JP2008063967A - Glow plug control device - Google Patents

Abstract

Provided is a configuration capable of performing backup drive by appropriately reflecting a state before occurrence of an abnormality when an abnormality occurs in a microprocessor that controls a glow plug.
A glow plug control device includes a switch unit provided between a battery and a glow plug, and a microprocessor that outputs an on signal and an off signal to the switch unit. Yes. Further, the glow plug control device 1 includes an RS flip-flop circuit 12 that stores information (control information) related to the control of the switch unit 20 by the microprocessor 10, and the supply voltage level to the microprocessor 10 is lower than the normal level. In the case of a lowered state (abnormal state), the switch unit 20 is configured to be backed up by the transistors 14 and 16 based on the control information stored in the RS flip-flop circuit 12 before the abnormal state.
[Selection] Figure 1

Description

  The present invention relates to a glow plug control device.

2. Description of the Related Art Conventionally, there has been provided a control device that performs energization control of a glow plug used in a diesel vehicle by a control means such as a microprocessor. In such a control device, the inoperability of the control means due to a decrease in the terminal voltage of the battery becomes a problem.
Japanese Patent Laid-Open No. 2005-220921

  A technique such as Patent Document 1 is provided to solve the above problems. In the technique of Patent Document 1, even when a microprocessor as a control means cannot be driven due to a voltage drop caused by cranking or the like, the glow plug can be driven by a backup circuit provided in parallel with the microprocessor. .

  However, the backup circuit disclosed in Patent Document 1 has a configuration in which the glow plug is continuously driven when the power supply level of the microprocessor is equal to or higher than a predetermined level and the output port is high impedance. Even so, there is a problem that the glow plug is backed up.

  The present invention has been completed based on the above circumstances, and when an abnormality occurs in the control means for controlling the glow plug, the state before the abnormality can be appropriately reflected and backup drive can be performed. The purpose is to provide a configuration.

As a means for achieving the above object, the invention of claim 1 provides a glow plug control device comprising:
A switch means provided between the battery and the glow plug, for switching between energization and de-energization of the glow plug;
Control means for outputting an on signal and an off signal to the switch means;
Storage means for storing control information of the switch means by the control means;
A drive unit that drives the switch unit based on the control information stored in the storage unit before the abnormal state when the supply voltage supplied to the control unit is in an abnormal state that is lower than a normal level;
It is provided with.

The invention of claim 2 is the glow plug control device according to claim 1 or 2,
The storage means can be driven with a voltage lower than that of the control means.

The invention of claim 3 is the glow plug control device according to claim 1 or 2,
The control means outputs a first signal from a predetermined output terminal when starting energization control of the switch means, and outputs a second signal from the output terminal when stopping energization control of the switch means. ,
The storage means is configured to store energization control information as the control information from when the first signal is output by the control means until the second signal is output,
The drive means outputs a drive signal for backup to the switch means when the power-on-control information is stored in the storage means in the abnormal state.

The invention of claim 4 is the glow plug control device according to claim 1 or 2,
The control means outputs a first signal from a predetermined output terminal when starting energization control of the switch means, and outputs a second signal from the output terminal when stopping energization control of the switch means. ,
The storage means is configured to store non-controlling information as the control information until the first signal is output after the second signal is output by the control means,
The drive means does not drive the switch means when the non-controlling information is stored in the storage means in the abnormal state.

The invention of claim 5 is the glow plug control device according to claim 3 or claim 4, wherein
The storage means is in a set state until either one of the first signal and the second signal is output until the other is output, and the other is output after the other is output. Until the predetermined terminal is a flip-flop circuit in a reset state,
The drive means turns on the switch means when the predetermined terminal of the flip-flop circuit is in a state corresponding to the first signal in the set state and the reset state, and the second signal The switch means is turned off when it is in a state corresponding to.

The invention of claim 6 is the glow plug control device according to claim 5,
The output terminal is in a high impedance state during the abnormal state.

The invention according to claim 7 is the glow plug control device according to any one of claims 1 to 6,
The control means is configured to continuously output the ON signal to the switch means when the glow plug is energized,
The first signal is emitted in response to the output start of the on signal, and the second signal is emitted in response to the output stop of the on signal.

The invention of claim 8 is the glow plug control device according to any one of claims 1 to 6,
The control means is configured to output a PWM signal to the switch means,
The first signal is emitted in response to the start of PWM signal output, and the second signal is emitted in response to the output stop of the PWM signal.

<Invention of Claim 1>
According to the invention of claim 1, when an abnormality occurs in the control means for controlling the glow plug, the switch means is backed up by appropriately reflecting the state before the abnormality occurs based on the control information stored in the storage means. It becomes possible to drive.

<Invention of Claim 2>
According to the invention of claim 2, the storage means can be driven even when the supply voltage to the control means is lower than the normal level for the control means. I can remember.

<Invention of Claim 3>
According to the invention of claim 3, when the control means is in an abnormal state, it can be confirmed whether or not the energization control was performed before the occurrence of the abnormality (that is, whether or not the energization control was being performed). When the energization control is being performed, the glow plug can be appropriately backed up to reflect the state.

<Invention of Claim 4>
According to the invention of claim 4, when the control means is in an abnormal state, it is possible to confirm whether the energization control has not been performed before the abnormal state. Further, when the non-control is being performed, the glow plug can be prevented from being back-up driven, so that useless backup driving can be appropriately prevented.

<Invention of Claim 5>
According to the invention of claim 5, whether or not the energization control for the switch means has been performed before the supply voltage drop to the control means can be stored with a simple and inexpensive configuration, and appropriately based on the control information. Backup drive will be possible.

<Invention of Claim 6>
According to the invention of claim 6, since the output terminal becomes high impedance when an abnormality occurs, the predetermined terminal of the flip-flop circuit does not change to the set state or the reset state, and the control information before the occurrence of the abnormality is stored well. I can leave.

<Invention of Claim 7>
According to the seventh aspect of the present invention, the switch means can be appropriately back-up driven in the configuration in which the ON signal is continuously output to the switch means when the glow plug is energized.

<Invention of Claim 8>
According to the eighth aspect of the present invention, in the configuration in which the PWM signal is output to the switch means when the glow plug is energized, the switch means can be appropriately backed up.

<Embodiment 1>
Embodiment 1 of the present invention will be described with reference to the drawings.
1. Overall Configuration FIG. 1 is a block diagram conceptually illustrating a glow plug control device 1 according to Embodiment 1 of the present invention. FIG. 2 is a timing chart for explaining various timings by the glow plug control device 1. FIG. 3 is a flowchart illustrating the flow of control by the glow plug control device 1.

  The glow plug control device 1 controls the glow plug 30 by receiving power supply from an automobile battery 3 (hereinafter also referred to as a battery 3). The glow plug control device 1 includes a switch unit 20 provided between the battery 3 and the glow plug 30 and a microprocessor 10 that controls the switch unit 20.

  The microprocessor 10 is connected to the constant voltage circuit 4 and is configured to operate upon receiving power supply from the constant voltage circuit 4. The microprocessor 10 is configured such that the terminal P3 is connected to the switch unit 20 and outputs an ON signal and an OFF signal to the switch unit 20. The microprocessor 10 corresponds to an example of a control unit.

  The constant voltage circuit 4 is configured as a known power supply circuit, and is configured to receive power from the battery 3 and apply a constant voltage to the microprocessor 10 when the ignition switch 2 is on. .

  The switch unit 20 is connected to the power supply line 5 from the battery 3 to the glow plug 30 and is configured to switch between energization and de-energization of the glow plugs 30 connected in parallel. Specifically, a mechanical relay 21 and a transistor 22 that switches driving and non-driving of the relay are provided. The base of the transistor 22 is connected to the terminal P3 of the microprocessor 10 via the resistor 24. When the H level signal is output from the terminal P3, the transistor 22 is turned on, and the relay 21 is turned on accordingly. ing. One end of a resistor 25 is connected between the resistor 24 and the transistor 22, and the other end of the resistor 25 is grounded.

  Each of the glow plugs 30 is configured as a known glow plug, and here, a glow plug group is configured by four glow plugs 30. One end of the four glow plugs 30 is connected in common and connected to one end of the relay 21. The other end of the glow plug 30 is grounded, and when the relay 21 is turned on, the four glow plugs 30 are energized simultaneously.

2. Configuration related to backup drive Next, a configuration related to backup drive when an abnormality occurs in the microprocessor 10 will be described.
In the glow plug control device 1 according to the present embodiment, an RS flip-flop circuit 12 is connected to a predetermined output terminal P1 of the microprocessor 10. The RS flip-flop circuit 12 stores control information of switch means by the microprocessor 10.

  The microprocessor 10 is configured to continuously output an on signal from the terminal P3 to the switch 20 when the glow plug 30 is energized. In response to the continuous on signal, the switch 22 is turned on and the relay 21 is turned on. Turns on. When such energization control is started (when a continuous ON signal is output from the terminal P3), the first signal is output from the output terminal P1, and when the energization control is stopped, the second signal is output from the output terminal P1. A signal is output.

  More specifically, an H level signal is output from the output terminal P1 during the energization process by the microprocessor 10 (during the period when the ON signal is output from the terminal P3 in this embodiment). The H level signal at the output terminal P1 corresponds to the first signal. Further, an L level signal is output from the output terminal P1 during a period when the energization processing by the microprocessor 10 is not performed (in the present embodiment, during a period when an OFF signal is output from the terminal P3). The L level signal from the output terminal P1 corresponds to the second signal.

  The RS flip-flop circuit 12 corresponding to an example of the storage means has an S terminal connected to the output terminal P1 of the microprocessor 10 and an R terminal connected to the output terminal P1 via the inverter 11. That is, when the H level signal is output from the output terminal P1, the H level signal is input to the S terminal and the L level signal is input to the R terminal. When an H level signal is input to the S terminal and an L level signal is input to the R terminal, an H level signal is output from the Q terminal. On the contrary, when the L level signal is output from the output terminal P1, the L level signal is input to the S terminal and the H level signal is input to the R terminal. The Q terminal corresponds to an example of a predetermined terminal.

  The RS flip-flop circuit 12 is configured to store energization control information as control information from when the first signal is output from the output terminal P3 by the microprocessor 10 until the second signal is output. In the present embodiment, the information for holding the terminal Q at the H level corresponds to “power-on-control information”. Similarly, during the period from when the second signal is output by the microprocessor 10 to when the first signal is output, non-controlling information is stored as control information. In this embodiment, the terminal Q is set to L Information held in the level corresponds to “non-controlling information”.

  In the present embodiment, when the supply voltage supplied to the microprocessor 10 is in an abnormal state in which the supply voltage is lower than the normal level, the switch unit 20 operates based on the control information stored in the RS flip-flop circuit 12 before the abnormal state. It is designed to be driven. In the present embodiment, the transistor 14 and the transistor 16 correspond to an example of a driving unit.

  The transistor 16 is configured as a PNP bipolar transistor, the base terminal is connected to the microprocessor terminal P2 via the resistor 17, and the emitter terminal is connected to the power supply line 6 from the constant voltage circuit. Yes. The collector terminal of the transistor 16 is connected to the base terminal of the transistor 14. One end of the resistor 15 is connected to a connection line between the collector terminal of the transistor 16 and the base terminal of the transistor 14, and the other end of the resistor 15 is grounded.

  The transistor 14 is configured as a PNP transistor, and the emitter terminal is connected to the Q terminal of the RS flip-flop circuit 12. The collector terminal of the transistor 14 is connected to the output line 7 from the terminal P3 (that is, connected to the switch unit 20).

3. Backup Operation Next, the backup operation will be described.
The RS flip-flop circuit 12 is connected to the power supply line 6 from the constant voltage circuit 4 and can be driven with a voltage lower than that of the microprocessor 10, and the supply voltage supplied to the microprocessor 10 is lower than the normal level. Even in the case of a lowered abnormal state, the RS flip-flop circuit 12 operates normally as long as it is equal to or higher than the drive voltage of the RS flip-flop circuit 12. There are many logic ICs that operate at an operating voltage lower than the operating voltage of the microprocessor, such as the RS flip-flop circuit 12 of the present embodiment. In this embodiment, the normal operating voltage of the microprocessor is VA1. ˜VA2 and the case where the normal operation voltage of the RS flip-flop circuit 12 is VB1 to VB2 (where VB1 <VA1) will be described as an example.

  FIG. 3 is a flowchart illustrating the flow of port control processing. A program relating to this flowchart is stored in a ROM or the like in the microprocessor 10, and the program is executed by the CPU in the microprocessor 10 when the energization process for the glow plug 30 is started or stopped. It has become.

  When the process is executed, it is determined in S10 whether the energization process is performed. Whether or not this energization process can be performed can be determined by a known method. As an example, the energization process is performed when the ignition switch 2 is turned on and the engine water temperature, the crank position, and the glow plug temperature satisfy predetermined conditions. It is determined that the process is being executed.

  When the energization process is performed (Yes in S10, the terminal P1 is set to the H level and the terminal P2 is set to the L level. On the other hand, when it is determined that the energization process is not performed in S10, S10 The terminal P1 is set to the L level and the terminal P2 is set to the H level in Fig. 2. In Fig. 2, after the energization process is started at T1, an abnormal state (constant voltage circuit 4) is set for the period T2 to T3. In the case where the supply voltage from the power supply to the normal level of the microprocessor 10 occurs).

  As shown in FIG. 2, the setting that the terminal P1 is set to the H level and the terminal P2 is set to the L level is made almost simultaneously with the ON signal output from the terminal P3. In the present embodiment, an ON signal is continuously output to the switch unit 20 when the glow plug 30 is energized. Note that the H level signal from the output terminal P1 corresponding to the first signal is issued in response to the start of the output of this ON signal (H level signal from the terminal P3), and is output from the output terminal P1 corresponding to the second signal. The L level signal is issued in response to the output stop of the ON signal (L level signal from the terminal P3). Since the terminal P1 is kept at the H level and the terminal P2 is kept at the L level during the period from T1 to T2 when the ON signal is output from the terminal P3, the Q terminal of the RS flip-flop circuit 12 is set to the H level. Is done.

  During this period T1 to T2, since the terminal P2 is at L level, the transistor 16 is turned on, and the output from the transistor 16 is at H level. Accordingly, the transistor 14 is turned off and no backup signal is output, and the switch unit 20 is driven by the on signal from the terminal P3. In the switch unit 20, the relay 21 is turned on when an ON signal is input to the base terminal of the transistor 22, whereby the glow plug 30 is energized.

  On the other hand, when the supply voltage from the constant voltage circuit 4 becomes equal to or lower than the normal operating voltage VA1 of the microprocessor 10, the microprocessor 10 stops driving and enters a reset state. At this time, both the terminals P1 and P2 are in a high impedance state without outputting the H level signal and the L level signal. FIG. 2 shows an example in which the microprocessor 10 is in an abnormal state during the period T2 to T3. When this abnormal state occurs, the ON signal output from the terminal P3 is cut off.

  At this time, since the output terminal P1 has not changed to the L level, the memory of the RS flip-flop circuit 12 is retained, and the Q terminal is still maintained at the H level. That is, in the RS flip-flop circuit 12, the Q terminal is set until the second signal (L level signal from the output terminal P1) is output after the first signal (H level signal from the output terminal P1) is output. Since the Q terminal is in a reset state from when the second signal (L level signal from the output terminal P1) is output until (H level signal from the output terminal P1) is output, the output terminal P1 has a high impedance. The Q terminal does not change even if it becomes a state.

  On the other hand, since the terminal P2 is in a high impedance state, the transistor 16 is turned off, and the output of the transistor 16 is at L level. Then, the transistor 14 is turned on, and the output of the transistor 14 becomes H level. The H level output of the transistor 14 becomes a backup signal, the transistor 22 is operated, and the switch unit 20 is turned on. That is, in this configuration, when the transistors 14 and 16 corresponding to an example of the drive unit store abnormally controlled information in the storage unit in an abnormal state (that is, the Q terminal of the RS flip-flop circuit 12 is held at the H level). In this case, a backup drive signal is output to the switch unit 20.

  As shown in FIG. 2, when the supply voltage to the microprocessor 10 returns to the normal level or higher of the microprocessor 10 at time T3, the microprocessor 10 again determines whether or not to perform the energization processing of the glow plug 30. When energization processing is performed, an ON signal is output from the terminal P3, and the terminals P1 and P2 are set to H level and L level, respectively.

  At this time, since the transistor 14 is turned off and the transistor 16 is turned on similarly to the periods T1 to T2, the backup drive signal is not output. When the microprocessor 10 determines to end the energization process of the glow plug 30, the on signal from P3 is stopped as shown in T4, the terminal P1 is set to the L level as shown in the flowchart of FIG. Terminal P2 is set to H level. At this time, the transistors 14 and 16 are both turned off.

  During such energization stop, the S terminal is at the L level and the R terminal is at the H level based on the terminal P1 being set at the L level. Therefore, the Q terminal is set to the L level. After the Q terminal is set to the L level, the microprocessor 10 has an abnormality, and even if both the terminals P1 and P2 become high impedance, the Q terminal is still at the L level. Retained. Therefore, even if the output of the transistor 16 becomes L level, the transistor 14 is not turned on and no backup drive signal is output. That is, the transistors 14 and 16 corresponding to an example of the driving unit do not drive the switch unit 20 when the non-controlling information is stored in the RS flip-flop circuit 12 serving as the storage unit in an abnormal state.

  As described above, according to the configuration of the present embodiment, when an abnormality occurs in the microprocessor 10 that controls the glow plug 30, the control information stored in the RS flip-flop circuit 12 corresponding to an example of a storage unit is stored. Based on this, the state before the occurrence of abnormality is appropriately reflected, and the switch unit 20 corresponding to an example of the switch means can be backed up.

  Further, the RS flip-flop circuit 12 corresponding to an example of a storage unit can be driven with a voltage lower than that of the microprocessor 10. Therefore, even when the supply voltage to the microprocessor 10 is lower than the normal level for the microprocessor 10, the RS flip-flop circuit 12 can be driven, so that the control information before the abnormal state can be suitably stored. It becomes like this.

  The microprocessor 10 outputs an H level signal as the first signal from the output terminal P1 when starting the energization control of the switch unit 20, and as the second signal when stopping the energization control of the switch unit 20. The L level signal is output from the output terminal P1. The RS flip-flop circuit 12 is configured to store energization control information as control information from when the first signal is output by the microprocessor 10 until the second signal is output, and the transistor 14 corresponding to the driving means. , 16 operate to output a drive signal for backup to the switch unit 20 when the energization control information is stored in the RS flip-flop circuit 12 in an abnormal state. Therefore, when the microprocessor 10 is in an abnormal state, it can be confirmed whether or not the energization control was performed before the abnormality occurred (that is, whether or not the energization control was being performed). The glow plug 30 can be appropriately backed up to reflect the state.

  The RS flip-flop circuit 12 is configured to store non-controlling information as control information from when the second signal is output by the microprocessor 10 until the first signal is output, and corresponds to driving means. The transistors 14 and 16 are configured not to drive the switch unit 20 when non-controlling information is stored in the RS flip-flop circuit 12 in an abnormal state. Therefore, when the microprocessor 10 is in an abnormal state, it can be confirmed whether the energization control has not been performed before the occurrence of the abnormality. If the microprocessor 10 is not being controlled, the glow plug 30 is not driven to be backed up. Therefore, useless backup drive can be appropriately prevented.

  In addition, the memory means is constituted by the flip-flop circuit 12, and the transistors 14 and 16 as the driving means have the Q terminal (predetermined terminal) of the flip-flop circuit 12 in a set state corresponding to the first signal. The switch unit 20 is turned on, and the switch unit 20 is turned off when the reset state corresponding to the second signal is established. Therefore, it is possible to store whether or not the energization control for the switch unit 20 has been performed before the supply voltage is lowered to the microprocessor 10 as the control means with a simple and inexpensive configuration, and appropriately perform backup drive based on the control information. become able to.

  Since the output terminal P1 of the microprocessor 10 is in a high impedance state in an abnormal state, even if an abnormality occurs, the Q terminal of the flip-flop circuit 12 does not change to the set state or the reset state, and control before the abnormality occurs Information can be stored well.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described with reference to FIG.
The second embodiment is different from the first embodiment in that the switch unit 20 is changed to the switch unit 120 and a PWM signal is output from the terminal P3 during the energization process. Therefore, FIG. 1 is changed to FIG. 4 and will be described with reference to FIG. 4 and FIGS. In addition, about the part same as Embodiment 1, the code | symbol same as Embodiment 1 is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 4, in this embodiment, a switch unit 120 made of an FET (for example, a power MOSFET) is provided instead of the switch unit 20. Similar to the switch unit 20 of the first embodiment, the switch unit 120 is turned on by an H level signal from the terminal P3 or an almost H level signal from the transistor 14, and the terminal P3 is at the L level and the output of the transistor 14 is at the L level. It is configured to turn off.

  In the present embodiment, a PWM signal is output during energization control (between periods T1 to T2 and between engines T3 to T4 in FIG. 2). The H level signal (first signal) at the output terminal P1 is issued in response to the start of output of the PWM signal, and the L level signal (second signal) at the output terminal P1 is issued in response to the output stop of the PWM signal. When outputting the PWM signal, the terminal P1 is set to H level and the terminal P2 is set to L level. Conversely, when stopping the output of the PWM signal, the terminal P1 is set to L level and the terminal P2 is set to H level. During energization control by the microprocessor 10 (during the output period of the PWM signal), the Q terminal is kept at the H level, and when the supply voltage to the microprocessor 10 drops to an abnormal level, the output terminals P1 and P2 become high impedance. The Q terminal is still kept at the H level. At this time, as in the first embodiment, the transistor 14 is turned on and a drive signal for backup is supplied to the switch unit 120.

  On the other hand, during the non-energization control (during the period when the PWM signal is not output), the Q terminal is at the L level, and when the supply voltage to the microprocessor 10 decreases to an abnormal level during the de-energization control, the output terminals P1, Although P2 becomes high impedance, the Q terminal is still kept at the L level and the transistor 14 is not turned on, so that the backup drive signal is not output.

<Embodiment 3>
Next, Embodiment 3 will be described with reference to FIG.
The present embodiment is different from the first embodiment in that a plurality of switch means are provided and an ON signal can be individually output from the microprocessor 10 to each switch means.

  Specifically, the power supply line 5 from the battery is divided into a plurality of branch lines 5A to 5D, and switch units 221 to 224 are provided in the branch lines 5A to 5D, respectively. Plugs 30A to 30D are connected. That is, switch units 221 to 224 are respectively provided in parallel lines of glow plugs 30A to 30D connected in parallel, and these switch units 221 to 224 are turned on in response to ON signals from the terminals P4 to P7. It has a configuration.

  Specifically, the switch units 221 to 224 are each configured by an FET (power MOSFET or the like), and the gate terminals of the switch units 221 to 224 are connected to the terminals P4 to P7, respectively. More specifically, the gate terminal of the switch unit 221 is connected to the terminal P4 via the resistor 231. The cathode side of the diode 211 is connected between the resistor 231 and the terminal P4. One end of the resistor 231 is connected to the line between the resistor 231 and the switch unit 221, and the other end of the resistor 231 is grounded. The gate terminal of the switch unit 222 is connected to the terminal P5 via the resistor 233, and the cathode side of the diode 212 is connected between the resistor 233 and the terminal P5. One end of a resistor 234 is connected to the line between the resistor 233 and the switch unit 222, and the other end of the resistor 234 is grounded. The gate terminal of the switch unit 223 is connected to the terminal P6 via the resistor 235, and the cathode side of the diode 213 is connected between the resistor 235 and the terminal P6. One end of a resistor 236 is connected to the line between the resistor 235 and the switch unit 223, and the other end of the resistor 236 is grounded. The gate terminal of the switch unit 224 is connected to the terminal P7 via the resistor 237, and the cathode side of the diode 214 is connected between the resistor 237 and the terminal P7. One end of a resistor 238 is connected to the line between the resistor 237 and the switch unit 224, and the other end of the resistor 238 is grounded.

  The anode side of each of the diodes 211 to 214 is commonly connected to the transistor 14. In the present embodiment, when the energization process of the glow plug 30 is performed, PWM signals are output from the terminals P4 to P7, and the output start timings at the terminals P4 to P7 may be the same or different. May be. Further, when the energization process is not performed, the output of each of the terminals P4 to P7 is stopped, and the output stop timing of each of the terminals P4 to P7 may be the same or different.

  In the present embodiment, when energization control is started (when a PWM signal is output from at least one of the terminals P4 to P7), an H level signal as the first signal is output from the terminal P1, When the energization control is stopped (when the PWM signals of all the terminals P4 are stopped), the L level signal as the second signal is output from the terminal P2. During energization control by the microprocessor 10 (during the period when the PWM signal is output from at least one of the terminals), the Q terminal is kept at the H level, and when the supply voltage to the microprocessor 10 drops to an abnormal level, the output terminal P1 and P2 become high impedance, but the Q terminal is still kept at the H level. At this time, as in the first embodiment, the transistor 14 is turned on and a drive signal for backup is supplied to the switch units 221 to 224.

  On the other hand, during the de-energization control (during the period when the PWM signal is not output in all of the terminals P4 to P7), the Q terminal is at the L level, and the supply voltage to the microprocessor 10 becomes an abnormal level during the de-energization control. When the voltage drops, the output terminals P1 and P2 become high impedance, but the Q terminal is still kept at the L level and the transistor 14 is not turned on. Therefore, no backup drive signal is given to each of the switches 221 to 224. It becomes.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

(1) In the above embodiment, a continuous H level signal (that is, a direct current signal) and a PWM signal are exemplified as the control signal to the switch means. However, the present invention is not limited to this as long as the signal can be controlled by the switch means. For example, it may be a PAM signal.
(2) In the above embodiment, the switch units 20, 120, and 220 are exemplified as the switch means, but the present invention is not limited to this as long as it can be controlled on and off by a signal from the control means. For example, it may be configured by an IGBT, a thyristor, a bipolar transistor, or the like.
(3) In the above embodiment, an example is shown in which power is supplied from the constant voltage circuit 4 to the microprocessor 10 and the RS flip-flop circuit 12 when the ignition switch 2 is turned on. However, the constant voltage circuit 4 does not depend on whether the ignition switch 2 is turned on or off. The power supply may be performed from the voltage circuit to the microprocessor and the RS flip-flop circuit. For example, the constant voltage circuit 4 of FIG. 1 is connected to the battery 3 without passing through the ignition switch 2, and power is supplied to the microprocessor 10 and the RS flip-flop circuit 12 by the constant voltage circuit 4 that receives power directly from the battery 3. You may do it.

1 is a block diagram conceptually illustrating a glow plug control device according to a first embodiment of the invention. Timing chart for explaining various timings by the glow plug control device 1 Flowchart illustrating port control processing The block diagram which illustrates notionally the glow plug control device concerning Embodiment 2 The block diagram which illustrates notionally the glow plug control device concerning Embodiment 3

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Glow plug control apparatus 3 ... Battery 10 ... Microprocessor (control means)
12 ... RS flip-flop circuit (memory means)
14 ... Transistor (driving means)
16 ... Transistor (drive means)
20 ... Switch part (switch means)
30 ... Glow plug P1 ... Output terminal Q ... Q terminal (predetermined terminal)

Claims (8)

A switch means provided between the battery and the glow plug, for switching between energization and de-energization of the glow plug;
Control means for outputting an on signal and an off signal to the switch means;
Storage means for storing control information of the switch means by the control means;
A drive unit that drives the switch unit based on the control information stored in the storage unit before the abnormal state when the supply voltage supplied to the control unit is in an abnormal state that is lower than a normal level;
A glow plug control device comprising:   The glow plug control device according to claim 1, wherein the storage unit can be driven with a voltage lower than that of the control unit. The control means outputs a first signal from a predetermined output terminal when starting energization control of the switch means, and outputs a second signal from the output terminal when stopping energization control of the switch means. ,
The storage means is configured to store energization control information as the control information from when the first signal is output by the control means until the second signal is output,
The drive means outputs a drive signal for backup to the switch means when the information on energization control is stored in the storage means in the abnormal state. Item 3. The glow plug control device according to Item 2. The control means outputs a first signal from a predetermined output terminal when starting energization control of the switch means, and outputs a second signal from the output terminal when stopping energization control of the switch means. ,
The storage means is configured to store non-controlling information as the control information until the first signal is output after the second signal is output by the control means,
The glow plug control according to claim 1 or 2, wherein the driving means does not drive the switch means when the non-controlling information is stored in the storage means in the abnormal state. apparatus. The storage means is in a set state until either one of the first signal and the second signal is output until the other is output, and the other is output after the other is output. Until the predetermined terminal is a flip-flop circuit in a reset state,
The drive means turns on the switch means when the predetermined terminal of the flip-flop circuit is in a state corresponding to the first signal in the set state and the reset state, and the second signal The glow plug control device according to claim 3 or 4, wherein the switch means is turned off when the state corresponds to the above.   The glow plug control device according to claim 5, wherein the output terminal is in a high impedance state during the abnormal state. The control means is configured to continuously output the ON signal to the switch means when the glow plug is energized,
The first signal is generated in response to the start of output of the ON signal, and the second signal is output in response to the stop of output of the ON signal. The glow plug control device described in 1. The control means is configured to output a PWM signal to the switch means,
The said 1st signal is emitted according to the output start of a PWM signal, The said 2nd signal is emitted according to the output stop of a PWM signal, The Claim 1 thru | or 6 characterized by the above-mentioned. Glow plug control device.

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