher than the ground potential VG (S 105 ). When it is determined that the second monitor potential V2 is higher than the ground potential VG, S 104  mentioned above is performed and the monitor part  33  sets the flag to 1, which shows that a short-circuit has occurred. On the other hand, when it is determined that the second monitor potential V2 is not higher than the ground potential VG in S 105 , the monitor part  33  sets the flag to 0, which shows that a short-circuiting has not occurred (S 106 ). 
     Next, the microcomputer  30  determines whether the value of the flag is set to 1 (S 107 ), and, if the flag value is 1, the injection instruction part  31  sets an injection start instruction timing to an earlier timing th0, which is earlier than a normal timing for a non-short-circuited time, i.e., when the charge switch  25  or the capacitor  27  has no trouble (S 108 ), and the process proceeds to S 110 . On the other hand, if the flag value is 0, the injection instruction part  31  sets the injection start instruction timing to a timing t0, which is the normal timing (S 109 ), and the process proceeds to S 110 . 
     In S 110 , the injection instruction part  31  sets up an injection stop instruction timing tf according to the injection amount set up in S 101  and the injection start instruction timing set up in S 108  or S 109 . 
     Next, the injection instruction part  31  sends an injection start instruction to the switch instruction part  32  at the injection start instruction timing set up in S 108  or S 109  (S 111 ). Specifically, an injection signal which is a signal sent from the injection instruction part  31  to the switch instruction part  32  to instruct an injection start and an injection stop is turned from an OFF state to an ON state. Thereby, when a short-circuit has not occurred, as shown in  FIG. 4 , an injection signal is turned from OFF to ON at a timing t0 that is set up in S 109 . On the other hand, when a short-circuit has occurred, an injection signal is turned from OFF to ON at a timing th0 that is set up in S 108 . 
     The switch instruction part  32  sends an ON instruction or an OFF instruction to the constant current switch  11 , the discharge switch  12 , and the downstream switch  13  (i.e., switching instruction to switches in  FIG. 3 ), in response to the turning ON of the injection signal (S 112 ). More specifically, when the flag value is 0, i.e., when not short-circuited has occurred, the switch instruction part  32  sends an ON instruction to the constant current switch  11 , the discharge switch  12 , and the downstream switch  13 . In such manner, as shown in  FIG. 4 , the constant current switch  11 , the discharge switch  12 , and the downstream switch  13  are turned ON, and the battery voltage VB and boosted voltage are applied to the magnet coil  502   a  of the injector  502 , and the electric current flowing in the magnet coil  502   a  steeply increases. When the electric current flowing in the magnet coil  502   a  exceeds a predetermined valve-opening electric current value, an electromagnetic valve moves toward a valve opening position. Then, after the electromagnetic valve opens completely, as described later, the battery voltage VB is applied to the magnet coil  502   a , and the open state of the electromagnetic valve is maintained. 
     On the other hand, when the flag value is 1, i.e., when a short-circuit has occurred, the operation is as described in the following. That is, in  FIG. 5 , a solid line shows an operation of each of the components in the ECU  100  concerning the present embodiment, and a dashed-dotted line shows an operation of each of the components of the conventional ECU. 
     When the flag value is 1, i.e., when a short-circuit has occurred, in response to the turning ON of the injection signal, the switch instruction part  32  sends an ON instruction to the constant electric current switch  11  and the downstream switch  13 . Thereby, as shown in  FIG. 5 , with the discharge switch  12  kept in an OFF state, the constant electric current switch  11  and the downstream switch  13  are turned ON, and the battery voltage VB is applied to the magnet coil  502   a  of the injector  502 , and the electromagnetic valve moves the valve opening position. 
     In such a case, the voltage applied to the magnet coil  502   a  is the battery voltage VB that is lower than the boosted voltage. The increase speed of the electric current flowing in the magnet coil  502   a  at the time of a short-circuit is, as shown in  FIGS. 4 and 5 , slower than the increase speed at a not short-circuited time. As a result, when a short-circuit has occurred, a valve opening time which is a time from an application of the voltage to the electromagnetic valve to a complete opening of the valve is longer than the one at a non-short-circuited time. 
     Conventionally, as indicated by the dashed-dotted line in  FIG. 5 , since the application of the voltage to the magnet coil  502   a  starts at time t0 at the time of a short-circuit, a timing tu 1  at which the electromagnetic valve opens completely is later than a timing t1 at a non-short-circuited time. 
     On the other hand, in the ECU  100  concerning the present embodiment, when a short-circuit has occurred, a voltage application start timing for starting an application of the voltage to the magnet coil  502   a  (i.e., an interrupted power supply start timing) is set (i.e., advanced) to the earlier timing th0 that is earlier than the timing t0 (i.e., non-interrupted power supply start timing), which is a normal timing of non-short-circuited time as mentioned above. Thereby, the timing th1, at which the electromagnetic valve opens completely, at the time of a short-circuit can be brought close to the timing t1 of non-short-circuited time, which is indicated by the solid line in  FIG. 5 . 
     Then, it is determined by the microcomputer  30  whether the electromagnetic valve has opened completely (S 113 ). The determination is performed based on the electric current flowing in the magnet coil  502   a . The determination in S 113  is repeated until the electromagnetic valve opens completely, and, after the complete opening of the valve, the process proceeds to the next step S 114 . 
     In S 114 , since the electromagnetic valve has opened completely, the switch instruction part  32  sends an ON/OFF instruction to the constant electric current switch  11 , the discharge switch  12 , and the downstream switch  13  in order to maintain the open state of the electromagnetic valve. More specifically, when the flag value is 0, i.e., when short-circuiting has not occurred, first, the switch instruction part  32  sends an OFF instruction to the constant electric current switch  11  and the discharge switch  12  at the timing t1 at which the electromagnetic valve has opened completely. Then, in order to maintain the open state of the electromagnetic valve, the switch instruction part  32  repeatedly sends ON and OFF instructions to the constant electric current switch  11  so that a constant electric current flows in the magnet coil  502   a.    
     On the other hand, when the flag value is 1, i.e., when a short-circuit has occurred, first, the switch instruction part  32  sends an OFF instruction to the constant electric current switch  11  at the timing th1 at which the electromagnetic valve has opened completely. Then, in order to maintain the open state of the electromagnetic valve, the switch instruction part  32  repeatedly sends ON and OFF instructions to the constant electric current switch  11  so that a constant electric current flows in the magnet coil  502   a.    
     Next, the injection instruction part  31  turns the injection signal from the ON state to the OFF state at the timing if, i.e., at the injection stop instruction timing (S 115 ). In response to such change of the signal from ON to OFF, the switch instruction part  32  sends an OFF instruction to the constant electric current switch  11  and the downstream switch  13 . In such manner, the application of the voltage to the magnet coil  502   a  is stopped, and the electromagnetic valve closes, and the fuel injection stops. Thus, the process of the flowchart is finished. The above-described process from S 101  to S 115  is repeatedly performed at the time of an operation of the internal-combustion engine  500 . 
     The above explanation is a control of the ECU  100  for the injector  502  that is disposed in one cylinder. However, a control of each of the injectors  502  that are respectively disposed in, for example, four cylinders may be performed by the ECU  100  in the same manner. 
     In such a case, the ECU  100  performs a process in the flowchart of  FIG. 3  to each of the injectors  502 . Thereby, as shown in  FIG. 6 , the injection signal to instruct the injection start and the injection stop for each of the injectors  502  has an earlier injection start instruction timing when a short-circuit occurs (i.e., short-circuit trouble time), in comparison to a non-short-circuited time (i.e., in comparison to a normal time). In such manner, even when a short-circuit occurs and having a longer valve opening time, which is a time from the start of the application of the voltage to the magnet coil  502   a  to a complete opening of the electromagnetic valve, the earlier injection start instruction timing prevents a delay of the complete valve opening timing at which the electromagnetic valve opens completely. 
     Next, the effect of the ECU  100  concerning the present embodiment is explained. According to the ECU  100  in the present embodiment, when at least one of the charge switch  25  or the capacitor  27 , which are respectively connected in series to the interrupter wiring  28  or  29 , is short-circuited, the electric current flowing into the second electric current path  22  or the third electric current path  23  is interrupted by the interrupter wiring  28  or  29  that corresponds either to the charge switch  25  or the capacitor  27 . That is, the first electric current path  21  does not short-circuit to ground. Therefore, the booster circuit  20  is enabled to output a voltage that is higher than the voltage at the time of the short-circuit of the first electric current path  21  short-circuiting to the ground. That is, the first electric current path  21  is enabled to output a voltage substantially equal to the battery voltage VB. 
     Further, according to the ECU  100  of the present embodiment, a short-circuit and a fusing of the interrupter wirings  28  and  29  are detected by the monitor part  33 . Upon having such a detection, at the time of fuel injection, the battery voltage VB is applied to the injector  502  at an earlier timing earlier than the non-short-circuited time, under control of the microcomputer  30 . Since the battery voltage VB is lower than the boosted voltage, the time required for a valve opening, which is a time from the voltage application start time to the coil  502   a  to the complete opening of the valve, is longer than a normal time, i.e., a non-short-circuited time, in the above situation. However, according to the ECU  100  of the present embodiment, when a short-circuit has occurred, the application of the voltage to the injector  502  starts at an earlier timing (i.e., is advanced) relative to the normal time. Thereby, even when a short-circuit has occurred, a timing of complete opening of the electromagnetic valve can be brought close to a timing of the normal time. Therefore, a delay of the fuel injection start timing due to a short-circuit is prevented. 
     Further, according to the ECU  100 , when the charge switch  25  or the capacitor  27  is short-circuited, the voltage output by the booster circuit  20  is not applied to the magnet coil  502   a . Therefore, at the time of having a short-circuit, the application of the output voltage of the booster circuit  20  to the magnet coil  502   a , which leads to a flow of the electric current in the coil  24  and leads to heat generation in the coil  24 , is prevented. 
     Further, according to the ECU  100 , the interrupter wirings  28  and  29  are respectively arranged on a ground side of the charge switch  25  and the capacitor  27 . Such positioning of the interrupter wirings  28  and  29  is examined in the following in terms of how the monitor part  33  monitors a monitor potential. That is, a monitoring point of the monitor part  33  may be one of following two points. The first monitoring point may be an upstream of the interrupter wirings  28  and  29 , for monitoring an upstream potential. 
     First, the upstream potential of the interrupter wiring  28  that is disposed in the upstream of the charge switch  25  is the battery voltage VB at both of an interruption time of the interrupter wiring  28  and a normal time. Therefore, it cannot be determined whether it is a normal time or an interruption time based on the upstream potential of the interrupter wiring  28 . 
     Next, the upstream potential of the interrupter wiring  29  disposed in the upstream of the capacitor  27  is the boosted voltage that is charged by the capacitor  27  at the normal time, and is the battery voltage VB at an interruption time of the interrupter wiring  29 , since the booster circuit  20  loses its booster function at the interruption time. However, when the boosted voltage is not charged by the capacitor  27  such as a start-up time of the ECU  100 , the upstream potential of the interrupter wiring  29  is not the boosted voltage even in the normal time. Therefore, the determination of the normal/interruption time based on the upstream potential of the interrupter wiring  29  may be correctly performed only when it is ascertained that it is not a start-up time of the ECU  100  or the like, which requires a complicated processing. 
     On the other hand, as the second monitoring point, a downstream potential of the interrupter wirings  28  and  29  may be monitored, which is a potential between the interrupter wiring  28  or  29 , and the charge switch  25  or the capacitor  27 . Since the downstream potential is higher than the ground at the normal time, or, is equated to the ground potential at the interruption time, because the charge switch  25  or the capacitor  27  is short-circuited. However, the charge switch  25  or the capacitor  27  may not be completely short-circuited at the interruption time, depending on the manner of short-circuiting. In such a case, the downstream potential does not fall to the ground potential. Therefore, in order to correctly determine whether it is the interruption time or the normal time based on the downstream potential, it is necessary to consider the manner how the short-circuit has occurred, which also complicates the determination processing. 
     However, according to the ECU  100  in the present embodiment, the interrupter wirings  28  and  29  are respectively arranged on the ground side of the charge switch  25  or the capacitor  27 . Therefore, the monitor part  33  monitors the first monitor potential V1 and the second monitor potential V2, which are either a potential between the interrupter wiring  28  and the charge switch  25  or a potential between the interrupter wiring  29  and the capacitor  27 . Both of the first monitor potential V1 and the second monitor potential V2 are equated to the ground potential at the normal time, and are equated to a higher-than-the-ground potential at the interruption time. The potential at the normal time and the potential at the interruption time do not change depending on the charge state of the capacitor  27  and/or the manner of how a short-circuiting has occurred. Therefore, in the above-described manner, the determination of whether it is the interruption time or the normal time is performable simply and securely. 
     However, the present disclosure is not limited to the above. That is, the interrupter wirings  28  and  29  may be positioned on the upstream side of the charge switch  25  or the capacitor  27 . However, it is may be preferable to position the interrupter wirings  28  and  29  on the ground side of the charge switch  25  or the capacitor  27 , as mentioned above. 
     In the ECU  100  of the present embodiment, a ceramic multilayer capacitor is used as the capacitor  27 . The ceramic multilayer capacitor is a capacitor that is made by alternatingly layering a dielectric layer which consists of ceramic and a conductor layer. Thereby, although the ceramic multilayer capacitor has a smaller volume in comparison to the other electrolytic capacitors, the ceramic multilayer capacitor may be more prone to a short-circuiting. However, according to the ECU  100  of the present embodiment, since a control for preventing a delay of the fuel injection start timing is performed in the above-described manner when the capacitor  27  is short-circuited, the ECU  100  can have a smaller volume without having a delay of the fuel injection start timing at the short-circuit trouble time. 
     According to the ECU  100  of the present embodiment, the fusing temperature of the interrupter wirings  28  and  29  is set up so that the interrupter wirings  28  and  29  are fused before the temperature of the coil  24  exceeds a preset temperature by a self-generated heat that is caused by the electric current following therein. That is, in other words, since the interrupter wirings  28  and  29  are fused before the temperature of the coil  24  exceeds a preset temperature, which interrupts the electric current flowing in the coil  24  and stops a heat generation by such electric current, a burn-out of the coil  24  due to the excessive heat is prevented. 
     Other Embodiments 
     Although the present disclosure has been fully described in connection with preferred embodiment thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications become apparent to those skilled in the art. 
     According to the first embodiment, it is provided that the fuel is directly injected to the combustion chamber  501 . However, the injector  502  is not limited to such a configuration. That is, it may be provided that the fuel may be injected into an inlet pipe. 
     In the first embodiment, the interrupter wirings  28  and  29  are disposed in series to the charge switch  25  or the capacitor  27 , respectively. However, the interrupter wiring may be provided for only one of the charge switch  25  and the capacitor  27 . That is, only the charge switch  25  may have the interrupter wiring  28 , or only the capacitor  27  may have the interrupter wiring  29 . 
     In case that the interrupter wiring  28  is provided only for the charge switch  25 , since interrupter wiring  28  is interrupted when the charge switch  25  is short-circuited, the first electric current path  21  is not short-circuited to the ground. Thereby, the booster circuit  20  is enabled to output a voltage that is higher than a short-circuiting time of the first electric current path  21  to the ground, i.e., a voltage that is substantially the same as the battery voltage VB. 
     The interception of the interrupter wiring  28  is detected by the monitor part  33 , and, in response, the application of the voltage to the injector  502  is started at an earlier timing that is earlier relative to the normal time by the control of the microcomputer  30 . Thereby, the delay of the fuel injection start timing due to a short-circuiting is prevented. 
     On the other hand, in case that the interrupter wiring  29  is provided only for the capacitor  27 , since the interrupter wiring  29  is interrupted when the capacitor  27  is short-circuited, the first electric current path  21  is not short-circuited to the ground. Thereby, the booster circuit  20  is enabled to output a voltage that is higher than a first electric current path  21  short-circuiting time to the ground, i.e., a voltage that is substantially the same as the battery voltage VB. 
     The interception of the interrupter wiring  29  is detected by the monitor part  33 , and, in response, the application of the voltage to the injector  502  is started at an earlier timing earlier than the normal time by the control of the microcomputer  30 . Thereby, the delay of the fuel injection start timing due to short-circuiting is prevented. 
     Further, in the first embodiment described above, when the flag value is 0. i.e., when short-circuiting has not occurred, an example is shown in which the switch instruction part  32  in S 112  of the flowcharted process sends an ON instruction to the constant electric current switch  11 , the discharge switch  12 , and the downstream switch  13 . However, when the flag value is 0, i.e., when short-circuiting has not occurred, the switch instruction part  32  may, for example, send an ON instruction only to the discharge switch  12  and the downstream switch  13 , without sending an ON instruction to the constant electric current switch  11 . In such a case, the discharge switch  12  and the downstream switch  13  are turned ON, and the boosted voltage is applied to the magnet coil  502   a  of the injector  502 , and the electric current flowing in the magnet coil  502   a  steeply increases. 
     Further, in the first embodiment described above, when the flag value is 1, i.e., when a short-circuit has occurred, an example is shown in which the switch instruction part  32  in S 112  of the flowcharted process sends an ON instruction to the constant electric current switch  11  and the downstream switch  13 . However, when the flag value is 1, i.e., when a short-circuit has occurred, the switch instruction part  32  may, for example, send an ON instruction also to the discharge switch  12  while sending an ON instruction to the constant electric current switch  11  and the downstream switch  13 . 
     However, since the booster circuit  20  loses its booster function when the flag value is 1, i.e., when a short-circuit has occurred, the output voltage of the booster circuit  20  is the same as the battery voltage VB. Further, when the output voltage of the booster circuit  20  is used, electric current flows in the coil  24 , which generates heat. Therefore, the ECU  100  in the first embodiment is configured to turn ON the constant electric current switch  11  and to turn OFF the discharge switch  12 , for preventing the heat generation and for the application of the battery voltage VB, which is preferable. 
     Further, in the first embodiment, the fusing temperature of the interrupter wirings  28  and  29  is set to fuse them before the self-generated heat in the coil  24  exceeds a preset temperature. However, such configuration may be changed to a different setting. Even in such case, the fusing temperature of the interrupter wirings  28  and  29  is preferably set to fuse them before the self-generated heat in the coil  24  exceeds a preset temperature, for preventing an excessive temperature in the coil  24  which exceeds the preset temperature and burns out the coil  24  itself. 
     Although the configuration in the first embodiment opens the valve by supplying electric current to the magnet coil  502   a , the valve may be opened by supplying electric current to a piezoelectric element, for example. 
     Such changes, modifications, and summarized schemes are to be understood as being within the scope of the present disclosure as defined by appended claims.