JP2009206002A - Electromagnetic switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic switch in which a mechanical strength of a bolt base material portion is enhanced and a contact point member having an excellent abrasion resistance is connected easily and surely. <P>SOLUTION: The electromagnetic switch has a terminal bolt base material 13b which is embedded in a resin case and on the one end portion of which a fixed contact point member 13a is fixed. The terminal bolt base material 13b has a copper (Cu) plated layer on a connection side end surface made of iron-based steel, and the fixed contact point member 13a is made of a copper alloy, and the connection side end surface is plated with a tin (Sn) layer and is connected with the terminal bolt base material 13b by a resistance ohmic heating. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electromagnetic switch for opening and closing electrical continuity, and more particularly to an electromagnetic switch advantageous for an engine starter, for example.

  Fixed contact terminal bolts used for engine starter electromagnetic switches are fixed to resin case members, but are generally molded integrally with resin or fastened and fixed using nuts in through holes. (See, for example, Patent Document 1). A terminal of a lead wire (battery cable) connected to the battery terminal is fastened and fixed by a nut to one end of the pair of bolt bases protruding to the outside, and a copper alloy is attached to the other end of the bolt base. A copper alloy fixed contact member for obtaining contact conduction with the movable contact member is joined and fixed.

  On the other hand, a technique of integrally joining a copper alloy member by steel member brazing joining is also known (see, for example, Patent Document 2).

JP 2006-260846 A Japanese Patent Laid-Open No. 06-292963

  The reality is that the electromagnetic switch of the engine starter is always exposed to the harsh operation of the vehicle. Therefore, the threaded portion of the terminal bolt for the fixed contact is strong enough to withstand the fastening torque for fixing to the resin case member and the battery cable terminal, and to obtain contact continuity with the movable contact member. The copper alloy fixed contact member is required to have wear resistance capable of withstanding the collision of the movable contact and the spark phenomenon generated between the two contacts.

  However, for contact terminal bolts in which the copper alloy fixed contact member is integrated by brazing, the melting point of the brazing material used for joining is high, and the hardness of the copper alloy contact member after joining is There was a problem that the hardness of the former material was significantly reduced and the wear resistance of the copper alloy contact was deteriorated.

  In order to suppress the decrease in the hardness of the contact member in such a brazing process, it may be possible to employ an expensive special copper alloy material, but the cost is high and there is no practicality.

  On the other hand, as a terminal bolt for contact that gives top priority to electrical characteristics, a copper bolt specification in which the head contact portion and the screw fastening bolt portion are integrally plastic processed with a copper alloy has been put into practical use.

  However, in the copper bolt specification, the strength of the threaded part is not necessarily sufficient, and an unaccustomed worker may not be able to respond to the fastening torque request value for fixing the battery cable. Improvement in the mechanical strength of the substrate is required.

  In order to improve the bolt strength, it is necessary to change the material to the steel bolt base material. However, the bolt base head where the movable contact abuts is made of a copper alloy in consideration of the electrical characteristics of the contact structure. It is necessary to provide a fixed contact member.

  An object of the present invention is to provide an electromagnetic switch in which a contact member excellent in wear resistance is easily and surely joined while improving the mechanical strength of a bolt base material portion.

  The present invention is an electromagnetic switch in which a terminal bolt formed by bonding and fixing a fixed contact member to one end of a terminal bolt base material is embedded in a resin case, and the terminal bolt base material is made of a steel material made of iron. It is an electromagnetic switch provided with the copper alloy fixed contact member joined by resistance energization heating through the copper (Cu) plating layer at one end.

  Preferably, in the present invention, the copper alloy fixed contact member is provided with a tin (Sn) plating layer on the joining side end face.

  Preferably, the copper alloy fixed contact member of the present invention is joined to the terminal bolt base material via an annular protrusion disposed on the joining side end face and concentrically with the end face.

  Preferably, the present invention is bonded to the terminal bolt base material via a plurality of single protrusions arranged on the bonding side end face.

  Preferably, in the present invention, each protrusion has a tin (Sn) plating layer applied to the protrusion.

  In the present invention, preferably, the copper alloy fixed contact member is plastically hardened.

  ADVANTAGE OF THE INVENTION According to this invention, while improving the mechanical strength of a bolt base material part, the electromagnetic switch provided with the contact member excellent in abrasion resistance can be provided easily and reliably.

  An embodiment in which a contact terminal bolt of the present invention is applied to an engine starter will be described with reference to the drawings.

  FIG. 1 is a half longitudinal sectional view of an internal combustion engine starter, and FIG. 2 is an enlarged view of a main part of an electromagnetic switch portion in FIG.

  As shown in FIG. 1, the starter 1 is provided in a starting motor 2 that generates a rotational force, an electromagnetic switch 3 that is provided in an energization circuit of the starting motor 2, and controls the opening / closing of the motor, and decelerates the rotation of the starting motor 2. Planetary gear speed reduction mechanism (details omitted) 4, the pinion shaft 5 to which the rotation of the starter motor 2 is transmitted via the speed reduction mechanism, and the rotation of the pinion shaft 5 is transmitted via the one-way clutch 6. It consists of a pinion gear 7 and the like.

  The starter motor 2 is a DC motor including an armature 8, a fixed magnetic pole (permanent magnet) 9, a yoke 10, a brush 11, and the like. When an engine start switch (not shown) is turned on, the starter motor 2 The movable contact member 12a of the movable contact mechanism 12 abuts against the fixed contact members 13a, 14a of the pair of contact terminal bolts 13, 14, which are fixed contacts, and the armature 8 is energized via the brush 11 to start the motor 2. Rotates.

  Here, the structure of the electromagnetic switch 3 in FIG. 1 will be described with reference to FIG.

  Although a part of the configuration has been described above, a movable contact mechanism 12 is configured in the electromagnetic switch 3, and the electromagnetic switch mechanism MS is excited by turning on an engine start switch (not shown). Thus, the movable contact member 12a of the movable contact mechanism 12 comes into contact with the fixed contact members 13a and 14a of the contact terminal bolts 13 and 14 which are fixed contacts.

The contact terminal bolts 13 and 14 which are fixed contacts are respectively embedded in the insertion holes of the resin case member 15 and fastened and fixed by nuts 16 and 17. However, one of the contact terminal bolts 13 is tightened by the case member 15. This is performed between the terminal bolt head 13c and the nut 16 which are in contact with the inner surface of the nut. A terminal 20 integrated with a conductor (battery cable) 19 connected to a battery terminal (not shown) is attached to the terminal bolt 13 for contact, and is attached to a nut 16 for fixing and a terminal fixing nut 18. And are fastened and fixed by the nut.

  Similarly, a power supply terminal 21 electrically connected to the brush 11 is fastened and fixed to the other contact terminal bolt 14 with a nut 17. However, it is not necessary to replace the terminal after being mounted on the vehicle. The upper one nut 17 is sufficient and shared.

  Further, the structure of the contact terminal bolts 13 and 14 in FIG. 1 will be described with reference to FIG.

  The bolt base material 13b fastened and fixed to the resin case member 15 is generated by the fastening torque (fastening torque) of the nut 16 for fixing to the resin case member 15 and the terminal fixing nut 18 for fixing the terminal 19. Therefore, a steel bolt base made of iron is employed so as to sufficiently withstand the tensile axial force). If this kind bolt base material is an iron-type material including stainless steel, it is preferable that the same strength can be obtained.

  A fixed contact member 13a made of a copper alloy is integrated with the head portion 13c of the bolt base material 13b with which the movable contact member 12a shown in FIG.

  Next, integration of the copper alloy fixed contact member 13a with the head portion 13c of the bolt base material 13b will be described.

  As shown in FIG. 4, the fixed contact member 13a is a direct joint to the flat surface portion 13d of the bolt head 13c, and the convex protrusion 13e provided on the joint surface 13f side of the fixed contact member 13a is a bolt head plane. It is joined to the part 13d by resistance energization heating.

  As shown in FIGS. 5 and 6, the protrusion 13e has a plurality of independent protruding protrusions 13e provided on the same circumference at appropriate intervals. These protrusions do not necessarily have to be on the same circumference, and do not have to be arranged at an equal pitch, as long as the structure can contribute to joining.

  Further, as shown in FIGS. 7 and 8, it may be provided concentrically and continuously with the fixed contact member 13a, or may be provided intermittently. Furthermore, the shape of the tip portion 13g of the convex protrusion 13e may be a flat surface or a curved surface.

  For the purpose of increasing the hardness for the purpose of improving the wear resistance as a contact member, the fixed contact member 13a including the convex protrusion 13e is manufactured by plastic working by molding (increasing hardness by work hardening). Specifications) It is desirable to make it.

  Here, a method of fixing the fixed contact member 13a to the flat portion 13d of the head portion 13c of the bolt base material 13b will be described with reference to FIG.

  The bolt base material 13 b is generally T-shaped, and the lower seat surface portion 41 of the head portion 13 c is held in contact with the flat surface portion 43 of the lower electrode 42. On the flat surface portion 13d of the head portion 13c, a copper alloy fixed contact member 13a having a desired convex protruding portion 13e is disposed such that the protruding portion 13e contacts the flat surface portion 13d, and the other end surface 44 of the fixed contact member 13a. The flat portion 46 of the upper electrode 45 is in contact with.

  A desired pressing force is applied between the lower electrode 42 and the upper electrode 45, and then a desired short-time energization control is performed to complete the resistance energization heating.

  Due to the short-time energization control while the pressing force is applied, the vicinity of the protrusion 13e of the fixed contact member 13a (the flat portion of the steel bolt base 13b immediately below the protrusion 13e) becomes a heat-generating high temperature state, and the joining of both members is completed. .

  In addition, with respect to the resistance current heating of the fixed contact member 13a copper alloy material with respect to the steel material (iron-based material) of the bolt base material 13b, it is also an important management item to suppress the variation in the bonding quality due to the oxidation state change of the copper alloy material, etc. It can be said that adopting the fixed contact member 13a on which tin (Sn) plating has been applied in advance is an effective countermeasure.

  Further, the rust prevention treatment of the steel bolt base material 13b selected for securing the screw strength is generally galvanized chromate treatment specifications. However, the thin film subjected to the chromate treatment has poor conductivity, and a spark is generated between the seat surface portions 41 of the steel bolt base material 13b installed on the lower electrode 42 during the short-time energization control for bonding. It is conceivable that the contact surface 43 of the side electrode 42 is worn at an early stage. For these, by adopting a bolt base material 13b pre-plated with copper (Cu), the contact surface of the seat surface portion 41 with the lower electrode surface 42 is made of copper (Cu) having excellent conductivity. ) A thin film can be interposed, and the spark that would be generated during the short-time energization control for bonding is greatly suppressed, which is advantageous for prolonging the electrode life.

  As described above, the contact terminal bolt 13 used in the starter 1 is required to have a bolt strength capable of withstanding fastening and fixing with the nut 16 to the resin case member 15 and fastening of the terminal 20 with the terminal fixing nut 18. Needless to say, it must be strong enough to withstand the actual vehicle use environmental load conditions such as engine vibration.

  On the other hand, a steel material (iron-based material) is selected for the bolt base material 13b, and it can sufficiently cope with an actual vehicle use environment condition that requires high strength.

  In addition, the copper alloy fixed contact member 13a integrated with the head portion 13c of the steel bolt base material 13b with which the movable contact member 12a in the electromagnetic switch 3 serving as the energization circuit of the starter motor 2 comes into contact has a bolt base material. Wear resistance sufficient to withstand contact opening / closing operation with the movable contact member 12a as well as stable joining force with the contact 13b (mechanical wear resistance against direct contact and electrical resistance against spark phenomenon occurring during switching operation) Abrasion) is required.

  For this, the integration of the copper alloy fixed contact member 13a and the steel bolt base material 13b is realized by resistance energization heating, and the copper alloy fixed contact member which is the most important concern in the integrated joining. The softening phenomenon of 13a is very slight. In particular, the softening phenomenon on the contact surface side with which the movable contact member 12a abuts is almost none as shown in the hardness distribution characteristic of FIG. 9, and can provide a sufficient wear resistance characteristic. is there.

  9, a known technique (a contact terminal bolt with the highest priority on electrical characteristics includes a copper bolt specification and a steel bolt base in which a head contact portion and a screw fastening bolt portion are integrally plastic processed with a copper alloy. The fixed contact portion hardness distribution characteristics of the contact terminal bolt in which the copper alloy fixed contact member is brazed to the material and the contact terminal bolt of this embodiment will be described in detail.

  The horizontal axis indicates the distance from the contact surface 44 of the fixed contact member 13a to the steel bolt base material 13b and the flat portion 13d of the head portion 13c, and the vertical axis indicates the cross-sectional hardness of the fixed contact member 13a. Here, regarding the hardness shown on the vertical axis, the cross-sectional hardness of a copper bolt specification in which the head contact part and the screw fastening bolt part, which are known techniques, are integrally plastic processed with a copper alloy is 100 (almost constant hardness over the entire area). The hardness distribution of each specification is displayed as a ratio.

  Concerning the hardness distribution characteristic 91 (solid line) of the above copper bolt specification, the contact member is annealed by the high temperature environment in the brazing process for the integrated soldering specification using a general copper alloy contact material. As indicated by the hardness distribution characteristic 92 indicated by the chain line, the entire area is softened to about 40% of the hardness distribution characteristic 91 (solid line). It is possible to suppress softening due to a high temperature environment in such a brazing process, and by adopting an expensive special copper alloy contact material (for example, a copper alloy material added with Cr), the hardness distribution indicated by the dotted line Softening can be suppressed to about 93.

  The hardness distribution characteristic 94 (straight line) of the alternate long and short dash line is the material hardness before joining of the plastically processed contact material adopted in this embodiment, and has the same hardness distribution as the copper bolt specification integrally plastic processed with a known copper alloy. (In FIG. 9, the hardness distribution characteristic 91 indicated by a solid line and the hardness distribution characteristic 94 indicated by a one-dot chain line overlap each other and are intentionally shifted).

  The hardness distribution characteristic of the fixed contact member of the terminal bolt for resistance energization heating specification contact of this embodiment is the hardness distribution characteristic 94 of the material before joining shown by the one-dot chain line and the two-dot chain line seen in the fixed contact member brazing specification. This is a hardness distribution characteristic 95 that connects the hardness distribution characteristic 92 in which the softening phenomenon is observed on the vicinity of the joint surface.

  That is, since the joining of the bolt base material 13b and the fixed contact member 13a can be realized by local heating between the two members, the high hardness distribution characteristic 94 of the one-dot chain line is maintained in a wide range from the contact surface. The hardness distribution characteristic 95 is excellent as a contact member indicated by a broken line whose hardness gradually decreases (softens) in a region relatively close to the joining boundary.

  In addition, by adopting various protrusions 13e and tin (Sn) plating on the joint surface side of the copper alloy fixed contact member 13a, a more stable resistance energization heating strength can be realized and a contact surface side softening phenomenon can be achieved. Realization is possible.

  In addition, the resistance contact heating process with the fixed contact member 12a using the steel bolt base material 13b that has been plated with copper (Cu) in advance makes it possible to reduce the wear of the electrode contact surface, thereby prolonging the electrode life. realizable.

The principal part half sectional view of the starter for internal-combustion engine start in the example of the present invention. The electromagnetic switch part expanded sectional view in FIG. FIG. 3 is an enlarged sectional view of a contact terminal bolt portion in FIG. 2. The schematic of the integrated joining process of the terminal bolt base material for fixed contacts of FIG. 2, and a fixed contact member. The side view of the fixed contact member which shows the other Example of this invention. FIG. 6 is a bottom view of the fixed contact member of FIG. 5. The partially broken side view of the stationary contact member which shows the further another Example of this invention. The bottom view of the fixed contact member of FIG. The hardness distribution characteristic view of the fixed contact member in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Starter 12a Movable contact member 13, 14 Contact terminal bolt 13a, 14a Fixed contact member 13b Bolt base material 13c Head 13d Plane portion 13e Projection portion 15 Case member

Claims (6)

An electromagnetic switch in which a terminal bolt formed by bonding and fixing a fixed contact member to one end of a terminal bolt base material is embedded in a resin case,
The terminal bolt base material is made of a steel material made of an iron-based material, and is provided with a copper alloy fixed contact member that is resistance-energized and heated-bonded through a copper (Cu) plating layer at one end thereof. switch.   The electromagnetic switch according to claim 1, wherein the copper alloy fixed contact member is provided with a tin (Sn) plating layer on a joining side end face.   3. The copper alloy fixed contact member according to claim 1, wherein the copper alloy fixed contact member is joined to the terminal bolt base material via an annular protrusion disposed on the joining side end surface and concentrically with the end surface. Electromagnetic switch.   3. The electromagnetic switch according to claim 1, wherein the copper alloy fixed contact member is joined to a terminal bolt base material via a plurality of single protrusions arranged on a joining side end face. 4.   5. The electromagnetic switch according to claim 3, wherein each of the protrusions has a tin (Sn) plating layer at least on the protrusion.   6. The electromagnetic switch according to claim 3, wherein the copper alloy fixed contact member is plastically hardened.

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