Abstract:
A side-mount bracket system for locking the sensor position with respect to a side-mount bracket once the air gap is first established by the gauging layer method, wherein the sensor may be removed and then reinstalled without use of any position setting procedure, yet the air gap is automatically precisely reset to its original value. The side-mount bracket system according to the present invention includes a washer and a side-mount bracket having an elongated slot, wherein as the washer is brought into the slot, facial interaction therebetween, eg., teeth inscribing a smooth surface, causes the washer to be positionally fixed with respect to the bracket. Alternatively, the washer may be slidably trapped onto the bracket at the slot, and a tapered bolt having a varying cross-section which causes expansion of the washer as it is threaded home, thereby affixing the washer positionally with respect to the bracket.

Description:
TECHNICAL FIELD 
     The present invention relates to brackets for holding a first object with respect to a second object. More particularly, the present invention relates to a side-mount bracket for precisely locating a sensor relative to an object to be sensed. Still more particularly, the present invention relates to a side-mount bracket system, wherein facial interaction between a bracket and a washer results in the washer being fixed positionally with respect to the bracket. The present invention is further related to air gap setting methodologies incorporating abradable setting features, wherein the air gap thereby set is permanently captured at the side-mount bracket system. 
     BACKGROUND OF THE INVENTION 
     Magnetic sensors operate on the principle of detecting magnetic flux density modulation caused by the movement of appropriately configured reluctors (or targets). The magnetic sensor must be affixed very close to the reluctor since its sensitivity decreases very rapidly with the size of the air gap between the reluctor and the magnetic sensor. In most automotive applications, for example, the air gaps are on the order of 0.3 to 1.75 mm. Over such a range of air gaps, the sensor output signal decreases more than ten times. The signal attenuation at large air gaps makes the sensor operation more prone to noise induced failures as well as less accurate in detecting the elements of the reluctor as it spins in relation to the magnetic sensor. Both of these factors are often unacceptable in critical engine control and diagnostic applications. 
     It may at first glance appear that there would be no problem whatsoever to choose and achieve an appropriate air gap between the magnetic sensor and the reluctor. However, in the majority of production cases, the stack-up of tolerances of the many different components randomly influence the net size of the air gap, which consequently precludes achieving, at each assembly, a precisely predetermined air gap by mere assembly of the parts. As a result, because of the random variations caused by accumulation of tolerances, mere assembly of the parts risks damaging interference between the magnetic sensor and reluctor on the one hand, and inaccurate readings associated with too large an air gap on the other hand. To lessen all the tolerances so that mere assembly assures, at each assembly, the optimum air gap is physically unrealistic and involves inordinate costs associated with manufacturing such precise parts. 
     The majority of magnetic sensors used in automotive applications involve non-adjustable air gap placement, wherein the stack-up of tolerances causes deviation from the optimal air gap. For example, a rigid bracket is affixed to the body of a magnetic sensor. The magnetic sensor is placed into a sensor port in the engine block, and the bracket is bolted, via a bolt hole in the bracket, to a threaded mounting hole in a mounting surface of the engine block. When the bracket is bolted, the length of the sensor body from the bolt hole of the bracket to the sensor tip determines the air gap with respect to the reluctor, which air gap is affected by the stack-up of tolerances. Even though subject to tolerance related placement inaccuracy, this structural mounting methodology is used widely because of the simplicity of the hardware, and ease of assembly and service. 
     In situations where air gap variation cannot be tolerated, the air gap is preset during magnetic sensor installation by means of an adjustable bracket, often referred to as a “side-mount” bracket. The adjustability of side-mount brackets resides in a bolt slot which allows for the bracket to be adjusted along the slot elongation relative to the threaded mounting hole of the mounting surface. 
     In one form of operation of the side-mount bracket, the sensor body is placed into the sensor port of the engine block such that the sensor tip is allowed to touch the surface of the reluctor, and then it is withdrawn a distance equal to the predetermined optimum air gap. This method is more time consuming and is error prone. 
     In another form of operation of the side-mount bracket, a gauging layer of soft, abradable material is placed onto the sensor tip, wherein the thickness of the gauging layer is equal to the optimum air gap. The gauging layer may be either attached to the sensor body or be a part thereof, such as a protuberance, provided the sensor body is of a soft material. Now, the installer need merely place the sensor body into the sensor port until the gauging layer touches the reluctor, and then tighten the bolt on the mounting surface to thereby hold the sensor body at this position. During initial rotation of the reluctor, a portion of the gauging layer is sacrificial to abrasion due to reluctor run-out or differential thermal expansion without damage being incurred to the sensor body or the reluctor. 
     However, in the event the magnetic sensor must be re-installed, the abraded gauging layer cannot again provide position location for the sensor tip, as it was formerly able to do when it was unabraded. Therefore, before dismounting the magnetic sensor, the bracket must be marked to indicate the correct position of the bolt in the slot of the bracket so that when the “old” (original) magnetic sensor is re-installed, the original position of the bolt in the slot can be alignably sighted—not an exact procedure. Indeed, rather than try to reinstall the old, but still usable, sensor using the sighting method to reset the air gap, a technician would rather install a new sensor having the abradable layer intact, thereby circumventing the error prone sighting step otherwise needed to reinstall the old, but usable, sensor. This results in waste of otherwise good sensors and unnecessary expense for the customer or warranty provider. Accordingly, what remains needed in the art, is some way to eliminate the inherently error prone installation procedure of the sighting method, and enable precise and reliable resetting of the air gap during reinstallation of old, but still usable, sensors. 
     SUMMARY OF THE INVENTION 
     The present invention is a side-mount bracket system for locking the sensor position with respect to a side-mount bracket once the air gap is first established by the gauging layer method, wherein the sensor may be removed and then reinstalled without use of any position setting procedure, yet the air gap is automatically precisely reset to its original value. 
     The side-mount bracket system according to the present invention includes a washer and a side-mount bracket having an elongated slot, wherein as the washer is brought into the slot, facial interaction therebetween causes the washer to be positionally fixed with respect to the bracket. In this regard, either the slot sidewalls or the washer sidewalls are provided with teeth, the other of the sidewalls are smooth. The teeth are oriented parallel to the direction of insertion of the washer into the slot, referred to herein as the “transverse axis”. The member having the toothed sidewalls is formed of a material harder than the member having the smooth sidewalls. The teeth of the toothed sidewalls may be provided in any suitable form, such as for example serrations, cutting ridges or cutting surfaces. A slight draft is preferred to be provided on the washer sidewalls to facilitate an initial engagement surface of the washer to be inserted into the slot with minimum interference by the slot sidewalls. 
     The washer and slot are dimensioned so that the sidewalls of the washer tightly abut the sidewalls of the slot, wherein the teeth of the toothed sidewalls inscribe corresponding grooves into the smooth sidewalls as the washer is pressed into the slot along the transverse axis. Consequently, as the corresponding grooves are inscribed, the washer sidewalls are caused to become positionally fixed with respect to the bracket along a “longitudinal axis” that is perpendicular to the transverse axis. 
     Operationally, a sensor body having a sensor tip provided with a gauging layer is placed into a sensor port of an engine block so that the gauging layer comes to rest upon a surface of a reluctor. The gauging layer thereupon immediately establishes the optimum air gap between the sensor and the reluctor along the longitudinal axis. A washer having a bolt hole sized to just fit a preselected bolt is slipped onto the bolt. With a side-mount bracket having an elongated slot preconnected with the sensor, the bolt carrying the washer is passed through the slot and threadably into a threaded mounting hole of the vertical surface. The washer and the slot have complementary sidewalls, wherein one is toothed, the other is smooth, such that the fit therebetween is interfering, wherein the toothed sidewalls score into the smooth sidewalls. Accordingly, as the bolt is tightened, the washer moves along the transverse axis, and facial interaction between the toothed and smooth sidewalls causes the washer to become fixed to the bracket, wherein the position of the sensor is fixed along the longitudinal axis. 
     During engine operation, a portion of the gauging layer is sacrificially lost to abrasion. However, should the sensor need to be removed and then again replaced, the washer remains fixed to the bracket, and all the installer need do is place the bolt through the mounting hole of the sensor body, through the bolt hole of the washer, and then threadably engage it into the threaded mounting hole of the vertical surface, and the preset air gap will be precisely re-established. 
     In a second embodiment, the washer may be slidably trapped onto the bracket at the slot, and a tapered bolt having a varying cross-section which causes expansion of the washer as it is threaded home, thereby affixing the washer positionally with respect to the bracket. 
     In a third embodiment, as a bolt is threaded tightly, annular flanges at either end of a washer are caused to be squeezed onto the bracket adjacent the slot, thereby affixing the washer positionally with respect to the bracket. 
     Accordingly, it is an object of the present invention to provide a side-mount bracket system which affixes a washer to a side-mount bracket at a positional location indicative of a preset air gap of a sensor attached to the bracket. 
     It is a further object of the present invention to provide a side-mount bracket system, wherein a predetermined facial interaction between the sidewalls of a slot of a side-mount bracket and the sidewalls of a washer capture a positional location of a sensor with respect to the bracket which is precisely reproducible. 
     It is another object of the present invention to provide a side-mount bracket system which operates in concert with a gauging layer air gap positioning methodology which retains the air gap setting whether or not any of the gauging layer is sacrificially abraded during operation. 
     These, and additional objects, advantages, features and benefits of the present invention will become apparent from the following specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partly sectional side view of the side-mount bracket system according to the present invention, shown in a typical environment of operation wherein a magnetic sensor is spaced from a reluctor a distance equal to an optimum air gap that is established by a gauging layer. 
     FIG. 2 is a front side view of a first embodiment of the side-mount bracket system according to the present invention. 
     FIG. 3 is a partly sectional side view of the first embodiment of the side-mount bracket system, shown operationally prior to mutual engagement of the side-mount bracket and washer thereof. 
     FIG. 4 is a partly sectional side view of the first embodiment of the side-mount bracket system, shown operationally after mutual engagement of the side-mount bracket and washer thereof. 
     FIG. 5 is a partly sectional side view of a variation of the first embodiment of the side-mount bracket system, shown operationally after mutual engagement of the side-mount bracket and washer thereof. 
     FIG. 6 is a front side view of a second embodiment of the side-mount bracket system according to the present invention. 
     FIG. 7 is a partly sectional side view of the second embodiment of the side-mount bracket system, shown operationally after full engagement of a tapered bolt. 
     FIG. 8 is a detail, partly sectional side view of the second embodiment of the side-mount bracket system shown prior to full engagement of the tapered bolt. 
     FIG. 9 is a detail, partly sectional side view of a third embodiment of the side-mount bracket system, shown prior to full engagement of a bolt. 
     FIG. 10 is a detail, partly sectional side view of the third embodiment of the side-mount bracket system, shown after full engagement of the bolt. 
     FIG. 11 is a front side view of the third embodiment of the side-mount bracket system according to the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the Drawings, FIG. 1 generally depicts the side-mount bracket system  10  according to the present invention in an exemplar environment of operation, wherein the side-mount bracket system serves to locate a magnetic sensor  12  with respect to a reluctor  14 . In this regard, the magnetic sensor  12  has a sensor body  16  which includes a sensor tip  18 . The sensor tip  18  extends into a sensor port  20  of an engine block  22  and is spaced from the reluctor  14  a predetermined distance equal to an optimum air gap G which provides optimal sensing performance by the magnetic sensor of magnetic field variations as the reluctor spins. 
     The air gap G is defined when a gauging layer  25 , which is attached to, or is a formed part of, the sensor tip  18  abuts the reluctor  14 , as shown. The gauging layer  25  is composed of a soft abradable material which is sacrificed to abrasion as the reluctor rotates when differential thermal expansion or run-out causes the gauging layer to rub against the reluctor. 
     A side-mount bracket  26  (hereafter, simply “bracket”) of the side-mount bracket system  10  is affixed to the sensor body  16 . The bracket  26  may be L-shaped wherein a transverse leg is connected to the sensor body  16 , as shown at FIG. 1, or flatly connected with the sensor body, having a configuration analogous to that of a flag and its flagpole. The bracket  26  has a slot  28  which is elongated along a longitudinal axis L that is parallel to the cylindrical axis of the sensor body  16 , wherein the sensor tip  18  is oriented parallel to the longitudinal axis. A washer  30  of the side-mount bracket system  10  is dimensioned to fit into the slot  28  by a press-fit along a transverse axis T that is perpendicular to the longitudinal axis L. A bolt  32  carries the washer  30 , passes through the slot  28  and threadably engages a threaded mounting hole  34  formed in a vertical mounting surface  36  (by the term “vertical” is meant oriented parallel to the center axis of the sensor port  20 ). 
     With reference now to FIGS. 2 through 8, the structure and function of the side-mount bracket system will be further described whereby the setting of the air gap G is automatically memorized by the bracket  26  and washer  30  as the washer is press-fit into the slot  28 . 
     FIGS. 2 through 5 depict a first embodiment of the side-mount bracket system  10 , which is considered most preferred, and is the form of the side-mount bracket system shown at FIG.  1 . 
     The bracket  26  shown is of the L-shaped type, including a longitudinal leg  26 A oriented parallel to the longitudinal axis and having the slot  28  formed therein, and further including a transverse leg  26 B oriented parallel to the transverse axis and having connection to the sensor body  16 . The slot  28  has a pair of opposing slot sidewalls  38 ,  40  oriented parallel to the longitudinal axis L (of FIG. 1) which are smooth. 
     The washer  30  is constructed of a harder material than that of the bracket  26  and has a bolt hole  44  for receiving therethrough a bolt  32  (as shown at FIG.  1 ). The washer  30  is annularly shaped, most preferably somewhat conically so as to have a reduced draft for ease of initial entry into the slot  28 . The washer  30  is toothed, wherein the teeth  42  of opposing sidewalls  46 ,  48  respectively abut the sidewalls  38 ,  40  of the slot  28 . The teeth  42  may be finely spaced or coarsely spaced, and may be in any suitable form, such as for example serrations, cutting ridges or cutting surfaces arranged parallel to the bolt hole axis. 
     As shown at FIG. 2, when the washer  30  is aligned over the slot  28 , the crests  42 A of the teeth of the washer sidewalls  46 ,  48  are located so as to overlap the sidewalls  38 ,  40  of the slot. Thus, for the washer  30  to be received into the slot  28 , it must be press-fit therein, where during the teeth  42  inscribably cut or deform the slot sidewalls  38 ,  40 . It is preferred for the washer to be annular in shape, but other shapes may be used, such as for example a rectilinear shape. 
     FIGS. 3 and 4 depict the side-mount bracket system  10  in operation. 
     The installer grasps the magnetic sensor  12  and places the sensor tip  18  of the sensor body  16  into the sensor port  20  of the engine block  22  so that the gauging layer  25  touches the reluctor  14 . The washer  30  is placed onto the bolt  32  and the bolt is placed through the slot  28  and then loosely threaded into the threaded mounting hole  34  of the vertical mounting surface  36 , wherein the longitudinal leg  26 A of the bracket  26  lies against the vertical mounting surface, until the washer sidewalls  46 ,  48  touch the slot sidewalls  38 ,  40  (see FIG.  2 ). The installer continues to thread the bolt into the threaded mounting hole, thereby causing the washer  30  to be pressed into the slot  28  along the transverse axis T. As the washer penetrates into the slot, the teeth of the washer sidewalls inscribe the smooth slot sidewalls. Because of the inscribing, the washer becomes fixed upon the bracket, and as a result of this facial interaction is prevented from moving independent of the bracket in the longitudinal direction. 
     Now, if the sensor  12  ever needs to be removed, it can later be reinstalled by simply running the bolt through the bolt hole of the washer, and the fixed position of the washer in relation to the bracket provides a memory of the prior preset air gap G. 
     FIG. 5 depicts a variation of the first embodiment of the side-mount bracket system  10 , wherein the teeth  42 ′ are located on the sidewalls of the slot  28 ′ of the bracket  26 ′ (having longitudinal and transverse legs  26 A′,  26 B′), and wherein the sidewalls of the washer  30 ′ are smooth. Operation is similar to that above recounted, wherein like numerals reference like features, and wherein the washer penetrates into the slot. Now, however, the harder teeth of the slot sidewalls inscribe the softer smooth washer sidewalls. Again, because of the inscribing, the washer becomes fixed upon the bracket, and is prevented from moving independent of the bracket in the longitudinal direction. And again, if the sensor ever needs to be removed, it can later be reinstalled by simply running the bolt through the bolt hole of the washer, and the fixed position of the washer in relation to the bracket (FIG. 2) provides a memory of the prior preset air gap G. 
     Turning attention now to FIGS. 6 through 8, a second embodiment of the side-mount bracket  10 ′ will be detailed. 
     The bracket  26 ″ is again shown as the L-shaped type, and includes a longitudinal leg  26 A″ having a slot  28 ″ formed therein, and a transverse leg  26 B″ connected to the sensor body  16  of the sensor  12 . The slot  28 ″ has a pair of opposing slot sidewalls  38 ″,  40 ″ which are smooth. 
     The washer  30 ″ has a relatively thin-walled, sleeve-like central portion  30 A and a pair of annular flanges  30 B,  30 C (see FIG. 8) integrally connected at opposing ends thereof. The washer  30 ″ is trapped with respect to the slot  28 ″ (wherein the central portion is trapped in the slot) by the annular flanges  30 B,  30 C overhanging the sidewalls  38 ″,  40 ″, wherein the central portion  30 A is sized so as to be slidable in the slot. At least one sidewall  46 ″,  48 ″ of the central portion  30 A (or alternatively at least one of the sidewalls  38 ″,  40 ″ of the slot  28 ″) is provided with teeth  42 ″, wherein the teeth are harder than the opposing sidewall. To facilitate temporary placement of the washer  30 ″ with respect to the slot, it is preferred for the surfaces of the annular flanges  30 B,  30 C facing the bracket and/or a portion of the bracket capable of contacting the annular flanges to provide a frictional interplay  50 , such as by roughening. 
     A tapered bolt  32 ″ is provided, having a larger diameter neck  32 A, a narrower diameter threaded shank  32 B and a taper  32 C therebetween. The diameter of the central portion  30 A and the bolt hole  44 ″ of the washer  30 ″ are coordinated with the dimensions of the slot  28 ″ and the tapered bolt  32 ″. In this regard, the threaded shank  32 B of the tapered bolt  32 ″ passes through the bolt hole  44 ″ without causing distortion of the central portion  30 A. However, when the neck  32 A enters the bolt hole  44 ″, the central portion  30 A expands compressibly against the slot sidewalls which forces the teeth  42 ″ to be driven into the smooth sidewall of the slot  28 ″, and causes the washer  30 ″ to become positionally fixed with respect to the bracket  26 ″. The material of the washer  30 ″ is selected so that if the tapered bolt  32 ″ is removed, the expanded central portion remains permanently expanded and fixed with respect to the slot. 
     In operation, the installer grasps the magnetic sensor  12  and places the sensor tip  18  of the sensor body  16  into the sensor port  20  of the engine block  22  so that the gauging layer  25  touches the reluctor  14 . The washer  30 ″ is moved along the slot so that the bolt hole aligns with the threaded mounting hole  34  in the vertical surface  36 . The threaded shank  32 B of the tapered bolt  32 ″ is now threaded into the threaded mounting hole  34 . As the neck  32 C enters the bolt hole  44 ″, the central portion becomes expanded and the teeth bite into the slot sidewall to thereby fix the position of the washer with respect to the bracket, which, as a consequence of this facial interaction, is prevented from moving independent of the bracket in the longitudinal direction. 
     Now, if the sensor  12  ever needs to be removed, it can later be reinstalled by simply running the bolt through the bolt hole of the washer, and the fixed position of the washer in relation to the bracket (FIG. 6) provides a memory of the prior preset air gap G. 
     Turning attention now to FIGS. 9 though  11 , a third embodiment of the side-mount bracket  10 ″ will be detailed. 
     The bracket  26 ″ is as recounted with respect to the second embodiment, again being of the L-shaped type, and including a longitudinal leg  26 A″ having a slot  28 ″ formed therein, and a transverse leg  26 B″ connected to the sensor body  16  of the sensor  12 . The slot  28 ″ has a pair of opposing slot sidewalls  38 ″,  40 ″ which are smooth. 
     The washer  30 ′″ now has a central portion  30 A′ with a first annular flange  30 B′ at one end and, at the other end, either a flangeable portion  30 C″ capable of becoming a second annular flange  30 C′ when crimped by the head of the bolt  32  as the bolt is tightened (FIG.  9 ), or a preformed second annular flange  30 C′ (FIG.  10 ). The washer  30 ′″ is trapped with respect to the slot  28 ′ when the annular flanges are both present (FIG.  10 ), wherein the annular flanges overhang the sidewalls  38 ″,  40 ″, and wherein the central portion  30 A′ is sized so as to be slidable in the slot. To facilitate affixing of the washer  30 ′″ with respect to the slot when the annular flanges are crimped thereagainst, it is preferred for the surfaces of the annular flanges  30 B′,  30 C′ facing the bracket and/or a portion of the bracket capable of contacting the annular flanges to provide a frictional interplay  50 , such as by roughening. 
     A bolt  32  is provided for passing through the bolt hole  44 ′″ of the washer  30 ′″. In this regard, the bolt  32  passes through the bolt hole  44 ′″ without causing distortion of the central portion  30 A′. However, when the bolt  32  is tightened into the threaded mounting hole  34 , the annular flanges  30 B′,  30 C′ are caused to crimpably compress upon the bracket  26   a , thereby affixing the washer  30 ′″ to the bracket at that location. The material of the washer  30 ′″ is selected so that if the bolt  32  is removed, the annular flanges remain permanently crimped against the bracket. 
     In operation, the installer grasps the magnetic sensor  12  and places the sensor tip  18  of the sensor body  16  into the sensor port  20  of the engine block  22  so that the gauging layer  25  touches the reluctor  14 . Either the washer  30 ′″ is inserted into the slot  28 ″ via the flangeable portion  30 C″ or is pre-mated to the bracket by both annular flanges being already pre-formed. The washer  30 ′″ is moved along the slot so that the bolt hole aligns with the threaded mounting hole  34  in the vertical surface  36 . The bolt  32  is now threaded into the threaded mounting hole  34 . As the bolt tightens, if the flangeable portion is present, an annular flange is formed thereof as it is flattened by the bolt head. As the bolt is further tightened (in any event the second flange now being present), the annular flanges become crimped against the bracket adjacent the slot, thereby frictionally affixing the position of the washer with respect to the bracket, which, as a consequence of this facial interaction, is prevented from moving independent of the bracket in the longitudinal direction. 
     Now, if the sensor  12  ever needs to be removed, it can later be reinstalled by simply running the bolt through the bolt hole of the washer, and the fixed position of the washer in relation to the bracket (FIG. 11) provides a memory of the prior preset air gap G. 
     It is to be understood that the facial interaction in the first and second embodiments is preferred to include teeth, but this is not required, so long as the facial interaction provided locks the washer in position relative to the bracket. For example roughening (ie., roughening  50 ) may be provided on the harder sidewalls in place of the teeth, where teeth are shown. Further, the flanges may be other than annular in shape, and that by the term “smooth” as used herein is meant that the surface is able to accept inscribing by the teeth as described hereinabove, whether or not the surface is actually physically smooth. 
     To those skilled in the art to which this invention appertains, the above described preferred embodiments may be subject to change or modification. Such change or modification can be carried out without departing from the scope of the invention, which is intended to be limited only by the scope of the appended claims.