Abstract:
A method and system for orienting and calibrating a magnet for use with a speed sensor. A magnet can be mapped two or more planes thereof in order to locate the magnet accurately relative to one or more magnetoresistive elements maintained within a speed sensor housing. An optical location of the magnet with respect to the magnetoresistive element and the sensor housing can then be identified in response to mapping of the magnet. Thereafter, the magnet can be bonded to the speed sensor housing in order to implement a speed sensor thereof maintained by the speed sensor housing for use in speed detection operations.

Description:
TECHNICAL FIELD  
       [0001]     Embodiments are generally related to sensing devices and components thereof. Embodiments also relate to speed sensors. Embodiments additionally relate to turbochargers utilized in automotive systems.  
       BACKGROUND OF THE INVENTION  
       [0002]     Turbochargers are utilized in engines for improving the output power of the engine by increasing the airflow charge to the cylinders to support an increased fuel charge. Turbochargers are well known devices for pressurizing intake air entering the combustion chambers of an internal combustion engine to thereby increase the efficiency and power output of the engine. In general, pressurizing the intake air increases the quantity of air entering the engine cylinders during the intake stroke, and this allows more fuel to be utilized in establishing a desired air-to-fuel ratio. Increased available engine output torque and power is thereby realized.  
         [0003]     In a turbocharged engine, the exhaust manifold of the engine is fluidly coupled to a turbine component of the turbocharger via an exhaust conduit, and the exhaust gas flowing through the exhaust conduit causes a turbine wheel within the turbine to rotate at a rate determined by the pressure and flow rate of exhaust gas. A compressor wheel within a compressor component of the turbocharger is mechanically coupled to the turbine wheel, and is therefore rotatably driven by the turbine wheel. An inlet of the compressor receives fresh ambient air, and an outlet of the compressor is fluidly coupled to the intake manifold of the engine via an intake conduit. The rotatably driven action of the compressor wheel increases the amount of intake air supplied to the intake conduit, thereby resulting in an increased, or so-called “boost”, pressure therein:  
         [0004]     With the development of increasingly sophisticated turbocharger and related automotive components, a need has arisen for extremely small package designs for turbocharger speed sensors utilized, for example, in diesel and gasoline engines. Current turbocharger speed sensors are used chiefly in laboratory settings or in a very limited basis at the center of a turborcharger housing. Locating the speed sensor instead on the compressor housing of the turbocharger takes advantage of cooler temperatures for sensor operations. The compressor housing location means that the sensor detects the speed of the compressor wheel as it spins at high RPM in the turbocharger. Such an arrangement also means that a hole or sensor bore through the compressor housing is required for the sensor face to be in close proximity to the fins of the compressor wheel.  
         [0005]     Because the compressor wheel and compressor housing have been machined to close precision and the compressor wheel has been properly balanced, the added sensor bore and sensor must provide for a minimal operational impact. To prevent as little disruption as possible to the compressor wheel spinning at high RPM and to the airflow in the compressor housing, the speed sensor package should be configured in as compact and small an arrangement as possible. A small speed sensor package is also desirable for mounting or installation of the sensor on smaller sized turbochargers.  
       BRIEF SUMMARY  
       [0006]     The following summary is provided to facilitate an understanding of some of the innovative features unique to the embodiments disclosed and is not intended to be a full description. A full appreciation of the various aspects of the embodiments can be gained by taking the entire specification, claims, drawings, and abstract as a whole.  
         [0007]     It is, therefore, one aspect of the present invention to provide for an improved sensing device.  
         [0008]     It is another aspect of the present invention to provide for an improved speed sensor.  
         [0009]     It is yet another aspect of the present invention to provide for a turborcharger speed sensor.  
         [0010]     It is a further aspect of the present invention to provide for a single integrated turborcharger speed sensor package for use in turborcharger speed sensing operations.  
         [0011]     It as an additional aspect of the present invention to provide for a method and system for orienting and calibrating compact and small turborcharger speed sensor.  
         [0012]     The aforementioned aspects and other objectives and advantages can now be achieved as described herein. A method and system for orienting and calibrating a magnet for use with a speed sensor are disclosed. A magnet can be mapped two or more planes thereof in order to locate the magnet accurately relative to one or more magnetoresistive elements maintained within a speed sensor housing. An optical location of the magnet with respect to the magnetoresistive element and the sensor housing can then be identified in response to mapping of the magnet. Thereafter, the magnet can be bonded to the speed sensor housing in order to implement a speed sensor thereof maintained by the speed sensor housing for use in speed detection operations.  
         [0013]     The speed sensor housing can be implemented as a thermoplastic or thermoset plastic. A thermoset channel can be configured from the speed sensor housing, wherein the magnet is bonded to the thermoset housing of the speed sensor housing. The speed sensor housing can then be integrated with a leadframe, such that the leadframe maintains the speed sensor housing, including, for example, an ASIC, one or more bead components, and a plurality of capacitors thereof. The speed sensor can be calibrated a plurality of calibration terminals integrated with the speed sensor housing. The speed sensor is preferably adapted for use as a turborcharger speed sensor.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the embodiments and, together with the detailed description, serve to explain the embodiments disclosed herein.  
         [0015]      FIGS. 1A and 1B  illustrate respective top and side views of a leadframe configuration, which can be implemented in accordance with a preferred embodiment;  
         [0016]      FIG. 2  illustrates a perspective view of a thermoset packaging arrangement, which can be implemented in accordance with a preferred embodiment;  
         [0017]      FIG. 3  illustrates a bottom perspective view of a magnet calibration configuration for calibrating a magnet, in accordance with a preferred embodiment.  
         [0018]      FIG. 4  illustrates a perspective view of a second level over-mold, which can be implemented for maintaining the turbocharger speed sensor in accordance with an embodiment.  
         [0019]      FIG. 5  illustrates a mounting bolt, which can be implemented in accordance with an embodiment;  
         [0020]      FIG. 6  illustrates a machined bushing, which can be implemented in accordance with an embodiment; and  
         [0021]      FIG. 7  illustrates a perspective view of a sensor installed in a turbocharger, in accordance with an embodiment.  
     
    
     DETAILED DESCRIPTION  
       [0022]     The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment and are not intended to limit the scope thereof.  
         [0023]      FIGS. 1A and 1B  illustrate respective top and side views  101  and  103  of a configuration for a leadframe  100 , which can be implemented in accordance with a preferred embodiment. Note that in side views  101  and  103  of leadframe  100  identical or similar parts or elements are generally indicated by identical reference numerals. Leadframe  100  can thus be utilized to maintain a magnetoresistive element  102  (e.g., a GMR or AMR transducer) along with coupling capacitors  106  and  108 . An ASIC  104  can also be maintained by leadframe  100  in addition to a plurality  118  of beads  114  and  116 . One or more filtering capacitors  110  and  112  can also be maintained by leadframe  100 . Additionally, a plurality leadframe terminals  214 ,  216  and  218  are featured, which are configured from leadframe  100 . The foregoing components and leadframe  100  can be implemented in the context of a speed sensor utilized in association with a turbocharger.  
         [0024]      FIG. 2  illustrates respective “before” and “after” perspective views  201  and  203  of a thermoset packaging arrangement, which can be implemented in accordance with a preferred embodiment. Note that in views  201  and  203 , identical or similar parts or elements are indicated generally by identical reference numerals. Additionally, in  FIGS. 1-2  identical or similar parts or elements are also indicated by identical reference numerals. In the “before” view  201 , the leadframe  100  maintains a speed sensor housing  208 , which includes plastic ribs  206 , along with a location pin  202  that is utilized for thermoplastic over-molding. A protruded portion  204  is also provided by speed sensor housing  208  within which a magnet may be maintained relative to magnetoresistive component  104 . Arrow  205  illustrated in  FIG. 2  indicates the transition from the “before” view  201  to the “after” view  203 . As depicted in the “after view” a plurality of calibration terminals  210  protrude from speed sensor housing  208 , while a tie bar  212  is formed that includes terminals  214 ,  216  and  218 . The formation of tie bar  212  is based on a 90-degree bending thereof. In general, the aforementioned components along with speed sensor housing  208  form a speed sensor  220 .  
         [0025]      FIG. 3  illustrates a bottom perspective view  301  of a magnet calibration configuration for calibrating a magnet  302 , in accordance with a preferred embodiment. Note that in  FIGS. 1-3 , identical or similar parts or elements are generally indicated by identical reference numerals.  FIG. 3  generally illustrates a calibration procedure that can be implemented for calibrating magnet  302  for orientation and placement in association with speed sensor housing  208 . In general, magnet  302  can be moved until a desired magnetoresistive bridge circuit output is obtained. Plastic rails  304  and  306  can be integrated with speed sensor housing  208  in order to restrict the movement of magnet  302  perpendicular to the sensor formed from sensor housing  208 . Such a speed sensor essentially incorporates speed sensor housing  208  and leadframe terminals  214 ,  216 , and  218 . The magnet  302  can be bonded to a thermoset channel  308 , which is bounded by rails  304  and  306  and configured from the sensor housing  208 .  
         [0026]      FIG. 4  illustrates a perspective view of a second level over-mold  400 , which can be implemented for maintaining the turbocharger speed sensor  220  in accordance with an embodiment. Note that in  FIGS. 1-4 , identical or similar parts or elements are generally indicated by identical reference numerals. The over-mold  200  can be implemented with one or more O-rings  403  and a thermoplastic component  404 . A connecting mechanism or component  406  can also be provided in association with a machined bushing  600 , which is shown in greater detail herein with respect to  FIG. 6 . The second level over-mold depicted in  FIG. 4  generally surrounds and encases the sensor  220  depicted previously herein with respect to  FIGS. 1-3 . Over-mold  400  thus forms the general outlines of an enhanced speed sensor thereof, which is maintained within and by over-mold  400 . Thus, reference numeral  400  depicted in  FIG. 4  can be utilized not only to refer the over-mold thereof but also to the speed sensor, which incorporates speed sensor  220  described earlier.  
         [0027]      FIG. 5  illustrates a mounting bolt  500 , which can be implemented in accordance the embodiment depicted in  FIG. 4 . Similarly,  FIG. 6  illustrates the machined bushing  600 , which can be implemented in accordance with the embodiment of  FIG. 4 . The mounting bolt  500  can be provided with a thread lock feature, while the machined bushing  500  can be configured from brass, depending upon design considerations.  FIG. 7  illustrates a perspective view of sensor  400  installed in a turbocharger  700 , in accordance with an embodiment.  
         [0028]     Note that the size, orientation and position of magnet  302  are important for the small sensor construction and performance required for turbocharger speed sensor applications. Due to the limited space and packaging constraints, a half cylinder shaped magnet can be utilized for magnet  302 , which can fit within a small diameter and provide as much surface area as possible for signal strength. The magnetoresistive (MR) sensing element  102  depicted in  FIGS. 1A-1B , for example, is generally sensitive to magnet  302  movement in two planes. Therefore, to achieve an optimal signal strength, the calibration procedure described herein can be accomplished in order to place the magnet  302  in a “sweet” spot for maximum sensor performance. Magnet  302  can be attached to the speed sensor housing  208  (i.e., a thermoset package), which contains the MR sensing element  102  by using a UV curable epoxy until final package over-molding occurs.  
         [0029]     In order to the find the so-called “sweet” spot for optimal performance, a mapping procedure can be accomplished, which very accurately locates the magnet  302  relative to the MR sensing element  102 . The magnet  302  and mating thermoset package (e.g., sensor housing  208 ) can then be fixtured and the magnet  302  moved away from the thermoset package and the magnet  302  moved very accurately in two planes using a mapper with stepper motor controls. The mapping can be accomplished with the magnet  302  containing the full potential travel of the magnet  302  on the sensor housing  208  or thermoset package thereof.  
         [0030]     Resulting data can then be analyzed to determine the optimal “sweet” spot. The magnet  302  can then be moved away from the sensor housing  208  or thermoset package and a drop of UV curable epoxy placed on the thermoset package. The magnet  302  can then be moved back to the thermoset package, displacing the epoxy and creating a thin layer of epoxy between the magnet  302  and the thermoset package or housing  208 . A UV light can then be utilized to temporarily lock the magnet in place. A batch cure can later be utilized to final cure the epoxy prior to thermoplastic over-molding.  
         [0031]     A number of advantages can result from implementing the embodiments discussed herein. For example the cooler temperatures of approximately 190° C., for example, on the compressor housing side of the turbocharger allow all of the integrated circuits (IC&#39;s) and signal-conditioning electronics to be packaged together and over-molded with a thermoplastic into a single package with integral connectors. This eliminates the need for a so-called “pigtail” or wire-harness version of the sensor to remotely locate the electrical components. A single integrated package as described herein can therefore reduce the number of components required along with associated material costs and manufacturing processes that may be needed in a “pigtail” version. The use of an integral connector, for example, allows for enhanced sealing by eliminating multiple interconnects that are utilized in conventional “pigtail” versions.  
         [0032]     It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.