LIMIT SWITCH |
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申请号 | EP12864762.5 | 申请日 | 2012-03-14 | 公开(公告)号 | EP2804192B1 | 公开(公告)日 | 2018-05-09 |
申请人 | Omron Corporation; | 发明人 | TSUKIMORI, Kazuyuki; TAKAHASHI, Manabu; MORIYAMA, Hiroyuki; FUKUI, Shigenobu; | ||||
摘要 | The purpose of the invention is to provide a limit switch that facilitates lead wire connection work and has good work efficiency. To achieve said purpose, the invention is the limit switch, which: affixes a switch body (20) within a housing (10) having an opening (11) on the front surface thereof; on the bottom surface of the housing (10), has connection holes admitting lead wires (70-73); partitions the front surface of the switch body (20) into multiple upper/lower sections; embeds a pair of fixed contact terminals (25, 26, 27, 28) in each section; and opens/closes a contact by driving an operation shaft (30) exposed from the top surface of the switch body (20), said operation shaft (30) being driven in an axial direction. A first projection (22) is extendingly provided between fixed contact terminals (25, 26), and a second projection (23) is extendingly provided between fixed contact terminals (27, 28), said fixed contact terminals (25, 26, 27, 28) being embedded in the sections of the front surface of the switch body (20). | ||||||
权利要求 | |||||||
说明书全文 | The present invention relates to a limit switch, particularly to a wiring structure of a lead wire connected to a fixed contact terminal of the limit switch. Conventionally, in the case that the lead wire is connected to the fixed contact terminal of the limit switch, as illustrated in Patent Document 2 shows a limit switch according to the preamble of claim 1 and further shows the limit switch partitioned into two stages, each of which comprising a pair of fixed contact terminals. The pairs of contact terminals are separated by a partition wall extending therebetween inside the limit switch. Patent Document 3 shows a limit switch partitioned into two stages, each of which comprising a pair of fixed contact terminals. The upper stage is arranged such that it projects further than the lower stage towards a front side of the limit switch.
In the conventional limit switch, although work to connect the lead wires to the pair of fixed contact terminals at the lower stage is relatively easy to perform, it takes a lot of work to perform routing of the lead wire when the lead wire is connected to the pair of fixed contact terminals at the upper stage. Particularly, for the connection of the thick lead wire in a narrow space, it is necessary to fold the lead wire in a complicated way in order to connect the lead wire to the fixed contact terminal at a position different from the drawn position, which results in a problem in that work efficiency is degraded. In view of the problems, an object of the present invention is to provide a limit switch in which the connection of the lead wire is easily perform with good work efficiency. In order to attain this objective, the present invention provides a limit switch according to claim 1. According to the present invention, because the wiring can be performed by routing the lead wire through the projection, the connection work is facilitated to improve the work efficiency. Additionally, the limit switch having an excellent insulating characteristic is obtained because the fixed contact terminals adjacent to each other are partitioned by the projection. In accordance with the aspect of the present invention, in the limit switch, an outer circumferential surface of the projection may include a shape along a wiring route of the lead wire. According to the present invention, the work to connect the lead wire can more efficiently be performed. In accordance with the aspect of the present invention, in the limit switch, the fixed contact terminal located at an upper stage may be arranged so as to be pushed out toward a near side from the fixed contact terminal located at a lower stage. According to the present invention, a step is generated between the upper and lower fixed contact terminals. Therefore, even if the lead wire is connected to the fixed contact terminal on the lower stage side, the lead wire connected to the fixed contact terminal on the lower stage side does not obstruct the connection work of the fixed contact terminal on the upper stage side, and the efficiency of the connection work is further improved. In accordance with the aspect of the present invention, in the limit switch, an insulating wall may be provided, the insulating wall projecting toward the near side from an edge on at least one of both side surfaces of the switch main body. According to the present invention, the insulating characteristic is further improved because the insulating wall can prevent the lead wire from abutting directly on an inside surface of the housing. In accordance with the aspect of the present invention, in the limit switch, the lead wire in which a crimped terminal is provided at a leading end thereof may be connected to the fixed contact terminal by a connection screw. According to the present invention, because the lead wire can be connected to the fixed contact terminal through the crimped terminal, advantageously the connection work can further be facilitated to improve the work efficiency.
Hereinafter, a limit switch according to an exemplary embodiment of the present invention will be described with reference to As illustrated in Housing 10 has a box shape in which switch main body 20 can be accommodated, and circular rib 12 is formed along opening 11 provided in a front surface of housing 10. Circular seal member 13 is positioned in circular rib 12, and cover 14 is fixed to housing 10 by fixing screws 14a, thereby sealing opening 11. Connection hole 15 is made in a bottom surface of housing 10, and operation hole 16 is made in a ceiling surface of housing 10. Positioning slits 17 are radially formed in an inner circumferential surface of operation hole 16 at intervals of 90 degrees, and circular step 18 is concentrically formed near an opening edge of operation hole 16. Switch main body 20 has an outer shape of which switch main body 20 can be accommodated from opening 11 of housing 10, and switch main body 20 is fixed to an inside surface of housing 10 by three fixing screws 20a. As illustrated in Switch main body 20 is provided such that insulating walls 29 and 29 are pushed out onto a front side from end portions on both the sides of switch main body 20. As illustrated in As illustrated in As illustrated in That is, as illustrated in Particularly, as illustrated in On the other hand, as illustrated in Not only circular cams 63 and 64 are fixed by E-ring 65, but also circular cams 63 and 64 may be retained by stopper 65a press-fixed into the leading end portion of rotating shaft 61 like a second embodiment in A method for assembling the limit switch having the above constituent will be described below. Switch main body 20 is inserted from opening 11 of housing 10, and fixed by three fixing screws 20a. On the other hand, guide rib 43 of plunger 40 is selectively fitted in positioning slit 17 provided in operation hole 16 of housing 10. Seal ring 51 is fitted in circular step 18 provided around operation hole 16, and box 53 is fixed to housing 10 by fixing screws 52. On the other hand, circular cam 63, return coil spring 62, and circular cam 64 are sequentially inserted on the leading end side of rotating shaft 61, and retained by E-ring 65. Cylindrical bearing section 60 is press-fixed into attachment hole 55 after rotating shaft 61 is inserted from attachment hole 55 of box 53 to fit the leading end portion of rotating shaft 61 in bearing recess 56 ( After circular seal member 13 is positioned in circular rib 12, cover 14 is fixed to housing 10 by fixing screws 14a to complete the assembly work. In the case that lead wires are connected to switch main body 20 on site, after cover 14 is detached, connection terminals of lead wires 70 and 71 are fixed to fixed contact terminals 27 and 28 on the lower stage side, respectively, by connection screws 24 as illustrated in According to the first embodiment, a creeping distance is lengthened by partition rib 21, and first and second projections 22 and 23 act as the insulating wall. Therefore, the limit switch having an excellent insulating characteristic is obtained. In the case that the connection is performed by a connection structure different from that in According to the first embodiment, an outer circumferential surface of first projection 22 has a shape (a shape, such as a substantial hexagon and a substantial parallelogram, which includes a region where at least two pairs of line segments substantially parallel to each other are coupled to each other at an angle different from a right angle when first projection 22 is viewed from the front surface) along wiring routes of lead wires 72 and 73, so that advantageously the connection work can efficiently be performed. Action of the limit switch of the first embodiment will be described below. In the case that an external force is not applied to operation lever 69 as illustrated in When operation lever 69 rotates clockwise by the external force, the edge on one side of flat surface 61a provided in rotating shaft 61 is latched in ridge 63b of circular cam 63. Only circular cam 63 rotates to push down operating ridge 42 of plunger 40, thereby pushing down operation shaft 30. As a result, movable touch piece 32 is pushed down and inverted, and movable contact 33 is switched from fixed contact terminals 25 and 26 to fixed contact terminals 27 and 28. When the external load is released, rotating shaft 61 rotates in the opposite direction by the spring force of return coil spring 62, operation lever 69 returns to the original position, and operation shaft 30 and plunger 40 are pushed up by the spring force of coil spring 31. On the other hand, when operation lever 69 rotates counterclockwise by the external force, the edge on the other side of flat surface 61a provided in rotating shaft 61 is latched in ridge 64a of circular cam 64. Only circular cam 64 rotates to push down operating ridge 42 of plunger 40, thereby pushing down operation shaft 30. As a result, movable touch piece 32 is pushed down and inverted, and movable contact 33 is switched from fixed contact terminals 25 and 26 to fixed contact terminals 27 and 28. When the external load is released, rotating shaft 61 rotates in the opposite direction by the spring force of return coil spring 62, operation lever 69 returns to the original position, and operation shaft 30 and plunger 40 are pushed up by the spring force of coil spring 31. In the first embodiment, guide rib 43 is engaged with selected positioning slit 17 when plunger 40 is assembled in housing 10, for example, the clockwise external force can be detected while the counterclockwise external force is not detected. The operation lever is not necessarily attached in the vertical direction. For example, the operation lever may be attached in a horizontal or oblique direction. In the embodiment, the four lead wires are connected to the limit switch by way of example. Alternatively, for example, six or eight lead wires may be connected to the limit switch. One circular cam may be attached to the rotating shaft. The present invention can be applied to not only the limit switch of the embodiment but also limit switches having other shapes.
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