Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H27/00—Switches operated by a removable member, e.g. key, plug or plate; Switches operated by setting members according to a single predetermined combination out of several possible settings
  • H01H27/002—Switches operated by a removable member, e.g. key, plug or plate; Switches operated by setting members according to a single predetermined combination out of several possible settings wherein one single insertion movement of a key comprises an unlocking stroke and a switch actuating stroke, e.g. security switch for safety guards
  • H01H27/007—Switches operated by a removable member, e.g. key, plug or plate; Switches operated by setting members according to a single predetermined combination out of several possible settings wherein one single insertion movement of a key comprises an unlocking stroke and a switch actuating stroke, e.g. security switch for safety guards the switch being lockable by remote control, e.g. by electromagnet

Definitions

• the invention relates to a safety switch which has the features of the preamble of claim 1.
• Safety switches are used wherever it must be ensured that a door, a cover or the like, which in the closed state prevents access to the safety area of a machine, can only be opened when the machine is switched off, and a Switching on the machine is only possible when the door or the like is closed. If, in addition, it must be prevented that the key cannot be removed from the key channel of the safety switch and not the door or the like can be opened when the machine is switched off, but only when the machine has come to a standstill, the safety switches additionally indicate a locking device that causes the key to be held in the key channel during the period corresponding to the expiry time.
• Known safety switches have an electromagnet for this purpose, which in the excited state either holds a bolt in the locking position or pulls the bolt held in the locking position by a prestressed spring out of the locking position.
• the bolt acts in its locking position either with the plunger or directly with the key.
• the object of the invention is to create a safety switch of the type mentioned at the beginning, the locking device of which can be implemented in a cost-effective and space-saving manner.
• This problem is solved by a safety switch with the features of claim 1. Since, in the solution according to the invention, a section of the plunger is designed as an armature, only the stator part of the electromagnet is required as an additional component in comparison to safety switches without a blocking device, which leads to a significant cost reduction. But the space requirement is also reduced, on the one hand, by the fact that the stator part encompasses the plunger, and on the other hand, that components are not required which transmit the magnetic force generated by the stator part to the plunger in the form of a blocking force.
• the locking flank which rests on the tappet when the locking device is active, and thereby prevents the ratchet from rotating, which is a prerequisite for removing the key from the key channel, can be formed by the flank of a locking recess in the cam track , in which the plunger can engage in the position of the ratchet wheel in which the key is fully inserted into the key channel and therefore the door to be secured or the like is completely closed.
• the locking device can optionally effect a magnetic locking or a spring locking.
• the electromagnet presses the tappet, usually against the force of a spring, against the cam track.
• the tappet is pressed against the cam track by a prestressed spring. The electromagnet then unlocks the ratchet when excited.
• the invention is explained in detail below using an exemplary embodiment shown in the drawing.
• the single figure shows a schematically illustrated section of the embodiment in the direction of the longitudinal axis of its plunger.
• a safety switch designated as a whole by 1, has a cuboid housing 2 in the exemplary embodiment, which can be made of metal or plastic.
• the housing 3 of a head part adjoins one end of the housing 2 and forms the key channel 4 for a key 5 serving as a switch actuating member.
• the housing 3 made of metal or plastic, like the housing 2, is designed such that it is rotated not only in the position shown in the figure, but also in relation to this position by 90 ° or 180 ° with the housing 2 by means of not shown ter screws can be connected.
• a plunger 6 is slidably mounted in the housing 2 in its longitudinal direction. Its lower end is in contact with an actuating bolt 7 of a switch 8 which is aligned with the plunger 6 and which contains at least one switching path which is closed when the key is fully inserted into the key channel 4 and is open, when the key 5 is pulled out of the key channel 4.
• the upper end of the plunger 6 lies against a cam track 10 formed by a section of the outer surface of a ratchet wheel 9.
• the axis of rotation of the ratchet wheel 9 mounted in the housing 3 crosses at right angles the longitudinal axis of the plunger 6.
• the ratchet wheel 9 is provided with a radial incision 11, on one flank of which a transverse web 5 'of the key 5 is in contact comes when the key 5 is inserted into the key channel 4 becomes.
• a longitudinally extending key 5 5 1 1 in which the ratchet 9 engages when it is taken when inserting the key 5 into the key channel 4 from the crosspiece 5' in the angular position shown in the figure becomes.
• Locking elements (not shown) which can be actuated by means of the key 5 prevent the ratchet wheel 9 from being in the position shown in the drawing when the key is outside the key channel 4 with an aid, for example a screwdriver or a piece of wire Angular position can be rotated.
• the stator part 12 of an electromagnet is arranged in the housing 2 concentrically with the plunger 6.
• the stator part 12 surrounding the plunger 6 is connected to the housing 2 via a holder or the like.
• the plunger 6 has a central section 6 ', the diameter of which is larger than the diameter of the two end sections.
• the entire plunger 6 can therefore consist of a ferromagnetic material.
• the length of this central section 6 1 is approximately equal to the axial length of the stator part 12, between the inner wall and outer surface of the central section 6 'there is only a relatively small air gap.
• this is provided at the other end of the curved track 10, which has the smallest distance from the axis of rotation of the ratchet wheel 9, with a locking recess 15 into which the plunger 6 engages thanks to the force of the helical spring 13, when the ratchet wheel 9 is in the angular position in which the key 5 is fully inserted into the key channel 6.
• the locking recess 15 forms a locking flank 15 'against the curved path 10.
• Their course and the shape of the engaging in the locking recess 15 end of the plunger 6 are chosen so that self-locking is present.
• the plunger 6 can therefore not be pushed out of the latching recess 15 if a torque is exerted clockwise on the switching wheel 9 when looking in the direction shown in the figure. Such a torque occurs when a force is exerted on the key 5 in the sense of being pulled out of the key channel 4.
• the plunger 6 is held in engagement with the latching recess 15 by the coil spring 13. During this time, the key 5 cannot be removed from the key channel 4, since a corresponding rotation of the ratchet wheel 9 is prevented by the plunger 6. Switching off the machine does not yet result in release of the switching wheel 9 and thus the key 5. Only when the machine has come to a standstill is the stator part 12 excited and the plunger 6 is pulled out of the locking recess 15 by the electromagnet. The key 5 can then be pulled out of the key channel 4, the ratchet wheel 9 being rotated. The plunger 6 runs on the cam track 10 towards its high end, as a result of which the plunger 6 is moved against the force of the helical spring 13 against the switch 8 and inevitably opens the switching path located in the control circuit of the machine.

Landscapes

• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Engineering & Computer Science (AREA)
• Computer Security & Cryptography (AREA)
• Push-Button Switches (AREA)
• Switch Cases, Indication, And Locking (AREA)
• Electromagnets (AREA)
• Auxiliary Devices For Machine Tools (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=6495800

Family Applications (1)

Country Status (6)

Cited By (2)

Families Citing this family (71)

Family Cites Families (11)

• 1993
  • 1993-08-23 DE DE4328297A patent/DE4328297C1/de not_active Revoked
• 1994
  • 1994-07-05 AT AT94922260T patent/ATE166999T1/de not_active IP Right Cessation
  • 1994-07-05 US US08/602,756 patent/US5760353A/en not_active Expired - Lifetime
  • 1994-07-05 EP EP94922260A patent/EP0801801B1/fr not_active Expired - Lifetime
  • 1994-07-05 WO PCT/EP1994/002202 patent/WO1995006323A1/fr not_active Ceased
  • 1994-07-05 JP JP50728995A patent/JP3476827B2/ja not_active Expired - Lifetime

Non-Patent Citations (1)

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