Patent Abstract:
A sensor including a sensor core is disclosed. The sensor core includes a magnet, a pole piece, a bobbin, at least two terminals coupled to the bobbin, and a conductor wound about the bobbin and coupled to the terminals. At least a portion of the windings are disposed about at least a portion of the pole piece. The magnet is disposed substantially adjacent the pole piece. A support contacts at least a portion of the conductor. A supported portion of the conductor is located between the windings and the terminals. A sensor housing surrounds at least a portion of the sensor core. A method of manufacturing a sensor including providing a sensor core including a magnet, a pole piece, a bobbin, at least two terminals, and a conductor which is wound about the bobbin and coupled to the terminals is further disclosed. At least a portion of the windings surround at least a portion of the pole piece. The magnet is disposed substantially adjacent the pole piece. The method further includes adding support for a portion of conductor located in a region between windings, introducing the sensor core into a housing, and forming a seal between the sensor core and the housing. A manufacturing method including providing a magnetic circuit including a wire, the wire having a wound portion, a first portion conductively coupled to a first terminal, and second portion conductively coupled to a second terminal, the first terminal and the second terminal conductively coupled to a third terminal and a fourth terminal is also disclosed. The method further includes reinforcing a section of the wire located in a position between the wound portion and at least one of the first terminal and the second terminal, surrounding the magnetic circuit with a protective shell, and providing a seal effective to substantially seal the magnetic circuit within the shell.

Full Description:
CROSS REFERENCE  
       [0001]     This application is a continuation in part and claims the benefit of U.S. patent application Ser. Nos. 11/343,959, filed on Jan. 31, 2006, entitled “TRANSMISSION SENSOR WITH OVERMOLDING AND METHOD OF MANUFACTURING THE SAME,” and 11/358,603, filed on Feb. 21, 2006, entitled “TRANSMISSION SENSOR WITH OVERMOLDING AND METHOD OF MANUFACTURING THE SAME,” and those applications are hereby incorporated by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     The technical field relates to sensors for use in an automatic transmission of a motor vehicle, for example, and in particular, but not exclusively, to threaded transmission sensors for measuring the rotational speed of an input shaft or an output shaft.  
       BACKGROUND  
       [0003]     With the advance of improved controls for automatic transmission operation, the use of various electrical actuators and sensors has expanded greatly. Therefore, automotive electrical components such as transmission speed sensors have become high volume components within the automotive industry. Because such parts may experience failure within the operating life of the automobile, many of these components are offered through the aftermarket industry. Failure rates are generally affected by the type of part and the design. For example, the electromagnetic phenomenon of variable reluctance is commonly utilized in speed sensors. Typically, in such a sensor, a permanent magnet coupled with a wound coil is located in close proximity to a ferrous rotating member with teeth. As the magnetic field couples and decouples with each tooth on the member, an electrical signal is generated that varies in frequency depending on the angular speed of the member. Generally, this signal is remotely processed by a controller along with other inputs such as engine load, for controlling shifting of the transmission. U.S. Pat. No. 4,586,401 describes one example of such an automatic transmission control scheme. Variable reluctance sensors are often used in these applications because of the reliability of the signal that they output (i.e., low signal noise). However, such transmission sensors, including threaded speed sensors, may become inoperative because of various failure modes. This can occur even prior to damage or decay to the external covering of the sensor. The present invention addresses these and other problems associated with prior art sensors.  
         [0004]     One example of such a sensor is the output speed sensor (P/N 0400879) used in several Chrysler transmissions including the A604. This prior art sensor  39  is shown in an exploded view in  FIG. 35 . Sensor  39  includes shell  40  having threads  41 , stopping flange  42 , and tip  46 . Sensor  39  further includes bobbin assembly  50  having magnet  54 , pole piece  53 , wound copper wire  52 , bobbin  51 , and pins  55 . Sensor  39  is assembled as follows. Shell  40  is independently formed as a single piece using injection molding. Wire  52  is wound on bobbin  51  and the ends of wire  52  are soldered to pins  55 . Pole piece  53  is inserted into the bobbin assembly  50  and magnet  54  is placed at the end of pole piece  53 . Bobbin assembly  50  is then advanced into shell  40  in the direction indicated by arrow I so that magnet  54  pole piece  53 , wire  42  and pins  55  are positioned inside a cylindrical cavity formed inside shell  40 . Assembly is completed by bending a holding flange over the inserted bobbin assembly. Bending of the holding flange may be accomplished by using heat and pressure to bend the thin holding flange without breaking the plastic. The heat can be applied using convection, conduction or ultrasound. A similar prior art sensor is the input speed sensor (P/N 0400878) also used in several Chrysler transmissions including the A604.  
         [0005]     With reference to  FIG. 36  there is shown a top view of shell  40 . Identical reference numerals are used to indicate portions of shell  40  described above. Additionally, there is shown cylindrical cavity  43  including side surface  44  and tip cavity  45 . As described above, bobbin assembly  50  is advanced into cavity  43  during assembly of sensor  39 . In the assembled state, magnet  54  and an end portion of pole piece  53  are positioned in tip cavity  45 , and the rest of pole piece  53 , wire  52 , pins  55  and a portion of bobbin  51  are positioned in cavity  43 .  
       SUMMARY  
       [0006]     One embodiment according to the present invention includes a sensor including a sensor core. The sensor core includes a magnet, a pole piece, a bobbin, at least two terminals coupled to the bobbin, and a conductor wound about the bobbin and coupled to the terminals. At least a portion of the windings are disposed about at least a portion of the pole piece. The magnet is disposed substantially adjacent the pole piece. A support contacts at least a portion of the conductor. A supported portion of the conductor is located between the windings and the terminals. A sensor housing surrounds at least a portion of the sensor core.  
         [0007]     Another embodiment according to the present invention includes a method of manufacturing a sensor including providing a sensor core including a magnet, a pole piece, a bobbin, at least two terminals, and a conductor which is wound about the bobbin and coupled to the terminals. At least a portion of the windings surround at least a portion of the pole piece. The magnet is disposed substantially adjacent the pole piece. The method further includes adding support for a portion of conductor located in a region between windings and at least one of the terminals, introducing the sensor core into a housing, and forming a seal between the sensor core and the housing.  
         [0008]     A further embodiment according to the present invention includes a manufacturing method including providing a magnetic circuit including a wire, the wire having a wound portion, a first portion conductively coupled to a first terminal, and second portion conductively coupled to a second terminal, the first terminal and the second terminal conductively coupled to a third terminal and a fourth terminal. The method further includes reinforcing a section of the wire located in a position between the wound portion and at least one of the first terminal and the second terminal, surrounding the magnetic circuit with a protective shell, and providing a seal effective to substantially seal the magnetic circuit within the shell.  
         [0009]     Additional embodiments, aspects, objects, and advantages of the present invention will be apparent from the following description and claims.  
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0010]      FIG. 1  is a side view of an embodiment of an output sensor of the present invention.  
         [0011]      FIG. 2  is an enlarged detail view of Section  2  of  FIG. 1 .  
         [0012]      FIG. 3  is a side view of the embodiment of  FIG. 1  rotated 90°.  
         [0013]      FIG. 4  is a top view of the embodiment of  FIG. 3 .  
         [0014]      FIG. 5  is an enlarged detail view of Section  5  of  FIG. 3 .  
         [0015]      FIG. 6  is an enlarged detail view of Section  6  of the embodiment of  FIG. 3 .  
         [0016]      FIG. 7  is a top view of the embodiment of  FIG. 6 .  
         [0017]      FIG. 8  is a cross-sectional view of the embodiment of  FIG. 1  along the lines  8 - 8 .  
         [0018]      FIG. 9  is an enlarged detail view of Section  9  of  FIG. 8 .  
         [0019]      FIG. 10  is a rotated perspective view of the embodiment of the invention illustrated in  FIG. 1 .  
         [0020]      FIG. 11  illustrates a side view of a embodiment of an input sensor of the present invention.  
         [0021]      FIG. 12  is an enlarged detail view of Section  12  of  FIG. 11 .  
         [0022]      FIG. 13  is a side view of the embodiment of  FIG. 11  rotated 90°.  
         [0023]      FIG. 14  is a top view of the embodiment of  FIG. 13 .  
         [0024]      FIG. 15  is an enlarged detail view of Section  15  of  FIG. 13 .  
         [0025]      FIG. 16  is an enlarged detail view of Section  16  of the embodiment of  FIG. 13 .  
         [0026]      FIG. 17  is a top view of the embodiment of  FIG. 16 .  
         [0027]      FIG. 18  is a cross-sectional view of the embodiment of  FIG. 11  along the lines  18 - 18 .  
         [0028]      FIG. 19  is an enlarged detail view of Section  19  of  FIG. 18 .  
         [0029]      FIG. 20  is a rotated perspective view of the embodiment of the invention illustrated in  FIG. 11 .  
         [0030]      FIG. 21  is a side view of one embodiment of a locating cap of the present invention.  
         [0031]      FIG. 22  is a top view of the embodiment of  FIG. 21 .  
         [0032]      FIG. 23  is a cross-sectional view of the embodiment of  FIG. 21  along the lines  23 - 23 .  
         [0033]      FIG. 24  is an elevated side perspective view of the embodiment of  FIG. 21 .  
         [0034]      FIG. 25  is another elevated side perspective view of the embodiment of  FIG. 21 .  
         [0035]      FIG. 26  is a top view of another embodiment of a locating cap of the present invention.  
         [0036]      FIG. 27  is a cross-sectional view of the embodiment of  FIG. 26  along the lines  27 - 27 .  
         [0037]      FIG. 28  is an enlarged detail view of Section  28  of the embodiment of  FIG. 27 .  
         [0038]      FIG. 29  is a side view of the embodiment of  FIG. 26 .  
         [0039]      FIG. 30  is an elevated side perspective view of the embodiment of  FIG. 26 .  
         [0040]      FIG. 31  is a side view of one embodiment of the locator plug for holding the sensor in the mold.  
         [0041]      FIG. 32  is the side view of the embodiment of  FIG. 31  with added detail concerning various dimensions of this embodiment of the locator plug.  
         [0042]      FIG. 33  is an enlarged end view of the embodiment of  FIG. 32 .  
         [0043]      FIG. 34  is a flow diagram according to an embodiment of the present invention.  
         [0044]      FIG. 35  is an exploded view of a prior art sensor.  
         [0045]      FIG. 36  is a top view of the shell of the sensor of  FIG. 36 .  
         [0046]      FIG. 37  is a side sectional view of a sensor according to one embodiment of the present invention.  
         [0047]      FIG. 38  is an exploded side sectional view of a sensor according to one embodiment of the present invention.  
         [0048]      FIG. 39  is a side sectional view of a sensor according to one embodiment of the present invention showing the addition of resin.  
         [0049]      FIG. 40  is a side sectional view of a sensor according to one embodiment of the present invention showing the addition of resin.  
         [0050]      FIG. 41  is a side view of a portion of a sensor according to one embodiment of the present invention.  
         [0051]      FIG. 42  is a side view of a portion of a sensor according to one embodiment of the present invention.  
         [0052]      FIG. 43  is a side view of a portion of a sensor according to one embodiment of the present invention.  
         [0053]      FIG. 44  is a flowchart according to one embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0054]     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.  
         [0055]     The inventor has determined that the design and assembly of sensors such as prior art sensor  39  contributes to a high failure rate in the field. The inventor has determined that approximately 90% of the failure rate is due to wire failure. In prior art sensors some or all of the wire is unsupported and exposed after insertion in to the shell cavity within the sensor. Heat, vibration and/or corrosion can lead to fatigue failure of the wire. This creates an open circuit coil that will not generate a signal. Such a failure will create shifting problems in the transmission, as the controller has to default to open-loop control of the unit.  
         [0056]     With reference to  FIGS. 1-10  there are shown multiple views of an output transmission sensor according to a preferred embodiment of the present invention.  FIG. 1  shows output sensor  99  which is a threaded variable reluctance sensor for sensing the rotational speed of the output shaft of an automatic transmission. Output sensor  99  includes bobbin  120  and centering cap  140  which are partially encapsulated by overmolded resin shell  100 . Shell  100  includes threads  101 , stopping flange  102 , hexagonal section  103 , and top section  104 . Output sensor  99  also preferably includes O-ring  180 .  
         [0057]     Sensor  99  is preferably adapted to be installed in a threaded bore formed in the housing of an automatic transmission near a toothed ferrous rotating ring associated with the output shaft of an automatic transmission. Installation of Sensor  99  can be accomplished by advancing sensor  99  into the bore until threads  101  contact threads formed on the interior of the bore. A tool can then be used to engage hexagonal section  103  and rotate sensor  99  to cause threads  101  to engage the threads of the bore and advance sensor  99  into the bore. Sensor  99  is preferably rotated until a stopping flange  102  contacts the outside of the transmission housing and a seal is formed between sensor  99  and the housing by stopping flange  102  and O-ring  180 . Sensor  99  is then preferably torqued down to a particular force to prevent back out.  
         [0058]     With reference to  FIGS. 2-10  there are shown additional views of sensor  99 . Identical reference numerals are used to indicate aspects of sensor  99  described above. Additional aspects of sensor  99  are as follows.  FIG. 2  shows a detailed view of the portion of output sensor  99  indicated by arrows  2  in  FIG. 1 . A portion of the terminal connection end of bobbin  120  is shown in  FIG. 2  which includes fastener  121 . Fastener  121  is adapted to releasably engage a clip of a plug of an electrical cable that connects to terminal connection end of bobbin  120 .  
         [0059]      FIG. 3  shows sensor  99  with O-ring  180  removed and O-ring seat  181  visible.  FIG. 4  shows cavity  170  formed in the terminal connection end of sensor  99 . Terminals  171  and  172  are disposed within cavity  170  and are electrically interconnected to a wire wound around a portion of the bobbin  120  within sensor  99  as shown and described below in connection with  FIGS. 8 and 9 . During operation a plug of an electrical cable can be inserted into terminal cavity  170  to establish electrical connections with terminals  171  and  172 . In an alternative embodiment, instead of including terminals disposed within a cavity, sensor  99  includes lead wires extending from its end which lead to a plug connector remote from the body of bobbin  120 . These wires can be positioned outside a mold during the overmolding process used to form shell  100  which is described in greater detail below. Overmolded shell  100  can extend to and encapsulate the junction between the lead wires and bobbin  120 , or can extend along bobbin  120  to an area before the junction.  FIG. 5  shows an enlarged detailed view of the portion of sensor  99  indicated by arrow  5  in  FIG. 3 .  FIG. 6  shows an enlarged detailed view of the portion of sensor  99  indicated by arrow  6  in  FIG. 3 .  FIG. 7  shows a bottom view of sensor  99 .  
         [0060]      FIG. 8  shows a side sectional view of sensor  99 .  FIG. 8  shows wire  110  wound around bobbin  120 . One end portion of wire  110  extends from the windings and is electrically interconnected to pin terminal  141 , for example by soldering, and another end of wire  110  similarly extends from the windings and is electrically interconnected with pin terminal  142 . Pin terminals  141  and  142  are electrically interconnected with terminals  171  and  172  through a conductive pathway routed through bobbin  120 . As shown in  FIG. 8 , overmolded resin shell  100  contacts portions of bobbin  120 , wire  110  and portions of cap  140 . Shell  100  preferably contacts and supports wire  110  at its windings and further preferably contacts and supports portions of wire  110  extending between the windings around bobbin  120  and the pin terminals  141  and  142 .  FIG. 9  shows a detailed view of the portion of sensor  99  indicated by arrows  9  in  FIG. 8 . As shown in  FIG. 9 , sealing rings  160  are formed in cap  140  and overmolded resin shell  100  fills sealing rings  160 . Contact between shell  100  and cap  140  preferably forms a hermetic seal between the interior of sensor  99  and the exterior environment.  FIG. 10  shows a perspective view of sensor  99 .  
         [0061]     A preferred embodiment of sensor  99  according to the present invention can be manufactured according to dimensions and tolerances specified for use in connection with a variety of automatic transmissions from a variety of manufacturers including, for example, the dimensions of part number 0400879 which was mentioned above. These dimensions and tolerances are merely exemplary of one preferred embodiment, however, and sensors of a variety of different configurations, sizes, dimensions, and tolerances are contemplated as within the scope of the invention including, for example, dimensions and tolerances for sensors adapted for use in other automatic transmissions and those adapted for use in other applications and environments where it is desirable or useful to obtain information relating to the rotational speed of a toothed ring or other rotating structure.  
         [0062]     According to a preferred embodiment of the present invention, overmolded resin shell  100  is preferably formed from a resin material adapted for use in an injection molding system, most preferably of Zytel #70G43L NC010 resin which is a 43% glass filled, natural colored polyamide 6/6 grade nylon material available from DuPont corporation of Wilmington, Del. It is also contemplated that shell  100  could be formed from a variety of other materials, for example, other grades of Zytel with different glass contents, copolymers or colors, 4/6 grades of polyamide such as DSM Stanyl TW241F10 or others, other members of the polyamide family of resins including other 4/6 and 6/6 grades, other materials having similar properties, other plastics, thermoplastics, epoxy resins, and/or other materials suitable to maintain their integrity in an injection molding environment.  
         [0063]     According to a preferred embodiment of the present invention, wire  110  is preferably NEMA MW79-C which is a copper wire with polyurethane coating and is rated to 155 degrees Celsius. Wire  110  could also be a variety of other conductive materials including, for example, NEMA MW82C or 83C, or any other type of wire suitable for hermetic overmolding applications. A preferred embodiment according to the present invention includes 6200 turns or windings of wire  110  which gives a coil resistance of about 650 Ohms+/−about 10%. This number of windings and resistance are merely exemplary, however, and a variety of numbers of windings and resistances are contemplated as within the scope of the present invention.  
         [0064]     With reference to  FIGS. 11-20  there are illustrated multiple views of an input transmission sensor according to one embodiment of the present invention.  FIG. 11  shows input sensor  199  which is a threaded variable reluctance sensor for sensing the rotational speed of the input shaft of an automatic transmission. Input sensor  199  includes bobbin  220  and centering cap  240  which are hermetically encapsulated by overmolded resin shell  200 . Shell  200  includes threads  201 , stopping flange  202 , hexagonal section  203 , and top section  204 . Input sensor  199  also preferably includes O-ring  280 .  
         [0065]     Sensor  199  is preferably adapted to be installed in a threaded bore formed in the housing of an automatic transmission near a toothed ferrous rotating ring associated with the input shaft of an automatic transmission. Installation of sensor  199  can be accomplished by advancing sensor  199  into the bore until threads  201  contact threads formed on the interior of the bore. A tool can then be used to engage hexagonal section  203  and rotate sensor  199  to cause threads  201  to engage the threads of the bore and advance sensor  199  into the bore. Sensor  199  is preferably rotated until stopping flange  202  contacts the outside of the transmission housing and a seal is formed between sensor  199  and the housing by stopping flange  202  and O-ring  280 . Sensor  199  is preferably torqued down to a particular force to prevent back out.  
         [0066]     With reference to  FIGS. 12-20  there are shown additional views of sensor  199 . Identical reference numerals are used to indicate aspects of sensor  199  described above. Additional aspects of sensor  199  are as follows.  FIG. 12  shows a detailed view of the portion of input sensor  199  indicated by arrows  12  in  FIG. 11 . A portion of the terminal connection end of bobbin  220  is shown in  FIG. 12  which includes fastener  221 . Fastener  221  is adapted to releasably engage a clip of a plug of an electrical cable that connects to terminal connection end of bobbin  220 .  
         [0067]      FIG. 13  shows a side view of sensor  199  rotated 90 degrees.  FIG. 14  shows cavity  270  formed in the terminal connection end of sensor  199 . Terminals  271  and  272  are disposed within cavity  270  and are electrically interconnected to a wire wound around a portion of the bobbin  220  within sensor  199  as shown and described below in connection with  FIGS. 18 and 19 . During operation a plug of an electrical cable can be inserted into terminal cavity  270  to establish electrical connections with terminals  271  and  272 . In an alternative embodiment, instead of including terminals disposed within a cavity, sensor  199  includes lead wires extending from its end which lead to a plug connector remote from the body of bobbin  220 . These wires can be positioned outside a mold during the overmolding process used to form shell  200  which is described in greater detail below. Overmolded shell  200  can extend to and encapsulate the junction between the lead wires and bobbin  220 , or can extend along bobbin  220  to an area before the junction.  FIG. 15  shows an enlarged detailed view of the portion of sensor  199  indicated by arrow  15  in  FIG. 13 .  FIG. 15  shows a portion of sensor  199  with O-ring  280  removed and O-ring seat  281  visible:  FIG. 16  shows an enlarged detailed view of the portion of sensor  199  indicated by arrow  16  in  FIG. 13 .  FIG. 17  shows a bottom view of sensor  199 .  
         [0068]      FIG. 18  shows a side sectional view of sensor  199 .  FIG. 8  shows wire  210  wound around bobbin  220 . One end portion of wire  210  extends from the windings and is electrically interconnected to pin terminal  261 , for example by soldering, and another end of wire  210  similarly extends from the windings and is electrically interconnected with pin terminal  262 . Pin terminals  261  and  262  are electrically interconnected with terminals  271  and  272  through a conductive pathway routed through bobbin  220 . As shown in  FIG. 18 ,. overmolded resin shell  200  contacts portions of bobbin  220 , wire  210  and portions of cap  240 . Shell  200  preferably contacts and supports wire  210  at its windings and further preferably contacts and supports portions of wire  210  extending between the windings around bobbin  220  and the pin terminals  261  and  262 .  FIG. 19  shows a detailed view of the portion of sensor  199  indicated by arrows  19  in  FIG. 18 . As shown in  FIG. 19 , sealing rings  260  are formed in cap  240  and overmolded resin shell  200  fills sealing rings  260 . Contact between shell  200  and cap  240  preferably forms a hermetic seal between the interior of sensor  199  and the exterior environment.  FIG. 20  shows a perspective view of sensor  199 .  
         [0069]     A preferred embodiment of sensor  199  according to the present invention can be manufactured according to dimensions and tolerances specified for use in connection with a variety of automatic transmissions from a variety of manufacturers including, for example, the dimensions of part number 0400879 which was mentioned above. These dimensions and tolerances are merely exemplary of one preferred embodiment, however, and sensors of a variety of different configurations, sizes, dimensions, and tolerances are contemplated as within the scope of the invention including, for example, dimensions and tolerances for sensors adapted for use in other automatic transmissions and those adapted for use in other applications and environments where it is desirable or useful to obtain information relating to the rotational speed of a toothed ring or other rotating structure.  
         [0070]     According to a preferred embodiment of the present invention, overmolded resin shell  200  is preferably formed from a resin material adapted for use in an injection molding system, most preferably of Zytel #70G43L NC010 resin which is a 43% glass filled, natural colored polyamide 6/6 grade nylon material available from DuPont corporation of Wilmington, Del. It is also contemplated that shell  200  could be formed from a variety of other materials, for example, other grades of Zytel with different glass contents, copolymers or colors, 4/6 grades of polyamide such as DSM Stanyl TW241F10 or others, other members of the polyamide family of resins including other 4/6 and 6/6 grades, other materials having similar properties, other plastics, thermoplastics, epoxy resins, and/or other materials suitable to maintain their integrity in an injection molding environment.  
         [0071]     According to a preferred embodiment of the present invention, wire  210  is preferably NEMA MW79-C which is a copper wire with polyurethane coating and is rated to 155 degrees Celsius. Wire  110  could also be a variety of other conductive materials including, for example, NEMA MW82C or 83C, or any other type of wire suitable for hermetic overmolding applications. A preferred embodiment according to the present invention includes 6350 turns or windings of wire  210  which gives a coil resistance of about 760 Ohms+/−about 10%. This number of windings and resistance are merely exemplary, however, and a variety of numbers of windings and resistances are contemplated as within the scope of the present invention.  
         [0072]     With reference to  FIGS. 21-25  there are shown multiple views of centering cap  240  which is also illustrated and described above in connection with  FIGS. 11-20 . As shown in  FIGS. 21-25  cap  240  includes cap body  243 , cap flange  242 , sealing rings  260 , and cap cavity  241 . Cap cavity  241  receives magnet  250  and an end portion of pole piece  230 , as illustrated and described above. Cap body  243  has a generally hexagonal cross sectional shape and cap flange  242  and cap cavity  241  have generally circular cross sectional shapes for sections taken perpendicular to axis AA shown in  FIG. 23 .  
         [0073]     A preferred embodiment of cap  240  according to the present invention can be manufactured to dimensions and tolerances which allow magnet  250  and an end portion of pole piece  230  to fit snugly within cavity  241 . These dimensions and tolerances are merely exemplary of one preferred embodiment, however, and centering caps of a variety of different configurations, sizes, dimensions, and tolerances are contemplated as within the scope of the invention.  
         [0074]     With reference to  FIGS. 26-30  there are shown multiple views of centering cap  140  which is also illustrated and described above in connection with  FIGS. 1-10 . As shown in  FIGS. 26-30  cap  140  includes cap body  163 , cap flange  162 , sealing rings  160 , and cap cavity  161 . Cap cavity  161  receives magnet  150  and an end portion of pole piece  130 , as illustrated and described above. Cap body  163 , cap flange  162  and cap cavity  161  have generally circular cross sectional shapes for sections taken perpendicular to axis BB shown in  FIG. 27 .  
         [0075]     A preferred embodiment of cap  140  according to the present invention can be manufactured to dimensions and tolerances which allow magnet  150  and an end portion of pole piece  130  to fit snugly within cavity  161 . These dimensions and tolerances are merely exemplary of one preferred embodiment, however, and centering caps of a variety of different configurations, sizes, dimensions, and tolerances are contemplated as within the scope of the invention.  
         [0076]     Caps  140  and  240  are preferably formed from a resin material adapted for use in an injection molding system, most preferably of Zytel #70G43L NC010 resin which is a 43% glass filled, natural colored polyamide 6/6 grade nylon material available from DuPont corporation of Wilmington, Del. It is also contemplated that caps  140  and  240  could be formed from a variety of other materials, for example, other grades of Zytel with different glass contents, copolymers or colors, 4/6 grades of polyamide such as DSM Stanyl TW241F10 or others, other members of the polyamide family of resins including other 4/6 and 6/6 grades, other materials having similar properties, other plastics, thermoplastics, epoxy resins, and/or other materials suitable to maintain their integrity in an injection molding environment. In one embodiment according to the present invention, caps  140  and  240  are formed from a conductive thermoplastic material.  
         [0077]     With reference to  FIGS. 31-33  there are shown multiple views of locating plug  300  according to an embodiment of the present invention. Locating plug  300  includes tip portion  310 , middle portion  320  and body  330 . Tip portion and middle portion of locator plug  300  are preferably adapted to be inserted into and substantially or completely fill cavity  170  of sensor  99  or cavity  270  of sensor  199  which were described above, or to be inserted into and substantially or completely fill sensors cavities of a variety of other configurations, sizes, dimensions and tolerances. Plug  300  is preferably used in connection with the manufacturing of a sensor according to the present invention such as, for example, sensors  99  and  199  which are described above.  
         [0078]     With reference to  FIG. 34  there is shown flow diagram  500  according to a preferred embodiment of the present invention. Sensors according to the present invention, for example, sensors  99  and  199  described above and other sensors can be manufactured according to the manufacturing process of flow diagram  500 . For clarity flow diagram  500  is described using the reference numerals associated with sensor  99 , but similar or identical manufacturing operations could also be performed for sensor  199  and other sensors according to the present invention. At operation  510  centering cap  140  is formed as a single piece preferably using an injection molding technique and preferably using one or more materials described above in connection with  FIGS. 26-30 . It is contemplated however that cap  140  could be formed using a variety of other techniques, processes, and materials. From operation  510  flow diagram proceeds to operation  520 .  
         [0079]     At operation  520  wire  110  is wound around bobbin  120  and end portions of wire  110  are soldered to pin terminals  141  and  142 . Bobbin  140  could be formed by injection molding, other molding techniques, or using any other technique known to those of skill in the art. It is also contemplated that wire  110  and bobbin  120  could be provided as a preassembled unit. From operation  520  flow diagram proceeds to operation  530 .  
         [0080]     At operation  530 , pole piece  130  is inserted into bobbin  120  and magnet  150  is placed at the end of pole piece  130 . It is also contemplated that pole piece  130  and/or magnet  150  could be provided as part of a preassembled unit. From operation  530  flow diagram proceeds to operation  540 .  
         [0081]     At operation  540  centering cap  140  is placed over magnet  150  and an end portion of pole piece  130  so that its end surface contacts the end surface of bobbin  120 . It is also contemplated that centering cap  140  could be provided as part of a preassembled unit. Furthermore, it is contemplated that one or more of operations  510 ,  520 ,  530  and  540  could be performed as a single operation, could be performed in parallel, in series or a combinations of parallel and serial operations, or could be broken into sub-operations including additional separate steps. From operation  540 , flow diagram proceeds to operation  550 .  
         [0082]     At operation  550 , locating plug  300  is inserted into cavity  170  at the terminal end of bobbin  120  and substantially or completely fills cavity  170 , or fills a portion of cavity  170  and is effective to prevent resin from filling cavity  170  during injection molding and to support and maintain the position of the other components within a mold. From operation  550 , flow diagram  500  proceeds to operation  560 .  
         [0083]     At operation  560  the assembly including cap  140 , magnet  150 , pole piece  130 , bobbin  120  wire  110  and plug  300  is placed into a mold. The mold is preferably a book mold, and the assembly is placed into one half of the book mold and the other half of the book mold is closed over the assembly. The mold defines a cavity having the shape of overmolded resign shell  100 . Centering cap  140  and plug  300  support the assembly within the mold and maintain it in a position such that the assembly is spaced away from the interior surfaces of the mold. Thus, there is a void in the area between the inside surface of the mold and the outer region of the assembly. This void extends along the length of the assembly from before the sealing rings  160  of the locating cap  140  up to about the portion of bobbin  120  which is visible in  FIG. 1 . From operation  560 , flow diagram  500  proceeds to operation  570 .  
         [0084]     At operation  570 , molten resin is introduced into the mold under pressure and is forced to fill the void defined by any space not occupied by the assembly and/or plug. Introduction of molten resin is preferably accomplished using a rotary table rotating beneath an injection molding machine that injects the resin into the cavity of the book mold through various gates or ports formed in the book mold. From operation  570 , flow diagram  500  proceeds to operation  580 .  
         [0085]     At operation  580 , the molten resin cools within the sensor assembly with the overmolded resin shell is removed from the mold after an appropriate cooling period. From operation  580 , flow diagram proceeds to operation  590 .  
         [0086]     At operation  590  quality control procedures may be performed on the sensor. Additional post-mold procedures, such as addition of O-ring  180 , polishing, trimming or otherwise removing molding artifacts can also be performed.  
         [0087]     After operation  590 , the sensor is in a finished or substantially finished state. In the finished state resin shell  100  preferably hermetically encapsulates and supports all portions of the assembly not visible outside shell  100  as shown in  FIG. 1 . Seals are preferably formed between shell  100  and sealing rings  160  and between shell  100  and the bobbin sealing flanges located under top portion  104  as shown in  FIG. 8 . Thus, pole piece  130 , magnet  150 , wire  110 , pin terminals  141  and  142 , and portions of bobbin  120  are preferably hermetically encapsulated, contacted and supported by the overmolded resin shell  100 . Furthermore, overmolded resin shell  100  holds locating cap  140  in a position relative to the assembly as shown and described above in connection with  FIGS. 1-10 .  
         [0088]     A number of variations of the foregoing manufacturing process and devices are contemplated. For example, it is contemplated that two or more of the foregoing operations could be performed as a single operation, could be performed in parallel, in series or a combinations of parallel and serial operations, or that one or more of the foregoing operations could be broken into sub-operations including additional separate steps. It is also contemplated that one or more of the foregoing operations could be omitted, for example, operation  590  or other operations. It is further contemplated that additional operations could be interposed between the operations described above. Furthermore, it is contemplated that a centering cap could be omitted from the assembly that is introduced into the mold and the injected resin could form the structure of the assembly cap. According to this process overmolded resin shells  100  and  200  described above constitute the structure of caps  140  and  240 , respectively. This process reduces the number of parts of the assembly that is inserted into the mold. The absence of centering cap may result in undesired displacement of the magnet or other parts. Thus, it is contemplated that a thin sleeve could be used to hold the magnet in place relative to the pole piece during molding. It is also contemplated that a variety of molds and injection molding techniques could be utilized in addition to those discussed above. It is also contemplated that a thin sleeve or. ring with  2  or more tabs could be located on the tip of the sensor at  130  or  150 . These tabs would center the sensor within the mold, allowing the overmolded resin shells  100  and  200  to constitute the structure of the caps  140  and  240 , respectively, except in the areas where the tabs contact the mold.  
         [0089]     With reference to  FIG. 37  there is shown sensor  600  according to another embodiment of the present invention. Sensor  600  includes housing  610  which is formed, for example, using injection molding and/or other processes and techniques. Housing  610  includes a threaded portion  612  and tip portion  614  and could be a single piece or multiple coupled pieces. Housing  610 , and all other aspects of sensor  600 , could also include some or all of the features described above and those embodiments could likewise include some or all of the features described below.  
         [0090]     Sensor  600  also includes bobbin  620  including sections  628  and  269  which could be a unitary piece or compound or composite structures and could be formed, for example, using injection molding and/or other processes and techniques. Wire  630  is wound about section  628  and extends to and is coupled to terminals  634 A and  634 B, for example, with solder and/or other connector(s) or connection(s). Terminals  634 A and  634 B are electrically coupled to terminals  638  through conductive pathways in section  629 .  
         [0091]     Sensor  600  further includes pole piece  622 , which is inserted into a cavity or bore in bobbin  620 , and magnet  624  which, as illustrated, can be positioned adjacent pole piece  622  and at least partially within end portion  614 . Magnet and pole piece can also be in a variety of other shapes and configurations. During operation a current can be induced in wire  630  by virtue of a sensed element moving relative to magnet  624  as is the case in various variable reluctance sensors. It is also contemplated that other types of sensors could be used.  
         [0092]     Sensor  600  also includes a seal formed between housing  610  and bobbin  620 . As shown in  FIG. 37  the seal is formed by flange  635  extending into groove  631  of housing  610  and a sealing flange at the end of housing  635  being heat crimped into the illustrated position. A variety of other seals are also contemplated, including for example those formed by adding a sealant around the junction of housing  610  and bobbin  620 .  
         [0093]     With reference to  FIG. 38  there is shown an exploded view of sensor  600 . According to one preferred embodiment of the present invention sensor core  690  can be formed and assembled independent from housing  610 . Core  690  can be assembled in various steps, including, for example, those described herein, and can be preassembled or can be partially assembled. Once assembled, core  690  can be inserted into housing  610  and a seal can formed, for example, as described above.  
         [0094]     With reference to  FIG. 39  there is shown one example of the addition of resin to serve as a support structure for a portion of wire  632 A. Injector  695  can be positioned relative to the portion of wire  630  extending from the windings to terminal  634 A and can then introduce resin to form a support structure for a portion of wire  630 . Injector  695  can be held stationary during introduction, or can be moved during introduction of resin. Injector  695  can also be a variety of differently sized and shaped injectors. As illustrated in  FIG. 39 , introduction of resin and/or other support structures can occur prior to insertion of bobbin  620  into housing  610 .  
         [0095]     With reference to  FIG. 40  there is shown another example of the addition of resin to serve as a support structure for a portion of wire  632 A. Injector  696  can be positioned relative to the portion of wire  630  extending from the windings to terminal  634 A and can then introduce resin to form a support structure for a portion of wire  630 . Injector  695  can be held stationary during introduction, or can be moved during introduction of resin. Injector  696  can also be a variety of differently sized and shaped injectors. As illustrated in  FIG. 39 , introduction of support structure can occur after insertion of bobbin  620  into housing  610 . The hole in housing  610  created by injector  696  can be sealed with the resin itself or can be sealed with a separate material or sealant or heat sealed, for example.  
         [0096]     With reference to  FIGS. 41, 42  and  43  there are shown several examples of configurations of resin serving as support structure for a portion of wire  632 A. In  FIG. 41  resin  640 A extends to contact part of wire  632 A. In  FIG. 42  resin  640 A extends to encapsulate wire  632 A. In  FIG. 43  resin  640 A substantially fills a region extending between housing  610  and bobbin  620 . A variety configurations in addition to those illustrated in  FIGS. 41, 42  and  43  are also contemplated.  
         [0097]     In various embodiments according to the present invention support structure could include a variety or resins and thermosetting materials and other materials such as an adhesive thermoset, elastomer, epoxy, fluoropolymer, phenolic, polyester, silicone, vinyl ester or any combination of the aforementioned materials such as silicone adhesives, phenolic adhesives and other similar materials. These can be applied in a liquid, solid or semi-solid form such as a paste or foam. Examples of suitable materials include Aptek 2712-A/B adhesive, GE Silicones TSE392 Translucent Adhesive Sealant, GE Silicones RTV6136 Potting/Encapsulating Gel, Loctite® 5071 Silicone Encapsulant, Bayer MaterialScience Bayfit®, Cal Polymers ND3200 and Polyurethane Flexible Molded Foam. The above mentioned thermoplastic materials could include materials such as acrylonitrile-butadiene-styrene (ABS), acrylic, elastomers, fluoropolymers, nylons including 6/6 and 4/6, polyamides, polyimides, polyesters, polyetheretherketone (PEEK), polyethylene including low density (LDPE) and high density (HDPE), polypropylene, polystyrene, polysulfone, polyurethane and others. These can be applied in a molten form. Examples of suitable materials include Dupont Zytel #70G43L NC010 and DSM Stanyl TW241F10. The foregoing and additional materials, for example, numerous polymerized synthetics, chemically modified, or natural materials including cements, glues, plastics, putties, struts, tabs, other support structures and/or combinations of the foregoing are contemplated as examples of support structures according to the present invention.  
         [0098]     With reference to  FIG. 44  there is shown flow diagram  700  according to a preferred embodiment of the present invention. Flow diagram  700  begins at operation  710  where a sensor shell or housing is formed, for example by injection molding, or a preformed housing or shell is provided. From operation  710 , flow diagram  700  proceeds to operation  720 . At operation  720  a bobbin assembly is formed, for example, using injection molding, or a preformed bobbin assembly is provided. From operation  720 , flow diagram  700  proceeds to operation  730 . At operation  730  a wire is wound around a portion of the bobbin. From operation  730 , flow diagram  700  proceeds to operation  740 . At operation  740  the ends of the wire are electrically coupled to terminals of the bobbin, for example, by soldering. From operation  740 , flow diagram  700  proceeds to operation  750 . At operation  750 , a pole piece is introduced at least partially into the bobbin and a magnet is placed at one end of the pole piece. From operation  750 , flow diagram  700  proceeds to operation  760 . It will be appreciated that the foregoing operations could be performed in a variety of orders, or could have been previously performed to provide a pre-assembled bobbin assembly.  
         [0099]     At operation  760  a support structure, for example, one or more materials or structures described herein, such as a resin, is added to support a portion of wire. From operation  760 , flow diagram  700  proceeds to operation  770 . At operation  770  the resin can be cured, or subjected to thermal variation to cure or harden it. From operation  770 , flow diagram  700  proceeds to operation  780 . At operation  780  the bobbin assembly is introduced into a housing. From operation  780 , flow diagram  700  proceeds to operation  790 . At operation  790  a seal is formed between the housing and the inserted assembly. This can be accomplished, for example, by heat crimping a portion of the housing or shell around the inserted bobbin assembly. It will be appreciated that the foregoing operations could be performed in a variety of orders, for example the resin could be added before or after the assembly is inserted into the housing, and before or after the sealing of the housing and the bobbin assembly.  
         [0100]     According to one embodiment a portion of a wire extending between a windings and terminal area is supported by a thermosetting or thermoplastic material. In this embodiment, the body (incorporating the threaded, main body, holding flange and cap as one piece) is injection molded. Copper wire is wound on the bobbin (incorporating the black terminal connection end, pins and winding section) and soldered to the pins. A pole piece and magnet are positioned into a bobbin assembly. A thermosetting or thermoplastic material is either injected or applied in the area between the windings and the terminal connection. The wound bobbin with magnet and pole piece assembly is inserted into the body. This assembly is completed by bending the holding flange or end portion of the housing over the bobbin assembly, for example, by using heat and pressure to bend the thin holding flange without breaking the plastic. The heat can be applied using convection, conduction or ultrasonic.  
         [0101]     This sequence of the foregoing embodiment can be modified in multiple manners, for example, by applying the thermosetting or thermoplastic material before inserting the pole piece and magnet. The thermosetting or thermoplastic material can either be fully cured or cooled, or may be curing or cooled at the time of the insertion. In this case, the sequence above could be re-arranged in a variety of orders, for example by switching the third and fourth operations described above. It is envisioned that the magnet and pole piece could be assembled at a different times in the sequence. There are also a variety of other modifications to the manufacturing sequence that would result in the same or similar results.  
         [0102]     According to another embodiment a thermosetting or thermoplastic is applied into the cavity in the main body molding. In this case, the wound bobbin with pole piece and magnet would be inserted into the body while the thermosetting or thermoplastic material is still uncured or molten. As the wound bobbin assembly is inserted into the body, the thermosetting or thermoplastic material would flow up around the coil and into the void between the windings and terminals. In this embodiment, the thermosetting or thermoplastic material would cure or cool and form an encapsulation of both the windings and the void between the windings and terminals.  
         [0103]     A number of variations of the foregoing manufacturing processes and devices are contemplated. For example, it is contemplated that two or more of the foregoing operations could be performed as a single operation, could be performed in parallel, in series or a combinations of parallel and serial operations, or that one or more of the foregoing operations could be broken into sub-operations including additional separate steps. It is also contemplated that one or more of the foregoing operations could be omitted. It is further contemplated that additional operations could be interposed between the operations described above.  
         [0104]     As used herein terms relating to properties such as geometries, shapes, sizes, and physical configurations, include properties that are substantially or about the same or equal to the properties described unless explicitly indicated to the contrary.  
         [0105]     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.

Technology Classification (CPC): 6