CN108412656B

CN108412656B - Starter

Info

Publication number: CN108412656B
Application number: CN201810128548.2A
Authority: CN
Inventors: 松原健修; 龟井光一郎; 阿部雅美; 今村直树; 金田直人
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2017-02-10
Filing date: 2018-02-08
Publication date: 2020-03-10
Anticipated expiration: 2038-02-08
Also published as: CN108412656A; JP6388678B2; JP2018127991A; FR3062885B1; FR3062885A1

Abstract

The invention provides a starter which can start an engine with a simple structure without increasing the volume of the starter, reducing the output of the starter and causing instantaneous circuit breaking of electrical equipment and electronic equipment. In the starter of the present invention, a short-circuit switch connected in parallel to an exciting coil and short-circuiting the exciting coil includes: a short-circuit switch contact connected in series between the starter switch and the armature; a drive coil having one end connected between the exciting coil and the armature and the other end grounded and used for driving the movable contact of the short-circuit switch contact; and a plunger fixed to the movable contact of the short-circuiting switch contact, wherein the plunger is driven to close the short-circuiting switch contact after a voltage applied to the driving coil becomes higher than a predetermined voltage by a counter electromotive force generated by the rotation of the armature by the closing of the starter switch.

Description

Starter

Technical Field

The present invention relates to a starter for starting an engine of, for example, a vehicle.

Background

In a conventional electromagnetic push-type starter, when an engine is started, a coil of a starter switch is energized to close an internal contact of the starter switch, thereby supplying power from a battery to a motor and causing an armature of the motor to generate a rotational torque. Then, the rotational force of the armature is transmitted to the engine crankshaft via the pinion gear and the ring gear of the engine that mesh with each other, thereby starting the engine.

Here, when the starter switch is closed, the armature is still in a stationary state and no counter electromotive force is generated, so that a surge current of several hundreds to several thousands of hundreds of amperes flows due to extremely small internal resistance of the starter. At this time, the terminal voltage of the battery drops due to internal intrinsic resistance, and a voltage drop occurs.

Therefore, the voltage drop of the battery causes the following problems at the time of starting the engine: when other electrical and Electronic devices of the vehicle, such as audio, a navigation system, an ECU (Electronic Control Unit), and the like are used, an instantaneous disconnection is caused.

This instantaneous interruption is not particularly problematic in normal engine starting, but in a vehicle or the like equipped with an idle stop function, instantaneous interruption occurs at the time of restarting after idle stop, and may give a sense of discomfort to the driver and passengers. Therefore, in order to avoid this instantaneous disconnection, the following countermeasures are taken: a boosting DC/DC converter having a backup power supply is mounted to prevent a voltage drop of a battery.

In order to avoid the instantaneous disconnection, a starter is known which includes: an electromagnetic switch that opens and closes a main contact provided in a motor circuit, a current suppressing resistor connected in series to the main contact in the motor circuit, a short-circuit relay provided so as to short-circuit the current suppressing resistor, and a timer circuit that delays operation of the short-circuit relay (see, for example, patent document 1).

In this starter, when the main contact is closed, a current is blocked from the battery to the motor via the current suppressing resistor. At this time, since a voltage lower than the total voltage of the battery is applied to the motor, the inrush current, which is the starting current flowing to the motor, is reduced. After a predetermined time has elapsed, the exciting coil of the short-circuit relay is energized, the current suppressing resistor is short-circuited, and the total voltage of the battery is applied to the motor. This makes it possible to start the engine without a momentary interruption.

In order to avoid momentary disconnection, a starter is known that includes: a starter switch connected in series between a battery and a motor, a current suppressing resistor connected in series with the starter switch, a short-circuit switch connected in parallel with the current suppressing resistor and short-circuiting the current suppressing resistor, and a control circuit controlling opening and closing of the short-circuit switch (for example, refer to patent document 2).

In this starter, when a starter switch is closed, a current is blocked from a battery to a motor via a current suppressing current. At this time, since a voltage lower than the total voltage of the battery is applied to the motor, the inrush current, which is the starting current flowing to the motor, is reduced. After a predetermined time has elapsed, the short-circuit switch is closed to short-circuit the current suppressing resistor, and the total voltage of the battery is applied to the motor. This makes it possible to start the engine without a momentary interruption.

In order to avoid instantaneous disconnection, a starter including both a permanent magnet and an excitation coil in an excitation portion of a motor is also known (see, for example, patent document 3). In this starter, when the contacts are closed, a current flows from the battery to the motor via the exciting coil, and a surge current, which is a starting current flowing to the motor, is reduced. After a predetermined time has elapsed, the exciting coil is short-circuited. This makes it possible to start the engine without a momentary interruption.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2009-287459

Patent document 2: japanese patent laid-open publication No. 2011-94555

Patent document 3: japanese patent laid-open No. 2016 & 46906

Disclosure of Invention

Technical problem to be solved by the invention

However, the starter disclosed in patent document 1 requires a current suppressing resistor and a timer circuit, and thus has a problem that the structure becomes complicated and the size of the starter increases. However, the starter disclosed in patent document 1 uses a timer circuit, and therefore, when the friction torque of the engine is large, such as at low temperatures, the rotational speed of the motor does not increase even after a predetermined time has elapsed, and is equal to or less than a predetermined counter electromotive force, and a surge current after a short-circuit of a current suppressing resistor increases, which may cause a momentary disconnection.

In addition, the starter disclosed in patent document 2 has a small heat capacity of the current suppressing resistor, and the time for short-circuiting the current suppressing resistor is limited. Therefore, if the current is equal to or less than the predetermined counter electromotive force after the elapse of the predetermined time, the surge current after the short-circuiting of the current suppressing resistor becomes large, and there is a possibility of instantaneous disconnection, and therefore there is a problem that the volume of the starter becomes large in order to secure the heat capacity of the current suppressing resistor.

Further, since the starters described in patent documents 1 and 2 use the current suppressing resistor, there is a problem that the internal resistance of the starter increases and the output of the starter may decrease.

Further, the starter described in patent document 3 requires an exciting coil current control unit that controls the current flowing through the exciting coil to switch the short circuit of the exciting coil, and therefore has a problem of complicated configuration.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a starter capable of starting an engine with a simple configuration without increasing the size of the starter, reducing the output of the starter, and instantaneously disconnecting electrical and electronic devices.

Technical scheme for solving technical problem

The starter according to the present invention includes: an armature of the motor; a battery for supplying power to the armature; a starter switch connected in series between the battery and the armature; an excitation coil connected in series with the armature and generating a magnetic flux to the armature; and a short-circuiting switch connected in parallel with the exciting coil and short-circuiting the exciting coil, the short-circuiting switch including: a short-circuit switch contact connected in series between the starter switch and the armature; a drive coil having one end connected between the exciting coil and the armature and the other end grounded and used for driving the movable contact of the short-circuit switch contact; and a plunger fixed to the movable contact of the short-circuiting switch contact, wherein the plunger is driven to close the short-circuiting switch contact after a voltage applied to the driving coil becomes higher than a predetermined voltage by a counter electromotive force generated by the rotation of the armature by the closing of the starter switch.

Effects of the invention

According to the starter of the present invention, a short-circuit switch connected in parallel to an exciting coil and short-circuiting the exciting coil includes: a short-circuit switch contact connected in series between the starter switch and the armature; a drive coil having one end connected between the exciting coil and the armature and the other end grounded and used for driving the movable contact of the short-circuit switch contact; and a plunger fixed to the movable contact of the short-circuiting switch contact, wherein the plunger is driven to close the short-circuiting switch contact after a voltage applied to the driving coil becomes higher than a predetermined voltage by a counter electromotive force generated by the rotation of the armature by the closing of the starter switch.

Therefore, the engine can be started with a simple configuration without increasing the size of the starter, without lowering the output of the starter, and without causing instantaneous disconnection of the electrical and electronic devices.

Drawings

Fig. 1 is a circuit diagram showing a starter according to embodiment 1 of the present invention.

Fig. 2 is a graph showing a current-voltage waveform in the starter according to embodiment 1 of the present invention.

Fig. 3 is a circuit diagram showing another starter according to embodiment 1 of the present invention.

Detailed Description

Hereinafter, preferred embodiments of the starter according to the present invention will be described with reference to the drawings, and the same or corresponding portions in the drawings will be described with the same reference numerals.

Embodiment 1.

Fig. 1 is a circuit diagram showing a starter according to embodiment 1 of the present invention. In fig. 1, the starter 10 includes: an armature 1a of the motor 1; a battery 2 for supplying power to the armature 1 a; a start switch 3 connected to the battery 2; a starter switch 4 connected in series between the battery 2 and the armature 1 a; an exciting coil 1b as an exciting portion connected in series with the armature 1 a; and a short-circuit switch 5 connected in parallel with the exciting coil 1b to short-circuit the exciting coil 1 b.

Here, the electric motor 1 is used to start an engine, not shown, and is composed of the armature 1a, the field coil 1b, and a field portion 1c that is excited by the battery 2 or another power source to generate magnetic flux.

Further, the starter switch 4 is configured to include: a starter switch contact 4a which is a normally open contact connected in series between the battery 2 and the armature 1 a; a driving coil 4b for driving the movable contact of the starter switch contact 4 a; a holding coil 4c for holding the movable contact of the starter switch contact 4a at a position in contact with the fixed contact; and a plunger 4d fixed to the movable contact of the starter switch contact 4 a. One end of the holding coil 4c is connected to the starter switch 3, and the other end is grounded.

The short-circuit switch 5 includes: a normally open contact, i.e., a short-circuit switch contact 5a, connected in series between the starter switch contact 4a and the armature 1 a; a driving coil 5b for driving the movable contact of the short-circuiting switch contact 5 a; and a plunger 5c fixed to the movable contact of the short-circuit switch contact 5 a. One end of the driving coil 5b is connected between the exciting coil 1b and the armature 1a, and the other end is grounded.

Next, the operation of the starter 10 configured as described above will be described with reference to fig. 2. Fig. 2 is a graph showing a current-voltage waveform in the starter according to embodiment 1 of the present invention. In fig. 2, the vertical axis represents the power supply voltage of the battery 2 and the starter current flowing through the armature 1a, and the horizontal axis represents time.

First, as the 1 st step of the engine start, when the start switch 3 is closed in response to the engine start request at time T1, the current Ia starts to flow from the battery 2 to the armature 1a via the start switch 3, the driving coil 4b, and the exciting coil 1 b. At this time, current also flows from the battery 2 to the holding coil 4c via the start switch 3.

Next, as step 2, the plunger 4d is driven by energizing the driving coil 4b, and the starter switch contact 4a is closed at time T2. Here, since the holding coil 4c is also energized, the plunger 4d is held at this position, and the closed circuit of the starter switch contact 4a is maintained.

The starter switch contact 4a is closed, and the battery 2 supplies dc power to the armature 1a, and the armature 1a generates rotational torque, and moves toward a ring gear provided on a crankshaft of the engine via a pinion gear coupled to a shaft of the armature 1a via a one-way clutch, and engages with the ring gear.

When the starter switch contact 4a is closed, the current Ia flowing from the battery 2 to the driving coil 4b is substantially eliminated, and the current Ib flowing from the battery 2 to the closed starter switch contact 4a, the exciting coil 1b, and the armature 1a is set. Thereby, the rotational force of the armature 1a is transmitted to the engine crankshaft, and the engine start is started.

Next, as step 3, at time T3 when a predetermined time has elapsed since starter switch contact 4a was closed, short-circuit switch contact 5b is closed. That is, after the voltage applied to the driving coil 5b becomes higher than the predetermined voltage due to the action of the counter electromotive force generated by the rotation of the armature 1a and increased as the rotation speed of the armature 1a increases, the plunger 5c is driven, and the short-circuit switch contact 5a is closed.

The short-circuit switch contact 5b is closed, so that current flows from the battery 2 to the armature 1a via the starter switch contact 4a and the short-circuit switch contact 5 a. At this time, the short-circuiting switch contact 5a is closed and the exciting coil 1b is short-circuited, so that the starter current increases again as shown in fig. 2.

The exciting coil 1b is short-circuited, and the only means for generating magnetic flux to the armature 1a is the exciting portion 1 c. After the start of the engine is started, the start of the engine is completed at time T4.

Thus, the short-circuit switch 5 operates in accordance with the voltage applied to one end of the driving coil 5b by the action of the counter electromotive force, so that it is not necessary to perform complicated control using a rotation detection sensor of the motor 1, a timer circuit, or the like, and the configuration can be simplified. Further, by changing the voltage at which the short-circuit switch contact 5a closes, that is, the voltage at which the plunger 5c is driven, the timing of the short circuit and the amount of voltage drop during the short circuit can be adjusted.

Here, the inrush current flowing to the armature 1a at the time T2 when the starter switch contact 4a is closed is set to the starter current I1. At this time, when the voltage of the battery 2 is V0, the internal inherent resistance of the battery 2 is RB, the resistance of the exciting coil 1b is RF, the internal resistance of the armature 1a is RM, and the wiring resistances are RW, the starter current I1 is expressed by the following expression (1).

I1＝V0/(RB+RF+RM+RW)...(1)

The current flowing to the armature 1a at the time T3 when the shorting switch contact 5a closes is set as the starter current I2. Before time T3, since a current flows through the armature 1a and the armature 1a rotates, a counter electromotive force E is generated in the armature 1 a. At this time, the starter current I2 is expressed by the following equation (2) using the internal inherent resistance RB of the battery 2, the internal resistance RM of the armature 1a, and the wiring resistances RW.

I2＝(V0-E)/(RB+RW+RM)...(2)

When the motor constant is k, the magnetic flux is Φ, and the motor rotation speed is n, the back electromotive force E is expressed by the following expression (3). That is, the starter current I2 flowing through the armature 1a can be adjusted by changing the motor specification.

E＝k×Φ×n...(3)

Here, if the voltage at which the short-circuit switch contact 5a is closed is set high, the exciting coil 1b is not short-circuited until the back electromotive force E generated by the armature 1a becomes high. That is, the back electromotive force E becomes higher, so the relationship of I1 > I2 according to equation (2) holds, and the short-circuiting switch contact 5a closes according to equation (3) at the timing when the motor rotation speed becomes higher. Therefore, the time until the exciting coil 1b is short-circuited, i.e., the time from the time T2 to the time T3, becomes long, and it takes time for the engine to start.

Therefore, as shown in fig. 2, the voltage at which the short-circuiting switch contact 5b is closed is set so that the starter current I1 is equal to the starter current I2, and the short-circuiting switch contact 5a is closed, so that the time until the exciting coil 1b is short-circuited is shortened, and thus the engine can be started in a short time while suppressing instantaneous disconnection.

As a result, in step 1, the drive coil 4b, the excitation coil 1b, and the wiring resistances of the starter switch 4 are present in the circuit, in step 2, the excitation coil 1b and the wiring resistances are present, and in step 3, only the wiring resistances are present. Therefore, from step 1 to step 3, the resistance is gradually reduced in three stages.

In this case, by using the exciting coil 1b as the current suppressing resistor, it is possible to simplify the structure, reduce the size of the starter, and reduce the weight and cost without providing a separate current suppressing resistor. Before the 3 rd step, the armature 1a is rotated by the current Ia and the current Ib, and therefore, a counter electromotive force is generated, and the current is suppressed.

Further, even at a high load where the friction torque of the engine is large, such as at a low temperature, a higher torque can be generated than in the case of using the current suppressing resistor, and therefore the engine can be started quickly and reliably.

Further, by short-circuiting the exciting coil 1b by the short-circuiting switch 5, the current flowing through the exciting coil 1b can be reduced, and the exciting magnetic flux can be reduced. Accordingly, the starter characteristic is switched from the torque type to the rotation type, and the engine can be started in a short time, so that the operation time of the starter 10 can be shortened, and the quietness can be improved. Further, since copper loss generated by the exciting coil 1b is small, power consumption can be reduced and efficiency can be improved.

Thus, in the starter 10, at the time of starting the engine, the exciting coil 1b connected between the battery 2 and the armature 1a is first energized, and after a predetermined time has elapsed, the current flowing through the exciting coil 1b is reduced by the short-circuit switch 5. This reduces the initial inrush current, suppresses the voltage drop, and enables the engine to be started more efficiently without causing instantaneous disconnection of electrical equipment or the like.

As described above, according to embodiment 1, the short-circuit switch that is connected in parallel with the exciting coil and that short-circuits the exciting coil includes: a short-circuit switch contact connected in series between the starter switch and the armature; one end of the driving coil is connected between the exciting coil and the armature, and the other end of the driving coil is grounded and is used for driving the movable contact of the short-circuit switch contact; and a plunger fixed to the movable contact of the short-circuiting switch contact, wherein the plunger is driven to close the short-circuiting switch contact after a voltage applied to the driving coil becomes higher than a predetermined voltage by a counter electromotive force generated by the starter switch closing and the armature rotating.

In embodiment 1, as shown in fig. 3, a permanent magnet 1d that generates magnetic flux in the same manner as the field section 1c may be provided instead of the field section 1c shown in fig. 1 that generates magnetic flux to the armature 1 a.

In fig. 3, for example, the magnetic pole of the excitation portion is constituted by a plurality of N-poles and S-poles in pairs, one pole is constituted by the excitation coil 1b, and the other pole is constituted by the permanent magnet 1 d. Here, even in the motor 1 having both the field coil 1b and the permanent magnet 1d, the effect of suppressing the voltage drop is obtained, and the engine can be started more efficiently without causing instantaneous disconnection of electrical equipment and the like.

Specifically, since both the exciting coil 1b and the permanent magnet 1d are provided, the magnetic field strength when the exciting coil 1b is energized increases, and the motor torque increases, so that the engine can be reliably started even when the friction torque of the engine is large at low temperatures or the like.

In a low-load region where the load is light and the motor rotation speed increases, the short-circuit switch 5 cuts off or limits the current applied to the exciting coil 1b, so that the magnetic flux of the excitation becomes small and the motor rotates at a high speed. This shortens the operation time of the starter 10, and improves the quietness. Further, the motor rotation speed can be suppressed from becoming excessively high when no load is applied, and the life of the starter 10 can be extended.

Description of the reference symbols

1 motor, 1a armature, 1b excitation coil, 1c excitation part, 1d permanent magnet, 2 batteries, 3 starting switch, 4 starter switch, 4a starter switch contact, 4b drive coil, 4c hold coil, 4d plunger, 5 short-circuit switch, 5a short-circuit switch contact, 5b drive coil, 5c plunger, 10 starter.

Claims

1. A starter, comprising:

an armature of the motor;

a battery for supplying power to the armature; and

a starter switch connected in series between the battery and the armature,

the starter is characterized by further comprising:

an exciting coil connected in series with the armature and generating a magnetic flux to the armature; and

a short-circuit switch connected in parallel with the exciting coil to short-circuit the exciting coil,

the short-circuit switch includes:

a shorting switch contact connected in series between the starter switch and the armature; a drive coil having one end connected between the exciting coil and the armature and the other end grounded, and driving a movable contact of the short-circuit switch contact; and a plunger fixed to the movable contact of the short-circuit switch contact,

when the voltage applied to the driving coil becomes higher than a predetermined voltage by a counter electromotive force generated by the rotation of the armature when the starter switch is closed, the plunger is driven, and the short-circuit switch contact is closed.

2. The starter of claim 1,

the voltage required for the short-circuit switch to operate is set so that the starter current flowing through the armature when the armature is energized via the field coil is equal to the starter current flowing through the armature when the field coil is short-circuited by the short-circuit switch and the armature is energized.

3. Starter according to claim 1 or 2,

the permanent magnet is provided with a permanent magnet that generates a magnetic flux to the armature, in addition to the field coil.