JP2015224547A - Engine starter and engine starting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the torque of a starter motor at a time of starting a key while improving the quietness and startability at a time of automatically restarting an engine.SOLUTION: An engine starter comprises: starter motors (5, 6, 7, 8, 9) for starting an engine; and output change units (4, 10, 11) capable of changing outputs from the starter motors, the output change units actuating the starter motors so as to exhibit high revolving speed starter characteristics by keeping the normally-off contacts (4) closed without actuating the normally-off contacts (4) at a time of starting the engine if a restart condition is satisfied, and actuating the normally-off contacts (4) to be opened before or simultaneously with the actuation of the starter motors at the time of starting the engine if the restart condition is not satisfied, thereby changing the outputs from the starter motors that are set to exhibit the high resolving speed starter characteristics to high torque starter characteristics and actuating the starter motors.

Description

  The present invention relates to an engine start device and an engine start method for an automatic stop / restart system that automatically stops an engine when an engine automatic stop condition is satisfied and then restarts the engine when the restart condition is satisfied. .

  Conventionally, when a vehicle engine is started by a starter motor, a low-rotation, high-torque type characteristic has generally been adopted as the starter motor. This is because the engine can be reliably started even when the rotational resistance of the engine increases, for example, at a very low temperature.

  However, with the low-rotation high-torque characteristics, the engine speed cannot be increased, and it may take time to start the engine.

  On the other hand, for example, in an engine starting device, a starter motor for starting the engine, a detection means for detecting a physical quantity that affects the starting torque of the starter motor, and a torque-rotational speed characteristic of the starter motor are changed based on the physical quantity. There is a conventional technique provided with a control means (see, for example, Patent Document 1).

  When the control means in this patent document detects a physical quantity that is assumed that the starting torque exceeds a predetermined level, the control means changes the torque-rotational speed characteristic to the low torque side and assumes that the starting torque falls below the predetermined level. When the physical quantity to be detected is detected, the torque-rotational speed characteristic is changed to the high torque side.

JP 2003-328910 A

However, the prior art has the following problems.
In Patent Document 1 described above, the torque characteristic is changed based on the starting torque of the starter motor. For this reason, when the characteristic is changed during the automatic engine stop by idling stop or the like, which is more frequent than the key start, noise is generated by the relay operation. Furthermore, there is a problem that power is consumed for such a relay operation.

  The starter motor is generally energized with a current of several hundred amperes. For this reason, in a configuration using a semiconductor relay such as a transistor in order to change the characteristics, it is necessary to use a semiconductor relay having a large allowable current amount or to configure a plurality of semiconductor relays in parallel to reduce the current amount per one. is there. As a result, there has been a problem that the component cost is increased.

  The present invention has been made in order to solve the above-described problems in the conventional apparatus, and ensures both starter motor torque at the time of key start and improvement of quietness and startability at the time of automatic engine restart. It is an object of the present invention to provide an engine starter and an engine start method that can start an engine without causing a driver to feel more uncomfortable.

  The engine starter according to the present invention stops the combustion of the engine and automatically stops the engine when the engine automatic stop condition is satisfied, and when the restart condition is satisfied after the engine automatic stop condition is satisfied. An engine starter for restarting the engine, comprising: a starter motor for starting the engine; and an output changing unit capable of changing the output of the starter motor, wherein the output changing unit is provided when a restart condition is satisfied. When starting the engine, keep the closed state without operating the normally closed contact so that the starter motor operates so as to have a high rotation starter characteristic. The starter characteristic of high rotation is achieved by operating the normally closed contact in the open state before or simultaneously with the starter motor operation. The output of the starter motor being constant, is intended to operate the starter motor is changed to a starter characteristics of high torque.

  In addition, an engine start method according to the present invention includes a starter motor for starting an engine and an output changing unit that can change an output of the starter motor. When an engine automatic stop condition is satisfied, combustion of the engine is performed. When the restart condition is satisfied after the automatic engine stop condition is satisfied and the engine automatic stop condition is satisfied, the engine start method is applied to an engine start device that restarts the engine. A first step of operating the starter motor to have a high rotation starter characteristic by maintaining the closed state without operating the normally closed contact when the engine is started when the restart condition is satisfied; When starting the engine except when the restart condition is satisfied, the normally closed connection is performed before or simultaneously with the starter motor operation. The by operating in an open state, in which a second step of the output of the starter motor is set to a starter characteristic of high rotation, to operate the starter motor is changed to a starter characteristics of high torque.

  According to the present invention, at the time of automatic start, a high output starter characteristic can be realized while maintaining the normally closed contact in a closed state. In engine start other than automatic start such as key start, the operation of the starter motor By switching the normally closed contact to the open state before or at the same time as the operation, it is possible to change from a high-rotation starter characteristic to a high-torque starter characteristic. As a result, an engine starter capable of starting the engine without bothering the driver more comfortably while ensuring the torque of the starter motor at the time of key start and improving the quietness and startability at the time of automatic engine restart An engine starting method can be obtained.

It is a block diagram of the engine starting apparatus in Embodiment 1 of this invention, and shows the case where a changeover switch is an OFF state. It is a block diagram of the engine starting apparatus in Embodiment 1 of this invention, and shows the case where a changeover switch is an ON state. It is an image figure which shows the output-rotation speed characteristic of the engine starting apparatus in Embodiment 1 of this invention. It is an image figure which shows the torque-rotation speed characteristic of the engine starting apparatus in Embodiment 1 of this invention. It is a flowchart which shows a series of operation | movement of the engine starting apparatus in Embodiment 1 of this invention. It is a flowchart which shows a series of operation | movement of the engine starting apparatus in Embodiment 2 of this invention.

  Hereinafter, preferred embodiments of an engine starting device and an engine starting method of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of an engine starter according to Embodiment 1 of the present invention, and shows a case where a changeover switch is in an OFF state. On the other hand, FIG. 2 is a configuration diagram of the engine starter according to Embodiment 1 of the present invention, and shows a case where the changeover switch is in the ON state.

  As shown in FIGS. 1 and 2, the engine starter according to the first embodiment includes a power source 1, a key switch 2, a solenoid switch 3, field coil switching relays 4a and 4b, an armature coil 5, and positive brushes 6a and 6b. In addition to the negative electrode brushes 7a and 7b, the upstream field coils 8a and 8b, the downstream field coils 9a and 9b, the coil switching solenoid 10, and the changeover switch 11, an unillustrated ECU is provided.

  The power source 1 is composed of a 12V battery, a capacitor, and the like, and supplies power to the starter. The key switch 2 is turned on by a command from the ECU in accordance with a driver's key operation, button operation, or establishment of an engine automatic start condition.

  The solenoid switch 3 is configured as a mechanical relay, and is energized from a power source 1 to a solenoid coil (not shown) in the solenoid switch 3 when the key switch 2 is turned on. Then, when the solenoid coil is energized, the movable contact in the solenoid switch is turned on to turn on the relay, and the field coils 8a, 8b, 9a, and 9b are energized.

  The starter motor in the first embodiment is a direct current motor, and includes an armature coil 5, positive brushes 6a and 6b, negative brushes 7a and 7b, upstream field coils 8a and 8b, and downstream field coils 9a, 9b. Further, as shown in FIG. 1, the four field coils 8a, 8b, 9a, and 9b have a configuration in which two series circuits connected in series are connected in parallel.

  The field coil switching relays 4a and 4b are normally closed contacts. When the changeover switch 11 is turned on, the coil switching solenoid 10 is operated, and the field coil switching relays 4a and 4b are energized to open. It is comprised so that it may be in a state. Here, the field coil switching relays 4a and 4b, the coil switching solenoid 10, and the changeover switch 11 correspond to an output changing unit.

  Further, the upstream field coil 8a and the downstream field coil 9a, and the upstream field coil 8b and the downstream field coil 9b are short-circuited in the middle through field coil switching relays 4a and 4b, respectively. As shown in FIG. 1, when the field coil switching relays 4a and 4b are not in operation and are closed, they are short-circuited. On the other hand, as shown in FIG. 2, when the field coil switching relays 4a and 4b are switched to the open state with the operation of the coil switching solenoid 10, the short circuit is eliminated.

  Further, the ECU (not shown) includes, for example, an engine ECU, an idling stop ECU, and the like, determines the ON / OFF operation of the key switch 2 and the changeover switch 11, and controls the output changing unit.

  The engine starter according to the first embodiment does not operate the field coil switching relays 4a and 4b, which are normally closed contacts, in the engine start by the engine automatic start such as idling stop, and a part of the field coil is short-circuited. Energize with the power on. On the other hand, in engine starting other than engine automatic starting, for example, engine starting by key starting, the field coil switching relays 4a and 4b are operated to eliminate the short circuit.

  In general, in an engine automatic start such as an idling stop, a starter characteristic of high rotation is required so that the engine can be started quickly so that the driver can get on the traffic flow according to the driver's intention to start. On the other hand, in the key starting other than the automatic starting, a high torque starter characteristic is required so that the engine can be reliably started even in an environment where the engine torque becomes extremely low.

  FIG. 3 is an image diagram showing an output-rotational speed characteristic of the engine starting device according to Embodiment 1 of the present invention. FIG. 4 is an image diagram showing a torque-rotational speed characteristic of the engine starting device according to Embodiment 1 of the present invention. As shown in FIGS. 3 and 4, the operation of the field coil switching relays 4a and 4b switches the short-circuit state of the field coil, and the starter characteristic (that is, the output-rotation speed characteristic shown in FIG. The indicated torque-rotation speed characteristic changes.

  By using the field coil switching relays 4a and 4b as normally closed contacts, a high rotation starter characteristic (high output side) can be obtained without operating the field coil switching relays 4a and 4b when the engine is automatically started. Can do.

  On the other hand, at the time of engine start other than automatic start, the field coil switching relays 4a and 4b are operated to eliminate the short-circuit state, thereby increasing the number of turns of the field coil used for generating the field and short-circuit state. As compared with, a starter characteristic (low output side) of high torque and low rotation can be obtained.

  By performing such switching control, it is possible to satisfy the high-rotation starter characteristics required in the above-described automatic engine start and to realize the high-torque starter characteristics required in key start or the like. Also, at the time of key start, the number of turns of the field coil to be energized increases, so that the resistance and inductance of the circuit increase. As a result, when the key is started, the output is reduced as compared with the short-circuit state at the time of automatic start, but the current of the starter motor can be suppressed.

  The engine automatic start is performed in a state where the battery is charged. On the other hand, in the key start, the voltage may drop due to factors such as not charging the battery for a long time. In this case, if the energization current is large, the engine start may be delayed or the battery life may be affected. For this reason, it is desirable to suppress the current of the starter motor as much as possible at the time of key start, and the configuration of the first embodiment can realize such current suppression at the time of key start.

  Moreover, in this Embodiment 1, the structure which uses the field coil switching relays 4a and 4b as a normally closed contact is employ | adopted. For this reason, it is not necessary to operate the field coil switching relays 4a and 4b at the time of automatic engine start, which is more frequent than key start. As a result, it is possible to suppress noise due to relay operation, suppress operating power, and extend the life of operating components.

  Next, a series of operations of the engine starter according to Embodiment 1 will be described using a flowchart. FIG. 5 is a flowchart showing a series of operations of the engine starter according to Embodiment 1 of the present invention. First, in step S100, the ECU determines whether or not the current engine start is an automatic start.

  If it is determined in step S100 that the engine is automatically started, the process proceeds to step S101, where the ECU turns on the key switch 2 and energizes the starter motor. That is, the ECU makes the key switch 2 ON and the changeover switch 11 OFF.

  When the key switch 2 is turned on, the solenoid switch 3 is turned on to energize the field coil and simultaneously energize the amateur coil 5 to start the engine. At this time, since the changeover switch 11 is in the OFF state, the field coil changeover relays 4a and 4b remain closed. As a result, the upstream field coil 8a and the downstream field coil 9a, and the upstream field coil 8b and the downstream field coil 9b are partially short-circuited. Therefore, as described above, a starter characteristic of high rotation (high output) can be realized.

  On the other hand, if it is determined in step S100 that the engine is started other than automatic start, the process proceeds to step S102, where the ECU turns on the changeover switch 11 and energizes the coil switching solenoid 10. That is, the ECU makes the key switch 2 OFF and the changeover switch 11 ON.

  In this case, when the coil switching solenoid 10 is energized, the field coil switching relays 4a and 4b are energized. As a result, the field coil switching relays 4a and 4b are opened, and the field coil is short-circuited. Is resolved. Thereafter, the process proceeds to step S101, and the ECU turns on the key switch 2. That is, the ECU causes both the key switch 2 and the changeover switch 11 to be in the ON state.

  When the key switch 2 is turned on, the solenoid switch 3 is turned on, the field coil and the armature coil 5 are energized, and the engine is started. However, at this time, the field coil switching relays 4a and 4b are in the open state, and the short circuit is eliminated. Therefore, the upstream field coil 8a and the downstream field coil 9a, and the upstream field coil 8b and the downstream field coil 9b are all energized without being short-circuited in part. It becomes like this. Therefore, as described above, a starter characteristic with high torque (low output) can be realized.

  As described above, when the engine automatic stop condition is satisfied, the engine start device according to Embodiment 1 stops the combustion of the engine and automatically stops the engine. After the engine automatic stop condition is satisfied, the restart condition is The engine is restarted when it is established, and has an output changing unit that can change the output of the starter motor in accordance with the starting state.

  With such a configuration, a high rotation (high output) starter characteristic can be realized while maintaining the normally closed state of the field coil switching relay during automatic starting. On the other hand, when starting an engine other than automatic starting, the normally closed contact is switched to the open state before or simultaneously with the starter motor operation, so that the starter characteristic on the high output side (high rotation side) is switched to the low output side. The starter characteristic can be changed to (high torque side).

  As a result, it is possible to realize both a high-rotation starter characteristic required for automatic engine start and a high-torque starter characteristic required for key start or the like. Furthermore, at the time of starting the key, since the configuration is such that the number of energized coils increases, the resistance and inductance of the circuit increase. As a result, the output is reduced as compared with the short-circuit state at the time of automatic start, but the current of the starter motor can be suppressed.

  Furthermore, since the field coil switching relay is a normally closed contact, it is not necessary to operate the field coil switching relay at the time of engine automatic start, which is more frequent than key start. As a result, it is possible to suppress noise due to relay operation, suppress operating power, and extend the life of operating components.

Embodiment 2. FIG.
In the first embodiment, in the key start (corresponding to an example of engine start other than automatic start), the engine is started with a starter characteristic of high torque (low output). The case where the engine is started with the output) starter characteristic has been described. In contrast, in the second embodiment, when a predetermined output change condition is satisfied at the time of key start, the output of the starter motor is changed from the low output side (high torque side) to the high output side (high rotation side). The case where the structure which changes to is further provided is demonstrated.

  FIG. 6 is a flowchart showing a series of operations of the engine starter according to Embodiment 2 of the present invention. When the engine start is automatic start, the operation is the same as that of the first embodiment. First, in step S200, the ECU determines whether or not the current engine start is an automatic start.

  If it is determined in step S200 that the engine is automatically started, the process proceeds to step S201, where the ECU turns on the key switch 2 to energize the starter motor. That is, the ECU makes the key switch 2 ON and the changeover switch 11 OFF.

  When the key switch 2 is turned on, the solenoid switch 3 is turned on to energize the field coil and simultaneously energize the amateur coil 5 to start the engine. At this time, since the changeover switch 11 is in the OFF state, the field coil changeover relays 4a and 4b remain closed. As a result, the upstream field coil 8a and the downstream field coil 9a, and the upstream field coil 8b and the downstream field coil 9b are partially short-circuited. Therefore, as described above, a starter characteristic of high rotation (high output) can be realized.

  On the other hand, if it is determined in step S200 that the engine is started other than the automatic start, the process proceeds to step S202, where the ECU turns on the changeover switch 11 and energizes the coil switching solenoid 10. That is, the ECU makes the key switch 2 OFF and the changeover switch 11 ON.

  In this case, when the coil switching solenoid 10 is energized, the field coil switching relays 4a and 4b are energized. As a result, the field coil switching relays 4a and 4b are opened, and the field coil is short-circuited. Is resolved. Thereafter, the process proceeds to step S203, where the ECU turns on the key switch 2. That is, the ECU causes both the key switch 2 and the changeover switch 11 to be in the ON state.

  When the key switch 2 is turned on, the solenoid switch 3 is turned on, the field coil and the armature coil 5 are energized, and the engine is started. However, at this time, the field coil switching relays 4a and 4b are in the open state, and the short circuit is eliminated. Therefore, the upstream field coil 8a and the downstream field coil 9a, and the upstream field coil 8b and the downstream field coil 9b are all energized without being short-circuited in part. It becomes like this. Therefore, as described above, a starter characteristic with high torque (low output) can be realized.

  Further, in the second embodiment, in step S204, the ECU determines whether the starter rotation speed is equal to or higher than a predetermined rotation speed N1. The determination of whether or not the starter rotational speed is equal to or higher than the rotational speed N1 corresponds to a predetermined output change condition at the time of key start.

  This predetermined rotation speed N1 is the starter torque when the high output side (field coil switching relay non-operation) shown in FIG. 4 is the low output side (field coil switching relay operation). Corresponds to higher rotation speed. Therefore, by switching the starter characteristic according to the rotation speed N1, it is possible to use a high torque region on the high output side (non-operation of the rotating coil switching relay) at the time of key start.

  The starter rotation speed may be obtained directly from an actual measurement value using an encoder, an electromagnetic pickup, or the like, or an estimated value may be obtained from a back electromotive voltage, an elapsed time after energizing the starter, or the like.

  If it is determined in step S204 that the starter rotational speed is equal to or higher than the predetermined rotational speed N1, the process proceeds to step S205. On the other hand, if it is determined in step S204 that the starter rotation speed is less than the predetermined rotation speed N1, the process waits in step S204 until the starter rotation speed becomes equal to or higher than N1, and when it reaches N1 or higher, the process proceeds to step S205. Proceed with

  In step S205, the ECU turns off the changeover switch 11 and stops energization of the coil switching solenoid 10. As a result, the field coil switching relays 4a and 4b are closed, and the upstream field coil 8a and the downstream field coil 9a, and the upstream field coil 8b and the downstream field coil 9b are partly respectively. As described above, the short-circuited state is switched to the high rotation (high output) starter characteristic.

  As a result, the starter torque can be switched during key start, and the engine can be started more quickly. In the second embodiment, the operation state of the changeover switch 11 is switched only once during the starter rotation at the time of key start. However, the present invention is not limited to such a case, and it is possible to adopt a configuration in which the changeover switch 11 is switched in accordance with a torque change at the start of the engine.

  When the engine is started by the starter, a torque change caused by the expansion / compression torque of each cylinder of the engine occurs, and a so-called overrun state may occur in which the engine speed exceeds the starter speed.

  When starting the engine, the starter is generally connected to the engine via a one-way clutch. For this reason, even if it becomes an overrun state, a starter is not rotated by an engine. However, when the engine torque further changes in the overrun state, the engine speed starts to decrease, and the one-way clutch tries to transmit torque, a large impact is generated when the difference in rotational fluctuation between the engine and the starter is large. Become.

  Therefore, it is possible to reduce such an impact by operating the changeover switch 11 in accordance with the torque change at the start of the engine. Specifically, the starter can be changed to the high output side (high rotation side) by setting the changeover switch 11 to the OFF state while the rotation of the engine is accelerated due to the torque caused by the expansion stroke. On the other hand, when the engine is decelerated due to torque caused by the compression stroke, the starter can be changed to the low output side (high torque side) by turning on the changeover switch 11.

  Thereby, in an overrun state, it becomes a high output side (high rotation side), and rotation of a starter becomes high. On the other hand, when the overrun state ends and the one-way clutch tries to transmit torque, it can be changed to the low output side (high torque side), and the rotational fluctuation difference between the engine and the starter can be suppressed. . As a result, it is possible to suppress the occurrence of impact and reduce noise.

  As described above, the engine starter according to Embodiment 2 has a configuration in which the changeover switch can be switched to change to a desired starter characteristic in accordance with a change in the starter rotation speed during starter rotation at the time of key start. . With such a configuration, when a predetermined output change condition is satisfied at the time of key start, the output of the starter motor is changed from the low output side (high torque side) to the high output side (high rotation side). be able to. As a result, the engine can be started more quickly during key start.

  Furthermore, it is also possible to adopt a configuration in which the changeover switch is switched to change to a desired starter characteristic in accordance with the torque change. As a result, it is possible to suppress the occurrence of an impact at the time of starting the key and reduce the noise.

  1 power supply, 2 key switch, 3 solenoid switch, 4a, 4b field coil change relay, 8a, 8b upstream field coil, 9a, 9b downstream field coil, 10 coil change solenoid, 11 change switch.

The engine starter according to the present invention stops the combustion of the engine and automatically stops the engine when the engine automatic stop condition is satisfied, and when the restart condition is satisfied after the engine automatic stop condition is satisfied. An engine starter for restarting the engine, comprising: a starter motor for starting the engine; and an output changing unit capable of changing the output of the starter motor, wherein the output changing unit is provided when a restart condition is satisfied. When starting the engine, keep the closed state without operating the normally closed contact so that the starter motor operates so as to have a high rotation starter characteristic. The starter characteristic of high rotation is achieved by operating the normally closed contact in the open state before or simultaneously with the starter motor operation. The output of the starter motor being constant, to operate the starter motor is changed to a starter characteristics of high torque, further, the engine rotation is accelerated by the torque change due to the expansion stroke at the time of starting the engine is higher than the starter rotation In the overrun state, the output of the starter motor is changed to the high output side corresponding to the high rotation side, and the engine rotation is decelerated due to the torque change caused by the compression stroke at the start of the engine and becomes lower than the starter rotation. When the overrun state is released, the output of the starter motor is changed to the low output side corresponding to the high torque side .

In addition, an engine start method according to the present invention includes a starter motor for starting an engine and an output changing unit that can change an output of the starter motor. When an engine automatic stop condition is satisfied, combustion of the engine is performed. When the restart condition is satisfied after the automatic engine stop condition is satisfied and the engine automatic stop condition is satisfied, the engine start method is applied to an engine start device that restarts the engine. A first step of operating the starter motor to have a high rotation starter characteristic by maintaining the closed state without operating the normally closed contact when the engine is started when the restart condition is satisfied; When starting the engine except when the restart condition is satisfied, the normally closed connection is performed before or simultaneously with the starter motor operation. By operating the open state, a second step of operating the starter motor output of the starter motor is set to a starter characteristic of high rotation, change the starter characteristics of high torque, the expansion stroke at engine start If the engine rotation is accelerated by the torque change caused by the engine and the engine is in an overrun state that is higher than the starter rotation, the output of the starter motor is changed to the high output side corresponding to the high rotation side, and the compression stroke at the time of starting the engine A third step of changing the output of the starter motor to the low output side corresponding to the high torque side when the engine rotation is decelerated due to the torque change caused by It is what you have.

Claims (6)

When the engine automatic stop condition is satisfied, engine combustion is stopped and the engine is automatically stopped. When the restart condition is satisfied after the engine automatic stop condition is satisfied, the engine is restarted. A device,
A starter motor for starting the engine;
An output changing unit that can change the output of the starter motor,
The output changing unit
When starting the engine when the restart condition is satisfied, maintaining the closed state without operating the normally closed contact, the starter motor is operated to have a high rotation starter characteristic,
When starting the engine other than when the restart condition is satisfied, the starter characteristic of high rotation is set by operating the normally closed contact in the open state before or simultaneously with the operation of the starter motor. An engine starter that operates the starter motor by changing the output of the starter motor to a high torque starter characteristic. The engine starter according to claim 1,
In the engine start other than when the restart condition is satisfied, the output change unit changes the output of the starter motor to the starter characteristic of the high torque, and when a preset output change condition is satisfied, An engine starter that changes the output of the starter motor from the high torque starter characteristic to the high rotation starter characteristic. The engine starting device according to claim 2,
A starter rotational speed detector for obtaining an actual measurement value or an estimated value of the rotational speed of the starter motor;
The output changing unit includes a first torque obtained from the starter characteristic of the high torque and a second obtained from the starter characteristic of the high rotation as the torque corresponding to the rotation number obtained by the starter rotation number detection unit. An engine starter that compares torque and determines that the output change condition is satisfied when the second torque is equal to or greater than the first torque. The engine starting device according to any one of claims 1 to 3,
The normally closed contact is configured to increase the number of turns to be energized on the field side of the starter motor by switching from the closed state to the open state. The engine starting device according to claim 4,
The starter motor is a DC direct-winding motor having four or more poles, and a motor in which two or more field winding coils are connected in series,
In the closed state, the normally closed contact places a part of the coils of the field windings connected in series in a short-circuited state, and in the open state, the field-closed contact eliminates the shorted state. It is configured to increase the winding of the winding coil,
The output changing unit maintains the normally closed contact in the closed state, thereby controlling the output of the starter motor to have the high rotation starter characteristic, and opening the normally closed contact from the closed state to the open state. An engine starter that controls the output of the starter motor so as to have the high torque starter characteristic by switching to a state. A starter motor for starting the engine, and an output changing unit that can change the output of the starter motor, and when the engine automatic stop condition is satisfied, the engine is stopped and the engine is automatically stopped, When the restart condition is satisfied after the automatic engine stop condition is satisfied, the engine start method is applied to an engine starter that restarts the engine,
In the output changing unit,
A first step of operating the starter motor to have a high rotation starter characteristic by maintaining a closed state without operating a normally closed contact when starting the engine when the restart condition is satisfied When,
When starting the engine other than when the restart condition is satisfied, the starter characteristic of high rotation is set by operating the normally closed contact in the open state before or simultaneously with the operation of the starter motor. And a second step of operating the starter motor by changing the output of the starter motor to a starter characteristic of high torque.

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