Abstract:
An illumination device is provided at the handle-piece of a sniffing probe, in which the illumination device illuminates the region to be inspected. This incorporation considerably facilitates handling of the sniffing probe in difficult-to-access and poorly illuminated regions, for sniffing probes used for detecting gases, for example, for detecting a gas leakage in a cooling device of a motor vehicle.

Description:
FIELD OF THE INVENTION 
     The invention relates to a sniffing probe comprising a handle-piece and being used for detecting a leaking gas. 
     BACKGROUND OF THE INVENTION 
     Sniffing probes are used for determining the location of gas emanation, for example a gas emanating from the cooling circuit of air conditioning units or cooling systems in vehicles and buildings. For this purpose, the sniffing probe handle-piece comprises a gas inlet opening through which ambient gas is continuously taken in, which gas is then examined with respect to the test gas. If a concentration limit value of the test gas is exceeded, said exceeding is acoustically signaled by a detection device connected to the sniffing probe, for example. 
     Sniffing probes are frequently used in environments which are difficult to access and poorly lit or not lit at all, for example in the engine compartment of vehicles, in narrow shafts of buildings etc. Here, rapid and exact tracing and identification of the conduits and containers to be inspected and exact localization of a leakage are difficult. Frequently, a flashlight is to be used, which is quite inconvenient. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to improve handling of a sniffing probe in environments which are difficult to access and poorly lit. 
     According to the invention, the sniffing probe comprises at its handle-piece an illumination device. The illumination device allows the environment of the sniffing probe to be illuminated if the user wishes to do so. The illumination device considerably facilitates work carried out with the sniffing probe in regions which are difficult to access and poorly lit. As compared with the use of a flashlight, the illumination device provided at the handle-piece offers the advantage that the environment of the handle-piece is always reliably illuminated and that the user has one hand free. 
     Preferably, the illumination device is configured such that exclusively a region distal to, i.e. axially in front of the gas inlet opening, is illuminated. Exclusive illumination of the region in front of the gas inlet opening results in illuminating only that region in which the sniffing probe is capable of detecting a leaking gas. The user has to guide the sniffing probe so close to the location to be inspected that a leaking gas prevailing at the location to be inspected can actually be taken in and detected by the sniffing probe. Further, the user is prevented from being blinded by the illumination device. 
     Preferably, only that region in front of the gas inlet opening is illuminated in which a leaking gas can be detected under the prevailing circumstances. For example, illumination may be effected by an illumination device which emits a light cone approximately corresponding to the intake cone. 
     According to a preferred aspect, the light emerges in the region of the gas inlet opening. Thus, the user is prevented to a large extent from being blinded, and exclusively the region distal to the gas inlet opening is illuminated. 
     Preferably, the illumination device comprises an LED as a light source, said LED preferably emitting white, i.e. almost colorless, light. The light source configured as an LED is characterized by low power consumption and relatively low heat development. Generally, a light bulb or a gas discharge lamp can also be used as a light source. 
     The light source may be arranged in the region of the sniffing opening. Alternatively, the light source may be disposed remote from the light outlet at a different location at the sniffing probe, wherein the light flows from the light source through a light conductor arranged at the sniffing probe to the light outlet. The light outlet may be annularly disposed around the gas inlet opening such that shadow casting is reduced or prevented. 
     According to a preferred embodiment, a ready-for-measurement switch is associated with the sniffing probe, said ready-for-measurement switch switching on the illumination device when the sniffing probe is ready for measurement, and switches off the illumination device when the sniffing probe is not ready for measurement. Thus the user can be prevented from erroneously assuming a readiness for measurement and a non-presence of leaking gas when the sniffing probe is not ready for measurement. 
     According to a preferred aspect, a limit value switch is associated with the sniffing probe, said limit value switch controlling the illumination device such that the illumination changes when a leaking gas concentration limit value is exceeded. This is a direct optical indication to the user that the concentration limit value is exceeded or not reached. For example, the limit value switch may change the illumination color from white to red when the leaking gas limit value is exceeded. Likewise, exceeding of the leaking gas limit value may be indicated by blinking of the illumination device. 
     Both the ready-for-measurement switch and the limit value switch may be arranged in a separate detection device, but may also be disposed in or at the sniffing probe handle-piece itself and may be correspondingly controlled by the detection device. The detection device may also be arranged at or integrated in the sniffing probe handle-piece. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described in greater detail with reference to the drawings in which: 
         FIG. 1  shows a first embodiment of a sniffing probe handle-piece comprising a light source arranged in the region of the gas inlet opening; and 
         FIG. 2  shows a second embodiment of a sniffing probe handle-piece comprising a light source arranged remote from the gas inlet opening, and a light conductor. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a sniffing assembly  10  essentially comprising a sniffing probe  11  and a separate detection device  12 .  FIG. 2  shows a second embodiment of a sniffing probe  11 ′. 
     The sniffing assembly  10  serves for localization of a gas leakage where a leaking gas escapes. Sniffing assemblies are in particular used for detecting leakages in cooling circuits of motor vehicle air conditioning units, refrigerators etc. 
     The sniffing probe  11  essentially comprises a handle-piece  14  and a flexible connecting line  16  connecting the handle-piece  14  with the detection device  12 . The handle-piece  14  comprises a handhold  18 , which has coaxially attached thereto a sniffing tube  20 . The connecting line  16  has a length of 1-20 m, the handhold  18  is approximately 20 cm and the sniffing tube  20  is 5-50 cm long. 
     At the front distal end of the sniffing tube  20 , a gas inlet opening  22  is arranged through which the ambient gas in taken in. The ambient gas is taken in via a corresponding vacuum pump in the detection device  12  and flows through a gas capillary in the sniffing tube  20 , the handhold  18  and the connecting line  16  into a gas detector  24  of the detection device  12 . The gas detector  24  determines whether the ambient gas taken in via the gas inlet opening  22  contains leaking gas, and/or determines the proportional content of leaking gas in the ambient gas taken in. 
     The sniffing probe  11  is detachably connected via a plug  15  with the detection device  12 . 
     At the free end of the sniffing tube  20  comprising the gas inlet opening  22  an LED is provided as a light source  26  of an illumination device  25 , wherein the light outlet  28  is arranged at the distal end of the sniffing tube  20 . The light generated by the light source  26  emerges from the light outlet  28  in the form of a light cone  30  having a cone angle relative to the axial line of 10 degrees, for example. 
     The detection device  12  comprises a control device  31  which controls and checks all elements and operations of the sniffing assembly  10 . The control device  31  is connected with the gas detector  24  as well as with a ready-for-measurement switch  32  and a limit value switch  34 . 
     The ready-for-measurement switch  32  receives a ready-for-measurement signal from the control device  31  as long as the sniffing assembly  10  is ready for measurement, and it receives a not-ready signal when the sniffing assembly  10  is not ready for measurement, for example during the switch-on phase or when defects have been detected by the control device  31 . Upon receipt of a ready-for-measurement signal the ready-for-measurement switch  32  switches on the illumination device  25 , and it switches off the illumination device  25  when a not-ready signal has been received. This is a clear indication to the user as to whether the sniffing assembly  10  is ready for measurement. In this manner, the user is prevented from assuming, during non-readiness of the sniffing assembly  10 , that the sniffing assembly  10  is ready for measurement and that the ambient gas does not contain leaking gas. 
     The limit value switch  34  switches the illumination device  25  to a different mode as soon as a limit value of the leaking gas concentration has been exceeded or not reached. For example, the light source  26  may emit light of a different color, e.g. red instead of white, when the limit value is exceeded. Alternatively or additionally, the light emitted by the light source may be intermittently emitted, whereas it is continuously emitted when the limit value is not reached. Thereby, exceeding of the limit value can be detected exactly at the location the user is looking at, and the gas leakage is likely to be found. 
     The sniffing probe  11 ′ shown in  FIG. 2  differs from the sniffing probe  11  shown in  FIG. 1  only with regard to the illumination device  40 . The illumination device  40  at the handle-piece  14 ′ of the sniffing probe  11 ′ shown in  FIG. 2  essentially comprises a light source  42  arranged at the distal end of the handhold  18  or the proximal end of the sniffing tube  20 , and a tubular cylindrical light conductor  44  coaxially disposed around the sniffing tube  20 . The light conductor  44  comprises a light output  46  configured as a flat ring at its distal end, through which a light cone  48  emerges at a cone angle of approximately 10 degrees. The light source  42  may be composed of one or a plurality of LEDs. Instead of one or a plurality of LEDs a light bulb may serve as a light source. The light conductor  44  may be made from plastic material, for example Perspex. 
     The sniffing tube  20  and the light conductor  44  may be of rigid or flexible configuration. 
     By arrangement of an illumination device at the distal end of the sniffing tube  20 , the region in which a gas leakage is supposed to be detected is well illuminated such that the objects to be inspected, for example pipes, seals, connectors etc., are easier to discern. It is not necessary to illuminate the whole measuring object. The light output at the distal end of the sniffing tube allows the user to easily determine and estimate the distance and the exact alignment of the sniffing tube and the gas inlet opening to the location to be inspected on the basis of the shape of the light cone and on the basis of the shadows cast.