Data processing: measuring – calibrating – or testing – Measurement system – Remote supervisory monitoring
Reexamination Certificate
1997-10-28
2001-09-25
Shah, Kamini (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Remote supervisory monitoring
C137S085000, C137S082000, C700S278000
Reexamination Certificate
active
06295511
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to an apparatus for controlling and monitoring actuators with an open/close characteristic, which apparatus consists of a drive switch unit for actuating a drive force unit, at least one limit or position signal generator that detects an end position of the actuator and an apparatus for actuating the drive switch unit as well as for outputting the limit signal generator state.
In the field of process automation, there are many developments that enable the realization of new possibilities for communicating with field apparatuses and, thus, of an improved controlling, savings of cost and fault monitoring. Thus, on the one hand, a quasi-analog method, already widely distributed, is given by the Highway Addressable Remote Transducer Field communication protocol or HART-field communication protocol, in which the digital signal with a mean value is superposed on a conventional analog signal. The apparatus operating according to the HART-field communications protocol can, without alteration, replace conventional processing apparatuses. On the other hand, great progress has been made in the use of purely digital process apparatuses that communicate with one another via a digital field bus. A digital field bus thereby enables, above all in a large processing installation, a considerable savings in the cost due to reduction in cabling expenses. However, it does have the disadvantage that convention analog apparatuses and field bus apparatuses cannot be exchanged with one another and the installation of the field bus system entails large investments and changes. Nonetheless, in particular for measuring transducers and controllers, such as, for example, position regulators on actuators, many field bus communication process apparatuses or HART-field communication process apparatuses are already available.
The preponderant number of actuators that are currently in use or will be used in the near future have an open/close characteristic, for which field bus communication process apparatuses or HART-field communication process apparatuses are however mostly too costly.
A large number of these controlling apparatuses with an open/close characteristic respectively operate with a drive switch unit for controlling a drive force unit and with at least one limit signal generator that detects an end position.
A typical apparatus for controlling and monitoring an actuator with an open/close characteristic according to the prior art is illustrated in FIG.
2
. In these systems, an actuator drive unit (not shown), for example a pneumatic drive, is controlled by a drive switch unit in the form of a solenoid valve
9
and two limit signal generators
11
and
13
. For the driving of the solenoid valve
9
and for the outputting of the limit signal generator states, specific apparatuses, such as a disconnecting or isolating amplifier
33
for the one limit signal generator
11
, a control valve module
35
for the solenoid valve
9
and a disconnecting or isolating amplifier
37
for the other limit signal generators
13
, are additionally provided and are respectively connected via separate cables
39
,
41
and
43
with the limit signal generators
11
and
13
and with the solenoid valve
9
, which are often arranged in an area in which there is a danger of explosion. The existence of the explosion-threatened area thereby militates against the integration into one unit of the apparatuses
33
,
35
and
37
with the solenoid valve
9
and the limit signal generators
11
and
13
. Thus, the known apparatuses for controlling and monitoring the actuators with an open/close characteristic are connected, in particular, with a high cabling expense.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an apparatus in which the controlling and monitoring of actuators with an open/close characteristic so as to overcome the problems with the prior art, particularly to save costs, to provide greater ease of surveying and to reduce the susceptibility to failure.
To accomplish these goals, the present invention is solved in that a first unit comprises the drive switch unit, the limit signal generator and additionally comprises an electronics unit, while the second unit comprises the apparatus for driving the drive switch unit as well as for outputting states of the limit signal generator and the first unit is connected with the second unit by means of a twin-core cable.
It can thereby be provided that the twin-core cable transmits analog signals during operation.
The invention further proposes that the electronic unit of the first unit is connected with the twin-core cable. The electronic unit produces a corresponding control signal for the drive switch unit from the drive signal of the second unit, and the electronic unit changes a controllable current source or its interior resistance in dependence on the state of the limit signal generators.
It can also be provided, according to the invention, that the first unit is arranged in an explosion-threatened area, and that the second unit is arranged in a safe area.
An embodiment of the invention is characterized in that the switch signal for the drive switch unit consists of two voltage areas for two different switch positions of the drive force unit.
It is thereby preferred that the second unit detects the change in the current and converts it into a separate output signal for the state of the limit signal generators of the drive switch unit and into possible fault diagnostic messages.
Another embodiment of the invention is characterized in that the switch signal for the actuator drive unit consists of two current ranges for two different switch positions of the drive force unit.
It can thereby be provided that the second unit detects the change of voltage and converts it into a separate output signal for the state of the limit signal generator of the drive switch unit and into possible fault diagnostic messages.
According to the invention, it is preferred that the actuator drive unit is a solenoid valve and/or the drive force unit is a pneumatic drive.
The invention further proposes that the second unit integrates in itself the function of at least one disconnect amplifier and/or a valve control module.
In addition, it can be provided according to the invention that the electronics of the first unit contain a microprocessor.
The invention also proposes that the second unit contains a microprocessor.
In addition, it is provided that the method for fault monitoring can be executed and, preferably, fault messages can be outputted.
Other advantages and features of the invention will be readily apparent from the following description of the preferred embodiments, the drawings and claims.
REFERENCES:
patent: 4942613 (1990-07-01), Lynch
patent: 5148000 (1992-09-01), Tews
patent: 5194790 (1993-03-01), Niimi
patent: 5699824 (1997-12-01), Kemmler et al.
patent: 39 27 973 (1991-02-01), None
patent: 43 03 560 (1994-08-01), None
patent: 44 41 620 (1996-05-01), None
Hill & Simpson
Samson Aktiengesellschaft
Shah Kamini
LandOfFree
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