Electrical transmission or interconnection systems – Switching systems – Condition responsive
Patent
1996-09-30
1998-05-26
Shoop, Jr., William M.
Electrical transmission or interconnection systems
Switching systems
Condition responsive
307112, 307140, 307 91, 364424048, B26F 100
Patent
active
057570884
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a remote control device, especially for conveying, spraying and distributing machines for concrete and mortar, having a central control device for controlling aggregates and signalling elements, and having a remote control unit connected to the central control device through a multicore remote control cable. The central control device has an emergency stop switch device for main and control circuits leading to the aggregates and signalling elements, which can be remote controlled by means of a manually mechanically actuatable emergency stop switch or key arranged in the remote control unit. The power supply is guided through a forced first switch contact of the emergency stop switch, which contact is designed as a break contact, and which triggers an emergency cut-off when the power supply is interrupted.
BACKGROUND OF THE INVENTION
In remote control devices for machines of the above type, the possibility of an emergency cut-off in dangerous situations, which can occur due to malfunctions or incorrect operations, on the one hand, or due to happenings in surrounding areas on the other hand, is intolerable. All instantaneous sequences of movement are usually interrupted during an emergency cut-off. Since the emergency stop function is thus of a central importance for reasons of operational safety, suitable precautions must be taken, which guarantee also during a breakdown, a reliable emergency cut-off. In cable remote control devices, consideration must particularly be noted that the long multicore remote control cables can experience a short in a cable in the emergency stop circuit during a rough building site operation, through which the switch contact of the emergency stop switch is bridged, and thus no longer functions. The operator notices hereby only in a case of danger during an operation of the emergency stop switch that the remote control cable is no longer in order.
Starting out from this, the basic purpose of the invention is to further improve the remote control device of the above-disclosed type in such a manner that also in the case of a short in a cable in the emergency stop circuit, especially in the area of the remote control cable, an emergency cut-off is still triggered by operating the emergency stop switch.
To attain this purpose, the characteristic combinations disclosed in claims 1 and 3 are suggested. An advantageous development of the invention results from the dependent claim.
The solution of the invention is based on the thought that also in the case of a short in a cable in the emergency stop circuit it must be assured that during operation of the emergency stop switch, the power supply to the emergency stop switch device is interrupted.
SUMMARY OF THE INVENTION
In order to achieve this, it is suggested according to a first modification of the invention that the first switch contact is connected at its first connection through a first cable core of the remote control cable and an overload fuse to the "hot" pole of a central control side voltage source, and with its second connection through a second cable core of the remote control cable to a power supply connecting terminal of the emergency stop switch device. The emergency stop switch has in addition a forced second switch contact designed as a make contact, the first connection of which is connected to the ground pole of the voltage source, and the second connection of which is short-circuited within the remote control unit to the second connection of the first switch contact, and that the first and the second switch contact react timely one after the other upon operation of the emergency stop switch forming a switch gap. The first and the second switch contact of the emergency stop switch can also be combined in a change-over switch.
With this measure it is achieved that upon operation of the emergency stop switch in the usual case, the power supply connection of the emergency stop switch device is switched over to ground potential and thus triggers the emergency cut-off.
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Stahl, Kurt: Pfuschen kann toedlich sein. In: industrie-elektrik + elektronik, 35. Jg., 1990, Nr. 7, S. 40-43.
Herman, Wolfgang; Weber, Stefan: Konstruktiv und strukturell. In: Maschinenmarkt, Wuerzburg 99, 1993, 19, S. 58-63;
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Baeumen Paul
Petzold Wolf-Michael
Ganjian Peter
Putzmeister-Werk Maschinenfabrik GmbH
Shoop Jr. William M.
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