Abstract:
A gas-measuring system is provided that is suitable for both mobile and stationary use. A mobile measuring device ( 2 ) with sensors ( 4, 5, 6, 7 ) for detecting gas concentrations and a base station ( 3 ) are provided for this purpose. The mobile measuring device ( 2 ) is inserted into a holder ( 31 ) of the base station ( 3 ) and the operating functions to the measuring device ( 2 ) are now switched over to the base station ( 3 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of priority under 35 U.S.C. § 119 of German Patent Application DE 10 2005 045 272.8 filed Sep. 22, 2005, the entire contents of which are incorporated herein by reference. 
   FIELD OF THE INVENTION 
   The present invention pertains to a gas-measuring system with a mobile measuring device and a base station. 
   BACKGROUND OF THE INVENTION 
   A mobile gas-measuring device for the simultaneous detection of different pollution gases is known from DE 101 40 945 A1. Three electrochemical sensors, which are used to measure the concentrations of possible pollution gases in a gas sample, are located in a device housing. The gas concentration values measured by the sensors are processed by an evaluating unit integrated in the measuring device and outputted via a display unit. The evaluating unit checks the measured values for plausibility and for compliance with certain, preset limit values. An optical or acoustic alarm is triggered if limit values are possibly exceeded or in case of implausible measured values. 
   The prior-art gas-measuring device is carried by the user as a personal monitoring device, so that pollution gases are rapidly recognized in the work area. Due to the mobility of the gas-measuring device, which is normally attached directly to the clothing or the upper body, it must have the most compact housing dimensions possible and be lightweight. The capacity of the power supply unit carried by the user is limited as a result. In case of longer-lasting measurement, this has the consequence that gas measurements are performed at certain time intervals only to save power or that the sound level of alarm generators is limited. 
   In case of a gas-measuring device, which is arranged stationarily in the environment of a user and continuously monitors the pollution gas content in the ambient atmosphere, it is required that the power supply should make possible a long use time and that possible warning messages be communicated to the user in a clearly perceptible manner, especially in case of high background noise level. Such gas-measuring devices can be carried by the user only to a limited extent. 
   Consequently, two different monitoring systems are normally needed, namely, a personal monitoring device, which is carried by the user, and a stationary monitoring device, which is arranged in the work area of persons. Different measuring systems must usually be kept ready for this purpose, which increases the costs, especially due to the fact that twice the number of gas-measuring systems must be kept ready. 
   SUMMARY OF THE INVENTION 
   The basic object of the present invention is to provide a gas-measuring system that is suitable for both mobile and stationary use. 
   According to the invention, a gas-measuring system is provided with a mobile measuring device, which comprises sensors for detecting gas concentrations and a first control and calculating unit for processing the measured signals sent by the sensors and means for data transmission. A base station is provided having a holder for receiving the measuring device, a power supply unit, a second control and calculating unit for actuating the alarm generators arranged in the base station and interfaces for supplying gas to be measured to the sensors and for data exchange between the mobile measuring device and the base station. 
   The advantage of the present invention is essentially that a base station for accommodating a mobile measuring device is designed such that the gas sampling takes place via the base station and warnings and alarms are communicated to the user from the base station via corresponding optical and acoustic transducers. Interfaces, which send the sample gas flow to the sensors, on the one hand, and couple the mobile measuring device to the base station for the transmission of data, on the other hand, are provided for this purpose between the mobile measuring device and the base station. The base station has a separate control and calculating unit, so that bidirectional data exchange is possible between the measuring device and the base station and the user can determine individually which functions are performed via the measuring device and what support is needed from the base station. The display fields and the alarm generators can be dimensioned larger at the base station, because the space available for installation is not limited here. This facilitates the reading of measured values and acoustic warnings can be communicated to the user in a more clearly audible manner. The user can also decide whether he performs the operation of the measuring device from the base station or whether certain settings take place directly at the mobile measuring device. Provisions are preferably made for the operating functions to be switched over automatically from the measuring device to the base station when the mobile measuring device is placed into the holder of the base station. 
   The base station is designed such that gas sampling can also be carried out from a remotely located measuring point. A gas sampling tube is connected for this purpose to a measured gas pump arranged in the base station. The housing of the base station has a cable drum-like design, so that a long measuring gas tube can also be carried with the base station. High stability is obtained due to the base station designed in the form of a cable, because a side surface of the cable drum can be used as a base. The opposite side surface is used to receive the mobile measuring device. The side surfaces of the base station are advantageously of an annular design, so that the ring can also be used as a grip surface for transporting the base station. 
   The base station advantageously has additionally an interface for transmitting electricity to the mobile measuring device. The use time of the mobile measuring device is thus prolonged, because the capacity of the power supply unit of the base station can be fully exhausted. 
   An exemplary embodiment of the present invention is shown in the drawings and will be explained in greater detail below. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
       FIG. 1  is a gas-measuring system with a mobile measuring device and a base station according to the invention; and 
       FIG. 2  is a perspective view of the mobile measuring device and the base station. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to the drawings, in particular  FIG. 1 , schematically illustrates a gas-measuring system  1 , which comprises a mobile measuring device  2  and a base station  3 . The mobile measuring device contains an oxygen sensor  4 , a CO sensor  5 , an H 2 S sensor  6  and a Kat-Ex sensor  7  that determines the concentration of combustible gases by catalytic combustion. The sensors  4 ,  5 ,  6 ,  7  are connected via a signal processing unit  8  to a first central control and calculating unit  9 , which evaluates the measured gas concentrations by means of a program module  10  and outputs them via a display unit  11 . Warning limits can be assigned to the individual measured gas concentration values via a keyboard  12 . Possible alarms are sent via an optical display  13 , an acoustic alarm generator  14  or via a vibrator  15 . A measured gas pump  16  delivers the gas sample to be analyzed to the sensors  4 ,  5 ,  6 ,  7 . A power supply unit  17  supplies the measuring device  2  with electricity. Measured and status data can be read via a bidirectional PC interface  18 . Program updates can also be read into the program module  10  with the PC interface. 
   The base station  3  contains a battery pack  19 , a second control and calculating unit  20 , a display unit  21 , an acoustic alarm generator  22 , an optical alarm generator  23  and a vibrator  24 . A keyboard  25  is used to enter data of warning limits, which are assigned, e.g., to the gas species. The gas sampling is carried out via a sampling tube  26  and a pump  27 . 
   The mobile measuring device  2  and the base station  3  are connected to one another via a pneumatic interface  28 , a plug type connection  29 , an infrared interface  30  and a receiving compartment  31 . 
   The pneumatic interface  28  is used to pass on the gas sample drawn in by the pump  27  via the measured gas pump  16  to the sensors  4 ,  5 ,  6 ,  7 . The plug type connection  29  couples the battery pack  19  with the power supply unit  17 , so that the capacity of both power supply units  17 ,  19  can be utilized. Bidirectional data connection is established via the infrared interface  30  between the control and calculating units  9 ,  20 . The mobile measuring device  2  is inserted into the receiving compartment  31  for operation and locked. The pneumatic and electric connections may then be established via the interfaces  28 ,  29 ,  30 . 
   When the mobile measuring device  2  is inserted into the receiving compartment  31 , the control and calculating unit  9  transmits a device code to the control and calculating unit  20  of the base station  3 . A comparison is performed there with stored, permissible codes, and a release signal is generated for the bidirectional data exchange. The display unit  11 , the alarm generators  13 ,  14 ,  15  and the keyboard  12  are deactivated in another step and the display unit  21 , the alarm generators  22 ,  23 ,  24  and the keyboard  25  of the base station  3  are connected to the mobile measuring device  2  via the infrared interface  30  for data exchange. The mobile measuring device  2  is operated exclusively from the base station  3 . 
   However, the program module  10  in the mobile measuring device is designed such that partial functions can also be transferred from the mobile measuring device to the base station  3 . Corresponding inputs can be made and values can be preset from the keyboards  12 ,  25 . 
     FIG. 2  shows a perspective view of the mobile measuring device  2  and the base station  3 . Identical components are designated by the same reference numbers as in  FIG. 1 . The housing of the base station has a design similar to that of a cable drum with an upper ring  32 , a middle part  33  and a lower ring  34 . The base station  3  is placed on the lower ring  34  during measuring operation and the measured gas tube  26  for gas sampling can be unwound from the middle part  33 . Due to the cable drum-like design of the base station, it is also possible to accommodate longer measured gas tubes  26  on the base station  3  without handling being compromised by this in any way. Depending on the particular application, a certain length of the measured gas tube  26  can be unwound from the base station  3 . The alarm generators  22 ,  23 ,  24 , which are not shown in greater detail, the keyboard  25  and the display unit  21  are arranged in a control panel  35  on the upper ring  32  of the base station  3 . 
   While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.