Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1998-03-02
2003-08-05
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C702S044000, C702S113000, C324S513000, C340S542000, C340S545100
Reexamination Certificate
active
06604014
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the testing of various types of guard mechanisms for preventing access to a machine containing safety hazards. Such guard devices can exist alone or in conjunction with interlock mechanisms.
The guards are typically structural barriers that are locked in position and can consist of doors, gates, covers, latches and so forth. They will be variously referred to in this application by the synonymous terms, guards, closures and guard closures. In the usual situation the guards are not intended to be open and are only to be opened when the machine has come to a complete rest. When the guard is open it is intended that the machine has been shut down and will remain in the changed condition until the guard is closed even if there is an attempt to restart or restore the operating state of the machine at the main control box of the machine or from elsewhere.
BACKGROUND OF THE INVENTION
Guarding devices have long been used to prevent access to hazardous areas of machinery. Unfortunately there is a constant and continuous need to work on industrial equipment and every precaution must be taken to insure that prior to permitting a worker to work on the machinery the machine has come to a complete stop. It thus must be insured that the guards that are ever present to prevent entry into hazardous areas can not be opened to permit access until the machine has in fact come to a complete stop.
The present invention is directed to testing systems and mechanisms for insuring the integrity of the devices that indicate the status of machine operation so that guards may not be opened until the machine is completely shut down. Such devices are known as run down completion detectors which, when operating without fault, determine if the machine components within the hazardous space have stopped moving or not. Safeguarding systems include electrical and electronic components that consists of control and sensing systems with associated circuitry. In addition there are mechanical components that in addition to the guard closure include a lock and very possibly interlocks and run down completion detectors such as 1) motion detectors, 2) zero speed switches or detectors, 3) timing devices that are predicated on the fact that the run down times are known and can be relied upon 4) delay devices that also require that the machine components run down times can be relied upon and 5) interference devices that can be inserted in to the motion path of the machine components to insure that the machine has come to a complete stop.
In addition to the aforementioned devices to insure that the machine has come to a complete rest, mechanical interlocks or motion blockers can be inserted to absolutely prevent the machine from restarting until they are removed.
The current state of the art for testing the electrical and electronic components of the safeguarding systems is quite advanced. Commercial self testing systems are available which continuously or intermittently, remotely or proximally check for electrical/electronic faults in the system for single or multiple guard closures, during the running of the machine or when stopped, with the guard closures closed or open. If a fault is detected during the running of the machine, the machine is stopped. If detected during stoppage the machine can not restart until the fault is corrected.
However, the state of the art for testing mechanical components of the safeguarding systems is very primitive. For example the previously mentioned commercial self testing systems are not designed to detect failure or breakdown of the mechanical components of the safeguarding system while the machine is running. For mechanical failure or breakdown to be revealed to its electrical/electronic sensing system the mechanical exercising of the guard closure is required. There are currently no provisions or devices provided to exercise the mechanical components for testing purposes during running of the machine probably because such exercising would stop the machine. If the machine is stopped and the guard closure is opened then closed the electrical/electronic test systems will detect mechanical failures or breakdowns in the protective system.
There exists the obvious approach for testing the mechanical components mechanically by opening and closing each guard closure manually or automatically to determine if the machine is at rest when the guard closure is first unlocked, if power is interrupted whenever the guard closure is open, and if restart is allowed immediately upon reclosing. This is not a practical testing system, except in very restrictive circumstances, e.g. where there are few guard closures and generous amounts of time available for testing.
Accordingly, it appears to be very desirable that there be a test system for the mechanical testing of the mechanical components of safeguarding systems during running of the machine to detect if they have failed or not. Such systems to be most useful must be capable of testing the machine while it is running without stopping it.
In addition it would be desirable if the testing of the guards could be done in conjunction with the testing of the interlocks systems which are present on machines adjacent to guards to shut down machines when the guards are opened if the machine has not previously been shut down and prevents the resumption of powered operation of the machine while the guard is open.
Novel interlocks, interlock testing, testing systems and methods of testing have been extensively detailed in an application Ser. No. 08/861,328 now U.S. Pat. No. 5,870,317 entitled REMOTE AND PROXIMAL INTERLOCK TESTING MECHANISMS AND TESTING SYSTEMS filed in the names of the present inventors and assigned to the same assignee TRIODYNE INC. as the present invention. The filing date of said application is May 21, 1997 and is incorporated by reference into this application as setting forth in detail various interlock systems and methods of testing interlocks. A provisional application covering the same was filed on Mar. 3, 1997.
Referring again to the instant invention there are testing systems and apparatus for sensing the movement of a force displacement device applied as an opening force to the guard closure. The force of the displacement device may be constant or variable as the test situation demands.
The instant invention directs the testing of the guard closures and the testing of the interlocks to be performed during running of the machine and during the rundown phase of the machine when the machine is shut down. It does so without shutting the machine down due to the testing, as described in this submission and the previously referenced U.S. Pat. No. 5,870,317. This is done so, because for reasons of safety it is important to establish that during running of the machine and during its rundown phase, access is denied to the guard protected spaces containing running machine components, and that the interlocks provide the protection for which it has been designed. The guard closure and interlock testing methods, processes, devices and systems of the instant invention and in the U.S. Pat. No. 5,870,317 are designed to determine if that is the case, or if the case is that any specific guard closure and/or interlock have failed, hence no longer provide the expected protection. These are conditions which would be unknown without testing.
The overall system is illustrated by example, schematically in FIG
1
. Examples of a main routine for testing interlocks and guard closures is illustrated in
FIGS. 8A
,
8
B,
8
C and
8
D and various novel subroutines of testing systems for separate guard closures and in conjunction with closure and interlocking and closure testing mechanisms and systems as illustrated in
FIGS. 2-7
and
9
-
15
. An overall description of applicants inventions are set forth under the following SUMMARY OF THE INVENTION and will be described in detail under the DESCRIPTION OF THE PREFERRED EMBODIMENTS.
SUMMARY OF THE INVENTION
The present invention includes a first novel system for testin
Barnett Ralph L.
Liber Theordore
Rodriguez Paul
Triodyne Safety Systems L.L.C.
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