WO2012054708A1

WO2012054708A1 - Light socket contact assembly

Info

Publication number: WO2012054708A1
Application number: PCT/US2011/057064
Authority: WO
Inventors: Richard R. Herzog; Michael Starozhitsky
Original assignee: Illinois Tool Works Inc.
Priority date: 2010-10-21
Filing date: 2011-10-20
Publication date: 2012-04-26

Abstract

A light socket assembly includes a base integrally connected to a circumferential wall, wherein a plug chamber is defined between the base and the circumferential wall, and an electrical contact having a free end and a fixed end secured proximate the base. The electrical contact is formed of multiple metallic layers, and is configured to prevent arcing within the base.

Description

LIGHT SOCKET CONTACT ASSEMBLY

RELATED APPLICATIONS

[0001] This application relates to and claims priority benefits from U.S. Provisional Patent Application No. 61/405,364 entitled "Light Socket Contact Assembly," filed October 21, 2010, which is hereby incorporated by reference in its entirety.

FIELD OF EMBODIMENTS OF THE INVENTION

[0002] Embodiments of the present invention generally relate to a light socket contact, and, more particularly, to a light socket contact formed of a bi-metal alloy.

BACKGROUND

[0003] Figure 1 illustrates a front view of a light bulb 10 secured within a light socket 12. The light bulb 10 includes a fully or semi-translucent bulb member 14 connected to a plug 16. The bulb member 14 defines a light chamber that houses a light emitting member (not shown), such as a filament of an incandescent bulb, a light emitting diode (LED), or the like. The light emitting member is electrically connected to a contact 18 positioned at a distal end of the plug 16.

[0004] The plug 16 typically includes a threaded circumferential outer wall 20 that threadably engages inner walls of the socket 12 so that the light bulb 10 secures to the socket 12. The socket 12 is generally electrically connected to a source of power. An electrical contact 24 is positioned proximate a base 26 of the socket 12. The contact 24 is typically formed of copper, or a copper-based alloy.

[0005] In general, electrical power passes from the source of power to the contact 24. The electrical power then passes from the contact 24 to the contact 18 of the light bulb 10 in order to illuminate the light bulb 10.

[0006] An air gap 28 often exists between the contact 18 of the light bulb 10 and the contact 24 of the socket 12. The air gap 28 may be caused by the light bulb 10 not being fully seated in the socket 12 during installation, or the light bulb 10 being slightly backed out of the socket 12.

[0007] Because of the air gap 28, when the light socket 12 is energized, an electrical arc may travel across the air gap 28 from the contact 24 to the contact 18, resulting in significant electrical resistance. The resulting heat between the contacts 24 and 18 may melt solder on the contact 18, cause the bulb 10 to fail, and/or melt the surrounding plastic housing of the light socket 12.

SUMMARY OF EMBODIMENTS OF THE INVENTION

[0008] Certain embodiments of the present invention provide a light socket assembly that includes a base integrally connected to a circumferential wall, wherein a plug chamber is defined between the base and the circumferential wall. The light socket assembly also includes an electrical contact having a free end and a fixed end secured proximate the base. The electrical contact is formed of multiple metallic layers, and is configured to prevent arcing within the base.

[0009] The multiple metallic layers may include a first layer secured within the base, and a second layer having a portion that passes through the base and that is configured to electrically connect to a source of electrical power. The first layer is formed of a first metal, and the second layer is formed of a second metal. The first layer may be permanently bonded to the second layer. The first metal may include a a high expansion alloy that may be formed of 2% Nickel (Ni), 3% Chromium (Cr), and 75% Iron (Fe), while the second metal may include a low expansion alloy that may be formed of 36% Nickel (Ni) and 64% Iron (Fe). The free end of the electrical contact is configured to move away from the base, and toward a contact of a bulb, when temperature rises.

[0010] The multiple metallic layers include two or more metallic layers having different coefficients of thermal expansion. [0011] The multiple metallic layers may include at least three metallic layers. The multiple metallic layers may include first and second inner layers bonded to one another.

[0012] Certain embodiments of the present invention provide an assembly that includes a light bulb and a light socket sub-assembly. The light bulb includes a bulb member connected to a plug having a bulb contact. The light socket sub-assembly includes a base integrally connected to a circumferential wall. A plug chamber is defined between the base and the circumferential wall. The plug is removably secured (such as through a threadable connection) within the plug chamber. The light socket subassembly also includes a socket contact having a free end and a fixed end secured proximate the base. The socket contact is formed of multiple metallic layers, and is configured to prevent arcing within said base by curving toward and contacting the bulb contact with increased temperature.

[0013] Certain embodiments of the present invention provide a light socket assembly that includes a base integrally connected to a circumferential wall, wherein a plug chamber is defined between the base and the circumferential wall, and an electrical contact having a free end and a fixed end secured proximate the base. The electrical contact is formed of a first metallic layer secured within the base, and a second metallic layer having a portion that passes through the base and is configured to electrically connect to a source of electrical power. The first metallic layer is permanently bonded to the second metallic layer. The first metallic layer is formed of a first metal having a first coefficient of thermal expansion, and the second metallic layer is formed of a second metal that is separate and distinct from the first metal and having a second coefficient of thermal expansion that differs from the first coefficient of thermal expansion. The electrical contact is configured to prevent arcing within the base by the free end of the electrical contact being configured to move away from the base when temperature rises. BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

[0014] Figure 1 illustrates a front view of a light bulb secured within a light socket.

[0015] Figure 2 illustrates a front view of a light bulb secured within a light socket, according to an embodiment of the present invention.

[0016] Figure 3 illustrates an axial cross-sectional view of a contact through line 3 of Figure 2, according to an embodiment of the present invention.

[0017] Figure 4 illustrates an axial cross-sectional view of a contact, according to an embodiment of the present invention.

[0018] Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of "including" and "comprising" and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0019] Figure 2 illustrates a front view of a light bulb 30 secured within a light socket 32, according to an embodiment of the present invention. The light bulb 30 includes a fully or semi-translucent bulb member 34 connected to a plug 36. The bulb member 34 defines a light chamber that houses a light emitting member (not shown), such as a filament of an incandescent bulb, a light emitting diode (LED), or the like. The light emitting member is electrically connected to a contact 38 positioned at a distal end of the plug 36. [0020] The plug 36 includes a threaded circumferential outer wall 40 that threadably engages inner walls of the socket 32 so that the light bulb 30 secures to the socket 32. The socket 32 is electrically connected to a source of power. An electrical contact 44 is positioned proximate a base 46 of the socket 32.

[0021] Electrical power passes from the source of power to the contact 44. The electrical power then passes from the contact 44 to the contact 38 of the light bulb 30 in order to illuminate the light bulb 30.

[0022] Unlike the contact 24 shown and described with respect to Figure 1, however, the contact 44 is formed of a bi-metal or composite alloy. The contact 44 includes two or more metallic layers having different coefficients of thermal expansion. For example, the contact may include a first layer formed of a high expansion alloy, and a second layer formed of a low expansion alloy. The layers are permanently bonded together. When subjected to a change in temperature, the contact 44 curves toward the contact 38, thereby eliminating any air gap between the contacts 38 and 44.

[0023] It has been found that a particularly-suitable high expansion alloy may be formed of 22% Nickel (Ni), 3% Chromium (Cr), and 75% Iron (Fe), while the low expansion alloy may be formed of 36% Nickel (Ni) and 64% Iron (Fe). In this example, the high expansion alloy made up 50.3% of the total weight of the contact 44, while the low expansion alloy made up 49.7% of the total weight of the contact 44. In particular, it was found that these materials, in these weight percentages, performed best all around in the temperatures range of 0 - 300° F. It is to be understood, however, that these materials, in these percentages, are merely examples. Other bi-metal or composite alloys may be used.

[0024] As shown in Figure 2, the contact 44 includes a bottom contact 47 secured within the base 46, and an upper contact 49 that passes out of the base 46. The bottom contact 47 may be formed of a first metal having a first coefficient of thermal expansion, while the upper contact 49 may be formed of a second metal having a second coefficient of thermal expansion. Thus, with increased heat, the bottom contact 47 bends upward, thereby forcing a free end 51 of the upper contact 49 into the contact 38 of the bulb 30.

[0025] The contact 44 is configured to curve toward the contact 38 when the temperature increases. For example, the layered contact 44 may have a lower layer that bends the top layer toward the contact 38 when an increase in temperature, such as caused by arcing, occurs.

[0026] Figure 3 illustrates an axial cross-sectional view of the contact 44 through line 3 of Figure 2, according to an embodiment of the present invention. The contact 44 includes an upper layer 48 formed of a first metal, and a bottom layer 50 formed of a second metal. The upper layer 48 is permanently bonded to the bottom layer 50. The upper layer 48 may be proximate the contact 38 of the light bulb 30 (shown in Figure 2), while the bottom layer 50 may be proximate the base 46 of the light socket 32 (shown in Figure 2). Depending upon the desired amount and rate of bending in relation to temperature, the relative amounts of upper and bottom layers 48 and 50, respectively, may be varied. For example, for increased bending, the upper layer 48 may be shallower than the bottom layer 50, or vice versa.

[0027] Referring to Figures 2 and 3, during operation, if an air gap exists between the contact 44 and the contact 38, thereby causing electrical arcing, the temperature of the bottom layer 50 increases. As the temperature of the bottom layer 50 increases, the bottom layer 50 curves toward the contact 38 of the light bulb 30. The bottom layer 50 continues to curve upward until the top layer 48 touches the contact 38. Therefore, any air gap is eliminated, and any electrical resistance from such an air gap is eliminated, thereby also preventing unsafe conditions.

[0028] Figure 4 illustrates an axial cross-sectional view of the contact 44, according to an embodiment of the present invention. In this embodiment, the contact 44 includes an upper layer 56 bonded to a middle layer 58, which, in turn, is permanently bonded to a lower layer 60. As such, the middle layer 58 is sandwiched between the upper and bottom layers 56 and 60, respectively. The upper layer 56 may be formed of a first metal, while the middle layer 58 may be formed of a second metal, and the bottom layer 60 be formed of a third metal. Optionally, the upper and bottom layers 56 and 60 may be formed of a first metal, while the middle layer 58 may be formed of a second metal.

[0029] Alternatively, the contact 44 may be formed of more layers than shown.

[0030] Thus, embodiments of the present invention provide a light socket contact assembly having an electrical contact formed of at least two layers of different metals. For example, the contact may include a first layer formed of a first metal, and a second layer formed of a second metal. This is in contrast to conventional assemblies having a contact formed merely of copper or a copper based alloy. Unlike conventional assemblies, the multi-layered contact is configured to allow the contact bend toward and touch the contact of a light bulb with increased temperature. As such, embodiments of the present invention, unlike conventional assemblies, prevent any air gaps between the socket contact and the bulb contact. Therefore, unlike conventional assemblies, embodiments of the present invention are less susceptible to bulb and socket damage/failure.

[0031] While various spatial and directional terms, such as top, bottom, lower, mid, lateral, horizontal, vertical, front and the like may used to describe embodiments of the present invention, it is understood that such terms are merely used with respect to the orientations shown in the drawings. The orientations may be inverted, rotated, or otherwise changed, such that an upper portion is a lower portion, and vice versa, horizontal becomes vertical, and the like.

[0032] Variations and modifications of the foregoing are within the scope of the present invention. It is understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art.

[0033] Various features of the invention are set forth in the following claims.

Claims

1. A light socket assembly comprising:

a base integrally connected to a circumferential wall, wherein a plug chamber is defined between said base and said circumferential wall; and

an electrical contact having a free end and a fixed end secured proximate said base, wherein said electrical contact is formed of multiple metallic layers, and wherein said electrical contact is configured to prevent arcing within said base.

2. The light socket assembly of claim 1, wherein said multiple metallic layers comprise a first layer secured within said base, and a second layer having a portion that passes through said base and is configured to electrically connect to a source of electrical power, and wherein said first layer is formed of a first metal, and said second layer is formed of a second metal.

3. The light socket assembly of claim 2, wherein said first layer is permanently bonded to said second layer.

4. The light socket assembly of claim 2, wherein said first metal comprises a a high expansion alloy formed of 2% Nickel (Ni), 3% Chromium (Cr), and 75% Iron (Fe), and wherein said second metal comprises a low expansion alloy formed of 36% Nickel (Ni) and 64% Iron (Fe).

5. The light socket assembly of claim 1, wherein said free end of said electrical contact is configured to move away from said base when temperature rises.

6. The light socket assembly of claim 1, wherein said multiple metallic layers comprise two or more metallic layers having different coefficients of thermal expansion.

7. The light socket assembly of claim 1, wherein said multiple metallic layers comprise at least three metallic layers.

8. An assembly comprising:

a light bulb including a bulb member connected to a plug having a bulb contact; and

a light socket sub-assembly including:

a base integrally connected to a circumferential wall, wherein a plug chamber is defined between said base and said circumferential wall, said plug being removably secured within said plug chamber; and

a socket contact having a free end and a fixed end secured proximate said base, wherein said socket contact is formed of multiple metallic layers, and wherein said socket contact is configured to prevent arcing within said base by curving toward and contacting said bulb contact with increased temperature.

9. The assembly of claim 8, wherein said multiple metallic layers comprise a first layer secured within said base, and a second layer having a portion that passes through said base and is configured to electrically connect to a source of electrical power, and wherein said first layer is formed of a first metal, and said second layer is formed of a second metal.

10. The assembly of claim 9, wherein said first layer is permanently bonded to said second layer.

11. The assembly of claim 8, wherein said first metal comprises a high expansion alloy formed of 2% Nickel (Ni), 3% Chromium (Cr), and 75% Iron (Fe), and wherein said second metal comprises a low expansion alloy formed of 36% Nickel (Ni) and 64% Iron (Fe).

12. The assembly of claim 8, wherein said free end of said socket contact is configured to move away from said base when the temperature rises.

13. The assembly of claim 8, wherein said multiple metallic layers comprise two or more metallic layers having different coefficients of thermal expansion.

14. The assembly of claim 8, wherein said multiple metallic layers comprise at least three metallic layers.

15. A light socket assembly comprising:

an electrical contact having a free end and a fixed end secured proximate said base, wherein said electrical contact is formed of a first metallic layer secured within said base, and a second metallic layer having a portion that passes through said base and is configured to electrically connect to a source of electrical power, wherein said first metallic layer is permanently bonded to said second metallic layer, wherein said first metallic layer is formed of a first metal having a first coefficient of thermal expansion, and said second metallic layer is formed of a second metal that is separate and distinct from said first metal and having a second coefficient of thermal expansion that differs from said first coefficient of thermal expansion, and wherein said electrical contact is configured to prevent arcing within said base by said free end of said electrical contact being configured to move away from said base when temperature rises.

16. The light socket assembly of claim 15, wherein said first metal comprises a high expansion alloy formed of 2% Nickel (Ni), 3% Chromium (Cr), and 75% Iron (Fe), and wherein said second metal comprises a low expansion alloy formed of 36% Nickel (Ni) and 64% Iron (Fe).