Abstract:
An apparatus and method for measuring and recording the torque applied to a bolt. The present invention utilizes a piezoelectric compound disposed between an upper member and a lower member. When the bolt is tightened, the piezoelectric compound is physically distorted and a net electrical potential is created across the piezoelectric compound. A processor in the bolt measures the electrical potential and calculates the torque based on the potential. The bolt then transmits a data packet comprising the torque value and bolt information to a wrench, which later transmits the data packet to a computer and a database. Alternatively, the bolt can be configured with a transmitter so that the data packet can be transmitted directly from the bolt to the computer and database. The bolt can also be configured with energizing circuitry that acts as a power source for the bolt.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Technical Field  
           [0002]    The present invention relates to an apparatus and method of measuring and recording the amount of torque applied to a specific bolt.  
           [0003]    2. Description of Related Art  
           [0004]    Apparatuses and methods of measuring the amount of torque applied to a bolt are well known in the art. FIG. 1 is an example of a typical torque wrench that measures the amount of torque applied to a bolt. However, tools like the torque wrench illustrated in FIG. 1 are not always precise in the exact measurement of torque applied the bolt. Moreover, these types of torque wrenches are not able to record the amount of torque applied to an individual bolt.  
           [0005]    In the many industries, a heightened standard exists for all facets of construction, assembly, and maintenance. This is especially true in the aircraft industry. In aircraft construction, assembly, and maintenance, it is desirable to measure and catalog the amount of torque applied to every single bolt in the aircraft. These torque values can then be reported to the Federal Aviation Administration and the owner of the aircraft. Current methods of measuring and recording the torque values involve measuring the torque with a torque wrench, like the one illustrated in FIG. 1, and recording the torque value in a database. Unfortunately, this method presents a large opportunity for erroneous measurement and recordation when a multiplicity of bolts are involved.  
           [0006]    Piezoelectric compounds are also well known in the art. FIG. 2A is an illustration of a piezoelectric crystal, such as quartz. Piezoelectric compounds physically deform when exposed to an electrical signal or field. Conversely, piezoelectric compounds also polarize and generate an electrical potential when an external force is applied to them. FIG. 2B is an illustration of the polarization of an individual piezoelectric crystal under an external pressure. The polarization of a plurality of crystals generates a net electrical potential across the entire piezoelectric compound. In fact, piezoelectric compounds exhibit this phenomenon so predictably and precisely that piezoelectric compounds can be used for very accurate pressure measurements. Piezoelectric compounds are preferable to other types of pressure measurement devices because they do not distort or otherwise deteriorate when repeatedly expanded and contracted. Because torque and pressure are directly related in a threaded apparatus like a bolt, the resulting electrical potential of a piezoelectric compound can be used to precisely measure the applied torque.  
           [0007]    Consequently, a need exists for an apparatus and method for measuring and recording the torque applied to a bolt without the need to physically record the measurement from a torque wrench. Furthermore, a need exists for an apparatus and method that measures the torque applied to a bolt using a piezoelectric compound. Moreover, a need exists for an apparatus and method for recording the amount of torque applied to a specific bolt.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention, which meets the needs identified above, comprises a bolt that measures the torque applied to it. The bolt comprises an upper member and a lower member that surround a piezoelectric layer. When the bolt is rotated, the upper member is pulled toward the threaded receptacle and the lower member is held in place by a surface. The piezoelectric compound between the upper member and the lower member is physically distorted, producing a net electrical potential across the compound.  
           [0009]    The bolt also comprises a processor that measures the net potential across the piezoelectric compound and uses that value to calculate the torque applied to the bolt. The processor is coupled to a memory that stores information regarding the bolt. When a wrench is used to tighten the bolt, an external connection on the bolt mates up with a similar connection on the socket. The processor in the bolt then transmits a data packet comprising the torque value and the bolt information to the wrench. The wrench can then be stored in a housing that is electrically coupled to a computer and a database. The housing collects the data packets from the wrench and transmits the data packets to the computer and database.  
           [0010]    Alternatively, the bolt can comprise an RF transmitter. The RF transmitter transmits the data packet either to the wrench or directly to the computer and database. Further in the alternative, the bolt can comprise circuitry that is energized by a signal transmitted at a specific frequency. The energized circuitry allows the bolt to transmit the data packet to an external receiver without the need for a power source.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:  
         [0012]    [0012]FIG. 1 is a perspective illustration of a torque wrench;  
         [0013]    [0013]FIG. 2A is a cross-section in elevation of a piezoelectric crystal;  
         [0014]    [0014]FIG. 2B is a cross-section in elevation of a physically distorted piezoelectric crystal;  
         [0015]    [0015]FIG. 3 is a perspective view of the bolt of the present invention;  
         [0016]    [0016]FIG. 4 is a cross-section in elevation of the bolt of the present invention;  
         [0017]    [0017]FIG. 5 is an illustration of the data packet of the present invention;  
         [0018]    [0018]FIG. 6 is a cross-section in elevation of the bolt and wrench of the present invention;  
         [0019]    [0019]FIG. 7 is a perspective view of the present invention;  
         [0020]    [0020]FIG. 8 is a cross-section in elevation of an alternative embodiment of the bolt of the present invention;  
         [0021]    [0021]FIG. 9 is a cross-section in elevation of an alternative embodiment of the bolt of the present invention; and  
         [0022]    [0022]FIG. 10 is a perspective view of an alternative embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    [0023]FIG. 3 is a perspective view of the bolt  30  of the present invention. Identical reference numerals will be used to identify identical elements throughout all of the drawings, unless otherwise indicated. The bolt  30  comprises an upper member  42 , a lower member  34 , a threaded shank  36 , and three external electrical connections  38 . The upper member  42  and the lower member  34  are hexagonally shaped and sized according to standardized metric or SAE bolt sizes. Alternatively, the bolt  30  can be square, rectangular, pentagonal, octagonal, shaped to accept an allen or torx wrench, or any other shape as determined by persons skilled in the art. The electrical connections  38  are located on three non-adjacent sides of the hexagonal bolt  30 . The electrical connections  38  are linked together so that the internal components of the bolt  30  may communicate with external devices through any one of the three electrical connections  38 .  
         [0024]    [0024]FIG. 4 is a cross-section in elevation of the bolt  30  of the present invention. The internal components of the bolt  30  comprise a piezoelectric compound  32 , a processor  40 , and a memory  33 . The processor  40  is electrically coupled to two opposite sides of the piezoelectric compound  32 . The processor  40  can measure the electric potential across the piezoelectric compound  32  either from top to bottom or from inside to outside, depending on the nature and properties of the specific piezoelectric compound  32 . The processor  40  is also electrically coupled to the electrical connection  38  so that the processor  40  can communicate with external devices. The processor  40  is also electrically coupled to the memory  33 . The memory  33  is a non-volatile memory that stores data comprising at least the torque applied to the bolt  30 . In the preferred embodiment, the memory  33  stores information pertaining to the bolt and the torque applied to the bolt  30 .  
         [0025]    When the threaded shank  36  is inserted into a threaded connection (not shown) and the bolt  30  is rotated, the lower member  34  will eventually contact a surface (not shown). Continued rotation of the bolt  30  will continue to lower the upper member  42  while the lower member  34  either rotates without lowering or remains still. In either case, the upper member  42  will compress the piezoelectric compound  32  against the lower member  34 . The upper member  42  and the lower member  34  may be configured so that there is room for the piezoelectric compound  32  to physically distort between upper member  42  and lower member  34 . The compression of the piezoelectric compound  32  produces an electrical potential within the crystalline structure of the piezoelectric compound  32 , which is measured by the processor  40 . The processor  40  uses the electrical potential to calculate the torque applied to the bolt  30  and stores this value in the memory  33 . Alternatively, the bolt  30  can communicate with the value of the electric potential to an external device that calculates the torque value  66 . The memory  33  can also store information about the bolt  30 . Examples of bolt information  64  that memory  33  can store are the bolt serial number, the size and shape of the bolt head, the size and pitch of the threaded shank  36 , the location of the bolt  30  on the assembled structure, and a detailed list of the parts that the bolt  30  connects (i.e. the bolt  30  connects piece X to piece Y). Persons skilled in the art will be aware of other types of bolt information  64  that can be stored in memory  33 . The value of the torque value  66  and the bolt information  64  are stored in a data packet  44  in the memory  33 . FIG. 5 is depiction of the data packet  44  comprising the bolt information  64  and the torque value  66 . The data packet  44  may then be transmitted to an external device, such as a wrench, sensor, or receiver, via electrical connection  38 . Bolt  30  may receive power from an external device or the electrical potential of the piezoelectric compound  32  may be sufficient to enable processor  40  to transmit the data packet  44  to an external device without the need for a power source.  
         [0026]    [0026]FIG. 6 is a cross-section in elevation of the bolt  30  and the wrench  46  of the present invention. The wrench  46  is connected to a socket  48 , which has a cavity shaped to accept the head of the bolt  30 . The cavity walls of the socket  48  have an electrical connection  39  that electrically couples with electrical connection  38  on bolt  30  whenever the socket  48  is placed onto the bolt  30 . In the preferred embodiment, the socket cavity is hexagonally shaped and has electrical connections  39  on two adjacent walls. In this configuration, when the socket  48  receives a bolt  30  configured with electrical connections  38  on three non-adjacent sides, one of the electrical connections  39  on the socket  48  will electrically couple with one of the electrical connects  38  on the bolt  30  regardless of the orientation of the connection (i.e. any one of the six ways a hexagonal socket cavity can fit onto a hexagonal bolt head) between the socket  48  and the bolt  30 .  
         [0027]    The wrench  46  comprises a processor  50 , a memory  52 , an optional power source  54 , and an electrical connection  56 . The processor  50  in the wrench  46  communicates with the processor  40  in the bolt  30  whenever the socket  48  is placed on the bolt  30 . The processor  40  in the bolt  30  transmits the data packet  44  to the processor  50  in the wrench  46  whenever the two processors communicate. The processor  50  in the wrench  46  stores the data packet  44  in the memory  52 . If necessary, the power source  54  can be utilized to provide power to the internal components of the wrench  46  (at least the processor  50  and the memory  52 ) and the internal components in the bolt  30  (at least the processor  40  and the memory  33 ).  
         [0028]    After the wrench  46  has received the data packet  44  from the bolt  30 , the wrench  46  can be stored in a housing  58 . FIG. 7 is a perspective view of a plurality of wrenches  46  stored in a housing  58 . The housing  58  recharges the power sources  54  in the wrenches  46 . The housing  58  also contains electrical connections (not shown) that mate up to the electrical connections  56  at the end of the wrenches  46 . The electrical connections in the housing  58  are electrically coupled to a computer  60  containing a database  62 . The processor  50  in the wrench  46  transmits the data packet  44  to the computer  60 , which stores the data packet  44  in the database  62 . The database  62  can store a multiplicity of data packets  44  such that the computer  60  can access the record of the data packets  44  and generate a report regarding the torque value  66  applied every bolt  30  (identified by the bolt information  64 ) in an assembled product.  
         [0029]    In some applications, it may be desirable for the bolt  30  to transmit the data packet  44  directly to the computer  60 , bypassing the transmission step to the wrench  46 . In this instance, a bolt  70  with a Radio Frequency (RF) transmitter/receiver  68  can be utilized, as seen in FIG. 8. FIG. 8 is a cross-section of the bolt  70  similar to the bolt  30 , but further comprising the RF transmitter/receiver  68 . Transmitter/receiver  68  can transmit and/or receive communications to an external device. When the socket  48  in FIG. 6 is placed onto the bolt  70  in FIG. 8, the power source  54  inside the wrench  46  provides power to the internal circuitry of the bolt  70  so that the processor  40  may transmit the data packet  44  to an external receiver (not shown). In this manner, the data packet  44  is transmitted to the computer  60  and the database  62  without the delay inherent in the process described in conjunction with FIGS. 4 through 7.  
         [0030]    Alternatively, the electrical potential of the piezoelectric compound  32  may be sufficient to enable processor  40  to transmit the data packet  44  to an external device without the need for the power source  54 . Further in the alternative, a signal may be transmitted from an external device to the bolt  70  requesting an update on the torque value  66  of the bolt  70 . The signal from the external device is received by the RF transmitter/receiver  68 , informing the processor  40  to measure the electric potential of the piezoelectric compound  32 , calculate the torque, and transmit the data packet  44  back to the external device. In this manner, the external device can communicate with the bolts  70  of an assembled product and determine which bolts  70  are not torqued to specification. The external receiver can then notify an operator to correct the torque of the specific bolt  70 .  
         [0031]    Even further in the alternative, the processor  40  can monitor the piezoelectric compound  32  and transmit the data packet  44  to the external device whenever the torque value  66  changes to a value outside of a specified value. In this manner, the bolts  70  notify the external device whenever their torque values  66  fall outside of the allowable torque value.  
         [0032]    In some applications, it may be desirable to power the bolt  70  without an external power source  54 . In this case, an energizing circuitry  72  can be utilized to power the bolt  70 . Energizing circuitry  72  is well known in the art as evidenced by products like the AT5100 TOLLTAG™ manufactured by the AMTECH® Corporation of Dallas, Tex. FIG. 9 is a cross-section in elevation of a bolt  74  utilizing energizing circuitry  72 . The bolt  74  is similar to the bolt  70 , but further comprises energizing circuitry  72 . FIG. 10 is a perspective view of transmitter/receiver  76  energizing and communicating with the bolt  74 . Although bolt  74  still contains an electrical connection  38  for backup power and/or communication, bolt  74  is useful because electrical connection  38  is not required to transmit data packet  44  from the bolt  74  to the database  62  via transmitter/receiver  76 . In this manner, whenever the torque value  66  of the bolt  74  is desired, transmitter/receiver  76  can energize the bolt  74  and the bolt  74  will transmit the data packet  44  containing the updated torque value  66  and the bolt information  64  to the transmitter/receiver  76 . By performing this operation on a multiplicity of bolts  74  on an entire aircraft, the computer  60  can determine whether the bolts  74  are torqued within specification with greater accuracy and in a fraction of the time required to check the bolts  74  by hand.  
         [0033]    It should be understood that while the present invention is described in conjunction with bolts, the present invention is operable with other types of securement devices. For example, the present invention can be utilized with screws, rivets, nails, and the like. Furthermore, the present invention is not limited solely to securement devices. The present invention is useful in any application where a low-cost pressure or torque measuring apparatus is required.  
         [0034]    The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention, the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.