Patent Application
20140048610
1. Field of the Invention
The invention relates to an assembly for a modular automation device, having a sensor, which is arranged in a housing capsule of the assembly, for detecting the temperature of the feed air in the housing capsule, where feed air flows through air-inlet openings in the housing capsule, across components, and finally through air-outlet openings in the housing capsule, and having a monitoring unit for evaluating the sensor that is detected by the sensor. The invention further relates to a modular automation device having a plurality of these types of assemblies.
2. Description of the Related Art
Siemens catalogue ST 70, chapter 5, issue 2011 discloses assemblies for a modular automation device. The assemblies, which can be mounted on a support, are a constituent part of a modular automation device and each have, within a housing capsule, a surface mount device (SMD) printed circuit board that is provided with electrical and electronic components. Heat is drawn from these components substantially by convection by means of air flowing through an opening in the lower face of the housing capsule, across the components, and finally through an opening in the upper face of the housing capsule, where the air that flows through the housing draws heat from the components. In many cases, the assemblies are designed for use in a harsh processing environment up to a predefined ambient temperature, and it is therefore necessary to know the feed-air temperature in the respective assembly during operation of the automation device to ensure that the assembly can operate at the ambient temperature which is specified for it.
In order to detect the temperature of the feed air, the SMD printed circuit board has an SMD sensor, where, if the temperature reaches or exceeds a threshold value, a temperature-monitoring unit indicates a fault to a user. Although the space requirement of the components on the printed circuit board is reduced on account of the SMD design, it is disadvantageous that the heat lost from the assembly has a disturbing influence on the SMD sensor with respect to accurate detection of the feed-in temperature. For example, heat sources that are arranged on the printed circuit board in the form of transformers or field-effect transistors corrupt the measurement result of the SMD sensor, i.e., the feed-air temperature that is detected by the sensor deviates from the actual feed-air temperature, where further interfering temperature influences that are caused by adjacent assemblies increase the deviations.
It is therefore an object of the invention to provide an assembly for a modular automation device and a modular automation device having assemblies of this kind, which assemblies and automation device enable the feed-air temperature to be evaluated more accurately.
This and other objects and advantages are achieved in accordance with the invention by an assembly and automation device in which the feed-air temperature can be advantageously determined more accurately by determining deviations in the feed-air temperature and taking into consideration these deviations to correct the feed-air temperature that is detected by a sensor. Corruption of the measurement result with respect to the feed-air temperature on account of heat sources that are arranged on a printed circuit board and/or disturbing temperature influences that are caused by adjacent assemblies are largely avoided, this meaning that these disturbances are largely eliminated or compensated for during determination of the actual feed-air temperature. Furthermore, no additional production costs and no additional outlay on installation is required, such as a further sensor, which is arranged outside the assembly or housing capsule, for detecting a reference temperature can be dispensed with. It is only necessary to adapt the assembly firmware a single time, i.e., once.
At least one reference curve is stored in the monitoring unit for a performance parameter, where the reference curve represents, for this one performance parameter, the deviations in the detected temperature or a reference temperature as a function of the heat-up time or a cool-down time of the assembly. In order to achieve good results with respect to the feed-air temperature that is to be determined, it is not absolutely necessary to store a large number of reference curves in the monitoring unit for a large number of detectable temperatures, such as temperatures of from 10° C. to 70° C. In a practical exemplary embodiment of the invention, a reference curve for a reference temperature of 60° C. is selected only for three performance parameters, because it has been found that the temperature deviations differ only insignificantly from the deviations for temperatures of from 5 to 50° C. as a function of the heat-up time or operating period after the assembly is switched on.
It should be understood that a reference curve can be stored in the monitoring unit for any performance parameters and any of the detectable temperatures in the temperature range of from 10° C. to 70° C. to achieve particularly good results in respect of the evaluation. A performance parameter is understood to be, for example, operation of the assembly under full-load, half-load or quarter-load.
In another embodiment, it possible to simply calculate the feed-air temperature during the heat-up time of the assembly. The assembly is operated, for example, under half- or full-load during this heat-up time. In the case in which the assembly comprises a source module or a power-supply assembly, this means that the assembly provides or outputs 50 or 100% of its rated power to the further assemblies or sink modules. In the case in which the assembly is comprises a sink module or an assembly that receives power, this module or this assembly draws 50 or 100% of its power requirement from a source module or from a power-supply assembly.
In another embodiment, it is possible to simply calculate the feed-air temperature during the cool-down time of the assembly. An assembly that comprises a source module or a power-supply assembly does not supply any further assemblies with energy and an assembly that comprises a sink module or an assembly that receives power does not draw any current from the source module or the power-supply assembly during this cool-down time.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.
The invention, the refinements of said invention and advantages of said invention will be explained in greater detail below with reference to the drawing which illustrates an exemplary embodiment of the invention, in which:
With initial reference to
In order to largely prevent heat sources that are arranged on the printed circuit board and/or disturbing temperature influences of adjacent assemblies (not illustrated) from corrupting the measurement result with respect to the feed-air temperature, provision is made for the feed-air temperature to be determined from the detected feed-air temperature and a time-dependent temperature deviation via a reference curve which is stored in a monitoring unit of the assembly. The reference curve represents, for a performance parameter, the deviations in the detected feed-air temperature or a reference temperature, which is associated with the detected feed-air temperature, as a function of a heat-up time or a cool-down time of the assembly. The disturbing influences are taken into account during the evaluation of the detected feed-air temperature and largely eliminated by such measures.
For a more detailed explanation in this respect, reference is made to
In general, the temperature deviation Ta during operation under load or during the heat-up phase for t>t0 is:
where:
th: heat-up time,
t0: delay or dead time,
T: time constant (approximately 15 minutes),
Tz: calculated feed-air temperature,
Tdet: the detected feed-air temperature or reference temperature,
Ta: temperature deviation,
Ts: empirically determined temperature deviation at the beginning of the heating-up process, and
Te: empirically determined temperature deviation at the end of the heating-up process.
The feed-air temperature Tz is generally:
T
z
=T
det
−T
a
In the text which follows, reference is made to
In the case in which, for example, the sensor of the assembly detects a feed-air temperature Tdet of 50° C. during operation of the assembly and the assembly is not in operation for approximately 28 minutes, a monitoring unit determines a temperature deviation Ta of 5° C. via the reference curve 9 and calculates a feed-air temperature Tz of 45° C. from the detected feed-air temperature Tdet of 50° C. and the temperature deviation Ta of 5° C.
In general, the temperature deviation Ta during the deactivation or cool-down phase for t>t0 is:
where:
tk: cool-down time,
t0: delay or dead time,
T: time constant,
Tz: calculated feed-air temperature,
Tdet: the detected feed-air temperature or reference temperature,
Ta: temperature deviation,
Tss: empirically determined temperature deviation at the beginning of the cooling-down process which corresponds to the empirically determined temperature deviation Te at the end of the heating-up process, and
Tee: empirically determined temperature deviation at the end of the cooling-down process.
In general, the feed-air temperature Tz is once again:
T
z
=T
det
−T
a
Therefore, the disclosed embodiments of the invention comprise an assembly for a modular automation device having a sensor, which is arranged in a housing capsule (3) of the assembly, for detecting the temperature (Tdet) of the feed air in the housing capsule (3), where the feed air flows through air-inlet openings in the housing capsule (3), across components, and finally through air-outlet openings (4) in the housing capsule (3), and having a monitoring unit for evaluating the temperature (Tdet) that is detected by the sensor. In accordance with the disclosed embodiments, at least one reference curve is stored in the monitoring unit, where the reference curve represents, for at least one performance parameter, the deviations in the detected temperature (Tdet) or a reference temperature, which is associated with the detected temperature (Tdet), as a function of a heat-up time or a cool-down time of the assembly, and where the monitoring unit is configured to determine the feed-air temperature (Tz) from the detected feed-air temperature (Tdet) or the reference temperature and the time-dependent temperature deviation (Ta) via the reference curve (see
As a result, it is possible to more accurately determine the feed-air temperature Tz.
Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.
| Number | Date | Country | Kind |
|---|---|---|---|
| 12180971 | Aug 2012 | EP | regional |
