THERMOMOTIVE OVERLOAD RELAY |
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申请号 | EP10824587.9 | 申请日 | 2010-07-26 | 公开(公告)号 | EP2492943A1 | 公开(公告)日 | 2012-08-29 |
申请人 | Fuji Electric Fa Components & Systems Co., Ltd.; | 发明人 | FURUHATA, Yukinari; MORISHITA, Fumihiro; KAMOSAKI, Takeo; | ||||
摘要 | A reset rod 43 of a thermal overload relay is configured to be switchable between a manual reset position in which a reversal mechanism 21 is manually returned to an initial state prior to reversal by performing a pushing-in operation, and an automatic reset position in which a pushed-in state is held by a pushing and rotating operation from this manual reset position, and the reversal mechanism 21 is automatically returned to the initial position. In addition, axial runout restriction portions 17b, 17d, 51, 46 and 47, which restrict axial runout of the reset rod 43 when the reset rod 43 is held in the automatic reset position, are provided. | ||||||
权利要求 | |||||||
说明书全文 | This invention relates to a thermal overload relay utilizing the characteristic curve due to temperature increase of a bimetal member, and relates to improvement of a mechanism to set a reset rod to an automatic reset position. The reset mechanism of a thermal overload relay generally comprises a reset rod loaded in a case so as to be freely pushed in, and is configured to return a reversal mechanism which performs a reversal operation accompanying the relay tripping, to the initial state by pushing in this reset rod. This reset mechanism is provided with a manual reset in which an operation of pushing in the reset rod is performed upon each reset, and an automatic reset in which the reversal mechanism is automatically returned to the initial state after bimetal member cooling by holding the reset rod in the pushed-in state; the manual reset and the automatic reset being configured to be switchable. As shown in When the bimetal member 2 curves, displacement is in the right direction in In the initial state of When the bimetal member 2 curves and is displaced due to heat generated by a passing current, the release lever 9 is rotated in the counterclockwise direction, the rotation of this release lever 9 rotates the tension spring 13 and reversal plate 12 in the counterclockwise direction, and as shown in When the thermal overload relay enters the tripped state and the current of the electromagnetic contactor is shut off, the bimetal member 2 cools and returns to its initial state. However, the reversal mechanism 4 which has been reversed does not return to the initial state if a reset operation is not applied. Hence a reset rod 16 is provided so as to protrude from the upper face of the case 1. As shown in In the upper face of the large-diameter head portion 16a is provided a groove 16c into which can be inserted a flat-blade screwdriver or other tool to rotate the reset rod 16. Further, on the small-diameter shaft portion 16b is provided an engaging piece 16d so as to protrude elastically, and in the tip at a position shifted 90° with respect to this engaging piece 16d is formed, by means of an inclined face and a vertical face, a cutout portion 16e cut out in an obtuse-angle shape. And as shown in The reset rod 16 loaded into the reset rod holding hole 3 is impelled in the direction of protrusion from the case 1 by a return spring 7 comprising a compression spring inserted into the small-diameter shaft portion 16b; in Next, in order to move from the manual reset position of Patent Reference 1: Japanese Patent Publication No. However, as shown in If axial runout of the reset rod 16 in the automatic reset position occurs in this way, there is a change in the amount of flexing of the fixed contact point leaf spring 6a, in contact with the small-diameter shaft portion 16b of the reset rod 16 via the leaf spring 6e, and the gap between the fixed and movable contact points 6b, 6d of the normally open contact 6 also changes, and so there is concern that the automatic reset characteristics by which the reversal mechanism 4 automatically returns to the initial position may become unstable. Hence this invention was devised focusing on the above-described unresolved problem of the prior art, and has as an object the provision of a thermal overload relay in which, by restricting axial runout of the reset rod in the automatic reset position, characteristics of the reversal mechanism at the time of automatic reset are made stable. In order to attain the above object, the thermal overload relay of one embodiment includes, within a case, a bimetal member which undergoes curving displacement due to heat generation caused by an overload current; a reversal mechanism which, when a displacement amount of the bimetal member exceeds a stipulated value, performs a reversal operation and switches a contact; a columnar reset rod which is loaded into a shaft loading portion formed in the case so as to be freely pushed in, and one end of which engages with a movable portion of the reversal mechanism when pushed in; and a return spring, the spring force of which acts on the reset rod such that the other end of the reset rod protrudes from the case, the reset rod being configured to be switchable between a manual reset position in which the reversal mechanism is manually returned to an initial state prior to reversal by performing a push-in operation, and an automatic reset position in which the pushed-in state is held by a pushing and rotating operation from this manual reset position and the reversal mechanism is automatically returned to the initial state, and the thermal overload relay further includes an axial runout restriction portion which restricts axial runout of the reset rod when the reset rod is held in the automatic reset position. By means of a thermal overload relay of this embodiment, the axial runout restriction portion restricts axial runout of the reset rod being held in the automatic reset position, so that the position of the movable portion of the reversal mechanism which is engaged with one end of the reset rod is always constant, and the automatic reset characteristics by which the reversal mechanism automatically returns to the initial state can be made stable. Further, as the axial runout restriction portion of the thermal overload relay of one embodiment, a bulging portion is formed in one among an outer periphery of the reset rod and an inner wall of the shaft loading portion, and when the reset rod is held in the automatic reset position, the bulging portion abuts the other among the outer periphery of the reset rod and the inner wall of the shaft loading portion, and a pressing force is generated between the reset rod and the shaft loading portion, thereby restricting axial runout of the reset rod. By means of the thermal overload relay of this embodiment, when the reset rod is held in the automatic reset position, because the bulging portion abuts the other among the outer periphery of the reset rod and the inner wall of the shaft loading portion, a pressing force is generated between the reset rod and the shaft loading portion, and axial runout of the reset rod is restricted, so that an axial runout restriction portion with a simple configuration can be provided. Further, in the thermal overload relay of one embodiment, the axial runout restriction portion is provided in at least two locations that are mutually separated in a length direction of the reset rod, and axial runout of the reset rod is thereby restricted. By means of this thermal overload relay of one embodiment, by providing the axial runout restriction portion in at least two locations that are mutually separated in the length direction of the reset rod, axial runout of the reset rod can be restricted still more reliably, and automatic reset characteristics can be improved. Further, in the thermal overload relay of one embodiment, a direction in which the spring force of the return spring acts on the reset rod is a direction which deviates from an axial line of the reset rod. By means of this thermal overload relay of one embodiment, by causing the spring force of the return spring to impel from a direction deviating from the axis of the reset rod, a force so as to cause rotation in a prescribed direction acts on the reset rod. By means of this force so as to cause rotation of the reset rod, a force pressing the reset rod in the automatic reset position appears, axial runout is further restricted, and automatic reset characteristics can be further improved. Further, in the thermal overload relay of one embodiment, the return spring is a leaf spring member that is engaged at a position which does not interfere with a rotation range of the one end of the reset rod. By means of this thermal overload relay of one embodiment, compared with a return spring comprising a coil spring disposed around the outer periphery of the reset rod such as is used in normal devices, disposition is easy even in a compact thermal overload relay in which there is little space for disposition of the return spring. Further, in the thermal overload relay of one embodiment, an automatic reset engaging portion is provided on the outer periphery of the reset rod, a latching plate, which holds the reset rod in the pushed-in state by engaging with the automatic reset engaging portion when the pushed-in reset rod is rotated to the automatic reset position, is provided within the case, and abutting portions of the automatic reset engagement portion and the latching plate which mutually abut at a position where the reset rod is halted midway during rotation to the automatic reset position, are formed as inclined faces that are inclined downward toward a direction in which the reset rod is rotated to the automatic reset position, and that are in planar contact with each other. By means of this thermal overload relay of one embodiment, when the reset rod is halted midway during rotation to the automatic reset position, the inclined face of the automatic reset engaging portion slides on the inclined face of the latching plate, so that latching of the automatic reset engaging portion and the latching plate is released, and the reset rod returns to the manual reset position. Hence the problem of halting of the reset rod at a neutral position between the manual reset position and the automatic reset position can be reliably prevented. By means of this invention, an axial runout restriction portion restricts axial runout of the reset rod being held at the automatic reset position, so that the position of the movable portion of the reversal mechanism engaged with one end of the reset rod is always constant, and the reversal mechanism characteristics during automatic reset can be made stable.
Below, an optimum mode for implementing the invention (hereafter called an embodiment) is explained in detail, referring to the drawings. As shown in As shown in The link support portion 25 comprises a pair of opposing plates 25a in the upper portions of which bearing holes 25a1 are formed, and which are mutually opposed, and a connecting plate 25c, connecting the pair of opposing plates 25a, and forming an opening portion 25b. The leg portion 26 extends downward from one among the pair of opposing plates 25a, and in the upper portion thereof is formed a bearing hole 26a. And as shown in As shown in And as shown in As shown in As shown in Further, as shown in As shown in This reset rod 43 comprises a column-shape head portion 45; a neck portion 46, with a column shape of diameter smaller than the diameter of the head portion 45, formed coaxially with the head portion 45; a substantially disc-shape return spring engaging portion 47, formed on the end in the direction of the axis P of the neck portion 46 at a position on the side opposite the head portion 45, and engaged with the return spring 44; and a basepiece 48, formed protruding from the return spring engaging portion 47 in the axial direction in a position on the side opposite the neck portion 46. As shown in As shown in On the outer periphery of the return spring engaging portion 47 of the neck portion 46 is formed an automatic reset engaging portion 52 to protrude as shown in As shown in And, a basepiece 48 is formed, in a range of substantially 90°, along the first outer peripheral face 47a of the lower face of the return spring engaging face 47 (the face on the side opposite the neck portion 46); the outer peripheral face of this basepiece 48 is an inclined face, the diameter of which is reduced gradually in the direction receding from the return spring engaging portion 47. This basepiece 48 moves about the axis P up to the position indicated by the dot-dash line by rotating the reset rod 43 substantially 90°, that is, by rotating clockwise substantially 90° in As shown in The protrusion 51 of the reset rod 43 and the automatic reset engaging portion 52 are formed on the opposite side in the circumferential direction (at a position separately by substantially 180° in the circumferential direction) of the indicator needle 50 formed on the head portion 45. And as shown in Here, as shown in The case of this invention corresponds to the insulating case 17, the inclined face of this invention corresponds to the reset rod return inclined face 17c1, the bimetal member of this invention corresponds to the main bimetal member 18, the reset rod other end of this invention corresponds to the neck portion 46, the bulging portion of this invention corresponds to the second outer peripheral face 47b, the one end of the reset rod of this invention corresponds to the basepiece 48, and the bulging portion of this invention corresponds to the protrusion 51. As shown in When rotation of the release lever 23 in the clockwise direction advances, and the pressing force of the reversal spring pressing portion 23f exceeds the spring force of the reversal spring 36, the movable plate 35 performs a reversal operation with the lower portion 35a as a fulcrum. Together with this reversal operation of the movable plate 35, the reversal operation of the movable plate 35 is transmitted via the first engaging pin 39a to the linking plate 34, which also rotates about the support shaft 33. By this means, the fixed contact point 38a and movable contact point 38b of the a contact 38, which had been in the open state of When the thermal overload relay enters the tripped state and the overload current of the electromagnetic contactor is shut off, after a prescribed time has elapsed, the curving of the cooled main bimetal member 18 is corrected, and the member returns to its initial state. However, the reversal mechanism 21, the contacts of which have switched, does not return to the initial state (in which the fixed contact point 38a and movable contact point 38b of the a contact 38 are in the open state, and the fixed contact point 42a and movable contact point 42b of the b contact 42 are in the closed state) unless a reset operation is applied. As shown in At this time, the protrusion 51 formed on the outer periphery of the head portion 45 of the reset rod 43 passes through the cutout portion of the first cutout hole 17a, and the automatic reset engaging portion 52 formed on the side of the return spring engaging portion 47 of the neck portion 46 passes through the cutout portion of the second cutout hole 17c. By means of the operation to push-in the reset rod 43, the basepiece 48 moves downward, so that the a contact side leaf spring 37 which is in contact with the inclined face of the basepiece 48 rides up onto and makes contact with the return spring engaging portion 47 while pressing the movable plate 35 in the reversed state. As a result, the movable plate 35 in the reversed state moves to the side of the initial position, and when the action of the reversal spring 36 exceeds the dead point, the movable plate 35 performs the return operation. By this means, the thermal overload relay returns to the initial state (with the fixed contact point 38a and movable contact point 38b of the a contact 38 in the open state, and the fixed contact point 42a and movable contact point 42b of the b contact 42 in the closed state). Next, the procedure for setting the reset rod 43, in the manual reset position with the head portion 45 protruding from the insulating case 17, in the automatic reset position, and the advantageous results of this action, are explained. As shown in At this time, the indicator needle 50 of the pushed-in reset rod 43 is directed rightward in the figure, and the protrusion 51 and automatic reset engaging portion 52, which are positioned on the side opposite the indicator needle 50 in the circumferential direction, move to the side of the side inner wall 17d of the insulating case 17. And, by means of engagement of the engaging face 52a of the automatic reset engaging portion 52 with the latching plate 17b, the pushed-in state of the reset rod 43 is held. Further, the protrusion 51 abuts the upper portion of the side inner wall 17d of the insulating case 17, and a pressing force F1 (see Further, by pushing-in the reset rod 43 and rotating 90° in the clockwise direction, the basepiece 48, while moving downward, rotates to a position which does not interfere with the return spring 44. The a contact side leaf spring 37, which is in contact with the inclined face of the basepiece 48, enters a state of riding up onto the return spring engaging portion 47, and moves to a position in proximity to the movable plate 35. By this means, even when the movable plate 35 is in the initial state and not performing a reversal operation, the gap between the fixed contact point 38a of the a contact 38 fixed on the a contact side leaf spring 37 and the movable contact point 38b of the a contact 38 fixed on the movable plate 35 becomes small. As a result, when the reset rod 43 is set in the automatic reset position, even when the current passed exceeds the stipulated value and the reversal mechanism 21 begins a reversal operation, the movable contact point 38b cannot come into contact with the fixed contact point 38a and complete reversal before the movable plate 35 completes the reversal operation. Hence when the main bimetal member 18 cools, the reversal mechanism 21 automatically returns to the initial state (with the fixed contact point 38a and movable contact point 38b of the a contact 38 in the open state, and the fixed contact point 42a and movable contact point 42b of the b contact 42 in the closed state). Here, when the reset rod 43 is set in the automatic reset position, the protrusion 51 of the reset rod 43 acts with a pressing force F1 on the upper portion of the side inner wall 17d of the insulating case 17, as shown in By this means, the reset rod 43 set in the automatic reset position acts with pressing forces F1, F2 on the same direction on both ends in the length direction, and while the center portion in the length direction acts with a pressing force F3 in the direction opposite the pressing forces F1, F2, the reset rod 43 is set in the insulating case 17, so that axial runout is restricted. When in this way axial runout of the reset rod 43 in the automatic reset position is restricted, the position of the a contact side leaf spring 37 engaged with the return spring engaging portion 47 is always constant, and the gap between the fixed contact point 38a and the movable contact point 38b of the a contact 38 is also constant, so that the automatic reset characteristic for automatic return to the initial state of the reversal mechanism 21 can be made stable. Further, as shown in Further, the return spring 44 is a leaf spring which is disposed and extended to the lower-face side of the return spring engaging portion 47 so as not to interfere with the rotation position (see Further, a spherical shape is formed on the tip 44a of the return spring 44, and the contact area of the tip 44a in contact with the lower face of the return spring engaging portion 47 is set to be small, in a structure in which sliding friction between the return spring engaging portion 47 and the contact portion of the return spring 44 is reduced, so that operation of the reset rod 43 is not impeded. A case is explained in which an operation of setting the reset rod 43 from the manual reset position to the automatic reset position is halted midway. For example, suppose that as shown in Upon releasing the pushed-in state of the reset rod 43, the reset rod 43 moves upward (in the direction in which the head portion 45 protrudes from the insulating case 17) due to the spring force of the return spring 44 as shown in And, the automatic reset engaging portion 52 passes through the cutout portion of the second cutout hole 17c, and is positioned above the latching plate 17b; by this means, the head portion 45 of the reset rod 43 returns to the manual reset position protruding from the insulating case 17. In this way, when an operation to set the reset rod 43 in the automatic reset position is halted midway, the inclined face 52b slides over the reset rod return inclined face 17c1 of the latching plate 17b, and by this means the engagement of the automatic reset engaging portion 52 and the latching plate 17b is released, and the reset rod 43 returns to the manual reset position, so that the problem in which the reset rod 43 halts at a neutral position between the manual reset position and the automatic reset position can be reliably prevented. As explained above, in a thermal overload relay of this invention, axial runout of the reset rod in the automatic reset position is restricted, so that the characteristics of the reversal mechanism during automatic reset can be made stable.
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