Patent ID: 12243701

DESCRIPTION OF EMBODIMENTS

In many relays, a leaf spring and/or a coil spring are used to generate an appropriate contact force and a disengagement force for opening and closing contacts. When such a relay is used for an application in which the relay is susceptible to impact or vibration, the spring may be plastically deformed by the impact, and an appropriate contact force or an appropriate opening force may not be obtained. On the other hand, if a reinforcing member, etc., for withstanding an impact is separately provided, the relay assembly work becomes complicated and may lead to an increase in cost.

Hereinafter, a description will be given of the present embodiment of the present invention with reference to the drawings.

FIGS.1and2are assembling and exploded perspective views of a relay10according to an embodiment, respectively. For example, the relay10is a relay for in-vehicle electrical equipment used in an electric vehicle. The relay10is a hinge type relay including a fixed contact part14having a fixed contact12(FIG.8), a movable contact part18having a movable contact16, an electromagnet20configured to displace the movable contact16relative to the fixed contact12so that the movable contact16can come into contact or move away from the fixed contact12, and a case22configured to contain the movable contact part18and the electromagnet20. The relay10is mounted on a printed circuit board (not shown), etc., using a metal collar24attached to the outside of the case22by caulking, etc. The fixed contact portion14and the movable contact portion18are collectively referred to as a “contact part”.

As shown inFIG.2, the movable contact part18and the electromagnet20(collectively referred to as a “main body21”) may be moved relative to the case22along a contact/separation direction (a left-right direction inFIG.2) between the fixed contact12and the movable contact16, whereby the main body21is inserted and incorporated into the case22. The case22can have a structure which opens only in the contact/separation direction, and it is not necessary to combine two parts divided in the vertical direction, for example. The fixed contact part14includes a base48and the fixed contact12provided on the base48. By inserting the fixed contact part14into the case22, a back surface of the fixed contact part14constitutes a lid of the relay10. The relay10is sealed by filling a boundary between the fixed contact part14and the case22with a resin or an adhesive. The case22can be manufactured, for example, from resin molding. By forming the case22as described above, the number of components can be reduced and the manufacturing cost can be reduced.

FIGS.3and4are perspective and front views of the inside of the case22, respectively. The case22has ribs26and28configured to guide and locate the main body21at a predetermined position in the case22. Each rib extends in the contact/separation direction of the contacts, and also in the mounting direction of the main body21to the case22.

FIG.5is a cross-sectional view showing a positional relationship between an armature60, a yoke72and each rib when the electromagnet20is positioned in the case22. The rib26formed on an inner bottom surface of the case22contacts a lower surface of the yoke72to support the movable contact part18, and contributes to the vertical positioning of the movable contact part18. The rib28formed on an inner side surface of the case22has a surface29inclined in the insertion direction of the main body21. The surface29functions as a guide in the width direction of the yoke72when the main body21is inserted into the case22. The rib28contacts the side surface of the yoke72after the main body21is inserted, and contributes to the positioning of the electromagnet20relative to the case22in the width direction.

A rib30formed on an upper surface of the case22is arranged spaced away from the armature60in the vertical direction, so that the rib does not come into contact with the armature60in normal operation. Further, even if the armature60jumps up beyond the movable range when the vehicle on which the relay10is mounted receives a strong impact, the movement of the armature60is limited by the rib30, whereby a large force is prevented from being applied to the contact and/or a return spring described later. By providing the rib30, damage to each part and/or plastic deformation of the spring can be avoided.

FIG.6shows the back side of the case22opposite to an opening into which the main body21is inserted. As shown inFIGS.2and9, the electromagnet20has two coil terminals78for supplying power to a coil68. The coil terminals78are inserted into an opening41inside the case22, and are exposed to the outside of the case22through an opening32formed on the back surface of the case22. The opening32has a space for routing electric wires34and36respectively connected to the two coil terminals78. After being introduced into a pocket38formed on the outer side of the case22, the electric wires34and36are drawn out from an opening40above the pocket38, and are electrically connected to a printed circuit board, etc., on which the relay10is mounted.

FIG.7shows a state in which the electric wires34and36are drawn out from the opening40and then the opening32is filled with a resin or an adhesive42and sealed. As shown inFIG.7, the electric wires34,36or related members do not protrude from the back surface of the case22, and the size of the relay in the contact/separation direction of the contacts can be reduced. It is preferable that the case22be provided with an air hole44in order to discharge the air expanded inside the case22when a thermosetting resin or adhesive is used. It is preferable that the air hole44be sealed with a resin, etc., after the opening32is sealed.

FIG.8is an exploded perspective view of the contact part. The fixed contact part14has at least one (two inFIG.8) fixed terminals46, each provided with a fixed contact12, and a frame-shaped or box-shaped base48to which the fixed terminal46is attached. A resin or an adhesive is filled between the fixed terminal46and the base48to seal a gap therebetween. The base48is manufactured, for example, by resin molding. A permanent magnet50and a permanent magnet yoke54are attached to the outer surface of the base48, and an arc-extinguishing plate52for extinguishing an arc is inserted into the base48, which will be described later.

The movable contact part18has a conductive plate56to which the movable contact16is attached by caulking, etc., a movable spring58to which the conductive plate56is attached, and the armature60to which the movable spring58is attached by a rivet62, etc.

FIG.9is an exploded perspective view of the electromagnet20. The electromagnet20has a bobbin70, an iron core66positioned in the bobbin70, a coil68wound around the bobbin70, a substantially L-shaped yoke72to which a lower end of the iron core66is connected, and a post74attached to the yoke72. The bobbin70has a terminal port76into which the coil terminal78is inserted, and a current flows through the coil68via the electric wires34,36and the coil terminals78. The armature60is swingably supported relative to the yoke72. As will be described later, the movable spring58and the post74are connected via the return spring64so as to be elastically displaceable relative to each other.

FIGS.10and11are a top view and a side view of the contact part, respectively, andFIG.12is a perspective view of the base48. The base48has a leg80extending in the mounting direction of the main body to the case22.FIG.13is a cross-sectional view along a B-B′ line ofFIG.10. As shown in a part “A” ofFIGS.10and11, an end surface of the leg80is configured to come into contact with the yoke72when the base48is incorporated into the case22. Therefore, the positional relationship of the contacts between the fixed contact part14and the electromagnet20in the contact/separation direction is uniquely determined, and thus each component in the case22can be accurately positioned.

As shown inFIG.13, the leg80is positioned above the armature60so as to be separated from the armature60by a certain distance. This distance is determined so that the upper surface of the armature60does not come into contact with the lower surface of the leg80in the normal operation of the armature60, but the upper surface of the armature60comes into contact with the lower surface of the leg80when the armature60jumps up beyond the movable range thereof due to, for example, a strong impact applied to the vehicle on which the relay10is mounted. Since a conventional relay does not include a member which suppresses a large displacement of the armature60due to the lifting thereof, etc., a large force may be applied to the return spring64in the extending direction thereof due to the displacement of the armature60, whereby the return spring64may be plastically deformed. In the embodiment, by virtue of the leg80, the movement of the armature60beyond the movable range is limited, the force applied to the contacts and the return spring64is reduced, and the plastic deformation of the return spring64is also prevented. The leg80not only improves the positioning accuracy between the fixed contact part14and the electromagnet20, but also prevents damage and plastic deformation of each component due to the impact, etc. The leg80can be integrally formed with the base48by resin molding, etc., and thus the number of components does not increase.

FIG.14is a side sectional view of the main body21,FIGS.15and16are perspective views of examples of the post74and the movable spring58, respectively. Although the return spring64inFIG.14is a coil spring, it may be formed by a leaf spring, etc. One end of the return spring64is engaged with and held by a recess86formed at a root of a front end84of the post74fixed to the yoke72, the front end84being arranged at the center of the post74in the width direction thereof. The other end of the return spring64is engaged with and held in a recess94at a root of a protrusion92formed on the movable spring58. When the electromagnet20is off, the urging force of the return spring64causes the armature60to tilt away from the iron core66, and the movable contact16separates from the fixed contact12. On the other hand, as shown inFIG.17, when the electromagnet20is on, the armature60is displaced toward the iron core66by the magnetic force against the urging force of the return spring64, and the movable contact16comes into contact with the fixed contact12.

When a strong impact and/or external force is applied to the relay10in the contact/separation direction of the movable contact16(the left-right direction inFIG.14), the movable contact16and the conductive plate56are largely displaced toward the yoke72, whereby the movable spring58may be plastically deformed. In the embodiment, this problem can be prevented by extending the front end84closer to the movable contact than the yoke72with respect to the contact/separation direction of the contacts. Even if the movable contact16is displaced toward the yoke72due to the impact, etc., the movable spring58or the conductive plate56abuts on the front end84to limit further displacement of the movable spring58, whereby damage or plastic deformation of the movable spring58can be prevented. Since the front end84is provided on the post to which the return spring is attached, it is not necessary to provide a separate member for limiting the displacement of the movable spring, and thus the number of components can be reduced.

When one end of the return spring is directly engaged with the yoke72, no member intervenes between the conductive plate and the yoke, and thus it is not possible to prevent the conductive plate from being largely displaced toward the yoke. Since the post74according to the embodiment has the front end84which holds the return spring64and limits the displacement of the conductive plate56in the left-right direction, plastic deformation, etc., of the movable spring58due to a large external force is prevented.

When downsizing of the relay is required, it is preferable that the distance between the yoke72and the conductive plate56be short. In the embodiment, as shown inFIG.9or14, a recess or opening96is formed in the yoke72so that a portion of the post74is positioned in the opening96. As shown inFIG.15, the post74has a base portion87fixed to the yoke72, a first bent portion88which bends in a direction extending from the base portion87into the opening96, and a second bent portion90extending from the first bent portion88which bends in a direction opposite to the bending direction of the first bent portion88. The front end84is provided to the second bent portion90. By positioning the portion of the post74in the opening96, the extending distance of the post74from the yoke72to the movable contact16can be minimized, whereby the relay can be downsized. Since the post74has two bent portions88and90which bend in the opposite directions, the post74can be elastically deformed in the contact/separation direction of the contacts, whereby damage or plastic deformation of the post74is prevented.

When a vibration with a frequency equal to the natural frequency of the moving part is applied to the relay, resonance of the moving part may occur. For example, when a vibration with a frequency equal to the natural frequency of the movable contact portion18is applied to the relay10, the movable contact16and the fixed contact12resonate in the contact/separation direction, whereby and the movable contact16may unintentionally come into contact with the fixed contact12. In such a case, there is a risk of malfunction of the relay10.

In the embodiment, when the relay10is not operated and the movable contact16is in the neutral position as shown inFIG.14, a distance d1between the front end84and the movable spring58or the conductive plate56in the contact/separation direction of the contacts is set to be smaller than a distance d2between the fixed contact12and the movable contact16. Since d1is smaller than d2, even if the movable contact part18vibrates due to resonance, the movable spring comes into contact with the post before the amplitude of the vibration becomes large, and thus the amplitude does not become larger any more. Therefore, it is possible to prevent the fixed contact12and the movable contact16from unintentionally contacting each other due to resonance. By virtue of the post74having the above-mentioned dimensional relationship, malfunction of the relay during the moving part resonates can be avoided.

In particular, in a DC relay to which a high voltage such as 400 to 800 V is applied, a member for extending or extinguishing an arc, specifically a permanent magnet or an arc extinguishing plate, is provided in order to protect the contacts. Since these members are attached to a component other than an arc-extinguishing chamber, etc., having an arc-extinguishing function, such members may increase costs and assembly man-hours of parts.

In the embodiment, as shown inFIGS.8and18, the base48is formed into a frame shape or a box shape by resin molding, etc. The base48has a recess100into which the permanent magnet50is fitted, a slot102into which the arc extinguishing plate52is inserted, and an outer surface104to which the yoke54is attached. The base48shown inFIG.8, etc., is integrally formed.

FIG.19shows a state in which the permanent magnet50(FIG.20), the arc-extinguishing plate52and the yoke54are attached to the base48, andFIG.20shows a state in which the base48is removed fromFIG.19for clarification. As shown inFIG.19, the yoke54, the permanent magnet50and the arc-extinguishing plate52can be attached to the base48to which the fixed contact12is attached. The base48also functions as an arc-extinguishing chamber having high arc-blocking property, including the permanent magnet50surrounding the fixed contact12, the yoke54and the arc-extinguishing plate52.

FIG.21is a side sectional view of the base48, showing how the arc is elongated and extinguished by the permanent magnet50, the arc-extinguishing plate52and the yoke54. The arc106generated between the fixed contact12and the movable contact16is elongated to the arc-extinguishing chamber within the base48by the magnetic flux from the permanent magnet50and the yoke54. It is preferable that the surfaces of the two permanent magnets50facing each other have the same poles, and such a homopolar facing arrangement can elongate the arcs generated between each contact in the same direction.

FIG.22shows a state of an arc in a comparative example in which the arc-extinguishing plate52is not provided. InFIG.21, the arc106is elongated by the arc-extinguishing plate52inserted into the base48. On the other hand, inFIG.22in which the arc-extinguishing plate52is not provided, the arc spreads in the base48without being elongated. InFIG.21, by attaching all of the members related to the arc-extinguishing function to the base48in which a space for extinguishing the arc is secured, the relay having a high arc-blocking property is provided without increasing the number of parts.

The embodiment is a so-called double-break type relay, and the fixed contact12is attached to the base48. Therefore, it is preferable to arrange the permanent magnet and/or the arc-extinguishing plate at a position close to each fixed contact. In the embodiment, the two permanent magnets50are attached to both sides of the base48, and the two arc-extinguishing plates52are positioned on the base48so as to extend to the immediate vicinity of the respective fixed contacts12. The yoke54is configured to be vertically divided into two parts and mounted from the vertical direction of the base48from the viewpoint of ease of assembly. However, the present disclosure is not limited as such, for example, the base may be horizontally divided into two parts, and mounted from the left-right direction of the base48.

FIG.23is an exploded perspective view of a fixed contact part14′. In the fixed contact portion14′, a magnetic shield110made of a material having a high magnetic permeability, such as iron, is arranged between the two fixed contacts12on a pedestal109of the base48. With respect to the other components similar to those inFIG.8, the same reference numerals are added thereto, and the detailed explanation thereof will be omitted.

FIG.24shows a state in which the base is removed fromFIG.23.FIG.24shows the permanent magnet50, the arc-extinguishing plate52, the yoke54and the magnetic shield110. In the embodiment, in addition to the arc-extinguishing function, the magnetic flux absorbing function described below can also be obtained.

FIG.25is a diagram for explaining the relationship between the current flowing through the fixed contact12and the magnetic flux when the magnetic shield is provided, andFIG.26shows the relationship between the current and the magnetic flux in a comparative example in which the magnetic shield110is not provided. When a DC relay is used, for example, the current, input to one of the fixed terminals46in the direction of an arrow112, passes through the fixed contact12, the movable contact16, the conductive plate56and the other fixed contact12, and then flows out from the other of the fixed terminals46in the direction of an arrow114. Due to the current flowing in this way, a magnetic flux116is generated between the two fixed contacts12and the two fixed terminals46in the direction perpendicular to the drawing sheet and from the back to the front. When a large current is applied to the closed contacts of the relay, an electromagnetic repulsive force is generated between the movable contact and the fixed contact, whereby the contacts may be separated or welded to each other.

As shown inFIG.26, when the magnetic shield110is not provided, the influence of the magnetic flux116extends to the range indicated by a broken line120, for example, so that the Lorentz force in the direction indicated by an arrow122acts on the conductive plate56within an area120. InFIG.26, a force in the contact opening direction is applied to the conductive plate56, whereby the fixed contact12and the movable contact16may be separated from each other by the Lorentz force.

On the other hand, when the magnetic shield110is provided as shown inFIG.25, the magnetic flux is absorbed by the magnetic shield110, so that it is possible to prevent the conductive plate56from generating a force in the opening direction of the contacts due to the influence of the magnetic flux. Therefore, according to the embodiment, a relay which is unlikely to malfunction even when a large current is passed is provided.

The magnetic shield110is positioned not on the movable part of the relay10but on the fixed part such as the base48. Although it is possible to locate the magnetic shield on the movable part, it is preferable to not locate the magnetic shield on the movable part, since malfunction tends to occur when an impact is applied to the relay having the relatively heavy movable part. In the embodiment, since the magnetic shield is positioned at the fixed part, the weight of the movable part is not increased by the magnetic shield, and such a defect can be prevented.

All examples and conditional language provided herein are intended for the purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although one or more embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.