Claims:We Claim:

1. A starter magnet switch (1) comprising:
an excitation coil (2,3) which generates a magnetic force for opening/closing a main circuit of a starter;
a bobbin (4) wound with the excitation coil (2,3);
a cap (7) provided with a metal terminal (10,12) to which an end portion of the excitation coil (2,3) is connected; and
a case (5) for retaining the bobbin (4) and the cap (7), wherein
the excitation coil (2,3) is formed from an aluminum wire,
the end portion of the excitation coil (2,3) formed from the aluminum wire is coated with first solder (13), and
the end portion of the excitation coil (2,3) coated with the first solder (13) and the metal terminal (10,12) provided to the cap (7) are joined to each other by second solder (14).

2. The starter magnet switch (1) according to claim 1, wherein
an end of the end portion of the excitation coil (2,3) coated with the first solder (13) protrudes from the second solder (14).

3. The starter magnet switch (1) according to claim 1 or 2, wherein
a melting point of the first solder (13) is higher than a melting point of the second solder (14).

4. A starter magnet switch (1) comprising:
an excitation coil (2,3) which generates a magnetic force for opening/closing a main circuit of a starter;
a bobbin (4) wound with the excitation coil (2,3);
a cap (7) provided with a metal terminal (10,12) to which an end portion of the excitation coil (2,3) is connected; and
a case (5) for retaining the bobbin (4) and the cap (7), wherein
the excitation coil (2,3) is formed from an aluminum wire,
the end portion of the excitation coil (2,3) formed from the aluminum wire and the metal terminal (10,12) provided to the cap (7) are joined to each other by second solder (14), and the end portion of the excitation coil (2,3) formed from the aluminum wire is covered with the second solder (14).

5. The starter magnet switch (1) according to any one of claims 1 to 4, wherein
the excitation coil (2,3) includes an attraction coil (2) and a retention coil (3), and at least one of the attraction coil (2) and the retention coil (3) is formed from the aluminum wire.

Dated this 08th day of June, 2021
FOR MITSUBISHI ELECTRIC CORPORATION
By their Agent

(ANSHUL SUNILKUMAR SAURASTRI) (IN/PA 3086)
KRISHNA & SAURASTRI ASSOCIATES LLP , Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
[See section 10, Rule 13]

STARTER MAGNET SWITCH;

MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001]
The present disclosure relates to a starter magnet switch.

2. Description of the Background Art
[0002]
A starter magnet switch is configured to convert electric energy to mechanical energy and open/close contacts using the energy and a spring mounted inside. Through the opening/closing, energy from a battery is supplied to a motor portion of a starter or interrupted.
There is known a starter magnet switch in which an attraction coil and a retention coil are provided, a plunger is attracted by current flowing through the attraction coil and the retention coil, and a movable contact is closed in conjunction with the plunger. After the movable contact is closed, when the potentials at both ends of the attraction coil become almost equal to each other, current conduction to the attraction coil is stopped, and the state in which the movable contact is closed is retained by a magnetic flux generated by the retention coil. In general, a copper wire is used for the attraction coil and the retention coil.
[0003]
Meanwhile, a starter magnet switch in which an aluminum wire is used for a retention coil is disclosed (see, for example, Patent Document 1). This has an advantage that the weight of the starter magnet switch is reduced by using aluminum which has a smaller specific weight than copper. However, aluminum has a high ionization tendency and thus undergoes corrosion with a metal part therearound when being in contact with water. Accordingly, disclosed is a starter magnet switch in which a joining portion between an aluminum wire and a metal part is placed in a space blocked from moisture, to cope with corrosion (see for example, Patent Document 2).
[0004]
Patent Document 1: Japanese Laid-Open Patent Publication No. 62-202435
Patent Document 2: Japanese Laid-Open Patent Publication No. 2009-93973
[0005]
In Patent Document 2, a joint portion between an aluminum wire and a metal part is placed in a space blocked from outside, and a seal material or a cap member is used for ensuring airtightness of the space in which the joint portion is placed. Therefore, due to increase in the number of components, there are problems such as deterioration in workability and increase in material cost.

SUMMARY OF THE INVENTION
[0006]
The present disclosure has been made to solve the above problems, and an object of the present disclosure is to provide a starter magnet switch in which the number of components is not increased even if an aluminum wire is used, and occurrence of corrosion of the aluminum wire can be prevented.
[0007]
A starter magnet switch according to the present disclosure includes: an excitation coil which generates a magnetic force for opening/closing a main circuit of a starter; a bobbin wound with the excitation coil; a cap provided with a metal terminal to which an end portion of the excitation coil is connected; and a case for retaining the bobbin and the cap, wherein the excitation coil is formed from an aluminum wire, the end portion of the excitation coil formed from the aluminum wire is coated with first solder, and the end portion of the excitation coil coated with the first solder and the metal terminal provided to the cap are joined to each other by second solder.
[0008]
The starter magnet switch according to the present disclosure can prevent occurrence of corrosion of an aluminum wire without increase in the number of components, and enables size reduction and weight reduction.

BRIEF DESCRIPTION OF THE DRAWINGS
[0009]
FIG. 1 shows the schematic structure of a starter magnet switch according to the first embodiment of the present disclosure;
FIG. 2 is an electric circuit diagram of a starter in which the magnet switch is used, according to the first embodiment;
FIG. 3 shows a processing procedure for an end portion in the case of using an aluminum wire for an excitation coil of the starter magnet switch according to the first embodiment;
FIG. 4 is a sectional view showing a connection state of the excitation coil on an S terminal side of the starter magnet switch according to the first embodiment;
FIG. 5 is a sectional view showing a connection state of the excitation coil on a connector side of the starter magnet switch according to the first embodiment;
FIG. 6 is a sectional view showing a connection state of an excitation coil on an S terminal side of a starter magnet switch according to the second embodiment of the present disclosure; and
FIG. 7 is a sectional view showing a connection state of the excitation coil on a connector side of the starter magnet switch according to the second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENTS OF THE INVENTION
[0010]
Hereinafter, embodiments of a starter magnet switch according to the present disclosure will be described with reference to the drawings. In the drawings, the same reference characters denote the same or corresponding parts.
[0011]
FIRST EMBODIMENT
Hereinafter, a starter magnet switch according to the first embodiment of the present disclosure will be described.
FIG. 1 shows the structure of a starter magnet switch 1 according to the first embodiment, in which FIG. 1A is a view as seen from X direction in FIG. 1B, and FIG. 1B is a partial sectional view along the axial direction. FIG. 2 is an electric circuit diagram of a starter.
First, the structure of the starter magnet switch 1 will be described. In FIGS. 1 and 2, the starter magnet switch 1 is for opening/closing a main contact provided to a main circuit of the starter. The starter magnet switch 1 has, in a case 5 with one end opened, an excitation coil including an attraction coil 2 and a retention coil 3 for generating a magnetic force through current conduction therein, a movable core 23 which is provided on the inner circumferential side of the excitation coil and moves in the axial direction by the magnetic force generated by the excitation coil, a bobbin 4 wound with the excitation coil and retained in the case 5, a fixed core 6 fitted to the case 5 on the opened one end side of the case 5, and a cap 7 attached to the fixed core 6 on the side opposite to the case 5.
[0012]
The cap 7 is provided with a B terminal 8 connected to a battery 21, an M terminal 9 connected to a starter motor 22, an S terminal 10 to which the attraction coil 2 and the retention coil 3 are connected, an S-terminal-side eyelet 11a for fixing the S terminal 10, a connector 12 to which the M terminal 9 and the attraction coil 2 are connected, and a connector-side eyelet 11b for fixing the connector 12 to the cap 7. The B terminal 8 and the M terminal 9 form a fixed contact.
[0013]
An S-terminal-side lead-out portion 2a of the attraction coil 2 and an S-terminal-side lead-out portion 3a of the retention coil 3 are mechanically and electrically connected to the S terminal 10 and the S-terminal-side eyelet 11a. In addition, a connector-side lead-out portion 2b of the attraction coil 2 is mechanically and electrically connected to the connector 12 and the connector-side eyelet 11b.
[0014]
Here, at least one of the attraction coil 2 and the retention coil 3 serving as the excitation coil is formed using an aluminum wire obtained by coating aluminum with an insulating coat. Although described later in detail, in the case of using an aluminum wire for the attraction coil 2, the insulating coat of each of the S-terminal-side lead-out portion 2a and the connector-side lead-out portion 2b is removed and then the part where aluminum is exposed is coated with first solder 13 (shown in FIG. 3 to FIG. 5) by, for example, plating. Thereafter, the S-terminal-side lead-out portion 2a, and the S-terminal-side eyelet 11a, the S-terminal-side lead-out portion 3a of the retention coil 3, and the S terminal 10, are connected using second solder 14. In addition, the connector-side lead-out portion 2b, and the connector-side eyelet 11b and the connector 12, are connected using second solder 14.
In the case of using an aluminum wire for the retention coil 3, the insulating coat of the S-terminal-side lead-out portion 3a of the retention coil 3 is removed and then the part where aluminum is exposed is plated with first solder 13. Thereafter, the S-terminal-side lead-out portion 3a, and the S-terminal-side eyelet 11a, the S-terminal-side lead-out portion 2a of the attraction coil 2, and the S terminal 10, are connected using second solder 14.
In the case of using aluminum wires for both of the attraction coil 2 and the retention coil 3, the insulating coat of each of the lead-out portions 2a, 2b, 3a of both coils is removed and the connection method as described above is performed.
[0015]
FIG. 3 shows a processing procedure for the S-terminal-side lead-out portion 2a in the case of using an aluminum wire for the attraction coil 2. FIG. 3A shows the S-terminal-side lead-out portion 2a of the attraction coil 2 coated with an insulating coat 2c. FIG. 3B shows a part 2d where the insulating coat 2c on the end side of the S-terminal-side lead-out portion 2a of the attraction coil 2 is partially removed, i.e., a part where aluminum is exposed. FIG. 3C shows a state in which the part where aluminum is exposed at the part 2d where the insulating coat 2c is removed is plated with the first solder 13. In FIG. 3C, of the S-terminal-side lead-out portion 2a, the entirety of the part 2d where the insulating coat 2c is removed is plated with the first solder 13, but as shown in FIG. 3D, the part 2d where the insulating coat 2c is removed may be partially plated.
Also for the connector-side lead-out portion 2b of the attraction coil 2, processing of plating with the first solder 13 is performed in the same manner.
[0016]
FIG. 4 is a sectional view showing a connection state between the S terminal 10, and the S-terminal-side lead-out portion 2a of the attraction coil 2 and the S-terminal-side lead-out portion 3a of the retention coil 3. The S-terminal-side lead-out portion 3a of the retention coil 3 forms a part 3d where the insulating coat 3c is removed at an end portion thereof. The part 3d where the insulating coat 3c is removed and the S-terminal-side lead-out portion 2a of the attraction coil 2 plated with the first solder 13 shown in FIG. 3 are fixed to the S terminal 10 and the S-terminal-side eyelet 11a by the second solder 14. That is, the exposed aluminum at the end portion of the attraction coil 2 formed from an aluminum wire is plated with the first solder 13 and joined to the S-terminal-side eyelet 11a and the S terminal 10 as a metal terminal by the second solder 14. Thus, the aluminum once exposed is not exposed to the outside.
Here, the retention coil 3 is formed from not an aluminum wire but a copper wire, for example. Therefore, the part 3d where the insulating coat 3c is removed at the end portion of the S-terminal-side lead-out portion 3a of the retention coil 3 may be exposed.
[0017]
FIG. 5 is a sectional view showing a connection state between the connector 12 and the connector-side lead-out portion 2b of the attraction coil 2. The connector-side lead-out portion 2b of the attraction coil 2 plated with the first solder 13 as shown in FIG. 3 is fixed to the connector 12 and the connector-side eyelet 11b by the second solder 14. That is, the exposed aluminum at the end portion of the attraction coil 2 formed from an aluminum wire is plated with the first solder 13, and is joined to the connector-side eyelet 11b and the connector 12 as a metal terminal by the second solder 14. Thus, the aluminum once exposed is not exposed to the outside.
[0018]
As shown in FIG. 4 and FIG. 5, the end portions of the S-terminal-side lead-out portion 2a and the connector-side lead-out portion 2b of the attraction coil 2, which are plated with the first solder 13, are each connected in a state exposed from the second solder 14 to the outside, whereby the connection state and the solder fitting condition can be visually confirmed. In this state, each exposed part where the insulating coat is removed is plated with the first solder 13, and thus the aluminum material of the attraction coil 2 using the aluminum wire is not exposed to the outside. Therefore, moisture can be blocked from coming into direct contact with the aluminum material, whereby occurrence of corrosion of the aluminum wire can be prevented.
[0019]
Further, if solder having a higher melting point than the second solder 14 is used as the first solder 13, it is possible to perform joining without melting the first solder 13 when connecting, by the second solder 14, each of the S-terminal-side lead-out portion 2a and the connector-side lead-out portion 2b which are plated with the first solder 13. Thus, the aluminum material of the coil can be prevented from being exposed to the outside by the first solder 13 being melted. Therefore, moisture does not come into direct contact with the aluminum wire, and thus occurrence of corrosion of the aluminum wire can be prevented.
[0020]
Next, with reference to FIG. 2 showing a usage example of the starter magnet switch 1, operation thereof will be described.
In response to an engine starting request, a switch 20 is closed and current flows from a battery 21 through the switch 20 to the attraction coil 2 and the retention coil 3 of the starter magnet switch 1. The movable core 23 is attracted by a magnetic field generated in the attraction coil 2 and the retention coil 3 through the current conduction, and a movable contact 24 moving in conjunction with the movable core 23 comes into contact with the B terminal 8 and the M terminal 9 which are the fixed contact, whereby the starter magnet switch 1 is closed. When the starter magnet switch 1 is closed, current is supplied to the starter motor 22 and rotation of the starter motor 22 is started.
[0021]
At the same time as the starter magnet switch 1 is closed, the potential of the connector 12 and the potential of the S terminal 10 become almost equal to each other, so that current no longer flows through the attraction coil 2. However, current continues to flow through the retention coil 3 and therefore the movable core 23 continues to be attracted, whereby the movable contact 24 keeps the circuit closed state, i.e., the state of being in contact with the fixed contact.
[0022]
After an engine (not shown) is started by a rotational force of the starter motor 22, when the switch 20 is opened, voltage application to the S terminal 10 is stopped, so that current conduction to the retention coil 3 is stopped. When current conduction to the retention coil 3 is stopped, the movable core 23 and the movable contact 24 are pushed back to the initial position by an energizing force of a spring (not shown).
[0023]
In a state in which the switch 20 is opened, i.e., in a state in which current is not flowing, the movable core 23 is energized in a direction away from the fixed core 6 by the energizing spring (not shown). This corresponds to the initial position. When the switch 20 is closed, the movable core 23 is attracted to move in the direction toward the fixed core 6.
[0024]
In the above description, the movable contact 24 which moves in conjunction with the movable core 23 by the magnetic field generated in the excitation coil through current conduction, comes into contact with the B terminal 8 and the M terminal 9 which are the fixed contact. Here, the movable core 23 and the movable contact 24 have only to move in conjunction with each other, and the movable core 23 and the movable contact 24 may be separated from each other.
[0025]
In the operation of the starter magnet switch 1 as described above, if corrosion has occurred in the excitation coil formed from an aluminum wire, there is a possibility that the operation is not performed normally. However, in the present embodiment, the structure that prevents occurrence of corrosion in the excitation coil formed from an aluminum wire is adopted, whereby reliability of the starter magnet switch 1 can be maintained.
[0026]
In the first embodiment, the case of using an aluminum wire for the attraction coil 2 has been described as an example. However, without limitation thereto, an aluminum wire may be used for the retention coil 3 or both of the attraction coil 2 and the retention coil 3.
In addition, the example in which the excitation coil is composed of two types of coils, i.e., the attraction coil 2 and the retention coil 3, has been described. However, a configuration in which the retention coil formed from an aluminum wire is imparted with a function as an attraction coil, may be adopted.
[0027]
As described above, in the starter magnet switch according to the first embodiment, an aluminum wire is used for at least one of the attraction coil 2 and the retention coil 3, i.e., an aluminum wire is used for the excitation coil, the insulating coat at the end portion of the coil formed from an aluminum wire, which is a part to be connected to a metal terminal, is removed, and this part is plated with the first solder 13. The part plated with the first solder 13 and the metal terminal are connected by the second solder 14. Thus, the aluminum material is not exposed to the outside and moisture can be blocked from coming into direct contact with the aluminum material, whereby occurrence of corrosion of the aluminum wire can be prevented. In addition, occurrence of corrosion of the aluminum wire can be prevented without increase in the number of components.
[0028]
SECOND EMBODIMENT
Hereinafter, a starter magnet switch according to the second embodiment of the present disclosure will be described.
FIG. 6 is a partial sectional view showing a connection state between the S terminal 10, and the S-terminal-side lead-out portion 2a of the attraction coil 2 formed from an aluminum wire and the S-terminal-side lead-out portion 3a of the retention coil 3 formed from a copper wire. The insulating coat 2c at the end portion of the S-terminal-side lead-out portion 2a of the attraction coil 2 is removed, and the insulating coat 3c at the end portion of the S-terminal-side lead-out portion 3a of the retention coil 3 is removed. The S-terminal-side lead-out portion 2a of the attraction coil 2 and the S-terminal-side lead-out portion 3a of the retention coil 3 from which the insulating coats have been removed, are fixed to the S terminal 10 and the S-terminal-side eyelet 11a by the second solder 14. That is, the exposed aluminum part at the end portion of the attraction coil 2 formed from an aluminum wire does not protrude to the outside from the second solder 14. Therefore, moisture can be blocked from coming into direct contact with the aluminum material, whereby occurrence of corrosion of the aluminum wire can be prevented.
[0029]
FIG. 7 is a partial sectional view showing a connection state between the connector 12 and the connector-side lead-out portion 2b of the attraction coil 2. The connector-side lead-out portion 2b of the attraction coil 2 from which the insulating coat 2c has been removed is fixed to the connector 12 and the connector-side eyelet 11b by the second solder 14. That is, the exposed aluminum part at the end portion of the attraction coil 2 formed from an aluminum wire does not protrude to the outside from the second solder 14. Therefore, moisture can be blocked from coming into direct contact with the aluminum material, whereby occurrence of corrosion of the aluminum wire can be prevented.
[0030]
In the above description, the attraction coil 2 formed from an aluminum wire and the retention coil 3 formed from a copper wire have been shown as an example. However, a copper wire may be used for the attraction coil 2 and an aluminum wire may be used for the retention coil 3, or aluminum wires may be used for both of the attraction coil 2 and the retention coil 3.
[0031]
In the second embodiment, the case where the end of the retention coil formed from a copper wire also does not protrude from the second solder 14 has been shown. However, the coil formed from a copper wire is less likely to be corroded, and therefore may protrude.
In addition, the example in which the excitation coil is composed of two types of coils, i.e., the attraction coil 2 and the retention coil 3, has been described. However, as described in the first embodiment, a configuration in which the retention coil formed from an aluminum wire is imparted with a function as an attraction coil, may be adopted.
[0032]
It is noted that the "aluminum wire" used in the first and second embodiments refers to a metal wire made of aluminum or a metal material containing aluminum as a main component.
[0033]
Although the disclosure is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects, and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead can be applied, alone or in various combinations to one or more of the embodiments of the disclosure.
It is therefore understood that numerous modifications which have not been exemplified can be devised without departing from the scope of the present disclosure. For example, at least one of the constituent components may be modified, added, or eliminated. At least one of the constituent components mentioned in at least one of the preferred embodiments may be selected and combined with the constituent components mentioned in another preferred embodiment.

DESCRIPTION OF THE REFERENCE CHARACTERS
[0034]
1 magnet switch
2 attraction coil
2a S-terminal-side lead-out portion
2b connector-side lead-out portion
2c insulating coat
2d part where insulating coat is removed
3 retention coil
3a S-terminal-side lead-out portion
3c insulating coat
3d part where insulating coat is removed
4 bobbin
5 case
6 fixed core
7 cap
8 B terminal
9 M terminal
10 S terminal
11a S-terminal-side eyelet
11b connector-side eyelet
12 connector
13 first solder
14 second solder
20 switch
21 battery
22 starter motor
23 movable core
24 movable contact