JP5099041B2 - Fuel pump control device - Google Patents

Description

  The present invention relates to a fuel pump control device that controls driving of a fuel pump for supplying fuel in a fuel tank to an engine.

  For example, a fuel pump control device mounted on a vehicle applies a predetermined voltage to a fuel pump based on a control signal given through a signal input line from an electronic control unit (ECU) for engine control. In such a fuel pump control device, in order to improve the startability of the engine, it is necessary to improve the responsiveness of the fuel pump when starting the engine. There is also a demand to be able to detect an abnormality in a signal input line that transmits a control signal.

  Thus, for example, it is conceivable to employ the technique disclosed in Patent Document 1. According to the technique described in Patent Document 1, a relay is provided in the power supply path to the fuel pump control device, and the power supply state is controlled by the ECU. When the fuel pump control device detects that power is supplied to itself and the control signal supplied from the ECU has a predetermined voltage value during a predetermined period when the engine is started, the fuel pump control device sets the maximum voltage to the fuel pump. The drive is applied to start driving, and a specific monitor signal is transmitted to the ECU. The ECU determines whether there is an abnormality in the transmission path of the control signal by confirming the presence or absence of this specific monitor signal. According to such a configuration, it is possible to detect an abnormality in the signal input line without impairing the startability of the engine.

JP 2007-291989 A

  However, the technique described in Patent Document 1 is a system that is turned on by a relay when the engine is started and turned off by a relay when the engine is stopped. For this reason, it is necessary to provide a relay in the power supply path, and a drive circuit for driving the relay is required, resulting in a problem that the configuration becomes complicated.

  The present invention has been made in view of the above circumstances, and its object is to reduce the startup time of the fuel pump at the start of the engine and detect an abnormality in the signal input line while suppressing the complication of the configuration. An object of the present invention is to provide a fuel pump control device that can be used.

  According to the first aspect of the present invention, for example, during normal operation of the engine, when a control signal is given from the outside through a signal input line, the control circuit applies a predetermined voltage to the fuel pump based on the control signal. Thus, the on / off of the switching element connected in series with the fuel pump between the pair of DC power supply lines is controlled. On the other hand, when the engine is started, no control signal is given to the control circuit until the control signal is generated outside. The potential fixing means fixes the potential of the signal input line to a predetermined potential during the period when the control signal is not applied. The control circuit turns on the switching element when it detects that the state where the potential of the signal input line is a predetermined potential (potential fixed state) continues only for the first period when the engine is started. The first period may be set to a period that can prevent erroneous detection due to noise in consideration of the possibility that the potential of the signal input line is erroneously set to a predetermined potential due to noise or the like.

  As a result, voltage application to the fuel pump is started from a period when no external control signal is given when the engine is started. Thereafter, when a control signal is given through the signal input line, the potential fixed state of the signal input line is released, and the applied voltage to the fuel pump is controlled based on the control signal in the same manner as in the normal operation described above.

  Here, in the case where the above-described potential fixing state of the signal input line continues for a long period of time, for example, a period sufficiently longer than that required for generating the control signal externally, the transmission path of the control signal, that is, the signal input line It is considered that an abnormality such as disconnection has occurred. Therefore, when the control circuit detects that the potential fixing state has continued for a second period longer than the first period, it determines that an abnormality has occurred in the signal input line. The second period may be set to a period longer than at least a period necessary for generating the control signal externally. According to the fuel pump control device having such a configuration, it is possible to reduce the startup time of the fuel pump at the time of starting the engine and detect an abnormality in the signal input line while suppressing the complexity of the configuration.

  According to the second aspect of the present invention, the control circuit maintains the ON state until the control signal is given after the switching element is turned ON at the time of starting the engine. As a result, the boosting capability of the fuel pump at the start of the engine can be sufficiently increased, so that the startup time of the fuel pump can be further reduced.

  According to a third aspect of the present invention, the potential fixing unit fixes the potential of the signal input line to one of the pair of DC power supply lines during a period when the control signal is not applied. When the potential of the signal input line is fixed to the high potential side potential, it is possible to detect a short circuit (power fault) state with the high potential side DC power supply line as an abnormality of the signal input line. On the other hand, when the potential is fixed to the low potential side potential, a short circuit (ground fault) state with the low potential side DC power supply line can be detected as an abnormality of the signal input line. Further, if the fuel pump control device is configured to operate by receiving power supply from a pair of DC power supply lines, the potential of the signal input line is fixed at a predetermined potential immediately after the power supply to the fuel pump control device is started. Therefore, it is possible to further reduce the startup time of the fuel pump when starting the engine.

  According to the means described in claim 4, the control signal given from the outside is a signal having a duty that changes continuously. The control circuit controls on / off of the switching element so as to apply a voltage corresponding to the duty of the control signal to the fuel pump. That is, the control circuit linearly controls the voltage applied to the fuel pump based on a control signal having a continuously changing duty. Here, it is assumed that the duty of the control signal continuously changes from a first predetermined value to a second predetermined value that is larger than the first predetermined value and less than 1. Further, the potential of the signal input line is fixed to the high potential side potential of the pair of DC power supply lines during a period when the control signal is not applied. For this reason, the potential fixed state of the signal input line is clearly distinguished from the state where the control signal is applied, and the potential fixed state can be easily detected by the control circuit. Therefore, even when the applied voltage to the fuel pump is linearly controlled, it is possible to reduce the startup time of the fuel pump when starting the engine and to detect an abnormality in the signal input line.

  According to the means described in claim 5, the control signal given from the outside is a signal having a duty that continuously changes. The control circuit controls on / off of the switching element so as to apply a voltage corresponding to the duty of the control signal to the fuel pump. That is, the control circuit linearly controls the voltage applied to the fuel pump based on a control signal having a continuously changing duty. Here, the duty of the control signal is assumed to continuously change from a first predetermined value larger than 0 to a second predetermined value larger than the first predetermined value. Further, the potential of the signal input line is fixed to the low potential side potential of the pair of DC power supply lines during a period when the control signal is not applied. For this reason, the potential fixed state of the signal input line is clearly distinguished from the state where the control signal is applied, and the potential fixed state can be easily detected by the control circuit. Therefore, even when the applied voltage to the fuel pump is linearly controlled, it is possible to reduce the startup time of the fuel pump when starting the engine and to detect an abnormality in the signal input line.

The block diagram of the fuel pump control system which shows one Embodiment of this invention The figure which shows the relationship between the duty of a control signal, and the applied voltage to a fuel pump The figure which shows the state of each part signal and voltage when the signal input line is normal FIG. 3 equivalent diagram when an abnormality occurs in the signal input line

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows the configuration of a fuel pump control system. A fuel pump control system shown in FIG. 1 includes, for example, a fuel pump control device 2 that controls driving of a fuel pump 1 for supplying fuel in a fuel tank provided in a vehicle to an engine, and the fuel pump control device 2. On the other hand, the engine control ECU 3 that gives a drive command for the fuel pump 1 is mainly configured. The fuel pump 1 includes a motor that rotates at a rotation speed corresponding to the voltage applied to both terminals, and thereby fuel corresponding to the applied voltage is supplied to the engine.

  The fuel pump control device 2 (hereinafter also referred to as FPC 2) includes a semiconductor integrated circuit 4 (hereinafter referred to as IC 4) that controls the voltage applied to the fuel pump 1 and a filter circuit 5. The IC 4 includes a control circuit 6 that operates according to a command given from the ECU 3, transistors M1 and M2 that are driven by the control circuit 6, and the like. A control signal Si is input to the control circuit 6 from the ECU 3 through the signal input line 7 and the control terminal SI of the FPC 2. Further, a diagnosis signal Di is output from the control circuit 6 to the ECU 3 through the diagnosis terminal DI and the monitor signal line 8.

  The control signal Si is a signal having a duty that indicates a command value of a voltage applied to the fuel pump 1. The diagnosis signal Di is a signal that becomes an active level described later when an abnormality occurs in the FPC 2, and the ECU 3 diagnoses the state of the FPC 2 based on the diagnosis signal Di.

  The FPC 2 operates by receiving power from the battery 9 of the vehicle. The positive terminal of the battery 9 is connected to the power supply terminal + B of the FPC 2 through the ignition switch 10 and the fuse 11. On the other hand, the negative terminal of the battery 9 is connected to the ground terminal E of the FPC 2. The power supply terminal + B and the ground terminal E are connected to the power supply line 13 and the ground line 14 (corresponding to a pair of DC power supply lines) in the FPC 2. The power line 13 is connected to the power terminal 15 of the IC 4, and the ground line 14 is connected to the ground terminal 16 of the IC 4 through the coil L 2 of the filter circuit 5. One terminal of the fuel pump 1 is connected to the output terminal 17 of the IC 4 through the terminal FP + of the FPC 2 and the coil L1 of the filter circuit 5, and the other terminal is connected to the ground line 14 through the terminal FP- of the FPC 2.

  The transistors M1 and M2 are both N-channel power MOSFETs. The transistor M1 (corresponding to a switching element) is connected in series with the coil L1 and the fuel pump 1 between the power supply line 13 and the ground line 14. The transistor M2 is connected between the output terminal 17 and the ground terminal 16. A drive signal is supplied from the control circuit 6 to the gates of the transistors M1 and M2. The transistors M1 and M2 are driven to turn on alternately based on this drive signal. That is, the transistor M1 as a driving element and the transistor M2 as a regenerative element are driven by a so-called synchronous rectification method. Further, a diode D1 for detecting an overheat state of the transistor M1 is provided in the vicinity of the transistor M1. The voltage between the terminals of the diode D <b> 1 is given to the control circuit 6.

  The filter circuit 5 includes coils L1 and L2 and capacitors C1 to C3. The coil L1 is provided between the output terminal 17 and the terminal FP +, and the coil L2 is provided between the ground terminal 16 and the earth terminal E. The capacitor C1 is provided between the power supply terminal + B and the ground terminal E. The capacitor C2 is provided between the power supply terminal + B and the terminal FP +. The capacitor C3 is provided between the power supply terminal + B and the ground terminal 16. The filter circuit 5 having such a configuration suppresses the influence of switching noise generated due to ON / OFF of the transistors M1 and M2 on other devices.

  The ECU 3 includes a control circuit (not shown), a transistor M3 for outputting a control signal Si, and a voltage dividing circuit 18 for inputting a diagnosis signal Di. The control circuit is mainly composed of a microcomputer provided with a CPU, ROM, RAM, A / D converter and the like. The control circuit generates a command signal having a duty for commanding a voltage value to be applied to the fuel pump 1, and controls on / off of the transistor M3, which is an N-channel MOSFET, based on the command signal.

  The control circuit operates by receiving supply of a power supply voltage (for example, +5 V) generated by stepping down the battery voltage VB supplied from the battery 9. Therefore, the maximum voltage value (H level) of the command signal is the power supply voltage. The maximum voltage value (H level) of the diagnosis signal Di given from the FPC 2 is a battery voltage VB (for example, +13 V). The voltage dividing circuit 18 converts the diagnosis signal Di into a voltage (for example, + 5V) that can be input to the control circuit. The control circuit performs failure diagnosis of the FPC 2 based on the divided voltage obtained from the interconnection point of the two resistance elements that constitute the voltage dividing circuit 18.

  The control circuit 6 includes a resistor R1, an input signal processing unit 19, an output setting unit 20, a drive unit 21, a duty determination unit 22, an overvoltage protection unit 23, an overheat protection unit 24, an overcurrent detection unit 25, a diagnosis determination unit 26, and a diagnosis. An output unit 27 is provided. The resistor R1 pulls up the signal input line 7 to the power supply line 13, and corresponds to a potential fixing unit. Thereby, the control signal Si given to the input signal processing unit 19 is fixed to the potential of the power supply line 13 (battery voltage VB) while the transistor M3 of the ECU 3 is off.

  The input signal processing unit 19 detects the duty of the control signal Si given from the ECU 3 through the signal input line 7 every predetermined time. The duty in the present embodiment means an on-duty indicating the ratio of the H level period in one cycle of the control signal Si in%. The input signal processing unit 19 outputs data indicating the detected duty to the output setting unit 20 and the duty determination unit 22, respectively.

  When the duty given from the input signal processing unit 19 every predetermined time is changed from the minimum value to the maximum value and the state of the maximum value continues only for a period T1, which will be described later, the duty determination unit 22 starts the engine. Judge that there is. Then, a full-on command for continuously energizing the fuel pump 1 by constantly turning on the transistor M1 is output to the output setting unit 20. The full-on command is output after a predetermined period and then stopped.

  In addition, when the above-described state in which the duty is the maximum value continues for a period T2, which will be described later, the duty determination unit 22 determines that an abnormality such as disconnection has occurred in the signal input line 7 that is the transmission path of the control signal Si. to decide. Then, a disconnection abnormality signal is output to the output setting unit 20 and the diagnosis determination unit 26. Details of these processes by the duty determination unit 22 will be described later.

  The output setting unit 20 performs output setting of the drive unit 21 so that a voltage corresponding to the duty of the control signal Si is applied to the fuel pump 1 when the full-on command is not given from the duty determination unit 22. Further, when the full-on command is given, the output setting unit 20 sets the output of the driving unit 21 so that the transistor M1 is continuously turned on and the transistor M2 is continuously turned off.

  The drive unit 21 generates a drive signal based on the output setting by the output setting unit 20, and outputs the drive signal to the gates of the transistors M1 and M2. The transistors M1 and M2 are turned on / off based on this drive signal. In this manner, the voltage applied to the fuel pump 1 is duty-controlled based on the control signal Si given from the ECU 3.

  Further, the voltage between both terminals of the fuel pump 1 is fed back to the output setting unit 20. Based on this feedback voltage, the output setting unit 20 sets the output of the driving unit 21 so that the voltage applied to the fuel pump 1 becomes a target value (command voltage value corresponding to the duty of the control signal Si). Thus, feedback control is performed so that the motor of the fuel pump 1 rotates at a desired rotation speed.

  The overvoltage protection unit 23 detects the voltage (battery voltage VB) of the power line 13. When the detected voltage exceeds a predetermined threshold voltage, the overvoltage protection unit 23 determines that the battery voltage VB is excessive and outputs an overvoltage abnormality signal to the drive unit 21. When the overvoltage abnormality signal is given, the driving unit 21 stops driving the transistors M1 and M2. Alternatively, only the transistor M1 may be turned on and the motor of the fuel pump 1 may consume energy.

  The overheat protection unit 24 detects the voltage across the terminals of the diode D1. The overheat protection unit 24 uses the temperature characteristic of the forward voltage of the diode D1 (the characteristic that the forward voltage decreases as the temperature rises), and estimates the temperature fluctuation of the transistor M1 based on this inter-terminal voltage. The overheat protection unit 24 determines that the temperature of the transistor M1 is excessively high when the estimated temperature fluctuation is a temperature increase exceeding a predetermined threshold, and the output setting unit 20 and the diagnosis determination unit 26 outputs an overheat abnormality signal.

  The overcurrent detection unit 25 detects the drain-source voltage of the transistor M1. When this voltage exceeds a predetermined threshold voltage, the overcurrent detection unit 25 determines that the current flowing through the transistor M1 and thus the fuel pump 1 is excessive, and the output setting unit 20 and the diagnosis determination unit 26. Output an overcurrent error signal.

  The output setting unit 20 sets the output of the driving unit 21 so as to stop the driving of the transistors M1 and M2 when any of the overheat abnormality signal, the overcurrent abnormality signal, or the disconnection abnormality signal is given. When any of the overheat abnormality signal, the overcurrent abnormality signal, or the disconnection abnormality signal is given, the diagnosis determination unit 26 determines that an abnormality has occurred in the FPC 2 and outputs a signal indicating the result to the diagnosis output unit 27. . In response to this, the diagnosis output unit 27 outputs a diagnosis signal Di of an active level (the potential of the ground line 14 = 0V). On the other hand, when none of the above abnormal signals is given to the diagnosis determination unit 26, that is, when the FPC 2 is normal, the diagnosis output unit 27 outputs the diagnosis signal Di at the inactive level (potential of the power supply line 13 = VB). Is output.

  FIG. 2 shows the relationship between the duty of the control signal Si and the applied voltage applied to the fuel pump 1. As shown in FIG. 2, the applied voltage is fixed to the minimum value (0 V) when the duty is less than about 10%. That is, the drive of the fuel pump 1 is stopped. In a state where the duty is about 10% to about 80%, the applied voltage changes continuously (steplessly) according to the duty. That is, the linear control method is used during this period. In a state where the duty is about 85% to about 90%, the transistor M1 is turned on 100% (always on) and the applied voltage is fixed to the maximum value (+ 13V). When the duty exceeds about 90%, it is determined that the control signal Si is fixed at the potential of the power supply line 13 (potential fixed state), and the applied voltage is fixed to the minimum value (0 V).

  Hysteresis is set near the duty for reducing the applied voltage to the minimum value, near the duty for the maximum value, and near the duty for determining that the potential is fixed. Thereby, it is suppressed that the state of the applied voltage (driving state of the fuel pump 1) largely changes due to a slight fluctuation of the duty due to the influence of noise or the like.

  In the present embodiment, the duty of the control signal Si generated in the ECU 3 is 0% (corresponding to the first predetermined value) to about 90% (corresponding to the second predetermined value). Therefore, a state in which a signal having a duty of 0% to about 90% is applied to the signal input line 7 corresponds to a state in which the control signal Si is given from the ECU 3. Further, as described above, the duty of the control signal Si generated in the ECU 3 does not exceed about 90%. For this reason, a state in which a signal having a duty of about 90% to 100% is applied to the signal input line 7 is that the signal input line 7 is fixed to the potential of the power supply line 13 and the control signal Si is given from the ECU 3. Corresponds to no state.

Next, the operation of the fuel pump control system of this embodiment will be described.
First, the operation when starting the engine when the signal input line 7 is normal will be described with reference to FIG. FIG. 3 shows the signal and voltage states of each part in such a case, and shows the control signal Si, the applied voltage to the fuel pump 1, and the diagnosis signal Di in order from the top.

  When the ignition switch 10 is turned on to start the engine, power is supplied to the ECU 3 via a power supply circuit (not shown) and power supply to the FPC 2 is started. At the same time, initialization of the CPU of the ECU 3 is started. When a command to start the engine is given during this initialization period (starter on), the transistor M3 is fixed in the OFF state without being controlled by the CPU. Thereby, the potential of the signal input line 7 (control signal Si) rises from 0 V together with the potential of the power supply line 13, and is fixed to the battery voltage VB (time t1).

  Then, the duty determination unit 22 determines that the duty of the control signal Si has changed from 0% which is the minimum value to 100% which is the maximum value. Thereafter, when the duty determination unit 22 detects that this duty = 100% state (potential fixed state) continues for the period T1, it outputs a full-on command to the output setting unit 20 (time t2). The period T1 (corresponding to the first period) in the present embodiment is set to 1 ms to 15 ms, for example. Note that the period T1 is not limited to this. For example, in consideration of the possibility that the potential of the signal input line 7 is erroneously changed to the potential of the power supply line 13 due to noise or the like, the period T1 is changed temporarily. On the other hand, the period may be set so as to prevent a situation in which it is erroneously determined that the potential is fixed.

  By giving a full-on command to the output setting unit 20, the transistor M1 is continuously turned on (always on) and the transistor M2 is continuously turned off (always off). As a result, the voltage applied to the fuel pump 1 reaches a maximum value (for example, +13 V), and the fuel pump 1 is immediately started. The duty determination unit 22 continues to output the full-on command until a point in time when the control signal Si is given from the ECU 3 and the potential fixed state is released and until the end point of a period T2 to be described later, whichever comes first. .

  Here, at the time t4, the initialization of the CPU of the ECU 3 is completed, and the supply of the control signal Si from the ECU 3 is started. That is, since the potential fixed state is released at time t4, the duty determination unit 22 stops outputting the full-on command to the output setting unit 20 at this time. In response to this, the output setting unit 20 performs output setting for the drive unit 21 in accordance with the duty of the control signal Si. Then, at time t5 when one cycle of the control signal Si elapses from time t4, on / off control based on the duty of the control signal Si is started for the transistors M1 and M2.

  As a result, the motor of the fuel pump 1 rotates at a rotational speed corresponding to the duty, and the fuel stored in the fuel tank is supplied to the engine at a target flow rate. Thus, the state in which the maximum voltage is applied to the fuel pump 1 is continued from the time t2 to the time t5 when the engine is started. The state of applying the maximum voltage may be canceled between time t2 and time t5, or may be continued until after time t5.

  The diagnostic signal Di output from the FPC 2 to the ECU 3 is fixed at the active level (L level) from time t1 to time t3, and then changes to the inactive level (H level). This is because a delay occurs until the diagnosis signal Di reaches its original value due to the signal processing time by the diagnosis determination unit 26 and the diagnosis output unit 27 from the start of power supply to the FPC 2, and the time for which the determination processing is reliably performed. This is to ensure

  However, during the period when the diagnosis signal Di is fixed at the active level, the CPU of the ECU 3 is being initialized, and failure diagnosis based on the diagnosis signal Di is not performed. Then, at the time when the initialization of the CPU is completed (time t4), the diagnosis signal Di is an original value (in this case, an inactive level). Therefore, even if the diagnosis signal Di is fixed at the active level immediately after the FPC 2 is started, there is no influence on the diagnostic operation of the FPC 2 by the ECU 3.

  When the potential fixing state continues from the time (time t1) when the duty of the control signal Si is determined to have changed from 0% to 100% (time t1) until the time T2 elapses (time t6), the signal is input. It is determined that an abnormality has occurred in the line 7. Here, after time t4, the control signal Si is normally supplied from the ECU 3, and the duty is not about 90% to 100% (potential fixed state). Therefore, the duty determination unit 22 determines that the signal input line 7 is normal, and the diagnosis signal Di output from the diagnosis output unit 27 is maintained at an inactive level (H level).

  In the present embodiment, the above-described period T2 (corresponding to the second period) is set to, for example, 100 ms to 2 s. The period T2 is not limited to this. Considering the time required for the ECU 3 to generate the control signal Si, at least the period necessary until the supply of the control signal Si from the ECU 3 to the FPC 2 is started. A longer period may be set.

  Subsequently, an operation at the time of engine start when an abnormality such as a disconnection occurs in the signal input line 7 will be described with reference to FIG. FIG. 4 is a diagram corresponding to FIG. 3 showing the signal and voltage states of the respective parts in such a case. In such a case as well, as in the case where the signal input line 7 shown in FIG. 3 is normal, power supply to the ECU 3 and the FPC 2 is started after the ignition switch 10 is turned on to start the engine. During the period when the CPU of the ECU 3 is initialized, the transistor M1 is continuously turned on and the transistor M2 is continuously turned off to apply the maximum voltage to the fuel pump 1, and the fuel pump 1 is immediately started. Is done.

  As described above, the duty determination unit 22 outputs the full-on command until the time point when the control signal Si is given from the ECU 3 and the potential fixed state is released and until the end point of the period T2, whichever is earlier. Keep doing. Here, the potential fixed state continues after the end of the period T2 (time t6), and the supply of the control signal Si to the FPC 2 is not started. Accordingly, the duty determination unit 22 continues to output a full-on command until the end of the period T2. In such a case, the state in which the maximum voltage is applied to the fuel pump 1 is continued from time t2 to time t6 when the engine is started.

  When the potential fixing state continues from the time (time t1) when the duty of the control signal Si is determined to have changed from 0% to 100% (time t1) until the time T2 elapses (time t6), the signal is input. It is determined that an abnormality has occurred in the line 7. Here, the potential fixed state is continued even at the end of the period T2 (time t6). For this reason, the duty determination unit 22 determines that an abnormality such as a disconnection has occurred in the signal input line 7. Thereafter, after a predetermined signal processing time has elapsed, the diagnosis signal Di output from the diagnosis output unit 27 changes to the active level (L level) (time t7). The ECU 3 receives this active level diagnosis signal Di, diagnoses that an abnormality has occurred in the FPC 2, and executes a predetermined abnormality handling process, for example, a process of storing a diagnosis code and warning the user.

  As described above, the fuel pump control device 2 of the present embodiment includes the resistor R1 that fixes the potential of the signal input line 7 to the potential of the power supply line 13 until the control signal Si is supplied from the ECU 3, and this potential. And a control circuit 6 for applying a maximum voltage to the fuel pump 1 when it is detected that the fixed state has continued for the period T1. Thereby, voltage application to the fuel pump 1 is started from a period when the control signal Si is not given from the ECU 3 when the engine is started, and the fuel pump 1 is immediately started. The control circuit 6 determines that an abnormality has occurred in the signal input line 7 when detecting that the potential fixed state of the signal input line 7 has continued for the period T2. According to the fuel pump control device 2 having such a configuration, it is possible to reduce the startup time of the fuel pump 1 when starting the engine and to detect an abnormality in the signal input line 7 while suppressing the complexity of the configuration.

  The control circuit 6 outputs the full-on command at the time of starting the engine, and then the time point between the time point when the control signal Si is given from the ECU 3 and the fixed potential state is released, and the time point when the period T2 ends, whichever comes first Until this full on command is output continuously. As a result, the boosting capability of the fuel pump 1 at the time of starting the engine can be sufficiently increased, so that the startup time of the fuel pump 1 can be further reduced.

  Since the potential of the signal input line 7 is fixed to the potential of the power supply power line 13 for supplying power to the fuel pump control device 2 during a period when the control signal Si is not applied, power supply to the fuel pump control device 2 is performed. Immediately after the start, the potential of the signal input line 7 is fixed. Thereby, the starting time of the fuel pump 1 at the time of engine starting can be further reduced. Further, according to such a configuration, it is possible to detect a short circuit (power fault) state between the positive terminal of the battery 9 and the same potential line (for example, the power supply line 13) as an abnormality of the signal input line 7.

  The control circuit 6 linearly controls the voltage applied to the fuel pump 1 based on a control signal Si having a duty that changes continuously. The duty of the control signal Si generated in the ECU 3 is 0% to about 90%. For this reason, the potential fixed state of the signal input line 7 and the state where the control signal Si is applied are clearly distinguished, and the potential fixed state can be easily detected by the control circuit 6. Therefore, even when the system is configured to linearly control the voltage applied to the fuel pump 1, it is possible to reduce the startup time of the fuel pump 1 when the engine is started and to detect an abnormality in the signal input line 7.

  By adopting the linear control method in this way, an effect that the IC 4 on which the control circuit 6 is mounted can be shared is obtained. That is, generally, the applied voltage value to the fuel pump 1 may be several types of switching. However, these several types of voltage values are changed according to the type of vehicle on which the fuel pump 1 is mounted, for example. Therefore, if the linear control method is employed as in the present embodiment, various applied voltage values can be realized by the control circuit 6, and therefore, the common IC 4 can be used to support various types of mounted vehicles. It becomes possible.

  In the above description, the abnormality detection of the signal input line 7 at the time of engine start has been described, but according to the present embodiment, the abnormality detection of the signal input line 7 after the engine start can be similarly performed. However, in this case, since the engine is stopped when the drive of the fuel pump 1 is stopped as a response to the abnormality, the state is controlled so that a predetermined voltage value is applied to the fuel pump 1 (including 100% energization = full-on state). At the same time, it is possible to notify the abnormality by the diagnosis signal Di.

The present invention is not limited to the embodiment described above and illustrated in the drawings, and the following modifications or expansions are possible.
A high-side drive method is used in which the transistor M1, which is a drive element, is connected to a higher potential side than the fuel pump 1, and a low-side drive method is used in which the drive element is connected to a lower potential side than the fuel pump. Also good. Although the transistor M2 which is a power MOSFET is used as the regenerative element, a diode may be used instead. As the driving element, for example, other switching elements such as a P-channel MOSFET and an IGBT may be used. A configuration for detecting each abnormality in the FPC 2 such as the overvoltage protection unit 23, the overheat protection unit 24, and the overcurrent protection unit 25 may be provided as necessary. Although a resistor that pulls up the potential of the signal input line 7 to the potential of the power supply line 13 is used as the potential fixing means, a resistor that pulls down to the potential of the ground line 14 may be used. According to such a configuration, it is possible to detect a short circuit (ground fault) state between the negative terminal of the battery 9 and a line having the same potential (for example, the ground line 14) as an abnormality of the signal input line 7. However, in that case, it is necessary to appropriately change the configuration of the output stage of the control signal Si in the ECU 3, the duty detection process in the input signal processing unit 19, the potential fixing state determination process in the duty determination unit 22, and the like. The potential fixing means may be means for fixing the potential of the signal input line 7 to a potential other than the power supply line 13 and the ground line 14.

The duty of the control signal Si generated in the ECU 3 is not limited to 0% to about 90%, but continuously changes from a first predetermined value to a second predetermined value that is greater than the first predetermined value and less than 100%. Anything to do. Further, the duty of the control signal Si may continuously change from a first predetermined value larger than 0% to a second predetermined value larger than the first predetermined value.
If the control circuit 6 is configured to change the diagnosis signal Di to the active level (L level) when the potential of the signal input line 7 is 0 V, the ECU 2 and the duty of the control signal Si to be output are input in the ECU 2. A system capable of detecting the ground fault state of the signal input line 7 based on the level of Di can be configured. In this case, if the lower limit value of the duty of the control signal Si is set to a value exceeding 0%, the ground fault state of the signal input line 7 can be reliably detected.
The duty of the control signal Si is not limited to continuously changing, and may be changed in multiple stages. That is, the control of the voltage applied to the fuel pump 1 based on the control signal Si is not limited to the linear control method. However, it is necessary to be able to distinguish between each duty and the potential fixed state. Further, the control signal Si is not limited to a signal having a duty indicating a command of the voltage applied to the fuel pump 1, but is a signal indicating a command of the voltage applied to the fuel pump 1 by a change in a state distinguishable from the potential fixed state. I just need it.

  In the drawing, 1 is a fuel pump, 2 is a fuel pump control device, 6 is a control circuit, 7 is a signal input line, 13 is a power supply line (DC power supply line), 14 is a ground line (DC power supply line), M1 is a transistor ( Switching element), R1 represents a resistance (potential fixing means).

Claims (5)

A fuel pump control device for controlling driving of a fuel pump for supplying fuel in a fuel tank to an engine,
A switching element connected in series with the fuel pump between a pair of DC power lines;
A control circuit for controlling a voltage applied to the fuel pump by turning on and off the switching element based on a control signal given from the outside through a signal input line;
A potential fixing means for fixing the potential of the signal input line to a predetermined potential during a period in which the control signal is not applied;
The control circuit turns on the switching element upon detecting that the state where the potential of the signal input line is the predetermined potential continues for a first period at the time of starting the engine, and the potential of the signal input line is A fuel pump control device, wherein when it is detected that the state at the predetermined potential has continued for a second period longer than the first period, it is determined that an abnormality has occurred in the signal input line.   2. The fuel pump control according to claim 1, wherein the control circuit maintains the ON state until the control signal is given after the switching element is turned ON at the time of starting the engine. apparatus.   3. The fuel pump control device according to claim 1, wherein the predetermined potential is one of the pair of DC power supply lines. When the predetermined potential is a high potential side potential of the pair of DC power supply lines,
The control signal is a signal having a duty that continuously changes from a first predetermined value to a second predetermined value that is greater than the first predetermined value and less than 1.
4. The fuel pump control device according to claim 3, wherein the control circuit controls on / off of the switching element so as to apply a voltage according to the duty to the fuel pump. When the predetermined potential is a low potential side potential of the pair of DC power supply lines,
The control signal is a signal having a duty that continuously changes from a first predetermined value larger than 0 to a second predetermined value larger than the first predetermined value;
4. The fuel pump control device according to claim 3, wherein the control circuit controls on / off of the switching element so as to apply a voltage according to the duty to the fuel pump.

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