JP2017020404A - Engine start control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably restart an engine while improving the durability of a starter motor.SOLUTION: When receiving an engine start request (Step S1:Yes), an engine start control device sets a first path with high resistance as a power circuit leading to a starter motor (Step S2), and executes start control by means of the starter motor and executes fuel injection into the engine and start control by means of ignition (Step S3). When an engine speed does not reach a threshold value or higher within a predetermined time (Step S4:No), the engine start control device changes the power circuit from the first path to a second path with low resistance (Step S6).SELECTED DRAWING: Figure 3

Description

  The present invention relates to an engine start control device.

  For example, Patent Document 1 describes that when the engine is not restarted when the engine is restarted, the engine is restarted by operating a starter motor, an injector, and a spark plug. Further, it is described that when the engine is in a region where it cannot be started, the injector and the spark plug are stopped, the starter motor is operated, and the engine is restarted.

  In Patent Document 2, the battery voltage drop width at the start of cranking is predicted based on the state of charge of the battery. If the minimum battery voltage is lower than the minimum operation guarantee voltage of the electric load, the resistance value of the starter energization circuit is increased. Is described. Patent Document 3 describes that the motor is energized through a starting resistor when the engine is started.

JP 2006-348862 A JP 2010-265878 A JP 2004-308645 A

  By the way, in the vehicle which can stop an engine automatically and can restart an engine, since the frequency which restarts an engine increases, the use frequency of a starter motor increases. However, since each patent document does not consider the case where the starter motor is used more frequently, there is room for improving the durability of the starter motor.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an engine start control device capable of improving the durability of a starter motor and reliably restarting the engine.

  The present invention provides an engine start control device for controlling a vehicle including an engine and a starter motor that starts the engine. An energization circuit from a battery to the starter motor includes a first path and a first path. Is configured to be switchable to the second path having a low resistance, and when there is an engine start request while the engine is stopped due to establishment of a predetermined stop condition, the energization circuit is connected to the second path. Engine start control means for executing start control by the starter motor by setting to one path and executing start control by fuel injection and ignition to the engine, and after the engine start control means has started each start control If the engine speed does not reach a threshold value within a predetermined time, the energization circuit is changed from the first path to the second path. Characterized in that it comprises a changing switch control means Ri.

  In the engine start control device according to the present invention, when there is an engine start request, the engine is started using both start control using a starter motor and start control by fuel injection and ignition. At that time, the energization circuit from the battery to the starter motor is set to the first path having a relatively large resistance. Thereby, the current load applied to the starter motor can be suppressed. Further, when the engine speed does not increase to the threshold value within a predetermined time after starting the start control, the energization circuit is switched to the second path having a smaller resistance than the first path. As a result, the current supplied to the starter motor increases and the output torque of the starter motor increases. Therefore, it is possible to suppress the increase in the engine speed by the starter motor and the inability to start. Since the magnitude of the current supplied to the starter motor is changed as necessary, the durability of the starter motor can be improved and the engine can be reliably restarted.

  The engine start control device according to the present invention is configured to start the engine using both start control by a starter motor and start control by fuel injection and ignition. In addition, during the start-up control, the energization circuit from the battery to the starter motor is configured to be switched between the first path having a high resistance and the second path having a low resistance. Thereby, since the magnitude | size of the electric current which flows into a starter motor at the time of engine starting can be changed as needed, durability of a starter motor can be improved and an engine can be restarted reliably.

FIG. 1 is a schematic diagram schematically showing an engine start control device and a vehicle according to the present embodiment. FIG. 2 is a schematic diagram illustrating an example of a starter. FIG. 3 is a flowchart showing an example of an engine start control flow. FIG. 4 is a time chart showing changes in engine speed when ignition is successful and when ignition is successful. FIG. 5 is a flowchart showing another example of the engine start control flow. FIG. 6 is a time chart for explaining the resistance switching timing when the engine is started.

  Hereinafter, an engine start control device according to an embodiment of the present invention will be described in detail with reference to the drawings.

[1. vehicle]
FIG. 1 is a schematic diagram schematically showing an engine start control device and a vehicle according to the present embodiment. The vehicle Ve includes an engine (ENG) 1 that is a power source, an automatic transmission (T / M) 2, an output shaft 3, a differential 4, an axle 5, and drive wheels 6. The power output from the engine 1 is transmitted from the crankshaft 1 a to the output shaft 3 via the automatic transmission 2, and is transmitted from the output shaft 3 to the axle 5 and the drive wheels 6 via the differential 4.

  The engine 1 is a well-known internal combustion engine such as a gasoline engine or a diesel engine, and has a direct injection type that injects fuel into each cylinder. The vehicle Ve includes a starter (engine starter) 7 that starts the engine 1. The automatic transmission 2 is a known transmission that can automatically change the gear ratio. The automatic transmission 2 is configured to be automatically set to the neutral state. The vehicle Ve may include a fluid transmission device (torque converter) that generates a torque amplifying action by a fluid flow, and the engine 1 may be connected to the automatic transmission 2 via the torque converter so as to be able to transmit torque.

[2. Starter]
FIG. 2 is a schematic diagram illustrating an example of the starter 7. The starter 7 includes a starter motor (hereinafter simply referred to as “motor”) 8 that cranks the engine 1, a battery 9 that is a secondary battery, and an ICR relay provided in an energization circuit between the battery 9 and the motor 8. 10 and. The battery 9 is electrically connected to the motor 8 via the ICR relay 10. The motor 8 is driven by the power supplied from the battery 9. The starter 7 can increase the rotation speed (engine rotation speed) of the crankshaft 1 a by the torque output from the motor 8.

The ICR relay 10 is capable of switching the path (energization circuit) through which the current flows from the battery 9 to the motor 8 between the first path S ₁ having a relatively large resistance and the second path S ₂ having a relatively small resistance. It is the comprised switching apparatus. The ICR relay 10 includes a relay coil 11, a relay contact 12, and a resistor 13. The relay coil 11 generates magnetic flux when energized. The relay coil 11 is configured to control opening and closing of the relay contact 12. The relay contact 12 is configured to open when the relay coil 11 is not energized and to close when the relay coil 11 is energized. The resistor 13 is provided in parallel with the relay contact 12.

When the relay contact 12 is open, the current reaches the motor 8 through a path (first path S ₁ ) through the resistor 13. When the relay contact 12 is closed, the current reaches the motor 8 through a path (second path S ₂ ) via the relay contact 12. First path _{S 1} has to include a resistor 13, it is greater resistance than the second path _{S 2.} Resistor 13 of the first path S in ₁ is set to a large resistance value. For example, when the second path S ₂ is selected, the resistance value of the resistor 13 is set such that the current flowing through the first path S ₁ is negligibly smaller than the current value flowing through the second path S _2. Is set.

[3. Engine start control device]
The engine start control device includes an electronic control device (hereinafter referred to as “ECU”) 20 that controls the vehicle Ve. The ECU 20 is mainly composed of a microcomputer, and executes calculations according to a predetermined program based on input data and data stored in advance. ECU20 outputs a command signal based on the result of having performed various arithmetic processes, and controls in-vehicle devices (including engine 1, automatic transmission 2, starter 7, etc.) to be controlled.

  As an example, the ECU 20 controls the amount of fuel supplied to the engine 1, the amount of intake air, fuel injection, ignition timing, and the like. Under the control of the ECU 20, fuel injection and ignition can be performed independently in each cylinder. Further, the ECU 20 is configured to execute control for temporarily automatically stopping the engine 1 in accordance with the vehicle state. The control includes so-called stop and start control (S & S control), eco-run control, idle stop control, and the like. In this description, these controls are collectively referred to as “S & S control”.

  The S & S control is a control (stop control) for automatically stopping the engine 1 when a predetermined execution condition (stop condition) is satisfied, and a control (start control) for restarting the engine 1 when a predetermined return condition (start condition) is satisfied. ). The stop control includes fuel cut control for stopping fuel injection and ignition to the engine 1. The stop condition is satisfied when the vehicle Ve is stopped or traveling. The ECU 20 executes S & S control while the vehicle Ve is stopped or traveling.

  For example, a stop S & S control for automatically stopping the engine 1 when the vehicle Ve is stopped due to a signal waiting, a deceleration S & S control for automatically stopping the engine 1 while the vehicle Ve is decelerating toward the stop, There is free-run S & S control in which the engine 1 is automatically stopped while traveling at a vehicle speed at which Ve is above a certain level. The stop S & S control is executed when the vehicle speed is “0” and the brake pedal is depressed. The engine 1 is restarted by returning the brake pedal during the stop S & S control. The deceleration S & S control is executed when the accelerator pedal is returned and the brake pedal is depressed while the vehicle Ve is traveling at a predetermined vehicle speed or less. The engine 1 is started when the brake pedal is returned or the accelerator pedal is depressed during the deceleration S & S control. The free-run S & S control is executed by returning the accelerator pedal while the vehicle Ve is traveling at a vehicle speed of a certain level or more. The engine 1 is started when the accelerator pedal is depressed or the brake pedal is depressed during the free-run S & S control.

  As shown in FIG. 1, signals are input to the ECU 20 from a crank angle sensor 31, an accelerator opening sensor 32, and a brake stroke sensor 33. The crank angle sensor 31 detects the crank angle and the engine speed (the rotational speed of the crankshaft 1a), and outputs a crank angle signal to the ECU 20. The accelerator opening sensor 32 detects an accelerator pedal operation amount and outputs an accelerator opening signal to the ECU 20. The brake stroke sensor 33 detects a brake pedal operation amount and outputs a brake signal to the ECU 20. Further, the ECU 20 may receive signals from various sensors (not shown) such as a vehicle speed sensor and a sensor that detects that the automatic transmission 2 is in the neutral state.

  The ECU 20 includes a detection unit 21, a determination unit 22, a start control unit 23, and a switching control unit 24. When the ECU 20 executes the S & S control, the determination unit 22 determines whether a stop condition or a start condition is satisfied based on the accelerator opening signal or the brake signal detected by the detection unit 21. When the determination unit 22 determines that the start condition is satisfied, that is, there is an engine start request, the start control unit 23 executes the start control.

  The detection unit 21 detects input signals from the sensors 31 to 33. For example, the detection unit 21 detects the crank angle, the engine speed, and the piston position in each cylinder based on the crank angle signal from the crank angle sensor 31. Based on the accelerator opening signal from the accelerator opening sensor 32, the detector 21 detects the amount of accelerator pedal operation and the presence or absence of pedal operation (accelerator ON, accelerator OFF). Based on the brake signal from the brake stroke sensor 33, the detector 21 detects the amount of brake pedal operation and the presence or absence of pedal operation (brake ON, brake OFF). Further, the detection unit 21 outputs a detection result signal to the determination unit 22. Note that the accelerator ON means that the accelerator pedal is depressed, and the accelerator OFF means that the accelerator pedal is returned without being depressed. The same applies to brake ON and OFF.

  The determination unit 22 determines whether various conditions are satisfied. For example, the determination unit 22 determines whether a condition (stop condition) for automatically stopping the engine 1 is satisfied, and determines whether a condition (start condition) for restarting the engine 1 during the automatic stop is satisfied. It is configured to determine.

  For example, when determining whether or not the start condition is satisfied, the determination unit 22 targets an engine start request by a driver request according to whether or not an accelerator pedal operation or a brake pedal operation is performed, and an engine start request by a system request according to a predetermined parameter. It can be. The system request includes a case where the battery voltage becomes lower than a predetermined threshold while the engine 1 is automatically stopped, and a case where the vehicle speed becomes a predetermined vehicle speed or less during the free-run S & S control. Further, the determination unit 22 outputs a determination result signal to the start control unit 23 and the switching control unit 24.

  The start control unit 23 performs control (start control) for restarting the engine 1. The start control executed by the start control unit 23 includes start control for cranking the engine 1 by the motor 8 (hereinafter referred to as “starter start”), and start control for rotating the crankshaft 1 a by fuel injection and ignition to the engine 1. (Hereinafter referred to as “ignition start”). The start control unit 23 is configured to restart the engine 1 by using two start controls, that is, a starter start and an ignition start. The start control unit 23 can be controlled when only the starter start is executed or when the starter start and the ignition start are executed simultaneously.

  For example, when the starter start and the ignition start are simultaneously executed by the start control unit 23, the engine torque is assisted by the engine torque generated by fuel injection and ignition while the engine 1 is being cranked by the motor 8. can do. As a result, when compared with the case where the load at the time of engine restart is the same, the power consumption of the motor 8 is less when the starter start and the ignition start are used together than when the engine 1 is restarted only by the starter start. . In addition, the start control unit 23 is configured to perform fuel injection and ignition in a cylinder whose piston position is in the expansion stroke (in a cylinder stopped in the expansion stroke) based on the crank angle signal.

Switching control unit 24 executes a switching control for switching the energizing circuit of the starter 7 the first path S ₁ and the second path S _2. Switching control unit 24, thereby opening the relay contacts 12 does not energize the relay coil 11, and executes control for selecting a first path S ₁ large resistance as the energizing circuit. Further, the switching control unit 24 outputs a resistance switching instruction (signal, current) to the relay coil 11 to energize the relay coil 11 to close the relay contact 12, and the second path S ₂ having a small resistance as an energizing circuit. Execute the selected control.

[4. Start control flow]
FIG. 3 is a flowchart showing an example of an engine start control flow. In a state where the stop condition is satisfied and the engine 1 is stopped, the ECU 20 executes the control flow shown in FIG.

  The determination unit 22 determines whether there is an engine start request while the engine 1 is stopped by the S & S control (step S1). In step S1, it is determined whether a start condition is satisfied. If the ECU 20 makes a negative determination in step S1 because there is no engine start request (step S1: No), the control routine ends.

If an affirmative determination is made in step S1 by that there is an engine start request (step S1: Yes), the switching control unit 24, executes a control for selecting a first path S ₁ large resistance as energizing circuit of the starter 7 (Step S2). Further, the start control unit 23 starts the start control of the engine 1 by using both the starter start for cranking the engine 1 by the motor 8 and the ignition start for performing fuel injection and ignition to the engine 1 (step S3). ).

  The determination unit 22 determines whether or not the engine speed has reached the threshold value within a predetermined time after starting each start-up control in step S3 (step S4). This threshold value is set to a predetermined value that is lower than, for example, an engine speed or an idle speed at which the engine 1 is in an independent state. The predetermined time may be an elapsed time from the time when the engine start request is detected in step S1, or may be an elapsed time from the time when the start control is started in step S3.

  If the determination in step S4 is affirmative because the engine speed has reached the threshold value within the predetermined time (step S4: Yes), the process proceeds to step S5.

On the other hand, when the engine speed does not reach the threshold value within the predetermined time and is negatively determined in step S4 (step S4: No), the switching control unit 24 is a second resistor having a small resistance as the energization circuit of the starter 7. executing a control for selecting the path _{S 2} (step S6). While the starting control unit 23 is executing the respective starting control, switching control unit 24 executes the control for switching the energizing circuit from the first path S ₁ to the second path S _2. Through the process of step S <b> 6, a resistance switching instruction (signal, current) is output from the ECU 20 to the relay coil 11 of the ICR relay 10. As a result, the relay coil 11 generates magnetic flux and the relay contact 12 is closed. The current reaches the motor 8 via the relay contact 12 without passing through the resistor 13 of the ICR relay 10. That is, after execution of step S6, a larger current flows to the motor 8 than before execution of step S6, so that the torque output from the motor 8 increases. And after performing step S6, it progresses to step S5.

  The determination unit 22 determines whether or not the restart of the engine 1 is completed (step S5). For example, when the engine speed reaches a self-supporting speed such as an idle speed, it is determined that the restart of the engine 1 is completed. If a positive determination is made in step S5 due to the completion of the restart of the engine 1 (step S5: Yes), the ECU 20 ends this control routine. If a negative determination is made in step S5 because the restart of the engine 1 is not completed (step S5: No), the ECU 20 repeats step S5. The determination process in step S5 may be a known determination method when the engine 1 is started.

  As described above, according to the engine start control device of the present embodiment, since the magnitude of the current supplied to the starter motor can be changed as necessary, an excess current is applied to the starter motor. This can be suppressed. As a result, the durability of the starter motor can be improved and the engine can be reliably restarted.

  The energization circuit of the starter 7 may include a known starter circuit. For example, a starter circuit may be provided between the battery 9 and the ICR relay 10. The starter circuit includes a pull-in coil, a holding coil, a plunger, and a main contact. In the starter circuit, the pull-in coil and the holding coil generate magnetic flux and the operation of the plunger is controlled, so that the main contact can be opened and closed. By closing the main contact, the rotor shaft of the starter motor 8 is connected to the crankshaft 1a via a transmission mechanism (not shown) so as to be able to transmit torque. By opening the main contact, the rotor shaft of the starter motor 8 and the crankshaft 1a are blocked so that torque cannot be transmitted.

[5. Modified example]
Next, a modified example of the engine start control device described above will be described. This modification includes a configuration that takes into account the case where ignition fails during start control. In the description of this modification, the description of the same configuration as that of the above-described embodiment is omitted, and the reference numerals thereof are cited.

FIG. 4 is a time chart showing changes in engine speed when ignition is successful and when ignition fails in ignition start. When the start condition is satisfied and the start request flag is turned on while the engine 1 is automatically stopped, start control using both starter start and ignition start is started (time t ₀ ). The starter start is started in a state where the energization circuit of the starter 7 is set to the first path S ₁ large resistance. When successful, the engine speed starts increasing immediately after the start request flag is turned ON. When the engine fails, the engine speed starts to increase slightly after the start request flag is turned on. Since the engine speed is increased only by the starter 7 at the time of failure, the increase in the engine speed is delayed as compared with the case where the ignition start and the starter start are used in combination. At the time of failure, the engine speed starts to increase at a rate similar to that at the time of success later than the time of success.

Therefore, in the engine start control device of this modification, at the time of ignition failure, it is configured to increase the torque motor 8 and selects and outputs the energizing circuit of the starter 7 in the second path S ₂ smaller resistance. Thereby, it is comprised so that the increase amount of an engine speed may be enlarged.

[5-1. Start control flow]
FIG. 5 is a flowchart showing an engine start control flow of this modification. Note that steps S11 to S13 and S15 shown in FIG. 5 are the same as steps S1 to S3 and S5 shown in FIG.

  The determination unit 22 determines whether or not the engine speed has reached the threshold A within a predetermined time after starting control is started in step S13 (step S14). The threshold A is set to a predetermined value that is lower than the engine speed at which the engine 1 is in a self-supporting state, for example. When it is determined affirmatively in step S14 that the engine speed has reached the threshold value A (step S14: Yes), the process proceeds to step S15.

  If the engine speed does not reach the threshold value A within a predetermined time, and a negative determination is made in step S14 (step S14: No), the determination unit 22 determines whether or not the engine speed has reached the threshold value B. Determination is made (step S16). The threshold value B is set to a predetermined value that is greater than zero and lower than the threshold value A. For example, the threshold value B is the number of rotations allowed to switch the resistance of the energization circuit. If it is determined negative in step S16 because the engine speed is lower than the threshold value B (step S16: No), step S16 is repeated.

If the engine speed is affirmative determination is made in step S16 by reaching the threshold value B (step S16: Yes), the switching control unit 24 selects the resistance of the small second path S ₂ as energizing circuit (step S17). Switching control unit 24 executes the control for switching the energizing circuit from the first path S ₁ to the second path S _2. The process of step S17 may be configured similarly to step S6 shown in FIG. 3 described above.

[5-2. Time chart]
FIG. 6 is a time chart for explaining the resistance switching timing when the engine is started. If there is an engine start request while the engine 1 is automatically stopped, the start request flag (starter flag) is switched from OFF to ON, and start control of the engine 1 is started (time t ₁ ). This start control is a combination of starter start and ignition start. When the start control is started, the engine speed starts to increase. In addition, since a current is supplied to the motor 8 by starting the starter, the voltage of the battery 9 drops. In time t ₁ before and after a flag energizing circuit of the starter 7 is set to the first path S ₁ (starter large resistance flag) is is ON.

After time t _1, when the engine speed despite running starting control in combination with ignition starting the starter start does not rise to the desired rotational speed is determined to ignition failure (time t ₂ ). For example, if the determination is negative in step S14 of FIG. The determination unit 22 is configured to determine that the ignition has failed when the engine speed is lower than the threshold value A.

When it is determined that the ignition has failed and the engine speed increases and reaches the threshold value B, resistance switching control is executed (time t ₃ ). That is, the starter large resistance flag is switched to OFF from ON, switch to the second path S ₂ energization circuit is smaller from the first path S ₁ large resistance of the resistor of the starter 7. As a result, the current supplied to the motor 8 is increased and the output torque of the motor 8 is increased, so that the rate of increase of the engine speed is increased. At this time, since the power consumption of the motor 8 increases, the voltage of the battery 9 drops. The present invention is not limited to the starter large resistance flag, ON flag for setting the energizing circuit of the starter 7 in the second path S _2, may be used means OFF.

Also, FIG. 6 shows a case where tentatively switching the energization circuit of the starter 7 immediately after it is determined that the ignition failure small second path S ₂ resistance by broken lines. The engine speed at that time is lower than the threshold value B. In this case, since the engine speed is too low, the voltage drop amount of the battery 9 is increased. As the voltage drop amount is greater than the amount of voltage drop above (voltage drop amount of time t ₃ or later). That is, as indicated by the broken line, if the resistance is switched from large to small while the engine speed is too low, the amount of voltage drop increases and the battery voltage may fall below the lower limit value of the normal operating range. That is, in the above-described modification, it is possible to suppress a battery voltage drop when starting the engine.

  As described above, according to this modification, it is possible to suppress the battery voltage drop when starting the engine and improve the durability of the starter motor. Further, it is possible to suppress the engine from being unable to start due to the ignition failure.

1 Engine 7 Starter (Engine starter)
8 Starter motor 10 ICR relay (switching device)
20 Electronic control unit (ECU)
23 Start Control Unit 24 Switching Control Unit Ve Vehicle

Claims (1)

In an engine start control device for controlling a vehicle including an engine and a starter motor that starts the engine,
The energization circuit from the battery to the starter motor is configured to be switchable between a first path and a second path having a smaller resistance than the first path.
If there is an engine start request while the engine is stopped due to the establishment of a predetermined stop condition, the energization circuit is set to the first path and start control by the starter motor is executed. Engine start control means for executing start control by fuel injection and ignition to the engine;
Switching control for switching the energization circuit from the first path to the second path when the engine speed does not reach a threshold value within a predetermined time after the engine start control means starts each start control. And an engine start control device.

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