Idec Corporation

Etsurou Komori

Takeo Yasui

Takao Fukui

Masaki Nobuhiro

Norifumi Obata

A safety switch is improved by the feature of staying in an open position in the event of breakage of a working rod or breakage or dropout of an operation portion and having a simple structure facilitating size reduction. Even if a rotary shaft is released from a supported state in an operation portion because an operating force of an operation or the number of operations of extracting an actuator from the operation portion exceeds a breakage tolerance, a working rod is permitted to move in an urging direction of a coil spring and is assuredly moved to the operation portion. Therefore, a switch can be assuredly set to an open position and, hence, the safety switch can achieve the safety improvement.

Safety switch

A safety switch is described in which a switching contact in a lock mechanism switches between an open and closed condition. Switching is coupled to a lock member moveable between a locked position, locking a drive cam, and an unlocked position, allowing the cam to rotate. A link member, cooperating with the lock member, switches between open and closed conditions of normally-open and normally-closed switching contacts, indicating movement of the lock member between the locked position and the unlocked position. By monitoring the open and closed conditions of the normally-open and normally-closed switching contacts, it is possible to determine the state of the lock member, i.e., whether it is in the locked position or in the unlocked position. It therefore can be determined whether the drive cam is in the locked or unlocked (i.e., free to rotate) state.

A safety switch is provided which is increased in durability and which offers a high degree of freedom of mounting the safety switch to place. A switch body has a rectangular solid shape. An actuator entrance hole is formed at one of the opposite corner portions of the switch body whereas a cable lead-out port is formed at the other corner portion, whereby the safety switch is increased in the degree of mounting freedom. Thus is offered a wider choice of place to mount the safety switch. The switch body is formed with only one actuator entrance hole so that the safety switch is prevented from suffering failure caused by foreign substances invading through an actuator entrance hole left unused. In addition, a driving cam may be formed with an engaging portion and a cam curve portion in spaced relation so that the driving cam is configured to be free from an area having poor strength. Thus, the driving cam is increased in strength. This leads to the increased durability of the safety switch.

A safety switch capable of detecting withdrawal of an actuator from a switch main unit in a sure and reliable manner even when the safely switch, including a lock mechanism, is in a locked condition and an attempt is made to forcibly withdraw the actuator from the switch main unit. Even when a drive cam becomes capable of rotation since not less than one of a notch cut-out section and a lock member is broken by forcibly extracting an actuator with rotation of the drive cam locked, a cam curve section of the drive cam and an operating rod are in a normal condition and free of breakage. Accordingly, if the drive cam rotates in a counter-clockwise direction, normally-closed contacts of a contact section adopt an open condition normally, and even in situations where the actuator is withdrawn from the switch main unit with a force equal to or greater than the fracture strength of the safety switch, withdrawal of the actuator from the switch main unit can be detected in a sure and reliable manner.

Growing community of inventors

Osaka, Japan

Etsurou Komori