Abstract:
An emergency safety switch for a safety control system used to terminate the operation of one or more automated machines includes a stop circuit that is electrically connected to a connection port. The connection port includes a pair of interface ports for in-line serial connection to a wiring circuit provided by the safety control system to monitor various emergency safety switch and other detection devices. As such, the connection port provides a quick and easy manner for attaching and detaching the emergency safety switch to the wiring circuit, which facilitates efforts to install a sufficient number of emergency stop switches on an automated production line.

Description:
TECHNICAL FIELD 
     The present invention relates generally to an emergency safety switch for automated machinery. More particularly, the present invention relates to an emergency safety switch configured for use with existing safety circuit wiring provided by a safety control system. More specifically, the present invention relates to an emergency safety switch having a connection port to facilitate the attachment of the emergency safety switch to existing safety circuit wiring provided by a safety control system. 
     BACKGROUND ART 
     Emergency safety switches, emergency stops, or E-stops are typically part of a comprehensive safety control system that is utilized to supervise the operation of automated production systems, such as those used, for example, for automated manufacturing. Specifically, the safety control system is in communication with one or more emergency safety switches and with various pieces of automated machinery that is part of the automated production line. In response to the actuation of the emergency safety switch to indicate that an unsafe event has occurred or is about to occur, the safety control system stops or terminates the operation of the automated machinery in order to prevent the occurrence of injury to workers, the machinery, or to the articles being handled by the machinery. Thus, emergency safety switches or E-stops are provided as manually-actuated switches, which are actuated by a worker when he or she identifies or anticipates an unsafe condition and needs to stop the automated movement of the production line machinery. 
     Current emergency stop switches or E-stop switches are required to be hardwired into the safety circuit wiring of the safety control system, which requires substantial time and effort to carry out. In the case of existing safety control systems that utilize proprietary wiring configurations, it can take an inexperienced technician a significant amount of time and effort to understand the wiring logic of such wiring configurations in order to correctly attach the emergency safety switch or E-stop to the safety system wiring. Such drawbacks may result in the lack of a sufficient number of emergency safety switches or E-stops being installed along the automated production line or, in some cases, the complete lack of the installation of any emergency safety switches altogether. 
     Therefore, there is a need for an emergency safety switch, or E-stop, that is configured to be easily retrofit or attached to the wiring of an existing safety control system for the machinery of an automated production line or process. In addition, there is a need for an emergency safety switch, or E-stop, that is low cost. 
     SUMMARY OF INVENTION 
     It is thus an object of one aspect of the present invention to provide an emergency safety switch that can easily be coupled to a safety control system for machinery in a production line. 
     It is an object of another aspect of the present invention to provide an emergency safety switch, as above, that can economically be retrofit to existing safety control systems. 
     These and other objects of the present invention, as well as the advantages thereof over existing prior art forms, which will become apparent from the description to follow, are accomplished by the improvements hereinafter described and claimed. 
     In general, an emergency safety switch configured to be coupled to a wiring circuit of a safety control system used to terminate the operation of one or more automated machines coupled thereto includes a first path having a first control switch. The emergency safety switch also includes a second path having a second control switch, and a main switch that is in operative communication with the first and second control switches. A first and second connection interface is adapted to be coupled in series with the wiring circuit of the safety control system. Each connection interface has at least four terminals, such that the first and third terminals of the first and second connection interfaces are coupled together by respective first and second bridge lines. As such, the first path is coupled between the fourth terminals of the first and second connection interfaces, and the second path is coupled between the second terminals of the first and second connection interfaces. Thus, when the main switch is actuated, the control switches are moved from a normally closed state to an open state. 
     A preferred exemplary emergency safety switch for a safety control system made according to the concepts of the present invention is shown by way of example in the accompanying drawing without attempting to show all the various forms and modifications in which the invention might be embodied, the invention being measured by the appended claims and not by the details of the specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is a schematic view of an emergency safety switch, or E-stop switch, in accordance with the concepts of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An emergency safety switch is generally referred to by the numeral  10  in the drawing. It should be appreciated, that the term “emergency safety switch” may be used herein interchangeably with the terms “E-stop” and “emergency stop switch”. Specifically, the emergency safety switch  10  includes a stop circuit  20  that is operatively coupled to a connection port  30  that allows the stop circuit  20  to be attached to a wiring circuit or harness  40  that is coupled to a safety control system  50  that monitors the operational status of the switch  10 . The safety control system  50  is configured to be coupled to various automated machinery  60  that is part of an automated production line, process, or manufacturing line. As such, the actuation of the emergency stop switch  10  causes the safety control system  50  to responsively stop the operation of the machinery  60  to which it is coupled. 
     Stop circuit  20  of the emergency safety switch  10  includes electrical connection terminals  100 ,  110 ,  120 ,  130 ,  140 , and  150 . Coupled between terminals  100  and  140  are a series of coupled light elements  160  and light switches  170 , which form a first path. It should be appreciated that the light element  160  may comprise any suitable illumination element, such as an LED (light emitting diode), or incandescent light for example. Coupled between terminals  110  and  130  is a control switch  200 , which forms a second path, and coupled between terminals  120  and  150  is a control switch  210 , which forms a third path. In one aspect, the light and control switches  170 ,  200 ,  210  may comprise push-button type switches that are configured to be moved between an ON and OFF position or state, such that the light switch  170  is normally in an OFF state or open position, while the control switches  200 ,  210  are normally in an ON state or closed position. In addition, the movement of the light switch  170  and control switches  200 ,  210  from their normal resting position or state is controlled by a main switch or actuator  250  that is operatively attached to the switches  170 ,  200 ,  210 . It should be appreciated that the actuator  250  and switches  170 ,  200 ,  210  are configured as maintained switches that are configured to remain in either a normal resting state or an active state, and are only moved from one state or the other upon the manual actuation of the actuator  250  by the user. For example, when the actuator  250  is configured as a push button and is depressed from its normal resting state, the actuator  250  and the switches  170 ,  200 ,  210  are moved to an active state where they remain until the actuator  250  is manually actuated again by the user, such as by pulling or twisting the actuator  250 , which results in the actuator and switches  170 ,  200 ,  210  returning to their normal resting state. 
     As such, during operation of the emergency safety switch  10 , when the actuator  250  is depressed by the user&#39;s hand, the light switch  170  and control switches  200 ,  210  are moved to their active position or state where they maintained. As a result, the light switch  170  is moved to an ON or closed position, and the control switches  200 ,  210  are moved to an OFF or open position. If it is desired to return the actuator  250  and switches  170 ,  200 ,  210  to the normal resting state then the actuator  250  is manually moved back to its normal resting state by pulling or twisting the actuator  250  backward. As a result, the actuator  250  and switches  170 ,  200 ,  210  are moved back to their normal resting state where they are maintained. 
     The connection port  30  includes interfaces  300  and  310  that allow the emergency safety switch  10  to be readily coupled in-line or in series with the wiring harness or circuit  40 . In one aspect, the connection interfaces  300  and  310  may be configured as threaded or quick-disconnect connectors that are compatible with counterpart connectors provided by the wiring harness or circuit  40 . Each interface  300  and  310  includes four interface terminals  320 A-D and  330 A-D, respectively. Terminals  320 A and  320 C of interface  300  are respectively coupled to terminal  330 A and terminal  330 C of interface  310  by respective wires or bridge lines  350  and  352 . Furthermore, interface terminals  320 A and  330 A of interfaces  300  and  310  are coupled to terminal  100  of the stop circuit  20  via wire  354 , while interface terminals  320 C and  330 C of interfaces  300  and  310  are coupled to terminal  140  via wire  356 . In addition, interface terminals  320 B and  320 D of interface  300  are respectively coupled to terminals  120  and  110  of the stop circuit  20 , while interface terminals  330 B and  330 D of interface  310  are respectively coupled to terminals  150  and  130  of the stop circuit  20 . It should also be appreciated that the stop circuit  20  and connection port  30  may be carried by any suitable housing. 
     The emergency safety switch  10  is configured to be coupled in-line with the wiring circuit or harness  40 , which includes four conductive lines or wires: a power wire  400 ; a safety control A wire or line  410 ; a ground (GND) wire  420 ; and a safety control B wire or line  430 . In one aspect, the power and ground (GND) wires or lines  400  and  420  may be coupled to any suitable power source, including a 24 VDC power source for example. The safety control wire A  410  and safety control wire B  430  are configured to communicate with the safety control system  50  that is configured to be interfaced with various machinery  60  that is part of the production line being monitored. 
     Thus, to place the emergency safety switch  10  into operation, the connection port  30  is attached in-line or in series with each end of the wiring circuit  40 , denoted as  40 A and  40 B, provided by the safety control system  50 , such that interface  300  is attached to end  40 A of the wiring  40  and interface  310  is attached to end  40 B of the wiring  40 . Once the emergency stop switch  10  is connected to the safety control system  50 , the light switch  170  is maintained in a normally open or OFF position, while the control switches  210  and  220  are both maintained in a normally closed or ON position. Upon depressing or otherwise actuating the main switch  250  by the user to identify an adverse event, such as the malfunction of the machinery  60 , the light and control switches  170 ,  200 ,  210  are placed in their active position, such that the light switch  170  is closed and the control switches  200 ,  210  are opened. As a result, the light element  160  is illuminated to indicate that the emergency safety switch  10  was actuated, while the safety A and safety B control lines  410  and  430  of the wiring circuit  40  are placed in an open circuit state. Specifically, the safety control system  50  interprets the open circuit state of the control lines  410 ,  430  as an adverse event, and correspondingly takes corrective action by shutting down or terminating the operation of the necessary machinery  60  to prevent the furtherance of damage to such machines and/or to prevent injury to persons in the vicinity. 
     It will, therefore, be appreciated that one advantage of one or more embodiments of the present invention is that an emergency safety switch that provides a connection port is configured to be readily and quickly attached to a wiring circuit provided by a safety control system. Another advantage of the present invention is that the emergency safety switch is configured to be connected to emergency control lines provided by the wiring circuit of a safety control system used to shut down automated machinery in the event of an adverse event. Still another advantage of the present invention is that the emergency safety switch provides a light element to identify that the emergency safety switch has been actuated. 
     Thus, it can be seen that the objects of the present invention have been satisfied by the structure and its method for use presented above.