Abstract:
A throttle valve position sensor in which a non-contacting, magnetic field sensor is coupled to or integral with a gear wheel of a geared throttle valve control. The sensor provides a more durable sensor. Sensor circuitry can be provided on the lid of the control, along with control motor electrical connections, so that the sensor and control motor can be connected by simple joining in a single operation. The throttle control valve is intended for internal combustion engines for motor vehicles.

Description:
BACKGROUND OF THE INVENTION 
     This application is related to U.S. Pat. No. 5,672,818 issued to Schaefer et al. on Sep. 30, 1997. 
     1. Technical Field 
     The present invention relates generally to throttle control valves and, more particularly, to throttle valve position sensors for a geared throttle control valve. 
     2. Related Art 
     Heretofore, throttle valve adjusting units with control motors with geared transmissions have been known. One such device is exhibited in U.S. Pat. No. 5,672,818 to Schaefer et al., incorporated herein by reference. This device provides the advantage that the lid includes motor electronic connection components thereon that would previously have required soldering between the lid and motor. Further, this device provides the advantage of having the potentiometer path mounted on the lid. As a result, the connection of the sensor and motor can be made simply by mounting the lid in a single operation. Further, the device can be easily produced by mass production. However, a disadvantage of this type device is that the sensor requires contact between components thereof, which deteriorate over time and, hence, can foul the geared transmission when breakage occurs. 
     While non-contacting position sensors, such as those of U.S. Pat. Nos. 5,798,639, 5,757,179 and 5,712,561, all to McCurley et al. and all incorporated herein by reference, have also been used, none of these devices have been applied in a geared transmission setting. 
     In view of the foregoing, there is a need for a non-contacting throttle valve position sensor for use with a throttle control valve having a throttle valve shaft controlled by a control motor through a geared transmission. 
     SUMMARY OF THE INVENTION 
     A first general aspect of the present invention is a throttle valve position sensor for use with a throttle control valve having a throttle valve shaft rotatably supported in a throttle housing and positionable by a control motor through a geared transmission. The throttle valve position sensor comprises a gear, fixed to the throttle valve shaft, for positioning the throttle valve shaft. There is also a magnetized portion positioned parallel to the gear and coupled to the gear to rotate therewith. Additionally, there is a flux density sensor for sensing a flux density indicative of a position of the magnetized portion and determining a position of the throttle valve shaft. 
     In a second general aspect of the invention, there is provided a throttle valve position sensor for use with a throttle control valve having a throttle valve shaft rotatably supported in a throttle housing and positionable by a control motor through a geared transmission. Specifically, the throttle valve position sensor comprises means for creating a variable magnetic field. There is also means for coupling the variable magnetic field means to a gear of the geared transmission such that the variable magnetic field moves with the gear, and a magnetic field sensor for sensing changes in position of the gear based on the variable magnetic field. 
     In a third general aspect of the invention, there is provided a throttle control device comprising a throttle valve secured to a throttle valve shaft that is rotatably supported in a throttle valve housing. There is also a control motor, supported by the throttle valve housing, including a drive gear operatively coupled to the throttle valve shaft for adjusting the rotational position thereof. Also, there is a magnetized portion coupled to the drive gear and a flux density sensor for detecting the rotational position of the magnetized portion. The sensor includes circuitry. A lid for the device is coupled to the throttle valve housing and the circuitry is mounted on the lid. A coupling part is formed onto the lid and includes electrical connections to the control motor and circuitry. 
     The throttle control valve device and throttle valve position sensor, according to the invention, offers advantages over the prior art. Specifically, there is a non-contacting sensor with a geared transmission that maintains the advantages of the above-identified related art device U.S. Pat. No. 5,672,818. The replacement of the potentiometer with a non-contacting throttle valve position sensor advantageously prevents fouling of the geared transmission or sensor through breakage of the wipers or gears and increases longevity of the device while maintaining the advantages. 
     The foregoing and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The preferred embodiments of this invention will be described in detail, with reference to the following figures, wherein like designations denote like elements, and wherein: 
     FIG. 1 shows a cross-section through a prior art throttle valve; 
     FIG. 2 shows an inner side of FIG. 1; 
     FIG. 3 shows a cross-section through a throttle valve in accordance with a first embodiment of the present invention; 
     FIG. 4 shows a partial cross-section view of the first embodiment along the throttle shaft; 
     FIG. 5 shows a detail of magnets in the present invention; 
     FIG. 6 shows a cross-section through a throttle valve in accordance with a second embodiment of the present invention; and 
     FIG. 7 shows a partial cross-section view of the second embodiment along the throttle shaft. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Although certain preferred embodiments of the present invention will be shown and described in detail, it should be understood that various changes and modifications may be made without departing from the scope of the appended claims. The scope of the present invention will in no way be limited to the number of constituting components, the materials thereof, the shapes thereof, the relative arrangement thereof, etc., and are disclosed simply as an example of the preferred embodiment. 
     The throttle control valve can be used in any internal combustion engine in which engine performance is to be influenced with the aid of a throttle valve adjustable by means of a control motor. 
     FIG. 1 shows a prior art throttle valve housing  2 . A gas conduit  4  extends through the throttle valve housing  2 . By way of example, the gas conduit  4  leads from an air filter, not shown, to a combustion chamber, not shown, or to a plurality of combustion chambers of an internal combustion engine, not shown. The section shown in FIG. 1 extends crosswise through the gas conduit  4 . Air or a fuel-air mixture can flow through the gas conduit  4 . 
     A throttle valve shaft  6  extends crosswise through the gas conduit  4 . The throttle valve shaft  6  has a left-hand end  6   a  and a right-hand end  6   b . The throttle valve shaft  6  is pivotally supported in the throttle valve housing  2  with the aid of two bearings  8   a  and  8   b  on either side of the gas conduit  4 . The imaginary center axis of the throttle valve shaft  6 , about which the throttle valve shaft  6  rotates, will hereinafter be called the pivot axis  6   c  and is represented by a dot-dashed line in prior art FIG.  1 . 
     A throttle valve  10  is secured by fastening screws or other fastening hardware, not shown, to the throttle valve shaft  6 . The throttle valve shaft  6  can be pivoted 90°, for instance, between two terminal positions. In one of the two terminal positions, the throttle valve  10  almost completely closes the gas conduit  4 . In the other terminal position of the pivoting range of the throttle valve shaft  6 , the gas conduit  4  is maximally opened. 
     Outside the gas conduit  4 , a gear wheel  12  is joined to the throttle valve shaft  6  in a manner fixed against rotation at the end  6   b  of the throttle valve shaft  6 . The gear wheel  12  has a face end  12   a  remote from the gas conduit  4 . 
     A shaft  16  is fixedly mounted to the throttle valve housing  2 . A further gear wheel  18  is rotatably supported on the shaft  14 . A throttle assembly lid or cover  24  is provided on one face end of the throttle valve housing  2 . The lid  24  is secured to the throttle valve housing  2  with fasteners, not shown. A connection chamber  32  is formed between the throttle valve housing  2  and the lid  24 . A control motor  20  is housed within the connection chamber  32 . 
     The lid  24  rests on a bearing surface  26  on the throttle valve housing  2 . The bearing surface  26  extends over the entire circumference of the lid  24 . A lid guide  30   b  is also provided on the lid  24 , and a housing guide  30   a  is provided on the throttle valve housing  2 . The lid guide  30   b  and the housing guide  30   a , in combination with one another, form a sensor guide  30  to assure proper alignment of the lid  24  and housing  2 . A seal  34  seals the connection chamber  32  off from the outside and is provided around the connection chamber  32 , between the lid  24  and the throttle valve housing  2 . Located in the connection chamber  32  are essentially the control motor  20 , a drive wheel  20   b , the two gear wheels  12  and  18 , a potentiometer sensor  40 , and an electrical motor coupling  22 . The connection chamber  32  may, depending on the version, be subdivided into plurality of individual chambers. The primary lengthwise direction of the lid  24  extends substantially crosswise to the pivot axis  6   c  of the throttle valve shaft  6  and crosswise to the pivot axis of both the drive shaft  20   a  and the gear wheel  18 . 
     The control motor  20  has a housing  20   c  that is firmly anchored in the throttle valve housing  2 . The control motor  20  has a drive shaft  20   a , which protrudes parallel to the pivot axis  6   c  from the housing  20   c  on the face end and on which a drive wheel  20   b , as a further gear wheel, is seated. The gear wheels  12 ,  18  and  20   b  are toothed wheels, for example, and arc in mutual engagement for the sake of translating torque from the control motor  20  to the throttle valve  10 . 
     Parallel to the pivot axis of the drive shaft  20   a  and parallel to the pivot axis  6   c  of the throttle valve shaft  6 , a motor counterpart plug contact  22   b  protrudes on the face end for the housing  20   c  of the control motor  20 . The motor counterpart plug contact  22   b  is part of an electrical motor coupling  22 . The motor counterpart plug contact  22   b  on the control motor  20  serves to supply electrical power to the control motor  20 . The motor plug contact  22   b  of the motor coupling  22  is secured to the lid  24  on the inner side  24   a  toward the connection chamber  32 . The lid  24  preferably comprises a nonconductive plastic but may be made of other nonconductive materials. The material of the lid  24  is pulled forward in the direction of the control motor  20 , in the region of the motor plug contact  22   b , and there forms a contact support  22   c . The contact support  22   c  fits at least partway around the motor plug contact  22   b.    
     A sheet-metal stamped part or electrical trace  56  connects the motor plug contact  22   b  to a coupling part  44 , shown FIG. 2, for connection to external wiring. As FIGS. 1 and 2 show, the electrical trace  56 , in the region where the motor counterpart plug contact  22   b  leading to the control motor  20  is located, is bent at and angle 90° and extends in the direction of the motor counterpart plug contact  22   b . There, the electrical trace  56  ends in the form of the motor plug contact  22   a . If the lid  24  is secured to the throttle valve housing  2 , then the control motor  20  has electrical contact via the motor counterpart plug contact  22   b , the motor plug contact  22   b  located on the end of the electrical trace  56 , and the electrical trace  56  to the coupling part  44 . 
     An oblong indentation  58  is provided on the inner side  24   a  of the lid  24 . The shaft  16  protrudes past the gear wheel  18  on both ends. On one end, the shaft  16  is retained in the throttle valve housing  2 , and on the other side of the gear wheel  18  the shaft  16  protrudes with slight radial play into the indentation  58 . This creates an assembly aid  60  that facilitates the mounting of the lid  24  on the throttle valve housing  2 . 
     The sensor  40  of the prior art device of FIG. 1 is a  20  potentiometer sensor which includes a wiper  14  fixedly mounted to the face end  12   a  of gear  12 . Three further wipers  14 ′,  14 ″,  14 ′″ are secured to the face end  12   a  beside the wiper  14 . The lid  24  has an inner side  24   a  toward the chamber  32 . A carrier material  36  for a potentiometer  40  is applied to the inner side  24   a , facing the wipers  14 ,  14 ′,  14 ″,  14 ′″. For example the carrier material  36  is glued to the inner side  24   a . The wipers  14 ,  14 ′,  14 ″ and  14 ′″, sweep along a plurality of potentiometer paths  42 ,  42 ′,  42 ″ and  42 ′″, formed on the carrier material  36 , as the throttle valve shaft  6  rotates, thereby determining the rotational position of the throttle valve  10 . 
     Turning to FIGS. 3-7, the preferred embodiments of the invention are shown. In these embodiments, a non-contacting throttle valve position sensor  70 ,  170  for the throttle control valve  10  (which retains the throttle valve shaft  6  in the throttle housing  2 , control motor  20  and geared transmission  12 ,  18 ,  20   b ) is substituted for the potentiometer sensor  40 , which is illustrated in FIGS. 1 and 2. 
     Non-contacting throttle valve position sensors  70 ,  170  are preferably Hall effect type magnetic field sensors like those shown in U.S. Pat. Nos. 5,798,639, 5,757,179 and 5,712,561. In FIG. 3, sensor  70  is shown to include magnet structure  69  including first and second magnetized portions  72 ,  74 , which are attached to arms  83 ,  85 , or sensor shaft  78 , and air gap  100 . Sensors  70 ,  170  also include Hall effect sensors  90 , the function of which will be described below. 
     Referring specifically to FIG. 3, sensor shaft or extension portion  78  extends away from gear  12  to space magnetized portion  72  from magnetized portion  74  and may be magnetically permeable for flux routing. First and second magnetized portions  72 ,  74  extend in parallel to each other and gear wheel  12 , and are spaced apart from one another as they extend from extension  78  to create air gap  100 . Extension portion  78  may also be rotatably supported at an end thereof by lid  24 , which acts as the throttle valve cover. A pilot  80  may be provided on lid  24  to support extension portion  78  and throttle valve shaft  6 . 
     FIGS. 4 and 5 show detailed views of the first embodiment. FIG. 4 shows a cross-section view of FIG. 3 illustrating arm  83  mounted on gear  12 . FIG. 5 shows the inter-relation of magnetized portions  72 ,  74  and Hall effect sensor  90 . As shown in FIG. 4, gear  12  includes gear teeth  12   a  that may extend all the way around for meshing with gear wheel  18 . The arm  83  and, hence, sensor shaft  78  and arm  85  are locked in position with gear  12  by a lock  76  and are movable with gear wheel  12 . It is important to recognize that other mounting mechanisms, other than lock  76 , are possible. For instance, first magnetized portion  72  may be glued or welded to gear wheel  12 . 
     As best shown in FIG. 5, magnetized portions  72 ,  74  have thicker or larger ends  73  and narrower or smaller ends  71  with a gradually changing thickness therebetween. As a result, the magnetized portions  72 ,  74  include facing surfaces  79 ,  81  that widen away from each other as the magnetized portions  72 ,  74  thin out. By way of the thinning thicknesses, a magnetic field that varies along the lengths of the magnetized portions  72 ,  74  is created. The magnetic field has a larger/stronger signal between thicker sections  73  and a smaller/weaker signal between the narrower ends  71 . The magnetized portions  72 ,  74  are also arcuate about axis  77 , as shown in FIGS. 4 and 5. It is important to note that while two magnetized portions  72 ,  74  are preferred, one magnetic portion may be employed without departing from the scope of this invention. In that cage, the varying magnetic field would be created by one varying thickness magnetized portion and an opposing magnetically permeable plate, like steel. It is important to note that while a particular structure of magnetized portion has been disclosed, other structures are also possible, for example, as disclosed in related application to Duesler et al. entitled “Non-contacting Position Sensor Using Bipolar Tapered Magnets,” filed Dec. 9, 1998, having attorney docket number CTS-1835 or CTS-9599 and application Ser. No. 09/208,296, now U.S. Pat. No. 6,211,668 B1. 
     Magnetized portions  72 ,  74  are preferably formed by molding magnetic materials such as bonded ferrite. Bonded ferrite offers both a substantial cost advantage and also a significant advantage over other similar magnetic materials in structural loss due to corrosion and other environmental degradation. 
     Referring to FIG. 3, Hall effect sensor  90  is placed near, and preferably between, first and second magnetized portions  72 ,  74  to sense the flux density that changes with rotational position and determines the position of gear wheel  12  and, hence, throttle valve shaft  6 . Sensor  90  may have its circuitry  92  provided on lid  24  such that the above-described advantages of having an easily installed and manufactured, compact and accurate sensor mechanism are maintained. Circuitry  92  preferably couples to electrical traces  51 - 54  (FIG.  2 ), as necessary, for communication with an electric control unit via coupling part  44 , as described above. It is important to note, however, that the circuitry  92  of non-contacting sensor  70  may be provided in other positions as well. For instance, it is contemplated that circuitry  92  could be compartmentalized with the other components of sensor  70  for insertion as a separate structure between gear wheel  12  and lid  24 . Circuitry  92  could also be mounted on throttle valve housing  2  within connection chamber  32 . 
     FIGS. 6 and 7 show the sensor  170  in greater detail. FIG. 6 shows an alternative for extension portion  78  in which the extension may be an integral part of end  6   b  of throttle valve shaft  6 . Magnet structure  69  is coupled to and integral with gear  12 . Uniquely, first magnetized portion  72  is molded as part of or integral with gear  12 . This feature may be provided in a variety of fashions and not depart from the scope of this invention. For instance, gear wheel  12  can have a pocket formed therein in which first magnetized portion  72  is mounted. Also, halt of gear wheel  12  Could be formed as first magnetized portion  72  including possibly exterior gear teeth  12   b . Finally, if only a part of gear wheel  12  is utilized, a bottom portion of gear wheel  12  can be replaced by first magnetized portion  72 . In any regard, it is also preferable, although not necessary, to provide second magnetized portion  74  integrally mounted within an arm  75 , extending from extension portion  78 , spaced from and parallel to first magnetized portion  72 . Another alternative, illustrated in FIG. 7, is that gear  12  includes gear teeth  12   b  only around a portion thereof that is necessary for meshing with gear wheel  18 . This reduces the amount of machining. 
     Sensor  90  is placed near, and preferably between, first and second magnetized portions  72 ,  74  in the air gap  100  to sense the rotational position of magnetized portions  72 ,  74  and to determine the position of gear wheel  12  and, hence, throttle valve shaft  6 . 
     While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined in the following claims. 
     For instance, the extension portion or sensor shaft  78  may be most any shape or size. Further, the magnet structure  69  of the invention need not be coupled to gear wheel  12  as operation of the invention can be achieved by coupling non-contacting sensor  70  to any movable portion of the geared transmission, e.g., the sensor in accordance with the invention could be coupled to gears  18  or  20   b . The sensor  70  could also be mounted to the top of lid  24 , have a separate enclosure, with sensor shaft  78  being coupled to one of the rotating gear shafts that would extend up into the separate sensor enclosure. 
     It is noted that sensor  70  is mounted within chamber  32  and is covered by throttle valve cover or lid  24 . Additionally, sensor  70  and motor coupling  22  are in the same chamber  32 , along with gears  12 ,  18  and  20   b , and motor  20 . Although connector  44  is positioned away form sensor  70 , it is contemplated to move the connector close to sensor  70 .