Abstract:
A control system having a housing with a bore formed within the housing. A valve member is associated with the bore for controlling the passage of a fluid medium through the bore. An induction sensor is aligned with the valve and facilitates determining the valve position. An inductor is connected to an end of the valve member that is in close proximity to the induction sensor. It is contemplated that this control system can be used in a number of different applications including throttle control systems, turbo actuators, canister purge systems and shift control mechanisms. However, it is within the scope of this invention to incorporate the control system on virtually any type of vehicle system where it is possible to determine the position of a valve utilizing induction sensor technology.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. patent application Ser. No. 10/383,194 filed Mar. 6, 2003, which claims the benefit of U.S. Provisional Application No. 60/362,032, filed Mar. 6, 2002. The disclosures of the above applications are incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention generally relates to electronic throttle control systems and more particularly to electronic throttle control systems having non-contacting position sensors. 
   BACKGROUND OF THE INVENTION 
   Traditional engine fuel control systems use a mechanical linkage to connect the accelerator pedal to the throttle valve. Engine idle speed is then controlled by a mechanical system that manipulates the pedal position according to engine load. 
   Since the mid-1970&#39;s electronic throttle control or “drive-by-wire” systems have been developed. Electronic throttle control systems replace the mechanical linkage between the accelerator pedal and the throttle valve with an electronic linkage. These types of systems have become increasingly common on modern automobiles. 
   Generally, at least one sensor is typically placed at the base of the accelerator pedal and its position is communicated to the engine controller. At the engine, a throttle position sensor and an electronically controlled motor then regulate the throttle to maintain a precise engine speed through a feedback system between the throttle position sensor and the electronically controlled motor. An example of an electronic throttle control system can be found with reference to U.S. Pat. No. 6,289,874 to Keefover, the entire specification of which is incorporated herein by reference. 
   In conventional electronic throttle control systems, the various components of the throttle position sensor stator and connector assembly are mounted to the casting of the throttle body. The connector assembly is also connected to the motor. The throttle position sensor is placed in close proximity with the rotating shaft of the throttle valve. The throttle position sensor used to provide data so that the angular position of the throttle valve can be determined. Typical conventional throttle control systems use contact sensors such as potentiometers as well as non-contact sensors such as Hall Effect sensors which incorporate a magnet and stator configuration. These conventional sensors can often be bulky and difficult to align during assembly. Furthermore, angular position sensors have been incorporated with applications other than throttle control valves. For example, angular position sensors may be used in conjunction with other systems such as turbo actuators and exhaust gas recirculation valves, canister purge valves and transmission shift valves. 
   SUMMARY OF THE INVENTION 
   In accordance with the general teachings of the present invention, a new and improved electronic throttle control system is provided. 
   A control system having a housing with a bore formed within the housing. A valve member is associated with the bore for controlling the passage of a fluid medium through the bore. An induction sensor is aligned with the valve and facilitates determining the valve position. An inductor is connected to an end of the valve member that is in close proximity to the induction sensor. It is contemplated that this control system can be used in a number of different applications including throttle control systems, turbo actuators, canister purge systems and shift control mechanisms. However, it is within the scope of this invention to incorporate the control system on virtually any type of vehicle system where it is possible to determine the position of a valve utilizing induction sensor technology. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  is a cross-sectional view of an electronic throttle control system, in accordance with the general teachings of the present invention; 
       FIG. 2  is a cross-sectional side plan view taken about section line X—X of  FIG. 1 , however, this particular view also depicts a pre-molded casting that serves as one method of alignment during assembly of the electronic throttle control system; 
       FIG. 3  is a cross-sectional plan view of the sensor assembly taken about section line  3 — 3  on  FIG. 1 ; 
       FIG. 4  depicts a perspective view of the throttle control system taken about section line X—X in  FIG. 1 , wherein this particular view depicts the use of an alignment tool that is used to align the sensor assembly during assembly of the throttle control system; 
       FIG. 4   a  is a cross-sectional view taken about section line  4   a — 4   a  of  FIG. 5 ; 
       FIG. 4   b  is a cross-sectional view of the sensor assembly being aligned using the alignment tool; 
       FIG. 5  depicts a perspective view taken about section line X—X of  FIG. 1 , however, this particular embodiment incorporates the use of alignment holes that are used as an alternate to the alignment slots; 
       FIG. 6  depicts a schematic view of the operation of the throttle control system; 
       FIG. 7  is an expanded perspective view of the throttle body sensor arrangement and cover member; 
       FIG. 8  is an overhead plan view of the sensor arrangement with a partial view of the throttle shaft and inductor positioned near the sensor; and 
       FIG. 9  is a perspective partial view of the sensor aligned with the throttle shaft and inductor. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
   Referring to  FIG. 1  there is generally shown an electronic throttle control system  10 , in accordance with the general teachings of the present invention. 
   The system  10  generally includes a casting  12  that serves as a housing or support for the various components of the system. Formed within the casting  12  is a throttle bore  14  having a throttle plate  15  rotatably disposed inside the throttle bore  14 . A throttle shaft  16  is attached to and extends across the throttle plate  15  and together the throttle plate  15  and throttle shaft  16  form an actuator that controls the flow of fluid medium through the throttle bore  14 . The actuator can take other forms and the use of a throttle plate  15  and throttle shaft  16  in no way is intended to limit the scope of this invention. The throttle shaft  16  rotates the throttle plate  15  between the open and closed positions. The throttle shaft  16  is supported on both ends by a pair of bearings  18  to aid in the rotation of the throttle plate  15  and throttle shaft  16 . At one end of the throttle shaft  16 , a gear train  20  envelops the throttle shaft for effecting movement of the throttle shaft  16 . Additionally, a spring system  22  is also provided at one end of the throttle shaft  16  as part of a fail-safe system (not shown). 
   At the extreme end of the throttle shaft  16 , a substantially U-shaped sensor rotor  24  is fastened thereto. Although the rotor  24  is shown as being substantially U-shaped, it should be appreciated that the rotor  24  may be configured in any number of shapes, including but not limited to a cylindrical or flat member. The rotor  24  is preferably nested in close proximity to sensor stator  26  and together the two generally form a sensor assembly  27 . Thus, it should be appreciated that the rotor  24  is capable of rotating about the stator  26 . Although the stator  26  is shown as being substantially U-shaped, it should be appreciated that the stator  26  may be configured in any number of shapes, including but not limited to a flat member. 
   The axial position of the rotor  24  is preferably maintained by controlling the axial position at which it is attached to the throttle shaft  16 ; however, this position can be fixed or adjustable. 
   The stator  26  is fastened to a printed circuit board  32 , which is preferably fastened to the housing  12 . Axial position control is preferably maintained by attaching the printed circuit board  32  to a controlled fixed surface such as the casting  12 . Tight radial position control is preferably maintained between the rotor  24  and the stator  26  through the assembly process or through dimensional control of the printed circuit board  32  and a fixed surface such as the casting  12 . This tight radial positioning is preferably maintained by carrying out an alignment method which may incorporate an alignment means. One method of alignment involves the use of pre-molded slots (depicted in  FIG. 2 ) in the casting so each of the individual components can be aligned by sliding into the slots. A second method of alignment (depicted in  FIGS. 4 ,  4   a ,  4   b ) uses an alignment tool to hold the stator and printed circuit board in place. And yet a third method of alignment (depicted in  FIG. 5 .) use of tapered pins  50  that are inserted between the stator and rotor during attachment of the printed circuit board to the casting. Each of these alignment means will be described in greater detail later in this description. 
   The printed circuit board  32  and the stator  26  are preferably fastened in place by one or more fasteners (not shown) that are inserted through one or more apertures  34  formed on the surface of the casting  12  adjacent to the printed circuit board  32 . 
   Fastened to the printed circuit board  32  is a preferably flexible interconnect  36  that electrically connects the printed circuit board  32  to a connector  38 . The flexible interconnect  36  reduces stress on the printed circuit board  32  and allows the printed circuit board  32  to be positioned separately from the connector  38 . The connector is preferably fastened to the casting  12 . The connector  38  is in turn electrically connected to a motor  40  which is preferably fastened to the casting  12 . Several types of motors may be within the scope of this invention. For instance the motor may be a brush motor, a DC motor, a brushless motor, a solenoid, pneumatic or a stepper motor. Any type of actuator that can facilitate the rotation of the shaft  16  may be implemented. 
     FIG. 2  is a cross-sectional side plan view taken about section line X—X of  FIG. 1 , however, this particular view also depicts a pre-molded casting that serves as one method of alignment during assembly of the electronic throttle control system. As shown the electronic throttle control system  10  has a casting or housing  12  which houses all of the individual components of the system. The printed circuit board  32  and the electrical connector  38  are each independently mountable to the casting  12 . This is accomplished through the use of a flexible interconnect which connects the printed circuit board  32  and the electrical connector  38 . The flexible interconnect allows signals to be communicated between the electrical connector  38  and the sensor assembly  27  and is capable of bending or flexing to accommodate for a range of varying spatial distribution between the printed circuit board  32  and the electrical connector  38 . One of the main advantages of this feature is that during assembly it is important to maintain proper air gap between the rotor and the stator so that the sensor will function properly. The flexible interconnect  36  allows the printed circuit board  32 , which is fastened to the stator (not shown), to be independently and perfectly aligned with the rotor and the valve shaft, while still allowing for the electrical connector  38  to be independently aligned and connected to the casting. Not only does this feature provide an advantage during assembly of the electronic throttle control system  10  it also compensates for thermal expansion among the various components of the system  10 . For example, thermal expansion can occur unevenly among each of the components of the system  10 . It is possible for thermal expansion to occur in the printed circuit board region  32  before it occurs at the electrical connector  38 . While actual movement caused by thermal expansion is relatively small, it can cause misalignment or changes in the air gap space between the stator and rotor thus affecting the performance of the sensor assembly  27 . 
   As mentioned above,  FIG. 2  illustrates one particular method of aligning the electrical connector  38  and the printed circuit board  32 . The casting  12  of this particular embodiment has pre-molded alignment depressions. The printed circuit board  32  and sensor assembly  27  can be aligned by placing the printed circuit board  32  within a board depression  33 . Once the printed circuit board  32  is aligned it can be fastened to the housing  12  with fasteners  34 . The electrical connector  38  can then be aligned by placing the electrical connector  38  within a connector depression  37 . Once the electrical connector  38  is aligned it can then be fastened to the housing  12  with fasteners  39 . 
     FIG. 3  is a cross-sectional plan view of the sensor assembly  27  taken about section line  3 — 3  on  FIG. 1 . The sensor assembly  27  consists of a sensor rotor  24 , a sensor stator  26 , a magnet layer  28  and an air gap  30 . As shown the sensor stator  26  is disposed inside of a nested region of the sensor rotor  24 . Disposed on the surface of the sensor rotor  24  is a magnet layer  28 . The sensor rotor  24  and sensor stator  26  are positioned so they are not touching and there will be an air gap  30  between the surface of the sensor stator  26  and the magnet  28  layer on the surface of the sensor rotor  24 . A sensor assembly of this type is generally referred to as a non-contact sensor, such as a Hall Effect sensor. Examples of prior art Hall Effect sensors are known in the art and can be found with reference to U.S. Pat. No. 5,528,139 to Oudet et al., U.S. Pat. No. 5,532,585 to Oudet et al., and U.S. Pat. No. 5,789,917 to Oudet et al., the entire specifications of which are incorporated herein by reference. However, it is possible for the sensor assembly to incorporate other non-contact or contact sensors that require precise alignment of the sensor assembly. 
     FIG. 4  depicts a perspective view of the throttle control system taken about section line X—X in  FIG. 1 , wherein this particular view depicts the use of an alignment tool  42  that is used to align the sensor assembly  27  during assembly of the throttle control system  10 . As can be seen, the printed circuit board  32  has a number of slots  44  on its surface which defined the perimeter of the sensor stator  26 . The slots  44  allow the insertion of an alignment tool  42  which is used to engage the printed circuit board  32  and the sensor stator  26  so that the printed circuit board  32  and the sensor stator  26  can be properly aligned in relation to the sensor rotor (not shown) during assembly. 
   After the sensor stator is properly aligned the printed circuit board  32  can be fastened to the casting  12  with fasteners  34 . Once the printed circuit board  32  is secure the alignment tool  42  can be disengaged since the sensor stator  26  is not in proper alignment. After securing the printed circuit board  32  and the sensor assembly (not shown) the electrical connector  38  can be aligned and fastened  39  to the casting  12 . The flexible interconnect  36  allows electrical connector  38  and the printed circuit board  32  to be assembled independent of each other so that the sensor stator  26  does not become misaligned during completion of assembly. 
   The alignment tool  42  in this embodiment has six fingers  46  that align with the slots  44 . The fingers  46  on the alignment tool  42  are flexible and are capable of bending to grasp onto the sensor stator  26 . Once the printed circuit board  32  is fastened to the casting  12 , the alignment tool  42  can be easily removed by simply pulling the alignment tool  42  away from the printed circuit board  32 . 
     FIG. 4   a  is a cross-sectional view taken about section line  4   a — 4   a  of  FIG. 5 . The sensor stator  26  is connected to the printed circuit board  32  and the alignment tool  42  is used to position the sensor stator  26  in the nested region of the rotor  24 . Once the printed circuit board  32  is fastened to the casting  12 , alignment of the sensor stator  26  and the sensor rotor  24  will be maintained and the alignment tool  42  may be removed. 
     FIG. 4   b  is a cross-sectional view of the sensor assembly being aligned using the alignment tool. The rotor alignment tool  42  can have various configurations. The stator  26  can be positioned at the tip of the rotor alignment tool  42  and can be temporarily engaged to the tip of the rotor alignment tool  42  by pressing the stator  26  onto the tool. The tool  42  can then be used to align the stator  26  and the rotor  24  so that a proper air gap  30  is achieved. The tips of the tool  42  help aid in forming the proper air gap by holding the stator in place during fastening. 
     FIG. 5  depicts a perspective view taken about section line X—X of  FIG. 1 , however, this particular embodiment incorporates the use of alignment holes  52  that are used as an alternate to the alignment slots. During assembly and alignment of the printed circuit board  32  and stator  26  with respect to the magnet  28  and rotor  24 , individual tapered pins  50  are inserted through the alignment holes  52  in a manner similar to the alignment tool  42  depicted in  FIG. 5 . The tapered pins  50  are used to align the sensor stator  26  with respect to the magnets  28  of the rotor  24  so that a properly spaced air gap  30  is created during assembly. Once the printed circuit board  32  is fastened to the casting  12  the tapered pins  50  are then removed. In this particular embodiment of the invention the pins  50  are tapered to prevent over-insertion and ease the insertion and retraction of the pins  50 , however, it is possible to use pins  50  of virtually any type of configuration. 
   Once the printed circuit board  32  is fastened to the casting the electrical connector  38  can also independently be aligned and fastened to the casting  12 . Once again the flexible interconnect  36  plays an important role by allowing the electrical connector  38  and the printed circuit board  32  to each be aligned and fastened to the casting  12  independently of each other. This eliminates the possibility of misalignments of the sensor assembly  27  when the electrical connector  38  is connected to the casting. Additionally, as stated earlier the use of the flexible interconnect  36  also prevents misalignment of the sensor assembly  27  during thermal expansion which may occur during normal operation of the throttle control system  10 . 
   In operation, the present invention functions by employing feedback between the various sensor systems (e.g., sensor rotor/sensor stator) and the various control assemblies (e.g., the motor) in order to properly position the throttle plate so as to achieve optimal performance of the electronic throttle control system. The present invention can be employed in any type of rotary actuator employing a position sensor. 
     FIG. 6  depicts a schematic view of the operation of the throttle control system. The throttle control system  10  operates using an external electrical control unit (ECU). The ECU is a logic circuit that receives a user input signal  64  and a throttle position signal  62  and generates a control signal  66  to the motor via the electrical connector. 
   The electrical connector of the throttle control system  10  also receives power  60  from a power source. The power is distributed through the electrical connector to the motor and the sensor stator via the flexible interconnect and sensor stator. 
   The user input signal  64  is a value that indicates the user&#39;s desired throttle position. The user input signal  64  can be generated from a user input such as, an accelerator pedal (not shown). 
   The throttle position signal  62  is generated by the sensor stator via the printed circuit board, the flexible interconnect and the electrical connector. The throttle position signal  62  is a value that indicates the present angular position of the throttle plate (not shown). In a preferred embodiment of the invention the throttle position signal is an analog position signal. However, it is in the scope of this invention to have a throttle position signal that is digital. 
   The ECU analyzes the values of the user input signal  64  and the throttle position signal  62  to determine if the throttle position signal  62  matches the user input signal  64 . If the two signal values do not match then the ECU will generate a control signal  66  to the motor which is inputed to the throttle control system  10  via the electrical connector. The motor receives the control signal  66  and actuates the throttle body so that actual angular position of the throttle valve matches the desired angular position of the user which will be confirmed by the ECU when the throttle position signal  62  and the user input signal  64  both match. 
   The printed circuit board serves as a housing for the sensor stator  26 . In a preferred embodiment of the invention, the sensor stator generates an analog to position signal that travels through wiring (not shown) on the printed circuit board. The position signal then exits the printed circuit board through the flexible interconnect and travels to the ECU via the electrical connector. The printed circuit board preferably has no logic, however, it may contain resistors, capacitors, and amplifiers necessary for the position signal. However, it should be understood that it is within the scope of this invention to incorporate a printed circuit board that has logic functions. 
   In addition to carrying the position signal, the flexible interconnect also supplies power from the electrical connecter to the sensor stator via the printed circuit board. In an embodiment where the printed circuit board has Logic functions it should also be understood that the flexible interconnect would also be capable of carrying a user input signal to the motor. The flexible interconnect can have many physical forms. For example, in the present embodiment the flexible interconnect may be bare metal wires, however, it is possible to use a ribbon wire or plastic coated wires in embodiments where the flexible interconnect will need to insulated. 
   The preferred embodiment of the invention has an external ECU. The ECU receives a position signal from the sensor stator. This signal indicates the angular position of the throttle plate. The ECU also receives a user input signal that indicates the user&#39;s desired angle of the throttle plate. The ECU takes the values of the user input signal and the position signal and generates a control signal based on the values. The control signal is sent to the motor and causes the motor to rotate the gear train, the throttle shaft and throttle plate (see  FIGS. 1–2 ) so the throttle plate reaches the angle desired by the user. 
     FIGS. 7–9  depict an alternate embodiment of the invention incorporating an induction sensor. As shown in  FIG. 7  there is an induction sensor  102 . The induction sensor  102  is a flat sensor, however, it is within the scope of this invention for the induction sensor  102  to have some other shape depending on the spatial requirements of certain designs. The induction sensor  102  is connected to the connector  38  via the flexible interconnect  36 . The flexible interconnect  36  allows the induction sensor  102  to be positioned independently from the electrical connector  38 , so that proper alignment can be obtained between the sensor  102  and an inductor  106  positioned at the end of a throttle shaft  104 . 
     FIG. 8  shows an overhead plan view of the connector  38 , sensor  102  and flexible interconnect  36  positioned relative to the throttle shaft  104 . The end of the throttle shaft  104  is positioned in close proximity to but does not contact the sensor  102 . The inductor  106  is positioned near the end of the throttle shaft  104 . The inductor  106  is in the form of a single copper loop that is bent in a sprocket-like shape. 
     FIG. 9  shows a close-up perspective view of the sensor  102  positioned near the throttle shaft  104  and inductor  106 . The sensor  102  has two layers (not shown) of printed circuit board (PCB)  108 . Three sets of two pickup coils  110  (i.e., 6 pickup coils total) traverse between the layers of printed circuit board  108 . As discussed below, each set of pickup coils  110  generates a signal value that can be used to determine the position of the throttle valve  106 . It is within the scope of this invention to use a greater or lesser number of pickup coils. 
   The induction sensor  102  operates by measuring fluxuation of a high frequency magnetic field. An activation coil  112  circumscribes the pickup coils  110 . When energized, the activation coil  112  induces a high frequency magnetic field between the actuation coil  112  and the pickup coils  110 , that in turn causes a secondary high frequency magnetic field to be induced between the inductor  106  and the pickup coils  110 . The secondary magnetic field is strongest when the sprockets of the inductor  106  are aligned with one of the pickup coils  110 . As the throttle shaft  104  rotates the secondary magnetic field between the inductor  106  and the pickup coils  110  will fluctuate as the inductor  106  is misaligned with one set of pickup coils  110  and moves into alignment with the second set of pickup coils  110 . Each set of three pickup coils  110  will generate a signal from which the throttle position can be derived. As the throttle shaft  104  moves out of alignment with the first set of pickup coils  110 , it will move into alignment with the second set of pickup coils  110 , thus the signal values from each set of pickup coils will be inverted and have unequal slopes. As the inductor  106  is rotated in and out alignment among the various sets of pickup coils  110 , the secondary magnetic field generated between the inductor  106  and a particular set of pickup coils  110  will become disrupted which in turn disrupts the high frequency magnetic field generated between the activation coil  112  in the pickup coils  110 . The disruption of the magnetic field between the activation coil  112  and the pickup coils  110  is what the throttle position signal is derived from. 
   The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.