JP2010257819A - Electromagnetic switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic switch with improved safety through a structure in which a protecting case shall not easily be taken off. <P>SOLUTION: A protective cover 10 covering a switching terminal 7 of the electromagnetic switch 2 is fixed as a nut 25 is screwed with a male screw part formed at a motor terminal bolt 9. Groove parts 25d alternately cut on tapered faces 25b and wall faces 25c in a peripheral direction are formed on a contact face of flange part 25a of the nut 25 with the protective cover 10, and the protective cover 10 has a pawl part 10d protruded toward the groove parts formed at the tip of an arm part 10c. Since the nut 25 is restrained from rotation in a loosening direction by mutual action of the pawl part 10d and the groove parts 25d, it is hard to take off the protective cover 10. With this, a starter 1 is prevented from making wrong operation due to short-circuiting of the switching terminal 7 and the terminal bolt 8, leading to enhancement of safety. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electromagnetic switch for a starter that turns on / off an energization current of a starter motor.

  2. Description of the Related Art Conventionally, a starter electromagnetic switch for turning on / off an energization current to a starter for starting an engine is known.

  In the electromagnetic switch disclosed in Patent Document 1, a movable contact driven by a magnetomotive force generated by an exciting coil comes into contact with a pair of fixed contacts and closes an electric circuit by short-circuiting between the fixed contacts. Have. The exciting coil is electrically connected to a switch terminal that is energized in response to an ON operation of the ignition switch. Further, the pair of fixed contacts are electrically connected to a battery terminal and a motor terminal, respectively, which are provided so as to protrude outward from a contact cover fitted to the yoke of the exciting coil. A battery cable is connected to the battery terminal, and a motor lead wire is connected to the motor terminal. When the electric circuit is closed, the motor receives power from the battery and generates a rotational force. This rotational force is decelerated by, for example, a planetary gear reduction device and transmitted to the pinion gear. The pinion gear meshes with a ring gear provided on the crankshaft of the engine, and starts the engine by rotating the crankshaft by the reduced rotational force of the motor.

  Here, in the electromagnetic switch, since the switch terminal is exposed to the outside from the contact cover, a resin protective cover that covers the switch terminal is attached to prevent the connection portion from being corroded by water. The protective cover has a plurality of through holes formed in the collar portion, and is fixed to the contact cover by inserting a plurality of fixing bolts therethrough.

JP 2008-128009 A

  By the way, the protective cover also has a function as a safety measure for preventing the starter from malfunctioning due to a short circuit between the battery terminal and the switch terminal due to some factor by covering the switch terminal. However, since the protective cover is fixed to the contact cover by the fixing bolt, there is a problem that the switch terminal can be exposed by loosening and removing the fixing bolt.

  The present invention has been made based on the above circumstances, and an object thereof is to provide an electromagnetic switch capable of enhancing safety by adopting a configuration in which a protective cover cannot be easily removed.

(Invention of Claim 1)
An excitation coil that generates a magnetomotive force when energized, a contact driven by the magnetomotive force of the excitation coil, a switch terminal that is electrically connected to the excitation coil, a pair of input and output terminals that are short-circuited by the contact, and a switch terminal In the electromagnetic switch including the bottomed protective cover for covering, the protective cover is screw-fastened by the fastening member, and the fastening member is restricted from rotating in the loosening direction by engaging the protective cover and the fastening member with each other. It is characterized by being.

Since the fastening member for fixing the protective cover is restricted from rotating in the loosening direction, it is difficult to remove the protective cover easily. As a result, the switch terminal cannot be exposed to the outside, so that the electrical equipment connected to the output terminal can be prevented from malfunctioning due to a short circuit between the switch terminal and the input terminal, thereby improving safety. Can do.
(Invention of Claim 2)
The electromagnetic switch according to claim 1, wherein the fastening member has a groove portion on a contact surface with the protective cover, the protective cover has a claw portion protruding toward the groove portion, and when the fastening member rotates in the tightening direction, The engagement with the groove portion is released to allow the fastening member to rotate, and when the fastening member rotates in the loosening direction, the claw portion engages with the groove portion to restrict the rotation.

Accordingly, the fastening member is allowed to rotate in the tightening direction by the interaction between the claw portion and the groove portion, but is restricted from rotating in the loosening direction. This makes it possible to achieve both ease of assembly of the protective cover and difficulty of removal.
(Invention of Claim 3)
3. The electromagnetic switch according to claim 2, wherein the claw portion is supported so as to be displaceable in the axial direction of the fastening member, and is displaced in the axial direction when the fastening member rotates in the tightening direction to release the engagement with the groove portion. The engagement with the groove is maintained without being displaced in the axial direction when the fastening member is rotated in the loosening direction.

As a result, the fastening member is allowed to rotate only in one direction.
(Invention of Claim 4)
The electromagnetic switch according to claim 3, wherein the claw portion is formed at a tip of an elastically deformable arm portion formed on the protective cover.

Thereby, the claw portion can be displaced by the elastic deformation of the arm portion.
(Invention of Claim 5)
The electromagnetic switch according to claim 4, wherein the thickness of the arm portion is thinner than the thickness of the peripheral portion of the arm portion of the protective cover.

Thereby, the elastic deformation of the arm portion can be facilitated.
(Invention of Claim 6)
6. The electromagnetic switch according to claim 5, wherein the total thickness of the claw portion is thinner than the thickness of the peripheral portion of the arm portion.

Thereby, when the arm portion is displaced in the axial direction during rotation of the fastening member in the tightening direction, the claw portion can be allowed to rotate in the tightening direction of the fastening member without being displaced beyond the thickness of the periphery of the arm portion, It is possible to prevent the displaced arm from interfering with a member interposed on the anti-fastening member side of the cover.
(Invention of Claim 7)
The electromagnetic switch according to any one of claims 1 to 6, wherein the fastening member is screwed into a male screw portion formed on the output terminal to fix the protective cover.

Thereby, since the output terminal can be used for fixing the protective cover, the number of parts can be reduced.
(Invention of Claim 8)
The electromagnetic switch according to any one of claims 1 to 7, wherein the protective cover is made of resin.

This makes it possible to reduce the weight of the protective cover and to ensure insulation.
(Invention of Claim 9)
The electromagnetic switch according to any one of claims 1 to 8, wherein the electromagnetic switch is used for intermittently energizing a starter for starting an internal combustion engine.

  In the case of an electromagnetic switch used in a starter for starting an internal combustion engine, when the switch terminal and the input terminal are short-circuited, the crankshaft is driven and rotated to start the engine. By providing the protective cover, it is possible to eliminate the danger when the engine is unexpectedly started suddenly.

It is a general view of a starter provided with an electromagnetic switch. It is a side view of a starter provided with an electromagnetic switch. It is an axial direction sectional view of an electromagnetic switch, and the upper side from a center line shows an operation state, and the lower side from a center line shows a non-operation state. It is an axial sectional view of a bobbin around which a coil is wound. FIG. 3 is a side view of the electromagnetic switch, and is an enlarged view of a main part of FIG. 2. It is a front view of a protective cover. (A) Front view of fixing nut, (b) Rear view of fixing nut, (c) Side view of fixing nut. It is explanatory drawing which shows the nail | claw part of a protective cover, and the groove part of a nut.

Example 1
As shown in FIGS. 1 and 2, the starter 1 of the first embodiment includes an electromagnetic switch 2 and a starter body 3 including a motor (not shown), and has a function of starting the internal combustion engine.

  First, the configuration of the electromagnetic switch 2 will be described.

  The electromagnetic switch 2 includes an exciting coil 4 that generates a magnetomotive force when energized, a contact 5 that is driven by the magnetomotive force of the exciting coil 4, a contact cover 6 that houses the contact 5, and a switch terminal 7 that is electrically connected to the exciting coil. A pair of battery terminal bolts 8 (input terminals of the present invention) and motor terminal bolts 9 (output terminals of the present invention) that are short-circuited by the contacts 5, and a bottomed protective cover 10 that covers the switch terminals 7. It is configured.

  As shown in FIG. 4, the exciting coil 4 includes a suction coil 4a and a holding coil 4b that are wound in a two-layer state on a bobbin 11 having a flange portion formed at both ends and having a cylindrical shape. A switch terminal fixing portion 11a to which the switch terminal metal fitting 12 is fixed and a motor terminal fixing portion 11b to which the motor terminal metal fitting 13 is fixed protrude from the flange portion on one end side of the bobbin 11. One end of each of the exciting coils 4a and 4b is connected to the switch terminal fitting 12 together. The other end of the suction coil 4a is electrically connected to the motor terminal bolt 9 through the motor terminal fitting 13. Further, the other end of the holding coil 4b is grounded via, for example, a stationary core 14. As shown in FIG. 3, the bobbin 11 is accommodated in a bottom wall portion 15 a formed on one end side of the cylindrical yoke 15. A stationary core 14 is caulked and fixed to the opening side of the yoke 15, and the bobbin 11 is held between the bottom wall 15a. Here, the stationary core 14 is assembled such that a convex portion 14 a extends in the axial direction on the inner peripheral portion, and the convex portion 14 a is inserted into the hollow portion of the bobbin 11. A plunger 17 is inserted on the bottom wall 15a side of the hollow portion of the bobbin 11 via a sleeve 16 for sliding lubrication, and is provided so as to be movable in the axial direction. The plunger 17 is urged toward the bottom of the yoke 15 by a return spring 18 provided between the plunger 17 and the stationary core 14.

  As shown in FIG. 3, the contact 5 includes a pair of fixed contacts 5 a fixed in the contact cover 6 and a movable contact 5 b that is indirectly driven by the magnetomotive force of the exciting coil 4.

  The pair of fixed contacts 5a are made of a conductive metal such as copper, for example, and as shown in FIG. 3, the heads of a battery terminal bolt 8 and a motor terminal bolt 9 provided so as to protrude from the bottom of a contact cover 6 described later. 8a and 9a.

  The movable contact 5b is made of a conductive metal such as copper, for example, and is supported at the tip of the rod 19 so as to face the pair of fixed contacts 5a via the insulating member 20, as shown in FIG. The movable contact 5b is slidable with respect to the rod 19 and is urged toward the stopper 22 by a contact pressure spring 21 interposed between the movable contact 5b and the plunger 17 with the rod 19 as an axis. Since the rod 19 is fixed to the end portion of the plunger 17 on the stationary core 14 side by press-fitting, the movable contact 5 b is provided so as to be movable in the axial direction in conjunction with the movement of the plunger 17. When the electromagnetic switch 2 is not operated, the movable contact 5b is held at a position separated from the pair of fixed contacts 5a in conjunction with the plunger 17 urged toward the anti-fixed iron core by the return spring 18.

  As shown in FIG. 3, the contact cover 6 has a bottomed cylindrical shape and is made of, for example, a non-conductive resin. A contact chamber for accommodating the contact 5 is formed inside the contact cover 6. A battery terminal bolt 8 and a motor terminal bolt 9 are insert-molded at the bottom of the contact cover 6. The opening of the contact cover 6 is fitted inside the opening of the yoke 15. A packing 23 is provided between the contact cover 6 and the stationary core 14 to prevent moisture from entering the electromagnetic switch 2 through the gap between the contact cover 6 and the yoke 15.

  As shown in FIG. 2, the switch terminal metal fixture 12 fixed to the switch terminal fixing portion 11 a of the bobbin 11 passes through a slit hole (not shown) provided at the bottom of the contact cover 6. It is assembled to. A wire connection bolt 7 a for connecting a wire from the ignition switch is screwed into the tip of the switch terminal metal 12, and between the switch terminal metal 12 and the ignition switch between the wire connection bolt 7 a and the switch metal 7. Wiring terminal 7b is sandwiched. When the ignition switch is turned on, the switch terminal 7 is supplied with power from a battery (not shown), the exciting coil 4 is energized through the switch terminal fitting 12, and the electromagnetic switch 2 is activated.

  As shown in FIG. 2, the battery terminal bolt 8 is provided by insert molding at the bottom of the contact cover 6 with the head 8 a facing inward, and the threaded portion 8 b protrudes outside the contact cover 6. And the cable (not shown) connected to a battery (not shown) is being fixed to the screw part 8b.

  As shown in FIG. 2, the motor terminal bolt 9 is provided by insert molding at the bottom of the contact cover 6 with the head portion 9 a facing inward, and the screw portion 9 b protrudes to the outside of the contact cover 6. A bus bar 24 (illustrated by a broken line) that is connected to the motor of the starter body 3 is fixed to the screw portion 9b.

  Then, the protective cover 10 which is the principal part of this invention is demonstrated.

  As shown in FIG. 5, the protective cover 10 is a bottomed member made of resin, for example, and is attached so as to cover the switch terminal 7. The protective cover 10 has an arc shape along the outer surface of the starter main body 3, and a bus bar protective portion 10 a that prevents the bus bar 24 from being wet is extended. The arc-shaped portion of the bus bar protection portion 10a is in contact with the starter main body portion 3 to position the protection cover 10. An insertion hole 10b is formed in the center of the protective cover 10, and a nut 25 (fastening member of the present invention) is screwed into a male screw portion formed on the motor terminal bolt 9 through the insertion hole 10b, thereby making a contact cover. 6 is fixed.

  As shown in FIG. 6, the nut 25 has groove portions 25 d in which tapered surfaces 25 b and wall surfaces 25 c are alternately formed in the circumferential direction on the contact surface of the flange portion 25 a with the protective cover 10. As shown in FIG. 7, the inclination angle of the tapered surface is such that the angle A <angle B when the angle formed by the flange portion 25 a and the tapered surface 25 b is the angle a, and the angle formed by the flange portion 25 a and the wall surface is the angle B. The relationship is established so that Further, as shown in FIG. 6, the protective cover 10 is formed with an elastically deformable arm portion 10c, and a claw portion 10d protruding toward the groove portion 25d is formed at its tip so as to be axially displaceable. Here, as shown in FIG. 8, the arm portion 10 c is formed thinner than the thickness of the periphery of the arm portion 10 c of the protective cover 10. Further, the claw portion 10d is designed so that the relationship L1 <L2 is established, where L1 is the total thickness of the claw portion 10d and L2 is the thickness of the peripheral portion. When the nut 25 is rotated in the tightening direction, the claw portion 10d is displaced in the axial direction while sliding on the tapered surface 25b, so that the engagement with the groove portion 25d is released and the rotation is allowed. At the time of rotation, the claw portion 10d regulates the rotation by maintaining the engagement with the wall surface 25c without being displaced in the axial direction.

  Next, the operation of the electromagnetic switch 2 will be described with reference to FIG.

  The upper side of the center line in FIG. 3 shows a state where the plunger 17 is attracted by the stationary core 14 (operating state), and the lower side of the center line shows a state where the plunger 17 is pushed back by the return spring 18 (inactive). State).

  When the ignition switch is turned on to energize the exciting coil 4 through the switch terminal 7 and the stationary core 14 is magnetized by the magnetomotive force of the exciting coil 4, an attractive force acts between the stationary core 14 and the plunger 17. Therefore, the plunger 17 is attracted by the stationary core 14 and moves to the right in FIG. 3 while the return spring 18 is compressed. The movable contact 5b approaches the pair of fixed contacts 5a in conjunction with the movement of the plunger 17, and when the movable contact 5b and the pair of fixed contacts 5a come into contact with each other, the movable contact 5b separates from the stopper 22 and contacts pressure. By pressing and contracting the spring 21, the contact pressure between the contacts is increased. When the movable contact 5b comes into contact with the pair of fixed contacts 5a, the battery terminal bolt 8 and the motor terminal bolt 9 are short-circuited, and the battery (not shown) and the motor (not shown) are conducted. As a result, the motor operates upon receiving power from the battery, and the pinion gear that receives the rotational force of the motor rotates the ring gear of the engine, thereby starting the engine.

After the engine starts, the ignition switch is turned off, and the attraction force disappears when the energization of the exciting coil 4 is stopped. Therefore, the plunger 17 is pushed back to the left in FIG. By leaving the fixed contact 5a, the contact 5 is opened. At the same time, power supply to the motor is stopped.
(Effect of Example 1)
In the electromagnetic switch 2 having the above configuration, the nut 25 for fixing the protective cover 10 is tightened by the interaction between the claw portion 10d formed on the protective cover 10 and the groove portion 25d formed on the flange portion 25a of the nut 25. Rotation in the direction is allowed, but rotation in the loosening direction is restricted. For this reason, it is difficult to remove the protective cover 10 easily. Accordingly, since the switch terminal 7 cannot be exposed to the outside, the switch terminal 7 and the battery terminal bolt 8 are short-circuited, so that the motor of the starter body 3 connected to the motor terminal bolt 9 malfunctions. Can be prevented. When the starter 1 is activated due to a malfunction of the motor, the crankshaft is driven and rotated to start the engine. However, by providing the protective cover 10 that is difficult to remove, the engine is unexpectedly started suddenly. Risk can be eliminated and safety can be improved.

  Further, the claw portion 10d is displaced in the axial direction by using the elasticity of the arm portion 10c formed on the protective cover 10, so that the claw portion 10d and the groove portion 25d are engaged with each other when the nut 25 is rotated in the tightening direction. Since it is released, it is possible to achieve both ease of assembly of the protective cover 10 and difficulty of removal. Since the arm portion 10c is made thinner and thinner, the arm portion is easily elastically deformed. Therefore, the rotational resistance in the tightening direction of the nut 25 can be reduced, and the assembling work is made easier. Further, by designing the claw portion 10d so that the relationship of L1 <L2 is established, when the arm portion 10c is displaced in the axial direction when the nut 25 is rotated in the tightening direction, the claw portion 10d is formed on the periphery of the arm portion 10c. The nut 25 can be allowed to rotate in the tightening direction without being displaced beyond the thickness, and the displaced arm portion 10c can be prevented from interfering with a member interposed on the side of the protective cover 10 opposite to the nut 25.

  Then, the number of parts can be reduced by fixing the protective cover 10 to the contact cover 6 using the motor terminal bolt 9. Further, by making the protective cover 10 made of resin, the protective cover 10 can be reduced in weight and insulation can be ensured.

2 Electromagnetic switch 4 Excitation coil 5 Contact 7 Switch terminal 8 Battery terminal bolt (input terminal of the present invention)
9 Motor terminal (output terminal of the present invention)
DESCRIPTION OF SYMBOLS 10 Protective cover 10c Arm part 10d Claw part 25 Nut (fastening member of this invention)
25d Groove

Claims (9)

An exciting coil that generates a magnetomotive force when energized;
A contact driven by the magnetomotive force of the exciting coil;
A switch terminal electrically connected to the exciting coil;
A pair of input terminals and output terminals short-circuited by the contacts;
In an electromagnetic switch comprising a bottomed protective cover that covers the switch terminal,
The protective cover is screwed by a fastening member,
The electromagnetic switch according to claim 1, wherein the fastening member restricts rotation in a loosening direction when the protective cover and the fastening member are engaged with each other. The electromagnetic switch according to claim 1,
The fastening member has a groove on the contact surface with the protective cover, the protective cover has a claw protruding toward the groove,
When the fastening member rotates in the tightening direction, the engagement with the groove portion is released to allow the fastening member to rotate, and when the fastening member rotates in the loosening direction, the claw portion engages with the groove portion. An electromagnetic switch characterized by restricting rotation. The electromagnetic switch according to claim 2,
The claw portion is supported so as to be displaceable in the axial direction of the fastening member. When the fastening member rotates in the fastening direction, the claw portion is displaced in the axial direction to release the engagement with the groove portion, and the fastening member is loosened. An electromagnetic switch characterized by maintaining engagement with the groove without being displaced in the axial direction when rotating in a direction. The electromagnetic switch according to claim 3,
The electromagnetic switch according to claim 1, wherein the claw portion is formed at a tip of an elastically deformable arm portion formed on the protective cover. The electromagnetic switch according to claim 4,
The electromagnetic switch according to claim 1, wherein a thickness of the arm portion is thinner than a thickness of a peripheral portion of the arm portion of the protective cover. The electromagnetic switch according to claim 5, wherein
The electromagnetic switch according to claim 1, wherein a total thickness of the claw portion is thinner than a thickness of a peripheral portion of the arm portion. The electromagnetic switch according to claim 1,
The electromagnetic switch, wherein the fastening member is screwed into a male screw portion formed on the output terminal to fix the protective cover. In the electromagnetic switch in any one of Claims 1-7,
The electromagnetic switch, wherein the protective cover is made of resin. The electromagnetic switch according to any one of claims 1 to 8,
An electromagnetic switch used for interrupting energization of a starter for starting an internal combustion engine.

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