Abstract:
A testing apparatus is provided for testing a product in various climatic conditions. The testing apparatus includes a testing cabinet defining a first testing chamber for receiving the product therein and a vibration chamber. A vibration table is positioned within the testing apparatus and has an upper surface communicating with the testing chamber and a lower surface. A plurality of vibrators are operatively connected to the lower surface of the vibration table and are disposed in the vibration chamber. A climate control structure communicates with the vibration chamber for controlling the environment thereof.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to testing equipment, and in particular, to an environmental testing apparatus incorporating a vibration table wherein the climate within the compartment which houses the vibrators for the vibration table is controlled.  
         BACKGROUND AND SUMMARY OF THE INVENTION  
         [0002]    Many types of devices undergo testing to improve the quality and reliability of the devices. Typically, these types of devices undergo a series of environmental tests under various combinations of temperature, humidity, and other climatic conditions to insure product reliability and performance in extreme environmental conditions. Further, many of these devices undergo repetitive, shock vibration testing to insure that the devices are not adversely effected during normal operation.  
           [0003]    In order to test their devices, manufacturers often utilize an environmental testing apparatus which is capable of producing rapid and extreme changes in temperature, humidity and other climatic conditions. A prominent designer and manufacturer of such environmental test apparatus is Thermotron Industries, Inc. of Holland, Mich. In operation, the devices to be tested are positioned within an environmental testing chamber in the testing apparatus wherein the devices are exposed to extreme climatic conditions.  
           [0004]    Vibration testing is carried out by mounting the product to be tested upon some sort of platform or table which communicates with the environmental testing chamber and by then vibrating the table using any type of vibrator. Examples of a vibration table and the vibrators for vibrating the vibration table are shown in Wetzel et al., U.S. Pat. No. 5,804,732, assigned to the assignee of the present invention and incorporated herein by reference. Typically, in an environmental testing apparatus, the vibrators of the vibration table are positioned in a vibration compartment which is physically isolated from the environmental testing chamber. However, the vibrators in the vibration compartment are still partially exposed to the temperature extremes provided in the environmental testing chamber. As such, it is possible that the vibration means may be adversely effected, thereby reducing the efficiency of the vibration table. Further, exposing the vibrators to temperature extremes will lead to the expansion and contraction of the components of the vibrators during operation. This expansion and contraction of the components of the vibrators reduces the useful life of the vibrators and may cause leaks at the connections of the vibrators to a pneumatic source.  
           [0005]    In order to minimize the effects of the temperature extremes within the vibration compartment, vents are often provided within the walls of the vibration compartment such that the interior of the vibration compartment communicates with the ambient air outside the environmental testing apparatus. By providing vents in the walls defining the vibration compartment, the noise external of the environmental testing apparatus is increased. Further, the vents in the walls allow particulate matter and moisture to enter the vibration compartment. Moisture within the vibration compartment has a tendency to penetrate and to freeze in the vibrators, thereby causing a decrease in the efficiency thereof. Heretofore, in order to prevent the moisture from freezing in the vibrators, dry-air or gaseous nitrogen was passed through the vibrators. This process of passing dry-air or gaseous nitrogen through the vibrators adds to the cost of the environmental testing apparatus. Therefore, it is highly desirable to eliminate this process while still preventing moisture from freezing in the vibrators.  
           [0006]    Therefore, it is a primary object and feature of the present invention to provide a testing apparatus wherein the temperature within the compartment housing of the vibrators thereof is controlled.  
           [0007]    It is a further object and feature of the present invention to provide a testing apparatus which discourages an accumulation of moisture within the vibrators thereof.  
           [0008]    It is a further object and feature of the present invention to provide a testing apparatus which is simple to operate and less expensive to manufacture than prior testing apparatus.  
           [0009]    In accordance with the present invention, a testing apparatus is provided for testing a product. The testing apparatus includes a testing cabinet which defines a first testing chamber and a vibration chamber. A vibration table has an upper surface communicating with the testing chamber and a lower surface. A plurality of vibrators are operatively connected to the lower surface of the vibration table and are disposed in the vibrator chamber. A climate control structure is provided for controlling the environment in the vibration chamber. The climate control structure includes a heating element communicating with the vibration chamber for heating the vibration chamber to a predetermined level. In addition, the climate controlling structure includes a cooling element communicating with the vibration chamber for cooling the vibration chamber to a predetermined level. A temperature sensor is positioned within the vibration chamber for sensing the temperature therein. A controller is operatively connected to the temperature sensor and to the heating and cooling elements. The controller controls the heating and cooling of the vibration chamber in response to the temperature sensed by the temperature sensor. It is contemplated that the vibration chamber be free from communication with the ambient air outside the testing cabinet.  
           [0010]    In accordance with a further aspect of the present invention, a testing apparatus is provided for testing a product. The testing apparatus includes a testing cabinet defining a first testing chamber and a second vibration chamber. A vibration table has an upper surface communicating with the testing chamber and a lower surface. A plurality of vibrators are operatively connected to the lower surface of the vibration table and are disposed in the vibration chamber. A vibration chamber heating and cooling system communicates with the vibration chamber for maintaining the temperature in the vibration chamber at a predetermined level. In addition, a testing chamber heating and cooling system communicates with the testing chamber for varying the temperature in the testing chamber to predetermined levels.  
           [0011]    The vibration chamber heating and cooling system includes a heating element communicating with the vibration chamber for heating the vibration chamber to a predetermined level. In addition, the vibration chamber heating and cooling system includes a cooling element communicating with the vibration chamber for cooling the vibration chamber to a predetermined level.  
           [0012]    The testing apparatus also includes a temperature sensor within the vibration chamber for sensing the temperature therein. A controller is operatively connected to the temperature sensor and to the vibration chamber heating and cooling system. The controller controls the vibration chamber heating and cooling system in response to the temperature sensed by the temperature sensor. The controller may also be operatively connected to the testing chamber heating and cooling system for controlling the same. It is contemplated that the vibration chamber be free from communication with ambient air outside the testing chamber.  
           [0013]    In accordance with a still further aspect of the present invention, an improvement is provided in the testing apparatus for testing a product. The testing apparatus includes a testing cabinet defining a first testing chamber for receiving the product therein and a vibration chamber; a vibration table having an upper surface communicating with the testing chamber and a lower surface; and a plurality of vibrators operatively connected to the lower surface of the vibration table and being disposed in the vibration chamber. The improvement includes providing a climate control structure communicating with the vibration chamber for controlling the environment therein.  
           [0014]    The climate control structure includes a heating element communicating with the vibration chamber for heating the vibration chamber to a predetermined level. In addition, the climate control structure includes a cooling element communicating with the vibration chamber for cooling the vibration chamber to a predetermined level. A temperature sensor is positioned within the vibration chamber for sensing the temperature therein. A controller is operatively connected to the temperature sensor and to the heating and cooling elements for controlling the heating and cooling of the vibration chamber in response to the temperature sensed by the temperature sensor. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The drawings furnished herewith illustrate a preferred construction of the present invention in which the above advantages and features are clearly disclosed as well as others which will be readily understood from the following description of the illustrated embodiment.  
         [0016]    In the drawings:  
         [0017]    [0017]FIG. 1 is a schematic view of an environmental testing apparatus in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]    Referring to FIG. 1, a testing apparatus in accordance with the present invention is generally designated by the reference numeral  10 . Testing apparatus  11  is defined by sidewalls  12  and  14 , upper and lower walls  16  and  18 , respectively, and a rear wall (not shown). Inner surfaces  20  and  22  of sidewalls  12  and  14 , respectively, and inner surface  24  of upper wall  16  partially define an environmental testing chamber  26  within testing apparatus  10 . Inner surfaces  20  and  22  of sidewalls  12  and  14 , respectively, and inner surface  28  of bottom wall  18  partially define a vibration compartment  30  within testing apparatus  10 . As is conventional, a door(s) (not shown) is provided for access to the interior of environmental testing chamber  26  and vibration compartment  30 . It is noted, however, that sidewalls  12  and  14  and rear wall (not shown) are free of any openings such as vents, louvers or the like, so as to prevent communication between vibration compartment  30  and the ambient air outside testing apparatus  10 , for reasons hereinafter described.  
         [0019]    Heating element  32  is mounted to the inner surface  24  of upper wall  16  so as to be in communication with the interior of environmental testing chamber  26 . In addition, heating element  32  is operatively connected to controller  38  through line  33 . Cooling element  34  is also mounted to the inner surface  24  of upper wall  16  so as to be in communication with environmental testing chamber  26 . Cooling element  34  is operatively connected to controller  38  through line  35 . As is conventional, heating element  32  is provided to heat environmental testing chamber  26  to a user desired level to test the reliability and performance of a product  36  positioned within environmental testing chamber  26 . Cooling element  34  is provided to cool environmental testing chamber  26  to a user desired temperature in order to test the reliability and performance of product  36 . Temperature sensor  40  is positioned within environmental testing chamber  26  and is operatively connected to controller  38  by line  41  so as to allow controller  38  to monitor the temperature within environmental testing chamber  26 . Controller  38  controls activation of heating element  32  and cooling element  34  in response to the temperature sensed within environmental testing chamber  26  by temperature sensor  40  so as to vary the climatic conditions provided within environmental testing chamber  26  to user desired levels.  
         [0020]    Testing apparatus  10  further includes a vibration table  44  having an upper surface  46  communicating with environmental testing chamber  26  and a lower surface  48  directed towards vibration compartment  30 . A flange  50  depends from the outer periphery of vibration table  44 . Flange  50  includes an outer surface  52  directed towards the inner surfaces  20  and  22  of sidewalls  12  and  14 , respectively. Seals  54  and  56  are affixed to corresponding surface  20  and  22 , respectively, of sidewalls  12  and  14 , respectively, so as to be aligned with outer surface  52  of flange  50 . Seals  54  and  56  are provided to environmentally isolate vibration chamber  30  from environmental testing chamber  26  within testing apparatus  10 .  
         [0021]    A plurality of vibrators  58  extend between lower surface  48  of vibration table  44  and corresponding supports  60  within the interior of vibration compartment  30 . It can be appreciated that vibrators  58  may be mounted to the lower surface  48  of vibration table  44  in any suitable manner, at any of several locations, and at any of one or more angles to lower surface  48  thereof. As is conventional, vibrators  58  are provided to vibrate vibration table  44 , and hence product  36 , during testing. Vibrators  58  may take the form of the vibrator fully described in Briggs et al., U.S. Pat. No. 6,044,709, assigned to the assignee of the present invention and incorporated herein by reference. It can be appreciated that other constructions of vibrators  58  may be utilized without deviating from the scope of the present invention.  
         [0022]    Heating element  62  is interconnected to the inner surface  28  of bottom wall  18  and is in communication with vibration compartment  30 . Heating element  62  is operatively connected to controller  38  through line  64 . In addition, cooling element  66  is interconnected to inner surface  28  of bottom wall  18  of testing apparatus  10  and is in communication with vibration compartment  30 . Cooling element  66  is operatively connected to controller  38  by line  68 . Temperature sensor  70  is positioned within vibration compartment  30  in testing apparatus  10  and is operatively connected to controller  38  by line  72 .  
         [0023]    In operation, product  36  is rigidly connected to upper surface  46  of vibration table  44 . Vibrators  58  vibrate vibration table  44  in a conventional manner. Heating element  32  and cooling element  34  raise and lower the temperature in environmental testing chamber  26  in order to test product  36  under various climate conditions. Temperature sensor  40  allows controller  38  to monitor the temperature within environmental testing chamber  26  such that controller  38  selectively activates heating element  32  and/or cooling element  34  to provide a user desired temperature within environmental testing chamber  26 .  
         [0024]    In addition, temperature sensor  70  allows controller  38  to monitor the temperature within vibration compartment  30 . Controller  38  selectively activates heating element  62  and/or cooling element  66  in response to the temperature sensed by temperature sensor  70  so as to maintain the temperature within vibration compartment  30  at a generally constant level to insure maximum performance and useful life of vibrators  58 .  
         [0025]    As described, vibration compartment  30  is isolated from the ambient air outside testing apparatus  10 . As such, the noise generated by testing apparatus  10  is reduced since a substantial portion of such noise is captured within the testing apparatus  10 . Further, since vibration compartment  30  does not communicate with the outside ambient air, particulate matter and moisture is prevented from entering vibration compartment  30 .  
         [0026]    It can be appreciated that the positions of heating element  32  and cooling element  34  may be varied. However, heating element  32  and cooling element  34  must communicate with the interior of environmental testing chamber  26 . Similarly, the positions of heating element  62  and cooling element  66  may be varied. However, heating element  62  and cooling element  66  must be in communication with the interior of vibration compartment  30 .  
         [0027]    Further, as described, controller  38  is represented as a single unit. However, it can be appreciated that multiple controllers may be utilized without deviating from the scope of the present invention.  
         [0028]    Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.