# Patent

## Title
Semi-circular alignment features of an elastic averaging alignment system

## Abstract

A semi-circular male alignment feature elastic averaging alignment system utilizing a plurality of semi-circular male alignment features which interface by elastic averaging with a plurality of female alignment features, wherein semi-circular male alignment features of a first component are received during a mating process by respective female alignment features formed in a second component, whereby precise alignment of the first and second components and stiffness are provided by elastic averaging of the male and female alignment features.

## Background
TECHNICAL FIELD
The present invention relates to location features for aligning of components during a mating operation. More particularly, the present invention relates to a plurality of mutually spaced apart semi-circularly shaped alignment features of a first component which are received by corresponding apertures formed in a second component during the mating therebetween, whereby precise alignment of the first and second components is provided by elastic averaging of the alignment features.
BACKGROUND OF THE INVENTION
Currently, components which are to be mated together in an assembly process are mutually located with respect to each other by 2-way and/or 4-way male alignment features, typically upstanding bosses, which are received into corresponding female alignment features, typically apertures in the form of holes or slots. There is a clearance between the male alignment features and their respective female alignment features which is predetermined to match anticipated geometrical variation tolerances of the male and female alignment features as a result of manufacturing (or fabrication). As a result of the clearance, there can occur significant positional variation as between the mated first and second components which contributes to the presence of undesirably large and varying gaps and otherwise poor fit therebetween.
By way of example, FIGS. 1 through 6 illustrate a prior art location modality for the aligning of two mating components as well as their mutual conjoining to each other with respect to an exemplar assembly 5.
With respect to alignment, a first component 10 has a plurality of male alignment features in the form of an upstanding star shaped lug 17, 27 connected to a first base 14 of the first component. A second component 18 has a second base 30. A plurality of female alignment features in the form of a round slot 19 and oblong slots having rounded ends 29 are formed in the second base, and disposed so that each male alignment feature 17, 27 is received by a respective female alignment feature 19, 29. In this regard, male alignment feature 17 and its round female alignment feature 19 provide a four-way alignment feature 15 of the first and second components with respect to each other; and, each of the other male alignment features 27 and their respective oblong female alignment feature 29 provide a two-way alignment feature 25 of the first and second components with respect to each other.
With respect to conjoining, the first component 10 has a plurality of male staking features in the form of an upstanding rectangular tab 12 connected to the first base 14 of the first component. At the first base 14, juxtaposed each tab 12, is a plurality of bosses 16, four of which being depicted at FIG. 3. The second component 18 at the second base 30 has inverted U-shape portions 32 which rest upon the bosses 16 when the first and second components are mated (see FIG. 4). A plurality of female staking features in the form of a rectangular slots 20 are formed in the second base, and disposed so that each slot receives a respective tab 12 when the first component is mated to the second component.
As best shown at FIG. 3, each tab 12 is loosely received into its respective slot 20, wherein the clearance (spacing or gap) 22 between the sides 24, 26 of the slot and the sides 28, 34 of the tab allow positional adjustment therebetween for accommodating geometric variances introduced during manufacture of the first and second components. For example, the clearance 22 between the tab 12 and the slot 20 may be 0.75 mm, whereby the error of mating of the first component to the second component may be up to about a 1.5 mm float. This float allows the male alignment features 17, 27 to be guidingly aligned by their respective female alignment features 19, 29.
In operation, as the first and second components are mated together, the initial contact therebetween occurs when the tabs pass into the respective slots, whereby the first and second components are kept in a general alignment to one another as they are mated. The clearance 22 allows the mating to proceed smoothly and effortlessly as the four-way alignment feature 15 and the two-way alignment features 25 guide the first and second components into alignment. Problematically, however, because of the clearance 22 provided at each of the male and female staking features 12, 20 and the clearance 35 provided at each of the four-way and two-way alignment features 15, 25, there is a float as between the first and second components 10, 18, and this float (or play), allows for the first component to be aligned relative to the second component generally, but not precisely. When the first and second components are affixed to each other (as for example by heat staking 45 (shown at FIG. 2) of the male staking features 12, by threaded fasteners, etc., any such misfit of alignment of the first component relative to the second component becomes manifest, and the visible joint between the two components may be irregular, have too large a gap, be unbalanced in appearance, etc.; in any event the misfit of alignment rendering the fit unacceptable for a Class A finish of the assembly 5.
Accordingly, what remains needed in the art is to somehow provide an alignment modality for the mating of components, wherein when mating is completed there is a lack of play as between the male and female alignment features and provided is a precise alignment, yet the aligned mating proceeds smoothly and effortlessly each time.
SUMMARY OF THE INVENTION
The present invention is a semi-circular male alignment feature elastic averaging alignment system utilizing a plurality of semi-circular male alignment features which interface by elastic averaging with a plurality of female alignment features, wherein semi-circular male alignment features of a first component are received during a mating process by respective female alignment features formed in a second component to provide an assembly having precise alignment of the first and second components, as well as stiffness therebetween, by elastic averaging of the male and female alignment features.
The semi-circular male alignment features are in the form of semi-circular studs vertically upstanding in perpendicular relation to a first base of a first component. Each semi-circular stud has a semi-circular cross-section characterized by a first face which is convexly shaped and a second face, opposed to the first face, which is characterized by a concavely shaped vertically disposed facial groove flanked on either side by left and right sidewalls which are planar truncated. Each semi-circular male alignment feature has a stud length which is much longer then a stud width. The semi-circular male alignment features have a stud height above the first base which preferably features tapering with increasing height from the first base, terminating at a generally rounded crest. Juxtaposed each male alignment feature is a plurality of bosses.
The female alignment features are apertures formed at a second base of a second component intended to be mated to the first component, wherein the second base is positioned, as for example by an inverted U-shape, so as to rest upon the bosses when the first and second components are fully mated. The shape of each aperture is preferably in the form of elongated slots, having an aperture length which is much longer than an aperture width.
The dimension of the female alignment features in relation to the semi-circular male alignment features is such that the aperture length exceeds the stud length, and the aperture width is less that the stud width adjacent the bosses. As such, as the first component is mated to the second component and the semi-circular studs are inserting into the apertures, the stud width will at first be less, then meet, and then exceed the aperture width, causing the second base to become elastically deformed, whereby the semi-circular studs become elastic averaged relative to the apertures.
In addition, the semi-circular studs may, on average, elastically deform by twisting. This stud twisting originates in situations in which each of the left and right sidewalls are not aligned exactly with a respectively facing aperture wall of the apertures during the mating process. In this regard, as mating completes, the semi-circular studs twist so that both the left and right sidewalls flatly and firmly abut their respectively facing aperture wall, while the twisting is upon the facial apex which firmly abuts its respectively facing aperture wall disposed opposite the first aperture wall. Preferably, the above mentioned elastic deformation of the second component occurs at the aperture wall abutting the first face of the semi-circular stud.
In accordance with the present invention, the elastic averaging provides a precise alignment of the components within a variance X′, defined by X′=X/√N, where X is the average geometrical variance of the studs and the apertures, and N is the number thereof. Thus, the needed clearance for the male and female alignment features of the prior art is obviated by the present invention.
Accordingly, it is an object of the present invention to provide a plurality of semi-circular male alignment features in the form of vertically upstanding semi-circular studs disposed on a first component and a corresponding plurality of female alignment features in the form of apertures formed in a second component, wherein during mating of the first and second components, elastic averaging of the male and female alignment features provides precise alignment of the first and second components, as well as imparting stiffness therebetween.
This and additional objects, features and advantages of the present invention will become clearer from the following specification of a preferred embodiment.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an assembly, wherein a first component is generally aligned to a second component, and wherein prior art alignment and conjoining modalities are utilized.
FIG. 2 is a detail, cut-away view, seen at demarcation 2 of FIG. 1.
FIG. 3 is a detail, cut-away view, seen at demarcation 3 of FIG. 2.
FIG. 4 is a detail, cut-away view, seen along line 4-4 of FIG. 2.
FIG. 5 is a detail, cut-away view, seen at demarcation 5 of FIG. 1.
FIG. 6 is a detail, cut-away view, seen at demarcation 6 of FIG. 1.
FIG. 7 is a perspective view of an assembly, wherein a first component is precisely aligned to a second component via elastic averaging of semi-circular male alignment features with respect to female alignment features in accordance with the present invention.
FIG. 8 is a perspective view, seen at demarcation 8 of FIG. 7.
FIG. 9 is a detail, cut-away view, seen at demarcation 9 of FIG. 8.
FIG. 10 is a plan view of a first face of a semi-circular male alignment feature according to the present invention.
FIG. 11 is a plan view of a second face of the semi-circular male alignment feature according to the present invention.
FIG. 12 is a top plan view of the semi-circular male alignment feature according to the present invention.
FIG. 13 is a perspective view of the semi-circular male alignment feature fully inserted into its respective female alignment feature in accordance with the present invention.
FIG. 14 is a plan view of the semi-circular male alignment feature fully inserted into its respective female alignment feature, seen from the first side of the semi-circular male alignment feature.
FIG. 15 is a plan view of the semi-circular male alignment feature fully inserted into its respective female alignment feature, seen from the second side of the semi-circular male alignment feature.
FIG. 16 is a top plan view of the semi-circular male alignment feature fully inserted into its respective female alignment feature.
FIG. 17 is a top plan view of the semi-circular male alignment feature fully inserted into its respective female alignment feature, demonstrating elastic twisting of a the semi-circular male alignment feature.



DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the Drawings, FIGS. 7 through 17 depict an example of the structure and function of the semi-circular male alignment feature elastic averaging alignment system 100 according to the present invention, wherein an assembly 105 is shown merely by way of example at FIG. 7. In this regard, semi-circular male alignment features 102 are upstandingly disposed at a first component 104 and are interfaced by elastic averaging with respect to female alignment features 106 disposed at second component 108 when the first and second components are mated to each other to form an assembly, such as the assembly 105.
The semi-circular male alignment features 102 are in the form of semi-circular studs 110 which are attached to a first base 112 of the first component 104 in vertically upstanding (i.e., perpendicular) relation thereto. Each semi-circular stud 110 has a semi-circular cross-section characterized by a first face 114 which is convexly shaped forming a vertically disposed facial apex 116. Each semi-circular stud 110 further has a second face 118, disposed in opposition to the first face 114, which is characterized by a concavely shaped vertically disposed facial groove 120 that is flanked on either side by left and right sidewalls 122, 124 which are planar truncated along a vertical truncation plane 126 (see FIGS. 11 and 12).
Each semi-circular male alignment feature 102 has a stud length 128, as determined at the first base 112, that is measured parallel to the truncation plane 126 (see FIG. 10). The stud length 128 is much longer than a stud width 130 (see FIG. 12), wherein the stud width, as determined between the first and second faces 114, 118, is measured with respect to either of the left and right sidewalls 122, 124 of the second face and the facial apex 116 of the first face. The semi-circular male alignment features 102 have a stud height 132 above the first base 112 which provides for initial alignment of the first and second components 104, 108 (see FIG. 10). The alignment stud is preferably tapering with increasing height from the first base, terminating at a generally rounded crest 134 which preferably is characterized by a generally flattened top 135, wherein the tapering is preferably characterized by a lower taper 137 and an upper taper 139, wherein the upper taper is more acutely angled than is the lower taper.
Juxtaposed each semi-circular male alignment feature 102 is a plurality of bosses 136 connected with the first base 112. By way of exemplification, four bosses 136 are shown, two at each of the first and second faces 114, 118, respectively.
The female alignment features 106 are apertures 140 formed in a second base 142 of the second component 108 (see FIG. 13). The second base 142 is positioned, as for example by an inverted U-shape 144, so as to rest upon the bosses 136 (see FIG. 14) when the first and second components 104, 108 are fully mated with each other. The shape of each aperture 140 is preferably in the form of elongated slots (as shown), but may be otherwise, such as oblong holes with rounded ends, having an aperture length 146 which is much larger than an aperture width 148.
The dimension of the female alignment features 106 in relation to the semi-circular male alignment features 102 is such that an interfering fit therebetween is provided, wherein the aperture length 146 exceeds the stud length 128, and the aperture width 148 is less than the stud width 130 adjacent the bosses 136 (see FIG. 14). Further the stud height 132 is much larger than the thickness (inclusive of the inverted U-shape 144) 150 of the second base 142. As such, as the first component 104 is mated to the second component 108 and the semi-circular studs 110 insert into the apertures 140, the stud width 130 will at first be less, then will become equal to (due to the aforementioned tapering thereof), and then exceed the aperture width 148 as the first base 112 nears the bosses 136, causing the second base 142 to become elastically deformed (see FIG. 16), whereby the semi-circular studs 110 become elastic averaged with respect to the apertures 140.
The afore described elastic averaging occurs as follows. As mating of the first and second components 104, 108 progresses, a point is reached where the first face 114 of a semi-circular stud 110 comes into abutment with a first aperture wall 152 of its respective aperture 140, while at the same moment the second face 118 comes into abutment with a second aperture wall 154. More particularly, the facial apex 116 abuts the first aperture wall 152 and the left and right sidewalls 122, 124 abut the second aperture wall 154. As mating progresses to its end result when the first base 112 rests upon the bosses 136, a state of elastic compression is applied at the interface of the semi-circular male alignment features and the female alignment features, whereby an interfering fit is provided by the semi-circular stud 110 to the second base 142 relative to the first and second aperture walls 152, 154. This is elastically averaged over all the semi-circular studs and their respective apertures. Preferably, in this regard, each semi-circular stud 110 as well as the second base 142 are structurally rigid sufficiently that elastic deformation occurs in the second base only at the first aperture wall 152 by pressure applied thereto by the facial apex 116.
If during mating of the first and second components 104, 108 the first and/or second sidewalls 122, 124 are not are not exactly aligned with the second aperture wall 154 due to geometrical variation, then as mating progresses to completion, the one or more semi-circular studs 110 which are misaligned will elastically twist so that both the left and right sidewalls become flatly and firmly abutted with the second aperture wall. During this twisting, there is a pivoting of the facial apex 116 upon the first aperture wall 152. This elastic twisting is facilitated by the bosses 136, which raise the twist torque 160 above the first base. By way of exemplification, see comparison of dashed and solid lines of the semicircular male alignment feature in FIG. 17, wherein the twisting is in the direction of arrow 125.
After the mating operation, the first and second components are then affixed to each other, as for example by heat staking 162 of the male alignment features (see FIG. 8), by threaded fasteners, etc.
A preferred plastic material for the second component 108 in which the apertures 140 are disposed is one having elastic properties so as to deform without fracture, as for example acrylonitrile butadiene styrene (ABS).
Thus, it is seen that the semi-circular male alignment features 102 in cooperation with the female alignment features 106 collectively provide a two-way alignment feature, wherein the alignment axis 155 (see FIG. 16) is perpendicular to the first and second aperture walls 152, 154, passing centrally through the male alignment features in bisecting relation to the first and second sidewalls 122, 124 and the facial apex 116. In this regard, it is seen by the exemplar assembly 105 depicted at FIG. 7 that the various orientations of the male alignment features (along with their respective female alignment features) provides multi-directional alignment for the first component relative to the second component such that the fit therebetween is precise due to elastic averaging of all the male and female alignment features.
In accordance with the present invention, the elastic averaging provides a precise alignment of the components within a variance X′, defined by X′=X/√N, where X is the average geometrical variance of the studs and the apertures, and N is the number thereof Thus, the needed clearance for the male and female alignment features of the prior art is obviated by the present invention. In the exemplar assembly 105 of FIG. 7, N equals five across the top row (shown at FIG. 8), whereby the alignment axis therefore is along an ordinate 165, and for the left and right side rows N totals eight, whereby the alignment axis therefore is along an abscissa 175.
The semi-circular male alignment features 102 my be used in conjunction with elastic tube male alignment features in accordance with U.S. patent application Ser. No. 13/187,675 to Steven E. Morris, filed on Jul. 21, 2011, the disclosure of which is hereby incorporated herein by reference. In this regard by way of example with respect to FIG. 7, the five semi-circular male alignment features 102 remain as shown at the top row, and elastic tube male alignment features are disposed at the left and rights sides of the assembly in substitution for the four semi-circular male alignment features depicted at each of the left and right sides of the assembly.
It will be understood from the foregoing description that there are several notable aspects of the present invention. The present invention: 1) eliminates the geometrical variation associated with the clearances needed for a 2-way and 4-way locating schemes of the prior art; 2) accommodates geometric variation by elastically averaging as between the semi-circular male alignment features and the female alignment features; 3) eliminates the float of components as is present in the prior art; 4) provides an over constrained condition at the interfaces between the semi-circular male alignment features and the female alignment features, whereby stiffening of the assembly of the mated first and second components is provided and rattle therebetween is eliminated; 5) provides a precise location of the first and second components; 6) the elastic averaging (which is calculable using standard beam calculation techniques) provides a predictable uniformity and consistency in the fit as between the first and second components when mated; 7) provides further elastic averaging by twisting of the semi-circular male alignment features relative to the female alignment features; and 8) serves the dual purpose of both an alignment feature and a staking feature (if desired).
To those skilled in the art to which this invention appertains, the above described preferred embodiment 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.

## Claims

1. A semi-circular male alignment feature elastic averaging alignment system, comprising:
a first component having a first base;
a second component having a second base, said second base having a base thickness;
a plurality of semi-circular male alignment features disposed at said first base in upstanding relation thereto; and
a plurality of female alignment features formed in said second base, wherein each semi-circular male alignment feature is received by a respective female alignment feature when said first component is mated to said second component;
wherein when each said semi-circular male alignment feature is received into the respective female alignment feature of the second base during mating of said first component with respect to said second component, elastic deformation occurs at an interface between each semi-circular male alignment feature and the respective female alignment feature of the second base, wherein said elastic deformation is responsive to each said semi-circular male alignment feature being interferingly received by the respective female alignment feature;
wherein said elastic deformation is elastically averaged over said plurality of semi-circular male alignment features such that said first component is precisely located relative to said second component; and
wherein each said semi-circular male alignment feature comprises a semi-circular stud having a semi-circular cross-section comprising:
a first face having a convex shape forming a facial apex;
a second face having a facial groove flanked by a left sidewall and by a right sidewall; and
a stud height which is greater than said base thickness;
wherein said semi-circular stud tapers from said first base and terminates distally therefrom in a generally rounded crest.

2. The semi-circular male alignment feature elastic averaging alignment system of claim 1, wherein each said semi-circular stud has a stud width adjacent said first base between said first and second faces; wherein the respective female alignment feature has an aperture width; and wherein said elastic deformation is responsive to said stud width exceeding said aperture width.

3. The semi-circular male alignment feature elastic averaging alignment system of claim 2, wherein said elastic deformation occurs in said second base adjoining said first face.

4. The semi-circular male alignment feature elastic averaging alignment system of claim 3, wherein each said left and right sidewall is planar truncated.

5. The semi-circular male alignment feature elastic averaging alignment system of claim 4, wherein said elastic averaging further occurs by twisting of any said semi-circular stud in which said left and right sidewalls are misaligned with respect to the respective female alignment feature prior to the mating of said first and second components.

6. The semi-circular male alignment feature elastic averaging alignment system of claim 5, wherein said elastic deformation provides a stiffened assembly of said first and second components when said first and second components are mutually mated to each other.

7. A semi-circular male alignment feature elastic averaging alignment system, comprising:
a first component having a first base;
a second component having a second base, said second base having a base thickness;
a plurality of semi-circular male alignment features disposed at said first base in upstanding relation thereto; and
a plurality of female alignment features formed in said second base, wherein each semi-circular male alignment feature is received by a respective female alignment feature when said first component is mated to said second component;
wherein when each said semi-circular male alignment feature is received into the respective female alignment feature during mating of said first component with respect to said second component, elastic deformation occurs at an interface between each semi-circular male alignment feature and the respective said female alignment feature, wherein said elastic deformation is responsive to each said semi-circular male alignment feature being interferingly received by the respective female alignment feature;
wherein each said semi-circular male alignment feature comprises a semi-circular stud having a semi-circular cross-section comprising:
a first face having a convex shape forming a facial apex;
a second face having a facial groove flanked by a left sidewall and by a right sidewall; and
a stud height which is greater than said base thickness;
wherein said semi-circular stud tapers from said first base and terminates distally therefrom in a generally rounded crest;

wherein each said semi-circular stud has a stud width adjacent said first base between said first and second faces; wherein the respective female alignment feature has an aperture width; and wherein said elastic deformation is responsive to said stud width exceeding said aperture width;
wherein said elastic deformation further comprises twisting of any said semi-circular stud in which said left and right sidewalls are misaligned with respect to the respective female alignment feature prior to the mating of said first and second components; and
wherein said elastic deformation is elastically averaged over said plurality of semi-circular male alignment features such that said first component is precisely located relative to said second component.