JP4174037B2 - Starter drive control circuit - Google Patents

Description

  The present invention relates to a starter drive control circuit, and more particularly to a drive control circuit for a vehicle starter motor that can start an engine even when an electronic control unit becomes inoperable due to a decrease in voltage level.

  Conventionally, the driver (driver) operates the ignition key to rotate it to the starter on position, supplies the operating power (electric power) from the battery to the starter motor, and starts the engine by driving the starter motor. Yes. At this time, the driver confirms that the engine has started with engine sound or the like, and then releases the ignition key to stop the starter motor drive.

  Therefore, even if the engine is completely started, if the driver does not release the ignition key, or conversely, if the driver still takes the action intended to start the engine, the starter motor is driven for an excessive period of time. As a result, deterioration of starter clutches and biting noise occurred. In addition, there is a case where the starter motor is driven again even when the engine is started, without noticing that the engine is idling as the engine is turned down.

  Therefore, in recent years, instead of driving the starter motor directly from the ignition key (ignition switch) via the starter relay, the fact that the driver turned the ignition switch to the starter on position is electronically controlled as a starter on signal. For vehicles whose units (Electronic Control Units (ECUs)) recognize the condition that the starter motor may be driven and the electronic control unit controls the start of the engine by driving the starter relay A drive control circuit for a starter motor is known.

  However, since the series of operations described above are performed by the electronic control unit, the minimum operating voltage (voltage drop threshold) of the electronic control unit becomes a problem. That is, the starter motor is driven to start the engine. However, since the operating power (electric power) supplied to the starter motor when the starter motor is first driven from the stopped state is large, the carry-out current from the battery is The battery voltage at the time of cranking is greatly reduced. At this time, if the battery voltage falls below the minimum operating voltage of the electronic control unit, the electronic control unit stops before the engine is completely started. As a result, a problem arises in that the operating power is not supplied to the starter motor and the engine cannot be started. In addition, although the driver was willing to turn the ignition switch to the starter on position to start the engine, the cranking stopped and the driver sometimes felt uncomfortable.

Therefore, in order to solve the above-described problem, for example, as shown in Patent Document 1, a normally closed relay is provided, and the normally closed relay includes an ignition switch (starter switch), an electronic control unit (engine ECU), and a starter motor. When the excitation coil is energized from the electronic control unit, the starter switch and the starter motor are de-energized. When the excitation coil is not energized, the starter switch and the starter motor are energized. A drive control circuit for a starter motor for a vehicle has been proposed in which the engine is started when the electronic control unit is not in operation.
JP 2003-293916 A (paragraph 0035, FIG. 1, etc.)

  However, in Patent Document 1 described above, two relatively high-capacity relays that can withstand an excessive current that can drive the starter motor are required, and power supply lines to the starter motor are provided in parallel. Since two systems are required, there is a disadvantage that the configuration of the drive control circuit becomes complicated.

  Furthermore, since the relay is switched on / off by mechanical contact, if an excessive current is passed, there is a possibility that an on failure occurs due to arc discharge when switching from on to off. In that case, the drive of the starter motor cannot be stopped unless the starter switch is turned off. Further, since the possibility of such an on-failure of the relay tends to be higher than that of the transistor, the reliability of starting the engine and the merchantability are not satisfied.

  Therefore, the object of the present invention is to solve the above-mentioned problems and to have a simple configuration, and even when the battery voltage is lower than the minimum operating voltage of the ECU and the operation of the ECU is stopped, the electric power is supplied to the starter motor. The starter motor can be started without stopping the driver from releasing the ignition key after the engine has started. An object of the present invention is to provide a drive control circuit for a starter motor for a vehicle that is improved in performance and merchantability.

In order to achieve the above object, in claim 1, a starter motor for starting an engine of a vehicle, a starter relay, a battery connected to the starter motor via a movable switch of the starter relay, An ignition switch interposed between the excitation coil of the starter relay and the battery; and an electronic control unit that receives supply of operating power from the battery in response to an operation of the ignition switch. A starter motor for a vehicle that controls driving of the starter motor by energizing the exciting coil in response to an operation of the ignition switch to make the movable switch conductive and supplying operation power from the battery to the starter motor. In the drive control circuit, the excitation coil While collector terminal is connected, a first transistor of NPN type whose emitter terminal is allowed to ground, a first resistor interposed between the base terminal of said battery and said first transistor, said A collector terminal is connected to a connection point between the first resistor and the second resistor, and a self-bias circuit composed of a second resistor inserted on the ground side of the base terminal of the first transistor. And an NPN-type second transistor whose emitter terminal is grounded, and the electronic control unit is connected to the base terminal of the second transistor , so that the voltage of the battery is connected to the electronic control unit. When the operating voltage drops below the minimum operating voltage, the battery continues to supply operating power from the battery to the starter motor, while the voltage of the battery When it is low operating voltage or more it has continued for a predetermined time, and adapted to return the operation of the electronic control unit.

  According to a second aspect of the present invention, the electronic control unit further includes start detection means for detecting start of the engine, and the electronic control unit is connected to the base terminal of the second transistor when the start of the engine is detected. Configured to provide level output.

In the vehicle starter motor drive control circuit according to claim 1, the collector terminal is connected to the exciting coil of the starter relay, the emitter terminal is grounded, and the NPN first transistor, and the battery And a first resistor inserted between the base terminal of the first transistor and a second resistor inserted on the ground side of the base terminal of the first transistor. A circuit, and an NPN-type second transistor having a collector terminal connected to a connection point of the first resistor and the second resistor and having an emitter terminal grounded, Since the electronic control unit is connected to the base terminal, even if the operation of the electronic control unit is stopped due to a decrease in battery voltage, it is a simple structure. The power supply to the starter motor can be continued as the driver wants to start the engine, and after the engine has started, the starter motor stops driving without having to remove the hand from the ignition key. Therefore, the reliability and commerciality of engine starting can be improved.

  The drive control circuit for a starter motor for a vehicle according to claim 2 further includes start detection means for detecting start of the engine, and the electronic control unit is configured to detect the start of the engine when the start of the engine is detected. Since the high-level output is supplied to the base terminal of the transistor, in addition to the above-described effect, after starting the engine, the drive of the starter motor can be stopped to immediately stop the cranking, Therefore, the reliability and commerciality of engine start can be further improved.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode of a vehicle starter motor drive control circuit according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a circuit diagram showing a configuration example of a drive control circuit for a vehicle starter motor according to a first embodiment of the present invention.

  In FIG. 1, reference numeral 10 denotes a drive control circuit for a vehicle starter motor (hereinafter referred to as “starter drive control circuit 10”). The starter drive control circuit 10 is connected to the starter motor 12 via a starter motor 12 for starting a vehicle engine (not shown), a starter relay 14 connected to the starter motor 12, and a movable switch 14a of the starter relay 14. Battery 16, an ignition switch 18 interposed between the excitation coil 14 b of the starter relay 14 and the battery 16, and an electronic control unit (ECU) that receives operation power from the battery 16 in response to the operation of the ignition switch 18. 20

  Before continuing the description of the starter drive control circuit 10, the configuration and function of the ignition switch 18 of the starter drive control circuit 10 will be outlined. FIGS. 2A to 2D are circuit diagrams of the starter motor 12, the starter relay 14, the battery 16, and the ignition switch 18.

  The ignition switch 18 is operated by inserting an ignition key into a keyhole by the driver and rotating the ignition key to a position desired by the driver. The ignition switch 18 includes an off (OFF) position for inserting / removing an ignition key, an accessory (ACC) position for supplying operation power from the battery 16 to accessory electrical equipment such as a car audio, and an ignition coil for an engine ignition system. An ignition (IG) position for supplying operating power from the battery 16 to the ECU 20 (not shown in FIG. 2), and a starter for supplying operating power from the battery 16 to the starter motor 12 for starting the engine Has an ON position.

  When the ignition key is rotated to the accessory position by the driver, the contact 18a of the ignition switch 18 is connected to the accessory terminal (terminal on the accessory electrical equipment side) as shown in FIG. Operation power is supplied from 16 to the accessory electrical equipment.

  Further, when the ignition key is rotated to the ignition position, the contact 18a of the ignition switch 18 is connected to the accessory terminal and the ignition terminal (ignition coil and ECU side terminal) as shown in FIG. 2 (c). In addition to the accessory electrical equipment described above, operating power is supplied from the battery 16 to the ignition coil, ECU, and the like.

  Further, when the ignition key is rotated to the starter on position, in other words, when starting the engine, the contact 18a of the ignition switch 18 is connected to the ignition terminal as shown in FIG. Are connected to the starter relay terminal (terminal on the starter relay 14 side), and in addition to the above-described ignition coil and ECU, if the first transistor (described later) is in the ON state, the excitation coil of the starter relay 14 from the battery 16 The operating power supply is energized at 14 b and the movable switch 14 a is turned on, and the operating power is supplied from the battery 16 to the starter motor 12. Thereby, cranking is executed and the engine is started. It should be noted that the ignition key is configured to return to the ignition position when the driver releases the hand at the starter on position.

  Returning to the description of the starter drive control circuit 10, as shown in FIG. 1, the ECU 20 of the starter drive control circuit 10 has a collector terminal connected to one end of the exciting coil 14b of the starter relay 14, and an emitter terminal grounded. The first transistor 24 inserted between the NPN-type first transistor 24, the other end of the exciting coil 14 b of the starter relay 14 (the starter relay terminal of the ignition switch 18), and the base terminal of the first transistor 24. A self-bias circuit 30 composed of a resistor 26 and a second resistor 28 inserted on the ground side of the base terminal of the first transistor 24, and a connection point between the first resistor 26 and the second resistor 28. And an NPN-type second transistor 32 having a collector terminal connected and an emitter terminal grounded. The CPU 38 is connected to the base terminal of the second transistor 32 via the third resistor 36. Note that a connection point between the base terminal of the second transistor 32 and the third resistor 36 is grounded via the first pull-down resistor 40.

  Further, an NPN type third terminal having a base terminal connected to the other end of the exciting coil 14b of the starter relay 14 (a starter relay terminal of the ignition switch 18) via a fourth resistor 44 and an emitter terminal grounded. And the CPU 38 is connected to the collector terminal of the third transistor 46. Note that the connection point between the base terminal of the third transistor 46 and the fourth resistor 44 is grounded via the second pull-down resistor 48, and the connection point between the collector terminal of the third transistor 46 and the CPU 38. A pull-up resistor 50 is connected.

  The CPU 38 is a microcomputer that comprehensively controls the entire apparatus based on a program stored in a memory such as a ROM (not shown). The CPU 38 detects whether the engine has started, for example, counts the output of a crank angle sensor (not shown) with a counter to detect the engine speed Ne, and whether the engine speed Ne has exceeded a predetermined value (for example, 300 rpm). Although not shown, a monitoring circuit for monitoring a decrease in battery voltage is connected.

  Next, the control of the starter drive control circuit 10 configured as described above will be specifically described with reference to FIGS.

  FIG. 3 is a flowchart showing engine start control by the CPU 38.

  The program shown in FIG. 3 is executed after the ignition switch 18 is rotated to the ignition position by the driver, that is, when operating power is supplied from the battery 16 to the ECU 20 (CPU 38). When the operating power is supplied (the power is turned on), the CPU 38 in the ECU 20 performs an initialization process in step S1 and shifts to the normal operation mode.

  Next, in step S2, the output from the starter relay drive port P (the output to the second transistor 32) is set to the low level “L”. Note that the output from the starter relay drive port P is kept at the low level “L” by the first pull-down resistor 40 from the start of supply of the operating power to the ECU 20 (the second transistor 32 is kept off). Therefore, step S2 can be skipped.

  Subsequently, in step S3, normal FI (Fuel Injection) and ignition control are performed, and in step S4, it is determined whether or not the ignition switch 18 is at the starter on position.

  Here, the determination as to whether or not the starter is in the position of the starter on position in step S4 will be described. When the ignition switch 18 is not in the position of the starter on position, as shown in FIG. Since the output to the base terminal 46 is held at the low level “L” by the second pull-down resistor 48, the third transistor 46 is turned off, so that the output from the collector terminal is “high level” by the pull-up resistor 50. Hold H ".

  On the other hand, when the ignition switch 18 is in the starter on position, the output to the base terminal of the third transistor 46 is at the high level “H”, so that the third transistor 46 is turned on. The output from the collector terminal becomes low level “L”.

  Therefore, the CPU 38 in the ECU 20 detects the output state (high level “H” or low level “L”) of the collector terminal of the third transistor 46, so that the ignition switch 18 is moved to the starter on position. Judge whether there is.

  Returning to the description of FIG. 3, when the result is negative in step S4, the CPU 38 in the ECU 20 returns to step S2 to perform the same operation as described above, whereas when the result is affirmative, the CPU 38 proceeds to step S5. ) Is started.

  For example, the detected engine speed Ne is compared with a predetermined value, and when the engine speed Ne is equal to or lower than the predetermined value, it is determined that the engine has not yet been started, and the process returns to step S2. On the other hand, when the engine speed Ne exceeds the predetermined value, it is determined that the engine has started, the process proceeds to step S6, and the output from the starter relay drive port P (the output to the second transistor 32) is set to the high level. Set to “H”.

  When the output from the starter relay drive port P becomes the high level “H”, the second transistor 32 is turned on, so that the first transistor 24 is turned off. As a result, the exciting coil 14b of the starter relay 14 is not energized and the movable switch 14a becomes non-conductive, so that no operating power is supplied from the battery 16 to the starter motor 12, and driving of the starter motor 12 is stopped. That is, cranking is not performed.

  Next, the operation when the battery voltage falls below the minimum operating voltage of the ECU 20 in the above-described starter drive control circuit 10 will be described. FIG. 4 is a timing chart showing the operation of the starter drive control circuit 10 and when the battery voltage falls below the minimum operating voltage of the ECU.

  As described above, when the ignition switch 18 is rotated to the starter on position, the low level “L” is output from the starter relay drive port P of the CPU 38 (to the second transistor 32) in step S2 of FIG. Since the second transistor 32 is kept off, the first transistor 24 is turned on, whereby the exciting coil 14b of the starter relay 14 is energized and the movable switch 14a is turned on. Accordingly, operating power is supplied from the battery 16 to the starter motor 12, and the starter motor 12 is driven, that is, cranking is performed.

  Immediately after the start of cranking, the voltage of the battery 16 (voltage of the starter motor 12) exceeds the minimum operating voltage (shown as “voltage drop threshold” in FIG. 4) as shown in FIG. If the engine does not start for a long time, in other words, if the operating power continues to be supplied to the starter motor 12 and cranking continues for a long time, the battery voltage falls below the voltage drop threshold (below the minimum operating voltage).

  The monitoring circuit that monitors the decrease in the battery voltage constantly monitors the voltage of the battery 16 as described above, and when the voltage falls below the voltage decrease threshold, a signal is output to the CPU 38 in the ECU 20. In accordance with the output signal, the CPU 38 sets the reset signal (RES) or the forced interrupt signal (NMI) to the high level “H” and stops the operation of the ECU 20 (CPU 38).

  Thus, even when the operation of the CPU 38 in the ECU 20 is stopped, in the starter drive control circuit 10 according to the present invention, the output to the second transistor 32 is low level “L” by the first pull-down resistor 40. Since the first transistor 24 is kept on by the self-bias circuit 30, the exciting coil 14b of the starter relay 14 (STR) is energized and the movable switch 14a remains conductive. Accordingly, the operation power is continuously supplied from the battery 16 to the starter motor 12, and the starter motor 12 (STM) is continuously driven.

  In this state, when the driver releases the ignition key with the intention of stopping the starter motor 12, the first transistor 24 is turned off, so that the excitation coil 14b of the starter relay 14 is not energized. As a result, the movable switch 14a is turned off, so that no operating power is supplied to the starter motor 12, and the drive of the starter motor 12 is stopped. Accordingly, the starter motor 12 is driven and stopped in accordance with the driver's intention to start the engine (execute cranking) or stop the engine start control (stop cranking).

  From the above, even when the operation of the CPU 38 in the ECU 20 is stopped, the operation power supply to the starter motor 12 is continued, and the drive (cranking) of the starter motor 12 is continued.

  By the way, as described above, when the starter motor 12 is first driven from the stopped state, a large amount of operating power (electric power) is supplied to the starter motor 12, but the operation of the CPU 38 is stopped and the starter motor 12 is stopped. When the motor 12 is driven and the cranking is continued for a certain period, the motor shaft of the starter motor 12 is continuously rotated, so that the motor current shifts from the excessive current region to the low current region. The carry-out current to the motor 12 is reduced. As a result, the voltage of the battery 16 increases and becomes equal to or higher than the voltage decrease threshold. When the battery voltage becomes equal to or higher than the voltage drop threshold and a predetermined time has elapsed, a signal is output to the CPU 38 in the ECU 20 by the monitoring circuit. In accordance with the output signal, the CPU 38 sets the reset signal (RES) or the forced interrupt signal (NMI) to the low level “L” to operate the ECU 20 (CPU 38). As a result, the engine is started, and the voltage of the battery 16 rises to a predetermined value by power generation by an alternator (generator) (not shown).

  Thereby, the CPU 38 in the ECU 20 starts the process of FIG. 3 again, and when it is determined in step S5 that the engine has started, the output from the starter relay drive port P becomes the high level “H”, and the second Since the transistor 32 of the transistor is turned on, the first transistor 24 is turned off. As a result, the exciting coil 14b of the starter relay 14 is not energized and the movable switch 14a becomes non-conductive, so that no operating power is supplied from the battery 16 to the starter motor 12, and driving of the starter motor 12 is stopped. That is, cranking is not performed. Therefore, even though the engine is completely started, the driver does not release the ignition key, that is, the ignition switch continues to be rotated to the starter on position (see FIG. Even if it is indicated by “excess time”, the drive of the starter motor 12 is stopped.

Thus, in the vehicle starter motor drive control circuit of the first embodiment, the NPN type first control circuit having the collector terminal connected to the excitation coil 14b of the starter relay 14 and the emitter terminal grounded. Transistor 24, a first resistor 26 inserted between the battery 16 and the base terminal of the first transistor 24, and a second resistor inserted to the ground side of the base terminal of the first transistor 24. An NPN-type second transistor having a collector terminal connected to a connection point between the first resistor 26 and the second resistor 28 and an emitter terminal grounded, and a self-bias circuit 30 composed of the resistor 28 32, and the CPU 38 is configured to be connected to the base terminal of the second transistor 32. Even when the operation of the CU 20 (CPU 38) stops, the supply of power to the starter motor 12 can be continued as the driver intends to start the engine, and after the engine has started, the driver can turn on the ignition. The drive of the starter motor 12 can be stopped without removing the hand from the key, so that the reliability of the engine start and the merchantability can be improved.

  The ECU 20 (CPU 38) is further configured to supply a high-level output to the base terminal of the second transistor 32 when engine start is detected. Therefore, in addition to the above-described effects, after the engine is started, the starter motor 12 can be stopped and the cranking can be stopped immediately, thereby further improving the reliability and commerciality of the engine start. be able to.

  When the battery voltage is almost gone, the starter relay 14 of the starter drive control circuit 10 is kept in the on state (the movable switch 14a is in the conductive state), and the operation power is continuously supplied to the starter motor 12. It is also assumed that the engine will not start at all. However, if the driver determines that the engine does not start at all and returns the ignition key to the ignition position, the starter relay 14 is in the off state (the movable switch 14a is not in operation) even if the operation of the ECU 20 (CPU 38) is stopped. And the supply of operating power to the starter motor 12 is stopped.

  In the above description, the ignition switch 18 is configured to be operated by the ignition key. However, a knob (knob) is provided in place of the key hole of the ignition switch 18 and a weak radio wave is transmitted and received instead of the ignition key. A driver's transceiver may be carried by the driver, and the vehicle may be provided with a vehicle transceiver that can communicate with the driver's transceiver. That is, the vehicle transceiver is permitted to turn the knob of the ignition switch 18 when it is determined that the authorized driver is in or near the vehicle by receiving the radio waves of the driver transceiver. When the knob of the ignition switch 18 is rotated by the driver, the contact 18b of the ignition switch 18 is connected to the accessory terminal, the ignition terminal, and the like in the same manner as the ignition key according to the rotation. Good.

  In addition, a circuit group including the first transistor 28, the second transistor 32, the third transistor 46, and the self-bias circuit 30 is provided in the ECU 20, but part or all of the circuit group is included in the ECU 20. You may make it prepare outside.

As described above, in the first embodiment of the present invention, the starter motor (12) for starting the vehicle engine, the starter relay (14), and the movable switch (14a) of the starter relay (14) are provided. A battery (16) connected to the starter motor (12), an ignition coil (14b) of the starter relay (14), and an ignition switch (18) interposed between the battery (16), An electronic control unit (ECU20 (CPU38)) that receives operation power from the battery (16) in response to an operation of an ignition switch (18), and the electronic control unit (ECU20 (CPU38)) includes the ignition In response to the operation of the switch (18), the exciting coil (14b) is energized and the movable switch ( 4a), and a starter motor drive control circuit (starter drive control circuit) for controlling the drive of the starter motor (12) by supplying operation power from the battery (16) to the starter motor (12). 10), an NPN type first transistor (24) having a collector terminal connected to the excitation coil (14b) and an emitter terminal grounded, the battery ( 16 ), and the first transistor ( 24) from a first resistor (26) inserted between the base terminal of the first transistor (24) and a second resistor (28) inserted to the ground side of the base terminal of the first transistor (24). The collector terminal is connected to the connection point of the self-bias circuit (30) configured, the first resistor (26), and the second resistor (28), while the emitter terminal An NPN-type second transistor (32) whose child is grounded, and the electronic control unit (specifically, the CPU 38 therein) is connected to the base terminal of the second transistor (32) Therefore, when the voltage of the battery (16) falls below the minimum operating voltage of the electronic control unit, the battery (16) continues to supply operating power to the starter motor (12), while the battery (16) The operation of the electronic control unit is resumed when the voltage is equal to or higher than the minimum operating voltage of the electronic control unit for a predetermined time .

  The electronic control unit (ECU 20 (CPU 38)) further includes start detection means (crank angle sensor; CPU 38) for detecting start of the engine, and the electronic control unit (ECU 20 (CPU 38)) detects the start of the engine. The high level output is supplied to the base terminal of the transistor (36).

1 is a circuit diagram showing a configuration example of a drive control circuit for a vehicle starter motor according to a first embodiment of the present invention; FIG. FIG. 2 is a circuit diagram of a starter motor, a starter relay, a battery, and an ignition switch shown in FIG. 1. It is a flowchart which shows the engine starting control by CPU shown in FIG. FIG. 3 is a timing chart showing the operation of the starter drive control circuit shown in FIG. 1 when the battery voltage is lower than the minimum operating voltage of the ECU.

Explanation of symbols

10 Starter drive control circuit (drive control circuit for vehicle starter motor)
12 Starter Motor 14 Starter Relay 14a Movable Switch 14b Excitation Coil 16 Battery 18 Ignition Switch 20 ECU (Electronic Control Unit)
24 first transistor 26 first resistor 28 second resistor 30 self-bias circuit 32 second transistor 38 CPU

Claims (2)

A starter motor for starting a vehicle engine, a starter relay, a battery connected to the starter motor via a movable switch of the starter relay, and an ignition inserted between an excitation coil of the starter relay and the battery A switch and an electronic control unit that receives supply of operating power from the battery in response to an operation of the ignition switch, and the electronic control unit energizes the excitation coil in response to an operation of the ignition switch. In a vehicle starter motor drive control circuit that controls the drive of the starter motor by conducting a movable switch and supplying operation power from the battery to the starter motor.
An NPN-type first transistor having a collector terminal connected to the exciting coil and an emitter terminal grounded;
A first resistor interposed between the battery and the base terminal of the first transistor; and a second resistor interposed on the ground side of the base terminal of the first transistor. A self-bias circuit;
An NPN-type second transistor having a collector terminal connected to a connection point of the first resistor and the second resistor, and an emitter terminal grounded;
And the electronic control unit is connected to the base terminal of the second transistor , so that when the voltage of the battery falls below the minimum operating voltage of the electronic control unit, an operating power is supplied from the battery to the starter motor. Drive control of a starter motor for a vehicle , wherein the operation of the electronic control unit is restored when the voltage of the battery continues to be supplied or higher for a predetermined period of time while being continuously supplied circuit. further,
Start detection means for detecting start of the engine;
2. The vehicle starter motor according to claim 1, wherein the electronic control unit supplies a high-level output to a base terminal of the second transistor when the start of the engine is detected. Drive control circuit.

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