JP7118215B1 - Starter - Google Patents

Abstract

Kind Code: A1 A starter capable of coping with a higher voltage power supply without enlarging the size and increasing the cost is provided. A field coil (2a) and an armature (2c), which are formed by combining a plurality of single field coils and are met by a starter for starting an internal combustion engine, are electrically connected in series to direct current. A field coil (2a) is arranged between an armature (2c) and a positive terminal of a power supply (5). When the armature resistance of the armature (2c) is Ra [Ω] and the output voltage of the power supply (5) is Vb [V], the relationship [Vb×Ra/(Rf+Ra)≦12] holds. there is [Selection drawing] Fig. 2

Description

The present application relates to starters.

2. Description of the Related Art In recent years, in vehicles such as automobiles, power sources such as batteries have been increasing in voltage, for example, 48 [V] power sources. By increasing the voltage of the power supply to a higher voltage than the conventional 12[V] power supply, it is possible to increase the output of many in-vehicle electrical components, reduce losses by reducing current, and improve power generation efficiency. , and because the voltage is not so high as to have a fatal effect on the human body even if it should come into contact, the main reason is that the increase in the cost required for protective measures for the human body can be suppressed.

However, since some in-vehicle electrical equipment does not support the 48[V] power supply, the conventional 12[V] voltage power supply is often installed together, and the starter for starting the internal combustion engine also operates at the conventional voltage. It is often one of the electrical components to be used. Having two circuits with different voltages in one vehicle increases the number of parts and is disadvantageous in terms of cost.

On the other hand, in the vehicle disclosed in Patent Document 1, for example, the power source is only a high voltage power source, and the low voltage power source is eliminated to reduce the cost. When power is supplied to a starter compatible with a low-voltage power supply, PWM (Pulse Width Modulation) control reduces the voltage to 12 [V], thereby achieving common use of the power supply.

On the other hand, as an example of making the starter compatible with a 48 [V] power supply, in the technology disclosed in Patent Document 2, the number of turns of the armature coil is four times that of the starter for the 12 [V] power supply. The electric resistance is quadrupled, the current amount is 1/4, and the motor output determined by the product of the number of turns of the armature coil and the current amount is equivalent to that of a 12 [V] power supply starter.

JP 2019-65791 A JP-A-6-33853

In the case of the conventional device disclosed in Patent Document 1, a separate step-down circuit is required. In particular, the starter requires the largest amount of current among the electrical components in the vehicle, so the circuit must also be able to withstand large currents, which increases costs and reduces the benefits of eliminating low-voltage power supplies. there were. Therefore, it can be said that it is desirable to make the starter compatible with the 48 [V] power supply.

However, increasing the number of turns of the armature coil as in the conventional device disclosed in Patent Document 2 is highly difficult in terms of both design and manufacturing, and requires an increase in the size of the armature. Therefore, the size of the starter itself must be increased. Also, if the armature resistance is increased, the potential difference between the positive and negative brushes increases, which increases the possibility of spark discharge occurring during commutation and damaging the brushes and armature. Alternatively, it is necessary to weave it into the commutator, resulting in an increase in cost.

The present application discloses a technique for solving the above-described problems, and an object of the present application is to provide a starter that can cope with the increase in voltage of the power supply without enlarging the size and increasing the cost.

The starter disclosed in the present application is
A starter having a motor that is energized by a power supply with an output voltage of 30 [V] or more to generate a rotational force, and a mechanism that transmits the rotational force of the motor to an engine to start the engine,
The motor is a DC series-wound motor in which a field coil and an armature are electrically connected in series.
The field coil is arranged between the armature and a positive terminal of the power supply,
When the combined resistance of the field coil is Rf [Ω], the armature resistance of the armature is Ra [Ω], and the output voltage of the power supply is Vb [V], [Vb×Ra/(Rf+Ra)≦12 ] is made to hold.

According to the starter disclosed in the present application, it is possible to obtain a starter that can cope with the increase in voltage of the power supply without enlarging the size and increasing the cost.

1 is a cross-sectional view of a starter according to Embodiment 1; FIG. 1 is an electric circuit diagram of a starter according to Embodiment 1; FIG.

Embodiment 1.
The starter according to Embodiment 1 will be described below. FIG. 1 is a cross-sectional view of a starter according to Embodiment 1, and FIG. 2 is an electric circuit diagram of the starter according to Embodiment 1. As shown in FIG. 1 and 2, a starter 1 for starting an internal combustion engine of a vehicle includes a motor 2 that generates a torque, a mechanical portion 4 that transmits the torque of the motor 2 to a ring gear 3 of the engine, and a battery 5 as a power source. and an electromagnetic switch 6 for turning on/off power supply from the motor 2 to the motor 2 and operating the mechanical section 4 . The output voltage of the battery 5 is 48 [V].

When the engine (not shown) is started, closing the ignition switch 61 activates the electromagnetic switch 6, pushes the pinion 4a of the mechanism 4 toward the ring gear 3, and couples it to the ring gear 3. A power supply path to the motor 2 is formed. That is, when the ignition switch 61 is turned on, the electric current from the battery 5 first passes through the field coil 2a of the motor 2 via the main coil 62 of the electromagnetic switch 6, and the armature constituting the rotor from the positive electrode side brush 2b. 2c, it reaches the negative electrode side brush 2d, and further flows to the ground terminal of the battery 5 via the housing of the starter 1, the housing of the engine, and the like. As a result, a rotational force is generated in the motor 2, and the rotational force is transmitted to the ring gear 3 via the pinion 4a of the mechanical portion 4, thereby starting the engine.

At the same time, when the ignition switch 61 is closed, the electric current from the battery 5 also flows through the auxiliary coil 63 of the electromagnetic switch 6, and the contact 64 of the electromagnetic switch 6 is self-held in the closed state. As a result, even if the ignition switch 61 is turned off, the motor 2 continues to rotate and the engine is started. When the engine starts, as is well known, the pinion 4a of the mechanism 4 is pulled back to its original position and disconnected from the ring gear 3, the contact 64 of the electromagnetic switch 6 is turned off, and the motor 2 stops. .

FIG. 2 shows the parts related to the starter 1 in the electric circuit of the vehicle in which the starter 1 is mounted. The motor 2 is a so-called DC series-wound motor in which a field coil 2a and an armature 2c are arranged in series. The field coil 2a is arranged between the armature 2c and the positive terminal of the battery 5. .

The number of field coils 2a is equal to the number of poles, and generally there is an even number of four or more. If at least some of these are connected in series, the electrical resistance of the field coils 2a is increased. becomes easier. In FIG. 2, the field coil 2a is configured by combining a plurality of single field coils. Although not shown in FIG. 1, the four-pole motor 2 is used in the first embodiment. It has four single field coils. Two field coil series bodies are provided by connecting two single field coil units in series, and these two field coil series bodies are connected in parallel to form a field coil 2a. .

This makes it easier to increase the electrical resistance of the motor 2 compared to using permanent magnets for the field poles or arranging the field coils and the armature in parallel. By matching the number of turns of the armature coil and the motor current to the conventional 12 [V] power supply, it is possible to set the motor output to the same level as the starter corresponding to the conventional 12 [V] power supply.

Also, if the combined resistance Rf [Ω] of the field coil 2a is three times or more the armature resistance Ra [Ω], the potential of the positive electrode side brush 2b will be 12 [V] or less, and the power source of 12 [V] By using the armature of the starter corresponding to , as it is as the starter for the 48 [V] power supply, it is possible to reduce the cost by sharing the parts.

Furthermore, by increasing the ratio [Rf/Ra] of the combined resistance Rf [Ω] of the field coil 2a and the armature resistance Ra, the potential of the positive electrode side brush 2b can be lowered. Since the potential of the negative electrode side brush 2d remains unchanged at 0 [V], the potential difference between the commutator segments becomes small, making spark discharge less likely to occur.

In the starter according to Embodiment 1 described above, the output voltage of the battery 5 as a power supply is set to 48 [V], but in reality the value of the output voltage varies depending on the state of the battery 5 . Depending on the insufficient charging of the battery 5, it may drop to near 30 [V], and may reach near 60 [V] when the large-capacity battery is fully charged. This is due to the selection of the type of the battery 5 or the difference in the charging control method. A ratio [Rf/Ra] to the resistance Ra [Ω] may be set.

Here, when the output voltage of the battery 5 as a power source is Vb [V] and the potential of the positive electrode side brush 2b is Vp [V], [Vp=Vb×Ra/(Rf+Ra)]. Therefore, even if the output voltage of the battery 5 as a power source reaches 60 [V], if the potential of the positive electrode side brush 2b is suppressed to 12 [V] or less, [60×Ra/(Rf+Ra)≦12] When this is solved, it becomes [Rf≧4Ra], and the combined resistance Rf of the field coil 2a should be set to be four times or more the armature resistance Ra.

Although this application describes exemplary embodiments, the various features, aspects, and functions described in the embodiments are not limited to application of particular embodiments, alone or Various combinations are applicable to the embodiments. Therefore, countless modifications not illustrated are envisioned within the scope of the technology disclosed in the present application. For example, the modification, addition, or omission of at least one component shall be included.

Reference Signs List 1 starter 2 motor 2a field coil 2b positive electrode brush 2c armature 2d negative electrode brush 3 ring gear 4 mechanical unit 4a pinion 5 battery 6 electromagnetic switch 61 ignition switch 62 main coil 63 auxiliary coil

Claims (3)

A starter having a motor that is energized by a power supply with an output voltage of 30 [V] or more to generate a rotational force, and a mechanism that transmits the rotational force of the motor to an engine to start the engine,
The motor is a DC series-wound motor in which a field coil configured by combining a plurality of single field coils and an armature are electrically connected in series,
The field coil is arranged between the armature and a positive terminal of the power supply,
When the combined resistance of the field coil is Rf [Ω], the armature resistance of the armature is Ra [Ω], and the output voltage of the power supply is Vb [V], [Vb×Ra/(Rf+Ra)≦12 ] is configured so that the relationship of
A starter characterized by: The field coil includes a field coil series body in which at least two field coil units are connected in series.
The starter according to claim 1, characterized in that: The field coil comprises a plurality of field coil series bodies connected in parallel,
The starter according to claim 2, characterized in that:

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