US20120261409A1

US20120261409A1 - Combined metal cover and anti-crush hole support

Info

Publication number: US20120261409A1
Application number: US13/086,811
Authority: US
Inventors: David Teteak; Thomas Brey
Original assignee: Continental Automotive Systems Inc
Current assignee: Continental Automotive Systems Inc
Priority date: 2011-04-14
Filing date: 2011-04-14
Publication date: 2012-10-18
Also published as: EP2698046A1; EP2698046B1; WO2012141850A1

Abstract

A housings for electronic devices is constructed from a plastic half and a metallic half and provided with a substantially crush-proof mounting foot. The mounting foot is made crush proof/crush resistant by a metallic insert into a plastic outer cylinder or collar. The metallic half and metallic insert are formed at the same time by stamping. The metallic insert is inserted as part of the housing assembly process and does not require a separate manual insertion.

Description

BACKGROUND

Packaging for electronic products continues to move away from heavy and bulky metal enclosures for cost and weight-saving purposes. While plastic housings reduce cost and weight, plastic housings can be difficult to mount because plastics that are usable as housings are brittle and have relatively low elastic moduli. Mounting flanges or feet are easily crushed when the plastics they are made from are subjected to c compressive stress. Plastics are therefore somewhat ill-suited for use as housings or enclosures of electronic devices.
FIG. 1 is a perspective view of a prior art housing 100 for electronic devices. The housing 100 is comprised of a plastic top portion 102 and a metallic lower portion 104. Two mounting feet 106 are cantilevered, i.e., they project outwardly, from a side surface 107 of the housing 100. The mounting feet 106 are structures that enable the housing 100 to be attached to a surface.
Each mounting foot 106 is comprised of a plastic upper, generally cylindrically-shaped lug 108. The lug 108 has a hole or cylinder, which receives a separately-made and separately installed metallic insert support 112. The plastic lug 108 is attached to a second lug 110 that is metallic and which extends' laterally away from the side 109 of a metallic lower portion 104 of the housing 100. The metal insert 112 extends from the top of the plastic lug 108 to the bottom of the second metal lug 110.
The metal insert 112 is installed into the foot 106 to provide a structure that can withstand compressive loads applied to the foot 106 by fasteners, which are not shown. Fasteners extend through the insert 112 and through an attachment surface to which the housing 100 is mounted. The insert 112 thus prevents the plastic lug 108 from being crushed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a prior art housing with mounting feet having separately inserted metal supports;

FIG. 2 is an exploded view of a combined metal cover and anti-crush hole inside a mounting foot;

FIG. 3A is bottom view of the structure depicted in FIG. 2 after assembly;

FIG. 3B is a top view of the structure shown in FIG. 2 after assembly;

FIG. 4 is an exploded view of a combined metal cover and anti-crush hole formed as part of a mounting foot;

FIG. 5 is cross sectional view of the structure shown in FIG. 4 after assembly;

FIG. 6 is a top view of an alternate embodiment of a metal cover and anti-crush hole, with the anti-crush hole located interior to a housing;

FIG. 7 and FIG. 8 are assembled and pre-assembled views of an alternate embodiment of a crush-resistant metal portion of a mounting foot;

DETAILED DESCRIPTION

Prior art metal inserts 112 that are inserted separately require manual insertion. They are also relatively expensive to manufacture because they are typically formed by rolling a flat metal tab into a cylinder as shown. Reference numeral 114 identifies a seam formed by rolling the insert 112. A housing having a combined metal cover and a crush-resistant or an anti-crush hole would be an improvement an improvement over the prior art.
It is well known that the degree to which structures deform in response to an applied stress depends on the material's modulus of elasticity. When stress and strain are proportional to each other, deformation of a material is considered to be elastic. When a material is stressed to its proportional limit, deformation is plastic, i.e., the material does not return to its original shape. Stated another way, a material fails, when it is subjected to a stress that exceeds its proportional limit or yield strength.
Plastics are generally less dense than metals. Plastics are also generally non-conductive. Another difference between plastics and metals is their elastic modulus. Plastics are not as strong as metals.
Plastics that include low density polyethylene or LDPE, high density polyethylene (HDPE), polypropylene (PP) and polyvinyl chloride (PVC) have a modulus of elasticity of about 0.025×10⁶psi and about 5.0×10⁶psi. Light weight aluminum alloys however have elastic moduli of about 10×10⁶psi. Metals are therefore better able to withstand compressive loads.
FIG. 2 is an exploded view of a housing 200 comprised of a plastic top portion 202 and a metallic bottom portion 204. The plastic can be amorphous or polycrystalline. The housing 200 has crush-resistant or “anti-crush” supports 206 that extend from exterior sides of the housing 200.
The supports 206 are hereinafter referred to as mounting feet. A mounting foot is formed by the joinder or assembly of a top plastic portion 208 of the housing 200 and a metal bottom portion 210 of the housing 200. The metallic bottom portion 210 is formed to provide a metal, load-bearing insert, which when inserted into a plastic sleeve or cylinder resists crushing when a compressive stress is applied to the foot 206.
When viewed from the top, the foot 206 has a form reminiscent of a stilted arch. As used herein, “stilted arch” refers to an arch having a semi-circular rounded portion with straight legs or stilts that extend away from the ends of the semi-circular portion. In FIG. 2, the plastic top portion 208 of the mounting foot 206 has an arch-shaped portion identified by reference numeral 212. Plastic straight legs or stilts 214 extend laterally away from a side surface 215 of the plastic top portion 202 of the housing 200.
A cylindrical hole 218 is formed in the plastic top portion 208 of the foot 206. The circular-cross section hole 218 formed into the end of the foot 206 imbues the top portion 208 of the foot 206 with a structure that is cylindrical and formed from the plastic material surrounding the cylindrical hole 218. Reference numeral 220 identifies what is considered to be the outer circumference of a “cylinder” of material in the plastic top portion 208 of the foot 206. The plastic top portion 208 is thus considered to have a first cylindrical part 220 of the mounting foot 206.
The bottom portion 210 of the foot 206 is metallic. It therefore has an elastic modulus much greater than the plastic top portion 202.
The bottom portion 210 is comprised of a relatively thin, stilted arch-shaped tab portion 216 that extends laterally away from a side surface 222 of the metallic bottom portion 204.
The bottom portion 204 including the metal tab 216 is formed by stamping. A cylinder 224 extends upwardly from the tab 216 is also formed by a stamping process known as deep drawing. Being formed by stamping, the metal cylinder 224 is seamless. And, unlike prior art inserts that are stamped and rolled and therefore not really circular, the cross sectional shape of the stamped metallic cylinder 224 can be made into a nearly perfect circle.
In addition to being seamless and having nearly perfect circular cross sections, in one embodiment, the stamped metallic cylinder 224 has an outside diameter that tapers, or which has a “draft.” The outside diameter at the top of the cylinder 224 is slightly less than the outside diameter of the cylinder 224 where it meets the tab 216. Providing a draft to the cylinder 224 facilitates assembly of the two pieces 202 and 204 to each other. In other embodiments, the cylinder 224 outside diameter is constant.
The bottom or lower end of the cylinder 224 is surrounded by a relatively flat or planar annulus 225, which meets the plastic “cylinder” 220 portion of the plastic top portion 202. The metallic cylinder 224 has a height that is substantially equal to or slightly greater than the thickness of the plastic first cylindrical part 220 of the plastic top portion 208.
By deep drawing the metal lower portion 204, it is possible to stamp a lower metal panel 204 having a metallic second cylinder 224, the outside diameter of which is just equal to the inside diameter of the hole 218 in the plastic upper portion of the foot 206. The metallic second cylinder 224 also has an inside diameter 226 selected to correspond to the outside diameter of a fastener used to attach the housing 200 to a surface. Fasteners are not shown in FIG. 2 for clarity. A complete housing 200 with a crush-resistant mounting foot 206 is formed when the plastic top portion 202 is joined with the bottom metallic portion 204.
FIG. 3A is a bottom view of the housing 200 shown in FIG. 2. FIG. 3B is a top view of the housing 200.
Together, FIGS. 2, 3A and 3B show that the metallic cylinder 224 of the bottom portion 204 extends orthogonally from the tab 226 and extends completely through the thickness of the plastic top portion 208 of the foot 206. Unlike prior art metal inserts that are inserted manually and which have seams, the metallic cylinder 224 slides into the first plastic cylindrical part 220. The metallic cylinder 224, which extends through the first cylindrical part 220 and which has an elastic modulus greater than that of the plastic, significantly limits deformation of the first cylindrical portion responsive to a compressive load compressed on the foot 206 by a fastener. The metallic cylinder 224 thus provides the mounting foot 206 with an anti-crush hole.
FIG. 4 is an exploded view of one mounting foot 206 that extends from sides of upper and lower portions of a housing 200 depicted in FIG. 2. FIG. 4 also shows a fastener, comprised of a bolt 401 and hex nut 403, positioned to fasten the two portions of the housing 200 together.
The thickness 402 of the plastic upper portion 208 of the foot 206 is shown to be substantially equal to the height 404 of the metallic second cylinder 224. Since the height 404 of the inner cylinder 224 is at least equal to and preferably slightly greater than the thickness 402 of the upper portion 208, insertion of the inner cylinder 224 into the cylindrical hole 218 provides a metallic structure inside a plastic structure with the metallic structure bearing load applied to the mounting foot 206 by a fastener 406. Tightening the hex nut 403 on the bolt 401 exerts compressive force on the metallic inner cylinder 224 but not on the plastic outer cylinder. In one embodiment, the thickness 402 is slightly less than the height 404 to enable the metallic second cylinder 224 to engage a compressive load before the plastic.
FIG. 5 is a cross sectional view of the assembled foot 206 depicted in FIG. 4. The bolt 401 and hex nut 403 are shown assembled to each other and attach the housing 200 to a surface 502, such as a surface of a metal chassis of an automobile or other vehicle. By inserting a metal cylinder into the plastic cylinder, compressive stress on the plastic cylinder is significantly reduced or even eliminated.
FIG. 6 is a top view of an alternate embodiment of a housing 600 formed from a plastic top portion and a metal bottom portion. Unlike the supports 206 described above and which extend outwardly from sidewalls of a housing, an anti-crush support 602 is located within the exterior side walls 604 the housing 600.
FIG. 7 is an exploded view of the housing 600 depicted in FIG. 6 and showing the structure of the interior-located support 602. A plastic outer cylinder 704 of the support 602 is formed through the plastic top portion 702 of the housing 600. The plastic outer cylinder 704 has an inside diameter 706 large enough to slide over, i.e., receive, a seamless and metallic inner cylinder 708 formed by stamping, and preferably deep drawing. The metallic cylinder 708 is stamped as part of a metallic plate from which a metallic bottom portion 710 of the housing 600 is formed. As with the embodiment described above, the metallic inner cylinder 708 can be formed with a slight draft or taper to facilitate assembly of the housing portions.
The metallic inner cylinder 708 has a central hole 712 large enough to receive a fastener, such as a bolt 714. When the plastic top portion 702 is joined to the metallic bottom portion 710, the metallic inner cylinder 708 extends all the way through the plastic outer cylinder 704 as described above with regard to the exterior foot 206.
FIG. 8 is a side view of the assembled housing 600 of FIG. 6. A bolt 714 is shown inserted into the hole 712 that exists in the metallic inner cylinder 708. The bolt 714 also extends through a thin, flat panel 800 to which the housing 600 is attached by tightening the hex nut 716 on the bolt 714.
When the fastener 712 and nut 714 are tightened, compressive stress is applied to the metallic inner cylinder 706. The plastic outer cylinder 704 is thus spared from force that might otherwise permanently deform, i.e., crush, the plastic top portion 702 of the housing 600.
In the embodiments described above and depicted in the figures, the cylinders have circular cross sections. Alternate and equivalent embodiments include “cylinders” that have non-circular cross sections, such as square, triangular and rectangular cross sections.
Those of ordinary skill in the art will recognize that a light-weight housing can be constructed with robust mounting supports by using supports formed from both plastic and metallic components. A metallic insert inside a plastic outer portion is able to withstand compressive loads greater than having a plastic portion.
The foregoing description is for purposes of illustration only. The true scope of the disclosure is set forth in the appurtenant claims.

Claims

1. A housing having a first and second portions and a support, the support formed by joinder of the first and second portions to each other, the support being comprised of:

a first cylindrical part; and

a second cylindrical part, the second cylindrical part extending inside the first cylindrical part and configured to limit deformation of the first cylindrical portion responsive to a compressive load impressed on the support.

2. The housing of claim 1, wherein the first portion of the housing and the first cylindrical part are comprised of a first material having a first modulus of elasticity and wherein the second portion of the housing and the second cylindrical part are formed from a second material having a second modulus of elasticity greater than the first modulus of elasticity.

3. The housing of claim 2, wherein the first material is comprised of a plastic and the second material is metallic.

4. The housing of claim 1, wherein the first cylindrical part is cantilevered from a surface of the first housing portion and wherein the second support is cantilevered from a surface of the second housing portion.

5. The housing of claim 1, wherein the second cylindrical part is seamless.

6. The housing of claim 1, wherein the second cylindrical portion is formed by stamping.

7. The housing of claim 1, wherein the second cylindrical part is tapered.

8. The housing of claim 1, wherein the second cylindrical portion has a substantially perfect circular cross section.

9. The housing of claim 1, wherein the first outer cylinder has a first length and a first inside diameter and wherein the second cylinder has second length at least as long as the first length and an outside diameter less than the first inside diameter, whereby compressive load on the support is applied to and supported by the second cylinder prior to deformation of the first cylinder.

10. The housing of claim 9, wherein the second cylinder is additionally comprised of an annular foundation, proximate one end of the second cylinder, extending around the outside of the second cylinder and supporting the first cylinder.

11. The housing of claim 1, wherein the second cylinder is configured to align the first and second sections of the housing to each other.

12. The housing of claim 1, further comprised of a fastener extending through the support and applying a compressive load thereto.

13. The housing of claim 1, wherein the first portion is a top part of a housing and wherein the second portion is a bottom part of the housing.

14. The housing of claim 1, wherein the second portion is substantially planar.

15. A housing comprised of:

top and bottom portions and a crush-resistant support, the crush-resistant support being formed by the insertion of a second cylindrical part, formed as part of the bottom portion, into the interior of a first cylindrical part that is formed as part of the top portion, the first and second cylindrical parts being cantilevered from side surfaces of the top and bottom portions respectively, the second cylindrical portion extending orthogonally from a tab that extends away from the side surface of the bottom portion, the second cylindrical part having an inside diameter selected to receive a fastener to attach the housing, the first and second cylindrical parts being configured to align the top and bottom housing portions to each other when the second cylindrical part is inserted into the first cylindrical part.

16. The housing of claim 15, wherein the second cylindrical part is a material having a modulus of elasticity selected to prevent the first cylindrical part from being deformed upon the application of a compressive load to the support.

17. The housing of claim 15, wherein the compressive load is applied by the fastener.

18. The housing of claim 16, wherein the top portion is a plastic and wherein the bottom portion is metallic.

19. The housing of claim 15, wherein the second cylindrical part is tapered and seamless.

20. The housing of claim 19, wherein the bottom portion is formed by stamping.