EP2128426B1

EP2128426B1 - Starter having delay circuit

Info

Publication number: EP2128426B1
Application number: EP20090007110
Authority: EP
Inventors: Masami Niimi
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2008-05-29
Filing date: 2009-05-27
Publication date: 2015-05-13
Anticipated expiration: 2029-05-27
Also published as: EP2128426A2; EP2128426B8; JP2009287459A; EP2128426A3; JP5136214B2

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a starter having delay circuit, and in particular to the starter that controls the operation of a motor in a two-stage control manner.

2. Description of the Related Art

In a conventionally known electromagnetic push-in type starter, as shown in Fig. 1, when an electromagnetic switch closes a main contact point, a large electrical current (current value A0) referred to as a rush current flows from a battery to a motor. Therefore, the terminal voltage (voltage value V0) of the battery significantly decreases. Operation of electrical devices, such as meters and audio equipment, instantaneously stops, causing a so-called "temporary blackout".
Therefore, a starter is disclosed in Japanese Utility Model Laid-open Publication No. Showa 59-30564 that can suppress the rush current that flows when a motor is started. The starter includes a current suppressing resistor, a relay, a timer circuit, and the like. The current suppressing resistor is connected to a motor circuit in series with a main contact point. The relay short-circuits the current suppressing resistor. The timer circuit delays operation of the relay. When the motor is started, as shown in Fig. 4, the current suppressing resistor reduces the voltage to be applied to the motor, and a tow current (current value A1) flows to the motor. As a result, the motor rotates at a low speed. Then, when the relay operates with a delay by receiving a signal from the timer circuit and short-circuits the current suppressing resistor, a high current (current value A2) flows to the motor, and the motor rotates at a high speed. Further examples are shown in EP 1 041 277 A1 and EP 1 883 154 A1 .
In the above-described known technology (Japanese Utility Model Laid-open Publication No. Showa 59-30564 ), the value A1 of the rush current flowing to the motor through the current suppressing resistor when the motor is started is expressed by a following Expression (1). $A 1 = battery no - load voltage / (battery internal resistance + circuit wiring resistance + motor resistance + current suppressing resistance)$
On the other hand, a maximum value A2 of the current flowing to the motor when the current suppressing resistor is short-circuited is expressed by a following Expression (2). $A 2 = (battery no - load voltage - motor reverse voltage) / (battery internal resistance + circuit wiring resistance + motor resistance)$
In the above-described Expression (2) used to determine the current value A2, a term "motor reverse voltage" is included. The motor reverse voltage is a value proportional to the motor rotation speed. The rotation speed is significantly influenced by motor load, motor temperature, performance deterioration in the motor, and the like. Therefore, the electrical current value A2 changes depending on the value of the motor reverse voltage. A battery terminal voltage V2 that is determined by the current value A2 cannot be stabilized. On the other hand, Expression (1) does not include the term "motor reverse voltage". The current value A1 is determined by the battery no-load voltage and circuit resistance. Since the current value A1 can be a stable value, the battery terminal voltage (voltage value V1) is stabilized.
However, in Japanese Utility Model Laid-open Publication No. Showa 59-30564 , an object of the invention is to suppress the rush current when the motor is started. A delay time of the relay is set such that the current value A1 is smaller than the current value A2. In this instance, a minimum terminal voltage of the battery is determined by the current value A2. Voltage drop at the battery terminal cannot be stably suppressed. Therefore, preventing "temporary blackouts", caused by the drop at the battery terminal voltage, with any certainty is difficult.
In recent years, to reduce CO₂ emissions as a measure against global warming, development of an idling stop device for vehicles is being promoted. The idling stop device stops the engine every time the vehicle stops. Therefore, compared to a vehicle that does not include the idling stop device, the number of times the engine starts is significantly increased, and the frequency of "temporary blackouts" also increases. Moreover, in a vehicle including the idling stop device, the engine will often be started on a road on which vehicles are running. Therefore, compared to when the engine is started in a conventional manner, such as in a garage or at a parking lot, a driver experiences further inconvenience caused by the "temporary blackouts".

SUMMARY OF THE INVENTION

The present invention has been achieved in light of the above-described issues. An object of the present invention is to provide a starter that can stably suppress voltage drop at a battery terminal and prevent occurrence of "temporary blackouts", thereby relieving inconvenience experienced by a driver.
To achieve the above-described object, a first aspect of the present invention comprises a motor that generates rotational force through energization, a pinion gear that transmits the rotational force generated by the motor to a ring gear of an engine; a first electromagnetic switch that opens and closes a first contact point provided on a motor circuit for applying a current from a battery to the motor; a resistor that is connected to the motor circuit in series with the first contact point; a second electromagnetic switch that opens and closes a second contact point, the second contact point being connected to the motor circuit in parallel with the resistor; and a control device that controls a timing of the electromagnetic switches that opens and closes the contact points in order to allow a first current to flow through the resistor as long as the first contact point is closed and the second contact point is opened and to allow a second current to flow through the second contact point as long as the first and second contact points are closed; wherein the control device is configured to control the timing of the switches to make the first current to have a larger peak value than a peak value of the second current.
The maximum current flowing to the motor when the first electromagnetic switch is energized is not influenced by motor reverse power. Therefore, current value A1 is stable. On the other hand, the maximum current flowing to the motor when the second electromagnetic switch is energized is affected by the motor reverse power. Therefore, current value A2 is not easily stabilized.
A minimum value of a battery terminal voltage can be set using the current value A1, which is the more stable value, by appropriately setting the time from when the first electromagnetic switch is energized until the second electromagnetic switch is energized, namely the resistor energization time during which the motor is energized via the resistor, and controlling the maximum current value of the current flowing to the motor when the second electromagnetic switch is energized to be equal to or less than the maximum current value of the current flowing to the motor when the first electromagnetic switch is energized. The maximum current flowing to the motor when the first electromagnetic switch is energized is not influenced by the motor reverse power that changes depending on the current and with time. Therefore, changes in the current value A1 can be minimized even after prolonged use of the starter. As a result, voltage drop at the battery terminal can be stably suppressed, and occurrence of "temporary blackouts" caused by the voltage drop at the battery terminal can be prevented.
In the starter according to the first aspect of the invention, the resistor energization time is preferably set such that a delay circuit sets an ON timing at which the second electromagnetic switch is energized based on an ON time at which the first electromagnetic switch is energized.
In this configuration, the current value is not required to be detected and fed back to decide the ON timing of the second electromagnetic switch. The ON timing can be decided merely by a timer setting in the delay circuit. Therefore, circuit configuration can be simplified, and manufacturing cost can be reduced. Moreover, as a result of simplification of the circuit configuration, circuit scale can be reduced. Therefore, for example, the delay circuit can be mounted in a limited space within the second electromagnetic switch.
In the above-described starter, the delay circuit can preferably change the resistor energization time depending on any of a starter temperature, a starter ambient temperature, and an engine temperature.
Because the top dead point overriding torque required to rotate the engine changes depending on temperature, the motor rotation speed at the start of energization of the second electromagnetic switch changes. In other words, motor reverse power changes. Therefore, as a result of the delay time being changed depending on temperature, the maximum current flowing to the motor when the second electromagnetic switch is energized can be stabilized in relation to the maximum current flowing to the motor when the first electromagnetic switch is energized.
In the above-described starter, the delay circuit preferably shortens the resistor energization time as the starter ambient temperature or the engine temperature rises from a low temperature to a high temperature.
At a low temperature, the top dead point overriding torque of the engine is large, and the internal resistance of the battery is large. Therefore, the rise in the rotation speed of the motor when the first electromagnetic switch is energized is slow. The maximum current value when the second electromagnetic switch is energized may exceed the maximum current value when the first electromagnetic switch is energized. On the other hand, when the resistor energization time is extended, the second electromagnetic switch is energized when the rotation speed of the motor is higher. Therefore, the maximum current value when the second electromagnetic switch is energized can be further reduced. Risk of the maximum current value when the second electromagnetic switch is energized exceeding the maximum current value when the first electromagnetic switch is energized can be avoided.
In any of the above-described starters, the current flowing to the motor when the first electromagnetic switch is energized is preferably at least a current value corresponding to a torque sufficient to overcome the top dead point overriding torque. In the configuration, because the rotation speed of the motor when the first electromagnetic switch is energized is more easily increased, the rotation speed of the motor when the second electromagnetic switch is energized further increases. As a result, the resistor energization time from when the electromagnetic switch 7 is energized until the second electromagnetic switch is energized can be further shortened. The time required to start the engine can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

Fig.1 is a time chart showing an operation of a conventional starter;
Fig.2 is an electrical circuit diagram of a starter of an embodiment according to the present invention;
Fig.3 is a planar view of the starter;
Fig.4 is a time chart showing an operation of a conventional starter;
Fig.5 is a time chart showing an operation of the starter of the embodiment;
Fig.6 is a time chart showing an operation of the starter of the embodiment.
Fig.7 is a block diagram showing a timer circuit using a RC circuit in the embodiment.
Fig.8 is a block diagram showing a timer circuit using a counter circuit, which can be used as an alternative to the timer circuit as shown in Fig.7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the present invention will be described with reference to the attached drawings.
Fig. 2 is an electrical circuit diagram of a starter 1. Fig. 3 is a planar view of the starter 1.
As shown in Fig. 2, the starter 1 according to the embodiment includes a motor 2, a pinion gear 4, an electromagnetic switch 7, a current suppressing resistor 8, a short-circuit relay 9, a timer circuit 10, and the like. The motor 2 generates rotational force in an armature 2a by energization. The pinion gear 4 transmits the rotational force from the armature 2a to a ring gear 3 of an engine. The electromagnetic switch 7 opens and closes a main contact point (described hereafter) provided on a motor circuit for allowing a current to flow from a battery 5 to the motor 2. The electromagnetic switch 7 also pushes the pinion gear 4 in a counter-motor direction (rightward direction in Fig. 2) using a shift lever 6. The current suppressing resistor 8 is connected to the motor circuit in series with the main contact point. The short-circuit relay 9 is provided to short-circuit the current suppressing resistor 8. The timer circuit 10 delays operation of the short-circuit relay 9.
In the motor 2, a commutator 2b is provided on one end side (left side in Fig. 2) of the armature 2a shown in Fig. 2. The motor 2 is a known commutator motor that generates rotational force in the armature 2a by current being applied from the battery 5 to the armature 2a, via a brush 11 disposed on an outer perimeter of the commutator 2b, when the electromagnetic switch 7 closes the main contact point. As shown in Fig. 3, the motor 2 is fixed onto a housing 12 by a plurality of through-bolts 13 being tightened onto the housing 12.
As shown in Fig. 3, the housing 12 includes a flange section 12a and a switch attaching section 12b. The flange section 12a is fixed onto a starter attaching surface (not shown) on an engine side. The switch attaching section 12b is used to fix the electromagnetic switch 7.
The pinion gear 4 is disposed integrally with a clutch 15 on an outer perimeter of an output shaft 14 driven by the motor 2. The rotation of the output shaft 14 is transmitted via the clutch 15.
The electromagnetic switch 7 is configured by a solenoid that includes a switch coil 16 and a plunger 17. In the electromagnetic switch 7, an electromagnet is formed by current being applied to the switch coil 16 and the plunger 17 is attracted. With the movement of the attracted plunger 17, the main contact point is closed. When energization of the switch coil 16 is stopped and the attraction force dissipates, the plunger 17 is pushed back by the counter force of a spring (not shown), and the main contact point is opened. As shown in Fig. 3, the electromagnetic switch 7 is fixed by two bolts 18 being tightened onto the switch attaching section 12b provided in the housing 12.
The main contact point includes a B fixed contact point 19a, an M fixed contact point 20a, and a movable contact point 21. The B fixed contact point 19a is connected to the motor circuit by a B terminal bolt 19. The M fixed contact point 20a is connected to the motor circuit by an M terminal bolt 20. The variable contact point 21 moves integrally with the plunger 17, and connects and disconnects the fixed contact points 19a and 20a. These contact points 19a, 20a, 21 correspond to first contact points. As shown in Fig. 3, the B terminal bolt 19 is connected to a negative terminal 9b of the short-circuit relay 9 by a metal connecting plate 22. The M terminal bolt 20 is electrically connected to the brush 11 (see Fig. 2) on the positive side by a motor lead 23.
The switch coil 16 includes two coils (attracting coil 16a and a holding coil 16b). One end of the attracting coil 16a is connected to an excitation terminal 24. The other end is electrically connected to the M terminal bolt 20. One end of the holding coil 16b is connected to the excitation terminal 24 with the one end of the attracting coil 16a. The other end is connected to a grounded side (such as a fixed core of the electromagnetic switch 7).
The excitation terminal 24 is connected to the battery 5 via a starter relay 25. When the starter relay 25 is turned ON by an IG switch 26 being turned ON, current from the battery 5 is applied via the starter relay 25.
The current suppressing resistor 8 is connected further upstream than the main contact point of the motor circuit and is mounted on the short-circuit relay 9.
The short-circuit relay 9 includes a positive terminal 9a, a negative terminal 9b, a pair of relay contact points 9c, a movable contact point 9d, an excitation coil 9e, and the like.
The pair of relay contact points 9c and the movable contact point 9d corresponds to a second contact point.
The positive terminal 9a is connected to a positive terminal of the battery 5 by a battery cable. The negative terminal 9b is connected to the B terminal bolt 19 of the electromagnetic switch 7 by the connecting plate 22. The pair of relay contact points 9c are connected in parallel with the current suppressing resistor 8, between the positive terminal 9a and the negative terminal 9b. The movable contact point 9d connects and disconnects the pair of relay contact points 9c. One end of the excitation coil 9e is connected to a timer circuit 10 and the other end is connected to ground. As shown in Fig. 3, the short-circuit relay 9 is disposed near the excitation switch 7 and is fixed to the housing 12 via a blanket 27.
The short-circuit relay 9 is fixed by being welded onto a roughly disk-shaped end face on one end side of the blanket 27. The other end side of the blanket 27, on which two circular holes (not shown) are formed, is sandwiched between the switch attaching section 12b of the housing 12 and the electromagnetic switch 7. The blanket 27 is fixed onto the housing 12 with the electromagnetic switch 7 by two bolts 18 inserted into the circular holes.
As shown in the Fig. 2, the timer circuit 10 is mounted on the short-circuit relay 9. One end of the timer circuit 10 is connected to a low potential side of the IG switch 26, and the other end is connected to the ground. The timer circuit 10 can be connected on a downstream side of the excitation coil 9e. After the IG switch 26 is turned ON, the timer circuit 10 energizes the excitation coil 9e upon elapse of a delay time (resistor energization time of the present invention) set in advance. Figs 7 to 8 are block diagrams each showing configuration of the timer circuit 10. The starter of the present embodiment selectively employs the timer circuits from Figs 7 and 8. The timer circuit 10 can be configured with well-known delay circuits e.g. a RC delay circuit 29 or a counter circuit 30. Selection of the delay circuit is made based on required delay time accuracy. When the RC delay circuit is used for the Timer circuit 10, the range of the delay time (i.e., variable range of the delay time) can be adjusted using the adjustment terminal 28. Similarly, when the counter circuit is used for the timer circuit 10, the delay time(or range of the delay time) can be changed by external control units such as an electronic control unit (referred to as ECU). In addition, the timer circuit has a drive-amplifier 31 for driving the excitation coil 9e. As described above, the configuration of the delay time circuit can be adapted to various types of starters. The timer circuit 10 corresponds to a control device.
Next, operations of the starter 1 will be described with reference to Fig. 4 to Fig. 6.
Fig. 4 to Fig. 6 are time charts indicating ON and OFF operations of the electromagnetic switch 7 and the short-circuit relay 9, and changes in battery terminal voltage and motor current (voltage waveforms and current waveforms). The horizontal axis indicates time.
When the IG switch 26 is turned ON, the starter relay 25 is turned ON. Current from the battery 5 is applied to the switch coil 16. As a result, the pinion gear 4 is pushed in the counter-motor direction by the shift lever 6 by the plunger 17 being attracted and moved. Then, when the movable contact point 21 comes into contact with both fixed contact points 19a and 20a, and the main contact point closes, current (i.e., first current) flows from the battery 5 to the motor 2 via the current suppressing resistor 8. At this time, as shown in Fig. 4, a voltage (voltage value V1) lower than a full voltage of the battery 5 is applied to the motor 2. As a result of a suppressed current (current value A1) flowing to the motor 2, the motor 2 rotates at low speed.
After the pinion gear 4 meshes with the ring gear 3 by receiving the rotation of the motor 2, current is applied to the excitation coil 9e of the short-circuit relay 9 at a predetermined timing. Specifically, upon elapse of a predetermined delay time after the IG switch 26 is turned ON, current is applied to the excitation coil 9e of the short-circuit relay 9 through the timer circuit 10. The movable contact point 9d closes the area between the pair of relay contact points 9c, and the current suppressing resistor 8 is short-circuited. As a result, the full voltage of the battery 5 is applied to the motor 2. At this time, a current (i.e., second current, current value A2) higher than the current (i.e., first current, current value A1) at start-up flows to the motor 2, and the motor 2 rotates at high speed. As a result, the rotation of the motor 2 is transmitted to the ring gear 3 from the pinion gear 4, and the engine is cranked.
Here, the current that flows via the current suppressing resistor 8 when the motor 2 is started, namely the value A1 of the rush current, is expressed by the following Expression (1). $A 1 = battery no - load voltage / (battery internal resistance + circuit wiring resistance + motor resistance + current suppressing resistance)$
On the other hand, the maximum value A2 of the current flowing to the motor 2 when the short-circuit relay 9 is turned on and the current suppressing resistor 8 is short-circuited is expressed by the following Expression (2). $A 2 = (battery no - load voltage - motor reverse voltage) / (battery internal resistance + circuit wiring resistance + motor resistance)$
The battery terminal voltage is determined by the following Expression (3). $Battery terminal voltage = battery no - load voltage - (motor current \times battery internal resistance)$
In Expression (3) above, it is clear that, when the maximum current A1 is flowing to the motor 2 when the electromagnetic switch 7 closes the main contact point decreases, a higher battery terminal voltage V1 can be ensured. However, as shown in Fig. 4, when A2>A1, the battery terminal voltage V2 of A2 is lower than V1. Therefore, the minimum terminal voltage of the battery 5 is determined at this point.
Expression (2) used to determine the current value A2 includes a term "motor reverse voltage". The motor reverse voltage is a value proportional to the rotation speed of the motor 2, as expressed by a following Expression (4). $E = k \cdot Φ \cdot n [V]$

k: motor constant, Φ: amount of flux, and n: motor rotation speed [rpm]
The motor rotation speed is significantly influenced by motor load, motor temperature, performance deterioration of the motor 2, and the like. Therefore, in an actual vehicle, the motor rotation speed is a value that is difficult to stabilize during the entire lifetime of the motor. As a result, the current value A2 changes depending on the motor reverse voltage and does not become a stable value.
On the other hand, Expression (1) does not include the term "motor reverse voltage". Therefore, the current value A1 is determined by the battery no-load voltage and the circuit resistance. The current value A1 is can be more stable than the current value A2.
Because the motor reverse voltage continues to increase until the rise in the motor rotation speed is completed, the current value A2 continues to decrease. Therefore, when an appropriate delay time is set, as shown in Fig. 5, A1=A2. The minimum value of the battery terminal voltage can be set using A1, which is the more stable value. The motor current shown in Fig. 5 is a current waveform of when the delay time of the timer circuit 10 is set to an appropriate value (a delay time t2 that is longer than the delay time t1 shown in Fig. 4) and A1=A2.
As a result of the delay time of the timer circuit 10 being set in this way, i.e., the maximum(peak) current value A1 and the maximum(peak) value A2 are equal(A1=A2), a stable battery terminal voltage can be ensured (where A1 is a value of the current which flows to the motor 2 through the current suppressing resistor 8, and A2 is a value of the current which flows to the motor 2 when the current suppressing resistor 8 is short-circuited by the short-circuit relay 9).
However, depending on the type and model of the battery 5, voltage generated by the battery 5 may not return to the original voltage in the very short amount of time from after the current value A1 is output until the current value A2 is output. In this instance, because the internal resistance of the battery 5 appears to have risen, when the delay time is set such that A1=A2, as shown in Fig. 5, the battery terminal voltage V2 of when the short-circuit relay 9 is turned ON becomes lower than the battery terminal voltage V1 of when the electromagnetic switch 7 is turned ON.
Therefore, to make the battery terminal voltages equal (V1=V2), A2 is required to be reduced by an amount equivalent to the apparent increase in the internal resistance of the battery 5. This is expressed by the following Expression (5) $A 2 = (1 - δ \cdot A 1)$
Here, "δ" is an apparent internal resistance increase rate of the battery 5, and is a value of 4% to 10%. However, in actual application, the value is required to be confirmed under electrical current conditions to be used.
As a result of the delay time of the timer circuit 10 being set to an appropriate value (a delay time t3 that is longer than the delay time t2 shown in Fig. 5) such that the relationship in Expression (5) is established, V1=V2 can be achieved as shown in Fig. 6. The voltage drop in the battery terminal voltage can be effectively and stably suppressed. As a result, occurrence of "temporary blackouts" caused by the drop in battery terminal voltage can be prevented. In particular, in a vehicle including an idling stop device, the "temporary blackouts" can be prevented from occurring every time the engine is started on the road. Inconvenience experienced by the driver can be relieved.
According to the embodiment, the timer circuit 10 is used to set the time required (delay time) until the short-circuit relay 9 is turned ON after energization by the electromagnetic switch 7. In this instance, the current value is not required to be detected and fed back to decide the ON timing of the short-circuit relay 9. The ON timing can be decided merely by the time being set in the timer circuit 10. Therefore, circuit configuration can be simplified, and costs can be reduced. As a result of simplification of the circuit configuration, circuit scale can be reduced. Therefore, the timer circuit 10 can be mounted on the short-circuit relay 9.
The timer circuit 10 can change the delay time depending on any of a starter temperature, a starter ambient temperature, and an engine temperature. For this purpose, a temperature sensor 27 is disposed in the short-circuit relay 9. A top dead point overriding torque required to rotate the engine changes with temperature. Therefore, the motor rotation speed when the short-circuit relay 9 is turned ON changes or, in other words, motor reverse power changes.
Therefore, as a result of the delay time being changed depending on temperature, the maximum current value A2 of the current flowing to the motor 2 when the short-circuit relay 9 is energized can be stabilized in relation to the maximum current value A1 of the current flowing to the motor 2 when the electromagnetic switch 7 is energized.
The timer circuit 10 can perform control to shorten the delay time as the starter ambient temperature or the engine temperature rises from a low temperature to a high temperature.
At a low temperature, the top dead point overriding torque of the engine is large, and the internal resistance of the battery 5 is large. Therefore, the rise in the rotation speed of the motor 2 when the electromagnetic switch 7 is energized is slow. The maximum current value A2 when the short-circuit relay 9 is energized may exceed the maximum current value A1 when the electromagnetic switch 7 is energized. On the other hand, when the delay time is extended, the short-circuit relay 9 is turned ON when the rotation speed of the motor 2 is higher. Therefore, the maximum current value A2 when the short-circuit relay 9 is energized can be further reduced. Risk of the maximum current value A2 exceeding the maximum current value A1 when the electromagnetic switch 7 is energized can be avoided.
In the starter 1 according to the first embodiment, the current flowing to the motor 2 when the electromagnetic switch 7 is energized is at least a current value by which the torque generated by the motor 2 is a top dead point overriding torque of the engine or more.
In this case, because the rotation speed of the motor 2 when the electromagnetic switch 7 is energized is more easily increased, the rotation speed of the motor 2 when the short-circuit relay 9 is energized further increases. As a result, the delay time from when the electromagnetic switch 7 is energized until the short-circuit relay 9 is turned ON can be further shortened. The time required to start the engine can be reduced.

Claims

A starter (1) for an internal combustion engine equipped with a ring gear (3) receiving rotational force comprising:
a motor (2) that generates the rotational force through energization;

a pinion gear (4) that transmits the rotational force generated by the motor (2) to the ring gear (3) of the internal combustion engine;

a first electromagnetic switch (7) that opens and closes a first contact point (19a, 20a, 21) provided on a motor circuit for applying a current from a battery (5) to the motor (2) to be energized thereby rotating the motor (2);

a resistor (8) connected to the motor circuit in series with the first contact point (19a, 20a, 21);

a second electromagnetic switch (9) that opens and closes an second contact point (9c, 9d), the second contact point (9c, 9d) being connected to the motor circuit in parallel with the resistor (8); and

a control device (10) that controls a timing of the electromagnetic switches (7, 9) that opens and

closes the contact points (19a, 20a, 21, 9c, 9d) in order to allow a first current to flow through the resistor (8) when the first contact point (19a, 20a, 21) is closed and the second contact point (9c, 9d) is opened and to allow a second current to flow through the second contact point (9c, 9d) when the first and second contact points (19a, 20a, 21, 9c, 9d) are closed, the first current having a peak value depending on a resistance value of the resistor (8) and the second current having a peak value depending on a rotation speed of the motor (2),

characterised in that the control device (10) is configured to control the second electromagnetic switch (9) to set a duration during which the first current is flowing through the resistor (8) whereby the peak value of the first current is larger than the peak value of the second current.
The starter (1) according to claim 1, wherein the control device (10) includes a delay circuit that turns the second electromagnetic switch (9) ON at which a predetermined time passes from when the first electromagnetic switch (7) is turned ON,
so as to determine the duration during which the first current is flowing through the resistor (8).
The starter (1) according to claim 2, wherein the delay circuit is configured to determine the duration depending on any one of conditions including a starter temperature, a starter ambient temperature, and an engine temperature.
The starter (1) according to claim 3, wherein the delay circuit is configured to shorten the duration such that the higher an ambient temperature or an engine temperature, the shorter the duration.
The starter (1) according to any one of claims 1 to 4, wherein a current value of the first current is set to be higher than or equal to a current value corresponding to a torque sufficient to overcome the top dead point overriding torque.
The starter (1) according to any one of claims 2 to 4, wherein the delay circuit is a RC circuit.
The starter (1) according to any one of claims 2 to 4, wherein the delay circuit is a counter circuit.