JP4425828B2 - Thermal overload relay - Google Patents

Description

  The present invention relates to a thermal overload relay that opens a contact and interrupts a main circuit when a current exceeding a settling current value flows in a main circuit of a load such as an electric motor.

  Conventionally, a bimetal provided in the vicinity of a heater connected to the main circuit and displaced by heating of the heater at the time of overcurrent, and when the displacement of the bimetal reaches a predetermined amount, it is reversed beyond the dead point to open the main circuit A contact mechanism that outputs a contact signal, an operation lever that presses the contact mechanism in response to the amount of displacement of the bimetal, and a holding frame that houses the contact mechanism and the operation lever. A hemispherical tip of an adjustment screw is brought into contact with one end of the operation lever, and the operation lever is rotated by advancing and retreating the adjustment screw to adjust the reverse position of the contact mechanism. In the thermal relay (thermal overload relay), the holding frame is provided with a storage groove for storing the L-shaped base of the operation lever, and the frame wall tip line at the inlet of the storage groove is The L-shaped bent portion of the operating lever forms a fulcrum portion that is pivotally supported, and an adjustment screw screwing screw hole is formed in the upper frame wall portion of the storage groove, and the distal end portion of the base portion of the operation lever is stored There is a thermal relay (thermal overload relay) characterized in that it is held in contact with a hemispherical tip of an adjusting screw screwed into the upper frame of the groove (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 58-134849 (claim for utility model registration, page 9, line 10 to page 12, line 3, FIG. 2, FIG. 3)

  According to the above-described conventional technology, the operation lever is assembled to the holding frame so as to be rotatable with the bent portion as a fulcrum, and the adjustment screw presses the operation lever so that the operation lever rotates. Yes. The operating lever is biased in the direction of pressing the hemispherical tip of the adjusting screw by the biasing spring, and the hemispherical tip and the operating member are always in contact with each other. The operating lever is rotated by the adjusting screw. Positioning is performed.

  Since the hemispherical tip of the adjusting screw makes point contact with the flat surface of the operating lever, when the adjusting screw is screwed in, only the axial force of the adjusting screw is transmitted to the operating lever, and no twisting force is applied. It is like that. However, the apex of the hemispherical tip may be displaced from the axis of the adjustment screw due to a processing error at the tip of the adjustment screw.

  As described above, when the adjusting screw is rotated with the contact point of the operating lever and the adjusting screw deviating from the axis of the adjusting screw, the axial force of the adjusting screw acts on the operating lever. The torsional force in the rotation direction of the adjusting screw is applied to the operation lever due to the sliding friction. The operating lever can be rotated with respect to the holding frame with the bent portion serving as a fulcrum, and is pressed against the adjusting screw by an urging spring to position its rotational position.

  There is a slight gap between the holding frame and the operation lever in the direction other than the rotation direction at the bent portion. Therefore, when a twisting force is applied to the operation lever, the operation lever is moved in the direction other than the rotation direction by the twisting force. Is slightly displaced. Due to this error displacement, there is a problem that an error occurs in the adjustment value of the settling current.

  Further, the direction of the twisting force due to the sliding friction is reversed depending on the rotation direction of the adjusting screw. Therefore, when the adjustment screw is adjusted to the predetermined screwing position, the twisting force applied to the control lever is reversed between the case where the screw is turned clockwise and the case where the screw is turned counterclockwise to the same screwing position. Become. As a result, although the screwing position of the adjusting screw after the adjustment is the same, the rotational positioning position of the operation lever is different, and there is a problem that the adjustment value of the settling current is different.

  The present invention has been made in view of the above, and is a thermal overload capable of always obtaining a substantially single settling current adjustment value with respect to the screwing position of the adjusting screw regardless of the rotation direction of the adjusting screw. The purpose is to obtain a relay.

  In order to solve the above-mentioned problems and achieve the object, the present invention includes a contact opening / closing mechanism that opens and closes a fixed contact and a movable contact, and an interlocking bar that is displaced according to the current value of the main circuit. A main circuit which is installed in the housing so as to be swingable, transmits the displacement of the interlocking bar to the contact opening / closing mechanism to operate the contact opening / closing mechanism, and operates the contact opening / closing mechanism by swinging displacement. In the thermal overload relay, comprising: an adjustment mechanism that adjusts a settling current value; and an adjustment screw that is screwed through the housing wall and swings the adjustment mechanism in accordance with the screwing amount. A concave portion is formed at the tip of the spherical body, and a spherical body is sandwiched between the concave portion and the adjusting mechanism.

  According to this invention, since the spherical body is sandwiched between the concave portion at the tip of the adjustment screw and the adjustment mechanism, the frictional force between the concave portion and the adjustment mechanism is reduced, and the adjustment screw is screwed in. The rotation direction force is hardly transmitted to the adjustment mechanism, and only the axial direction force is transmitted, and the swinging position of the adjustment mechanism is always constant according to the screwing position of the adjustment screw regardless of the rotation direction of the adjustment screw. There is an effect that an adjustment value of a substantially single settling current is always obtained.

  Embodiments of a thermal overload relay according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
1 is a cross-sectional view showing a first embodiment of a thermal overload relay according to the present invention, FIG. 2 is an enlarged view of a portion D in FIG. 1, and FIG. 3 is an enlarged view of the portion D. FIG. 5 is a diagram showing a case where there is a processing error at the tip of the adjustment screw 10.

  A heater (not shown) is connected to a main circuit such as an electric motor (not shown), a bimetal (not shown) is fixed in the vicinity of the heater, and the amount of heat generated by the heater according to the current value of the main circuit is determined. Then, the base end portion is bent and displaced. An interlocking bar 43 (see FIG. 1) is connected to the tip of the bimetal so as to be oriented in the horizontal direction, and the bending displacement amount of the bimetal is the thermal overload as the horizontal displacement amount of the interlocking bar 43. It is input to the lower right side in the housing 20 of the relay.

  A contact opening / closing mechanism 50 that outputs a contact signal for opening / closing a main circuit such as an electric motor by opening / closing the fixed contact 53 and the movable contact 54 is installed on the lower left side in the housing 20. The contact opening / closing mechanism 50 operates when the current of the main circuit such as an electric motor exceeds a settling current and the bending displacement of the bimetal exceeds a predetermined amount, and opens the fixed contact 53 and the movable contact 54 to interrupt the main circuit. Output a contact signal.

  The contact opening / closing mechanism 50 includes a fixed contact 53 installed in the housing 20, a movable contact 54 contacting and separating from the fixed contact 53, a movable contact 55 having the movable contact 54 fixed to one end, and a lower part in the housing 20. An L-shaped support plate 51 installed on the left side and swingably supported by the upper support portion 51a; and an operation element 52 supported swingably by the lower support portion 51b of the support plate 51. The tension spring 56 is connected to the upper end of the operation element 52 and the central part of the movable contact 55.

  When the movable contact 54 is in contact with the fixed contact 53, the positions of the fixed contact 53 and the upper support portion 51a are set so that the movable contact 55 is slightly inclined to the right side, and the extension line of the axis of the movable contact 55 The lower support part 51b of the operation element 52 is provided on the right side in the vicinity. When the movable contact 54 contacts the fixed contact 53 and the movable contact 55 and the operation element 52 are connected by the tension spring 56, the operation element 52 is inclined to the right side, and the axis of the tension spring 56 is on the right side of the upper support portion 51a. Is located. In this state, the shape and size of the operation piece 42 are set so that the operation piece 52 and the operation piece 42 of the operation member 40 are in contact with each other or located in the vicinity thereof.

  A horizontal groove 20a is formed in the upper portion of the housing 20, and a horizontal portion 32b of a base portion 32 bent in an L shape of the adjustment member 30 is accommodated in the horizontal groove 20a. The entrance 20d of the lateral groove 20a is formed in an arc shape, and the lower surface 20b of the lateral groove 20a is formed as an inclined surface that descends toward the back. The bent portion 32b of the base portion 32 abuts and engages with the inlet portion 20d of the lateral groove 20a, and the adjustment member 30 can swing around the inlet portion 20d as a fulcrum. A concave portion is formed in the housing 20 facing the inlet portion 20d, and an adjustment spring 33 is installed in the concave portion. The adjustment spring 33 presses the base portion 32 of the adjustment member 30 so as to swing clockwise.

  The radius of the arc inside the bent portion 32b of the base portion 32 is made smaller than the radius of the arc of the inlet portion 20d so that the position of the fulcrum is not displaced by the swing of the adjusting member 30. For this reason, the bent portion 32b is abutted and supported at two points on the upper side and the right side of the inlet portion 20d regardless of the swing amount of the adjustment member 30, and the swing support point position of the base portion 32 is difficult to shift.

  A base end portion 40a of the operation member 40 is swingably supported at the lower end portion of the main body portion 31 of the adjustment member 30. The operating member 40 is fixed to the engaging piece 41 that engages with the interlocking bar 43 at the lower end and the upper part of the engaging piece 41, and contacts the operating element 52 of the contact opening / closing mechanism 50 to operate the contact opening / closing mechanism 50. And an operation piece 42. The horizontal displacement of the interlocking bar 43 according to the amount of bimetal bending displacement causes the engagement piece 41 to swing, and the operation piece 42 swings to operate the contact opening / closing mechanism 50.

  In the above configuration, when the bimetal is bent and the interlocking bar 42 is displaced in the direction of arrow A in FIG. 1, the operation member 40 is swung in the direction of arrow B in FIG. 1 is swung in the direction of arrow C. When the current of the main circuit such as an electric motor exceeds the settling current and the amount of bending displacement of the bimetal exceeds a predetermined amount, the axis of the tension spring 46 moves to the left side of the upper support portion 51a beyond the dead point, and the movable contactor 55 is actuated to reverse, moving the movable contact 54 away from the fixed contact 53, and outputting a contact signal for interrupting the main circuit. To reset the movable contact 55, the movable contact 55 is re-inverted by operating a reset lever (not shown). The adjustment member 30, the adjustment spring 33, and the operation member 40 are installed in the housing 20 so as to be swingable, and constitute an adjustment mechanism 60 that transmits the displacement of the interlocking bar 43 to the contact opening / closing mechanism 50 to operate the contact opening / closing mechanism 50. is doing.

  A vertical screw hole 20c is formed in the wall of the housing 20 above the lateral groove 20a, and an adjustment screw 10 that penetrates the wall of the housing 20 and projects the tip portion into the horizontal groove 20a is screwed into the screw hole 20c. It is.

  As shown in FIG. 2, a spherical recess 10 a centering on the axis is formed at the tip of the adjustment screw 10. The spherical body 11 is disposed in the spherical concave portion 10 a and the lower portion of the spherical body 11 is brought into contact with the horizontal portion 32 b of the base portion 32 of the adjustment member 30. The spherical body 11 is sandwiched between the spherical recess 10a and the adjustment member 30. The spherical concave portion 10a positions the spherical body 11 at the axial center position of the adjustment screw 10 and prevents the spherical body 11 from falling off between the adjustment screw 10 and the horizontal portion 32b. In order to make point contact between the spherical recess 10a and the spherical body 11, the radius of curvature of the spherical body 11 is made smaller than the radius of curvature of the spherical recess 10a.

  The adjusting member 30 is urged by the adjusting spring 33 so as to swing clockwise with the inlet 20d of the housing 20 as a fulcrum, and the horizontal portion 32b contacts the spherical body 11 and swings the adjusting member 30. An angular position is set. The swing angle position of the adjustment member 30 is adjusted by adjusting the screwing amount of the adjustment screw 10. When the swing angle position of the adjustment member 30 changes, the support position of the base end portion 40a of the operation member 30 is displaced. As a result, the steady contact position between the operation piece 42 and the operation element 52 is displaced, and the movable contact 55 is moved. It is possible to adjust the amount of bimetal bending required to actuate (reverse) and separate the fixed contact 53 and the movable contact 54 from each other. As described above, the adjusting mechanism 60 including the adjusting member 30, the adjusting spring 33, and the operating member 40 adjusts the settling current value of the main circuit that operates the contact opening / closing mechanism 50 by swinging displacement.

  As shown in FIG. 3, due to a processing error of the adjusting screw 10, the center of the spherical recess 10 a at the tip of the adjusting screw 10 may be displaced from the axis of the adjusting screw 10. In this case, the contact point 10 b between the adjusting screw 10 and the spherical body 11 is displaced from the axis of the adjusting screw 10. When the adjustment screw 10 is rotated in this state, a twisting force acts on the spherical body 11 due to friction between the adjustment screw 10 and the spherical body 11. This twisting force also acts on the adjustment member 30 due to friction between the spherical body 11 and the adjustment member 30.

  However, by interposing the spherical body 11, torsional force is transmitted by two point contacts between the adjusting screw 10 and the spherical body 11 and between the spherical body 11 and the adjusting member 30. Therefore, the twisting force applied to the adjustment member 30 can be greatly reduced as compared with the conventional structure in which the twisting force is directly transmitted from the adjustment screw 10 to the adjustment member 30. Even if the rotation direction of the adjusting screw 10 is reversed, the difference in torsional force acting on the adjusting member 30 is small, so that a substantially single settling current can be set regardless of the rotating direction of the adjusting screw 10. .

  In order to reduce the frictional force between the adjusting screw 10 and the spherical body 11 and between the adjusting member 30 and the spherical body 11, the spherical body 11 preferably has a smooth surface and high sphericity. Also, it is preferable to reduce the surface roughness of the contact surface of the adjustment screw 10 with the spherical recess 10a at the tip and the spherical body 11 of the adjustment member 30. The pressing force of the adjustment spring 33 acts on the adjustment member 30, and this pressing force also acts on the spherical body 11. When the spherical body 11 is deformed or creeps due to this pressing force, the adjustment member 30 is adjusted. The swing angle position of the member 30 changes, and a deviation occurs in the settling current value. Therefore, as the material for the spherical body 11, a metal such as iron or stainless steel, a high-strength resin, or the like is suitable.

  High-strength spherical bodies with a smooth surface and high sphericity as described above are used as rolling elements for rolling bearings, and these rolling elements are generally mass-produced with extremely high accuracy and high strength. It is relatively inexpensive. Therefore, according to the present embodiment, although the number of components as a product increases by one point, an increase in cost due to the increase is extremely small.

  As described above, the torsional force acting on the adjustment member 30 due to the friction caused by the rotation of the adjustment screw 10 is greatly reduced by sandwiching the spherical body 11 between the tip of the adjustment screw 10 and the adjustment member 30. Therefore, the positional deviation of the adjusting member 30 due to the twisting force is reduced, and if the screwing amount of the adjusting screw 10 is made equal, a settling current value that does not vary can be set even when the rotational directions are different.

  By the way, in the above description, the spherical recess was formed at the tip of the adjustment screw 10, but a recess was formed at the tip of the adjustment screw 10, and a spherical body was formed between the recess and the adjustment mechanism 60. 11 and the spherical body 11 may be configured not to be detached from the adjusting screw 10.

Embodiment 2. FIG.
The spherical body 11 of the thermal overload relay according to the first embodiment has a diameter of about 0.5 mm to about 2 mm. In the assembly process of the thermal overload relay, such a small part is attached to the adjusting screw 10. It is not easy to sandwich the front end portion and the adjustment member 30.

  In the thermal overload relay according to the second embodiment, the spherical body 11 and the adjusting screw 10 are formed of a material having magnetism, and the spherical body 11 and / or the adjusting screw 10 are magnetized in advance. The spherical body 11 is adsorbed to the spherical recess 10 a at the tip of the adjustment screw 10, and the adjustment screw 10 is screwed into the housing 20, so that the spherical body 11 can be easily placed between the spherical recess 10 a and the adjustment member 30. Can be pinched.

  Since the spherical body 11 has a diameter of about 0.5 mm to 2 mm and a small mass, the attracting force by magnetization may be small. Therefore, it is not necessary to use a material such as ferrite that provides a large residual magnetic flux as the material of the spherical body 11, and a general magnetic material such as carbon steel can be used. When a material such as carbon steel is used, the residual magnetic flux gradually decreases after magnetization and the adsorption force becomes weak. However, the spherical body 11 needs to be adsorbed to the adjusting screw 10 because of the thermal type overload. This is only when the load relay is assembled. After the assembly, the spherical body 11 is sandwiched between the spherical recess 10a and the adjustment member 30 and does not fall off. Therefore, there is no problem even if the residual magnetic flux of the spherical body 11 is reduced and the attractive force is reduced after assembly.

  Further, the adsorption force of the magnetized spherical body 11 to the adjustment screw 10 may be as much as necessary to attract and hold the spherical body 11, and this adsorption force acts between the adjustment screw 10 and the adjustment member 30. Since it is slightly larger than the force, the force acting between the spherical body 11 and the adjusting screw 10 or between the spherical body 11 and the adjusting member 30 is increased by the attraction force, and the frictional force is increased to increase the spherical body 11. The effect of reducing torsional force due to is not impaired.

Embodiment 3 FIG.
In the thermal overload relay according to the third embodiment, the spherical body 11 is formed of an electrical insulator, the dielectric strength of the thermal overload relay is improved, and the safety is further improved.

  The adjustment screw 10, the adjustment member 30, and the operation member 40 are usually formed of a metal material. Since the adjustment member 30 and the operation member 40 are electrically connected to the contact opening / closing mechanism 50, the adjustment member 30 and the operation member 40 are charging portions, and the adjustment screw 10 contacting the adjustment member 30 is also a charging portion.

  A knob cover 12 is attached to the head of the adjustment screw 10 and is fitted so as not to slide in the rotation direction of the adjustment screw 10. When adjusting the settling current value, the knob cover 12 is rotated and the adjustment screw 10 is rotated. The knob cover 12 is made of resin and has a function of insulating the adjusting screw 10 as a charging unit while being graduated with a scale of a settling current value.

  In the third embodiment, since the spherical body 11 sandwiched between the adjusting screw 10 and the adjusting member 30 is formed of an electrical insulator, double insulation is performed between the knob cover 12 and the spherical body 11, and the thermal overload is performed. Increases the dielectric strength of the load relay. As a material of the spherical body 11, ceramic, glass, resin, or the like can be used. When resin is used as the material, the wear resistance is inferior to that of a metal material such as iron. However, in the thermal overload relay, since the number of times of adjusting the settling current value is small, the wear resistance of the spherical body 11 is low. There is no problem.

  As described above, the thermal overload relay according to the present invention is useful as an overload relay with high adjustment accuracy of the settling current value.

It is sectional drawing which shows Embodiment 1 of the thermal overload relay concerning this invention. It is the D section enlarged view of FIG. FIG. 2 is an enlarged view of a part D in FIG. 1 and shows a case where there is a machining error at the tip of the adjustment screw.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Adjustment screw 10a Spherical recessed part 11 Spherical body 20 Housing 30 Adjustment member 40 Operation member 40a Base end part 43 Interlocking bar 50 Contact opening / closing mechanism 53 Fixed contact 54 Movable contact

Claims (4)

A contact opening / closing mechanism that opens and closes a fixed contact and a movable contact installed in the housing, an interlocking bar that displaces according to the current value of the main circuit, and a swingable member that is installed in the housing so that the displacement of the interlocking bar An adjustment mechanism for transmitting to the contact opening / closing mechanism to operate the contact opening / closing mechanism and adjusting a settling current value of a main circuit for operating the contact opening / closing mechanism by swinging displacement; and screwing through the housing wall A thermal overload relay comprising an adjustment screw that swings the adjustment mechanism in accordance with a screwing amount,
The tip of the adjustment screw a spherical recess is formed, between the adjustment mechanism and the spherical recess, the spherical radius of curvature is allowed to sandwich the radius of curvature smaller than the formed spheroids of the spherical recess A thermal overload relay characterized in that a point-shaped recess and a spherical body are brought into point contact . The adjustment mechanism is swingably supported by the interlocking bar to operate the contact opening / closing mechanism, and is supported in the housing so as to be swingable, and the operation member is supported at one end so as to be swingable. thermally activated overload relay according to claim 1, characterized in that it comprises a an adjustment member for adjusting the setting current value of the main circuit for actuating the contact switching mechanism by displacing the support position. The thermal overload relay according to claim 1 or 2 , wherein the spherical body and / or the adjusting screw are magnetized. The thermal overload relay according to claim 1 or 2 , wherein the spherical body is formed of an electrical insulator.

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