Electricity: circuit makers and breakers – Multiple circuit control – Operating means
Patent
1996-06-26
1998-06-02
Gellner, Michael L.
Electricity: circuit makers and breakers
Multiple circuit control
Operating means
200 4304, H01H 2700
Patent
active
057603537
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention pertains to a safety switch, which has an axially sliding ram, an indexing wheel with a cam having a locking flank, a pre-tensioned spring for holding the ram in place, a key for turning the indexing wheel, and an interlocking mechanism including an electromagnet having a stator and an armature.
BACKGROUND ART
Safety switches are used everywhere where it must be ensured that a door, cover or the like, which in the locked state prevents access to the secured area of a machine, can only be opened when the machine is shut off, and where the machine can only be turned on when the door or the like is shut. If, in addition, the key is not to be removed from the keyway of the safety lock exactly when the machine is turned off but rather when the machine comes to a standstill, the safety switch has an additional interlocking device in which the key is held in the keyway during the time span corresponding to the slow-down time. Known safety switches have an electromagnet for this purpose which either holds a latch in the locked position or pulls the latch, held in place with a pre-tensioned spring, out of the locked position. The latch coordinates in its locked position with either the ram or directly with the key.
Since this known solution is cost intensive and uses up space, the objective of creating a safety switch of the above named type whose interlocking mechanism can be realized cost-effectively and with minimal space is the basis of this invention. This objective is met with a safety switch with the features of the present invention.
DISCLOSURE OF INVENTION
Since a section of the ram is construed as an armature, only the stator portion of the electromagnet is required as an additional component compared to safety switches without interlocking mechanisms, which leads to a significant cost reduction. The space requirement is reduced for one reason because the stator surrounds the ram, for another since components are not required which transfer the magnetic force produced by the stator to the ram as a locking force.
The locking flank seated against the ram when the interlocking mechanism is in effect, preventing the indexing wheel from turning, which is a prerequisite for removal of the key from the keyway, can be formed by one flank of a resting notch in the cam, wherein the ram engages in the particular position of the indexing wheel in which the key is fully inserted into the keyway and thus the door or the like to be secured is completely closed.
The interlocking mechanism can effect either a magnetically driven lock or a spring-driven lock. In the first case, an electromagnet forces the ram against, generally, a spring force, onto the cam. In the second case, the ram pressed onto the cam by a pre-tensioned spring. The electromagnet then unlocks the indexing wheel in the energized state.
As long as the force of the stator of the electromagnet on the ram is sufficient to create the prescribed locking force for the key or compensate for the locking force produced by a pre-tensioned spring, no self-locking is needed between the locking flanks and the ram. Generally, it is an advantage to provide a self-lock, since then a considerably smaller magnetic force would be sufficient which leads to cost-effective and space-conserving electromagnets.
In what follows, the invention is detailed with the help of an example of an embodiment represented in the illustration.
BRIEF DESCRIPTION OF DRAWINGS
The single FIGURE shows a schematically represented section of the embodiment example in the axial direction of its ram.
BEST MODE FOR CARRYING OUT THE INVENTION
A safety switch shown in its entirety as 1 has a rectangular shaped housing 2 in this example which can consist of metal or plastic. On one end face of the housing 2, housing 3 of a head piece is attached, which forms the keyway 4 for a key 5 which serves to activate the switch. Housing 3, consisting of either metal or plastic as in housing 2, is constructed such that it can be mounted to housing 2 not only in the positio
REFERENCES:
patent: 4904829 (1990-02-01), Berthaud et al.
patent: 5464954 (1995-11-01), Kimura et al.
patent: 5488207 (1996-01-01), Niwa et al.
patent: 5584378 (1996-12-01), Wecke et al.
Prospectus, "Command Sytem", European Standard pr. EN 1088, May 1993.
Euchner & Co.
Friedhofer Michael A.
Gellner Michael L.
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