Abstract:
A sensing assembly protects a sensor and an electronic connector therefor from excess thermal energy. The sensing assembly includes a connector cover for housing the electronic connector. The connector cover includes a connector opening for accessing the electrical connector and a sensor opening for providing the sensor access to the electronic connector. The sensing assembly also includes a ceramic shield that covers the sensor extending out of the sensor opening. The ceramic shield protects the sensor and the electronic connector from excess thermal energy.

Description:
BACKGROUND ART  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates to a thermal shielding assembly. More particularly, the invention relates to a thermal shielding assembly for a sensor placed in a high temperature environment.  
         [0003]     2. Description of the Related Art  
         [0004]     Many mechanisms utilize multiple sensors to measure parameters thereof. These sensors may also measure parameters of the ambient conditions of the mechanism. The increased number of sensors is directly related to the increased technology in the manufacture of the sensors as well as the enhanced computing capability of control circuits that function to control the operations of the mechanisms that host the sensors.  
         [0005]     In the instance of a motor vehicle, many sensors are used to enhance the quality of the operation of the motor vehicle. The sensors are available in analog and digital format. The sensors translate the mechanical motions into electrical signals that are received and interpreted by a control circuit, e.g., an engine control unit, so that the control circuit may adjust certain parameters to maximize or optimize the output of the motor vehicle.  
         [0006]     In many instances, the mechanical motion of a ferromagnetic target wheel converts the rotational movement thereof into an electrical signal to identify speed and angular position of a particular component of the motor vehicle.  
         [0007]     One such component of the motor vehicle is the wheel and/or tire. Placing a sensor near the wheel provides excellent data to be utilized by the engine control unit. A major problem with placing a sensor at a location to measure the rotation of the wheel is that the environment is extremely hostile. More specifically, a sensor will experience a great deal of vibration. In addition, the sensor placed near the wheel will experience extreme temperature shifts. The increase in temperature is due to the friction between the tire and the road on which the motor vehicle is traveling. Friction is also generated by the application of a brake to stop the motor vehicle. In the instance when the brake is being applied, the temperature in the wheel becomes extremely high in a very short period of time. Therefore, thermal protection must be provided to prevent the sensor from failing prematurely.  
       SUMMARY OF THE INVENTION  
       [0008]     A sensing assembly protects a sensor and an electronic connector therefor from excess thermal energy. The sensing assembly includes a connector cover for housing the electronic connector. The connector cover includes a connector opening for accessing the electrical connector and a sensor opening for providing the sensor access to the electronic connector. The thermal shielding assembly also includes a ceramic shield that covers the sensor extending out of the sensor opening. The ceramic shield protects the sensor and the electronic connector from excess thermal energy. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     Advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:  
         [0010]      FIG. 1  is a perspective view of a wheel of a motor vehicle including one embodiment of the invention; and  
         [0011]      FIG. 2  is a side view of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0012]     Referring to  FIG. 1 , a motor vehicle  10  is shown partially cut away. The motor vehicle includes a wheel  12  having a tire  14  mounted thereto. It should be appreciated by those skilled in the art that a motor vehicle  10  may have any number of wheels  12  and tires  14  and only one is shown in the Figures for clarity purposes. The wheel  12  is rotated when a force generated by the internal combustion engine of the motor vehicle  10  is transferred to one or more of the wheels  12 . The motor vehicle  10  is stopped by activating the brakes disposed adjacent each of the wheels  12 . It is the activation of the brakes that creates the extreme spikes of temperature at locations surrounding the wheel  12 .  
         [0013]     A sensing assembly is generally indicated at  20 . The sensing assembly  20  is designed to place a sensor  16  adjacent the wheel  12 . The sensor  16  is capable of generating a sensing signal that is used by an engine control unit (not shown) to calculate the speed and angular displacement of the wheel  12 . The sensor  16  is connected to the engine control unit through an electronic connector  18 . The sensor  16  and electronic connector  18  may be well known in the art. Portions of the sensing assembly  20  are designed to protect the sensor  16  and the electrical connector  18  from excess thermal energy generated by the operation of the wheel  12 .  
         [0014]     When a temperature gradient exists in a body, experience has shown that there is an energy transfer from the high-temperature region to the low temperature region. The energy is transferred by conduction and the heat-transfer rate per unit area is proportional to the normal temperature gradient, as is indicated by the following formula: 
 
q/A≈δT/δx 
 
         [0015]     When the proportionality constant is inserted, 
 
 q=−kAδT/δx=−kA ( T 2 −T 1)/ X  
        where q is the heat transfer rate and δT/δx is the temperature gradient in the direction of the heat flow. The positive constant k is called the thermal conductivity of the material, and the minus sign is inserted so the second principle of thermodynamic will be satisfied.        
 
         [0017]     Then, using two materials, Nylon 6/6, 33% glass filled, and Ceramic Aluminate, a comparison of the temperature drop of Nylon polymer 66, 33% glass filled, versus a ceramic aluminate is made with identical thickness, the thermal conductivity comparison is as follows: 
        Nylon 6/6 33 GF: k=0.25 w/m ° C.; and     Ceramic Aluminite: k=70.79 w/m ° C.        
 
         [0020]     Therefore, the plastic offers less resistant to transmit the heat compared with the ceramic material, so the insulation sleeve will reduce the inside temperature of the embodiment.  
         [0021]     The sensing assembly  20  includes a connector cover  22 . The connector cover  22  houses the electrical connector  18 . The connector cover  22  includes a connector opening  24  that provides access for the electrical connector  18 . The connector opening  24  is adapted to receive a plug-style electrical connection to positively connect the electronic connector  18  to the engine control unit. The connector cover  22  includes a tab  26  extending out from the connector cover  22  that is received by an aperture or a snap in the plug-style connector to lock the plug-style connector to the electronic connector  18 .  
         [0022]     The connector cover  22  also includes the sensor opening  28  that provides the sensor  16  access to the electronic connector  18 . In the embodiment shown in the Figures, the sensor opening  28  and the connector opening  24  are generally perpendicular to each other. It should be appreciated by those skilled in the art that the orientation of the sensor opening  28  with respect to the connector opening  24  may vary without deviating from the scope of the invention.  
         [0023]     The connector cover  22  also includes a connection ring  30  that extends around the connector cover  22 . The connector ring  30  provides a connection abutment surface  32  that faces the majority of the connector cover  22 . The connector cover  22  also includes a fastener ring  34  that extends around the connector cover  22 . The fastener ring  34  provides a fastener abutment surface  36  that faces and complements the connection abutment surface  32 . More specifically, a fastener designed to hold the sensing assembly  20  in place with respect to the wheel  12  (not shown) would be held in place between the connection  32  and fastener  36  abutment surfaces. The sensing assembly  20  is held in place by preventing the connector cover  22  from moving with respect to the fastener by mounting the fastener between the connection abutment surface  32  and the fastener abutment surface  36 . Together, the fastener ring  34  and the connection ring  30  form a fastener channel  38  that receives the fastener therein.  
         [0024]     The connector cover  22  defines a sensor opening  28 . The sensor opening  28  is disposed adjacent a port to which the sensor  16  is connected to the electronic connector  18 . The sensor opening  28  defines a flange  42  that extends inwardly toward the center of the sensor opening  28 . The flange  42  will be discussed in greater detail subsequently.  
         [0025]     The sensing assembly  20  also includes a thermal shielding assembly, generally shown at  43 . The thermal shielding assembly  43  includes ceramic shield  44  that is received by the sensor opening  28  and secured to the connector cover  22 . The ceramic shield  44  extends around the entire sensor  16  and is designed to prevent the sensor  16  from absorbing thermal energy generated by the wheel  12 . The ceramic shield  44  includes a shield port  46  that receives the sensor  16  therethrough. The shield port  46  is an opening that communicates with the sensor opening  28 . The ceramic shield  44  also includes an outer wall  48 . In the embodiment shown, the ceramic shield  44  includes a single outer wall. It should be appreciated by those skilled in the art that there may be a plurality of outer walls  48 , depending on the design parameters of the sensor  16  being protected.  
         [0026]     A distal cover  50  extends over a distal end  52  of the outer wall  48 . The distal cover  50  prevents thermal energy from going around the outer wall  48 . Therefore, this ceramic shield  44  creates a closed environment to which there is no access to the sensor  16  without going through the ceramic shield  44 .  
         [0027]     The thermal shielding assembly  43  includes a fastener groove  54  that extends along the outer wall  48 . More specifically, the fastener groove  54  extends along the outer wall  48  at a location disposed adjacent the shield port  46 . The fastener groove  54  receives the flange  42  of the connector cover  22  therein. The flange  42  and fastener groove  54  work together to secure thermal shielding assembly  43  to the connector cover  22 .  
         [0028]     The ceramic shield  44  includes a seal groove  56  that extends along the outer wall  48  disposed adjacent the fastener grove  54 . The fastener groove  54  and the seal groove  56  are two grooves that extend peripherally around the outer wall  48 . In addition, the grooves  54 ,  56  are parallel to each other. The seal groove  56  receives an O-ring  58  that is fabricated from a suitable thermal set resin capable of withstanding the environment in which the thermal shielding assembly  43  is being placed while maintaining its pliability to prevent contaminants from entering the ceramic shield  44  and damaging the sensor  16 .  
         [0029]     The invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation.  
         [0030]     Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.