Electrical connector with waterproofing

Abstract

An electrical connector having a waterproof coating and a method for creating the waterproof coated electrical connector. The disclosed process involves the use of a liquid rubber composition to form an outer coating on an electrical connection, allowing for partial air drying of the outer coating and then manipulating the outer coating to form a seal followed by allowing the outer coating to further dry. The waterproof outer coating layer is extremely thin and does not significantly alter the footprint of the electrical connection. The process can be readily applied to existing electrical connectors without requiring a re-design of the electrical connection.

Description

Applicant: HARTIN Electronics GmbHTitle: ELECTRICAL CONNECTOR WITH WATERPROOFINGTechnical Field

[0001] The present disclosure relates generally to waterproofing electrical connectors, and more specifically, to forming waterproof electrical connectors utilizing a liquid elastomer composition.Background

[0002] Electrical connections find use in a variety of environments. One area of growth is in the communications and computer industries where electrical connections are used in a variety of power and signal conduction environments. Often these connections need to be made as small as possible to accommodate the size constraints in modern electronics systems. These connections have not generally included waterproofing. Most of these connections have an IP rating of IP20 using the standard Ingress Protection rating code defined by the International standard EN 60529, wherein the first digit refers to the ingress by solids and the second digit refers to the ingress by liquids. The digit values range from 0 to 6 with a higher number indicating a higher degree of protection. So, an IP20 means that there is ingress protection from touch by fingers and objects greater than 12 millimeters with no protection from liquids.

[0003] Electrical connections with an IP rating of IP64, meaning protected from total dust ingress and protected from water spray from any direction, are difficult to achieve.Past waterproofing solutions have included high pressure overmolding processes or heat shrink tubing solutions. An issue with high pressure overmolding processes is that they require high pressure overmolding of the electrical connector and this can damage or prevent use of pressure activated latching mechanisms or other fragile parts that are often found in these electrical connectors. Use of overmolding often requires a complete redesign of the electrical connector to take this into account, and the process and product can be expensive.

[0004] Use of heat shrink tubing often does not provide complete enclosure of the entire electrical connector and thus do not provide adequate protection, and may interfere with pressure activated latching mechanisms. These coverings are also subject to slippage and form excessively thick coatings on the electrical connectors. The other issue is that these shrink tube coatings are sensitive to temperature fluctuations.

[0005] Thus, there exists a need to provide a waterproof coating that can be easily applied to existing electrical connectors without requiring a re-design, that still permits latching mechanisms to function, that maintains fragile parts and that does not significantly increase the footprint or cost of the electrical connection.Summary

[0006] In at least some implementations, an electrical connector comprises an electrical connector having an outer housing and an electrical connector extending out of an end of the outer housing; and a waterproof outer coating applied to the outer housing, the waterproof outer coating comprising a liquid rubber composition that has been air dried into a solid elastomeric outer coating.

[0007] In other implementations, a method of providing a waterproof coating to an electrical connector comprises the steps of: a) providing an electrical connector having an outer housing and an electrical connection extending out of an end of the outer housing; b) providing a liquid rubber composition that is air driable or curable; c) applying the liquid rubber composition to at least the outer housing to form an outer coating on the outer housing; d) allowing the applied liquid rubber composition to air dry or cure for a first period of time sufficient for formation of an air dried or cured surface on the outer coating; e) manipulating a portion of the outer coating at the end of the outer housing adjacent to the electrical connection to form a seal; and f) allowing the applied liquid rubber composition to air dry or cure for a second period of time.Brief Description of the Drawings

[0008] The following detailed description of preferred implementations and best mode will be set forth with regard to the accompanying drawings, in which:

[0009] FIG. 1 is a perspective view of an electrical connector;

[0010] FIG. 2 is a perspective view of another electrical connector;

[0011] FIG. 3 is a partially sectioned side view of the electrical connector of FIG. 2 in use;

[0012] FIG. 4 is a perspective view of the electrical connector of FIG. 1 after application of a waterproof coating according to one embodiment;

[0013] FIG. 5 is a perspective view of the electrical connector of FIG. 2 after application of a waterproof coating according to another embodiment;

[0014] FIG. 6 is a perspective view of a cap for use in creating a waterproof coating on the electrical connector of FIG. 1 ; and

[0015] FIG. 7 is a perspective view of an electrical connection cap for use in creating a waterproof coating on the electrical connector of FIG. 2.Detailed Description

[0016] Referring in more detail to the drawings, FIGS. 1-3 illustrate two styles of electrical connectors and one of the electrical connectors in place in a typical environment. In FIG. 1 an electrical connector is shown generally at 10. The electrical connector 10 includes an outer housing 12 and a cable 14 extending out of one end of the outer housing 12. The other end of the connector 10 has extending from it an insert 16 that includes an insert body 18, typically made of a metal or plastic, and internal conductors 19 received in cavities extending inwardly into the covering 18 from an outer end of the insert 16. As shown in this example, the connector 10 further includes a pair of retaining latches 20 extending outwardly from opposite sides of the insert 16, with only one being shown in FIG. 1, to retain the electrical connector 10 in position when an electrical connection is made. So constructed, the electrical connector 10 may be a so-called male electrical connector that is operable by sliding the insert 16 into a complementary cavity of a mating female electrical connector to make an electrical connection. The female electrical connector will have corresponding slots to receive the retaining latches 20 to hold the electrical connector 10 in place. As shown the electrical connector 10 can also include a thickened section 22 where the cable 14 enters the outer housing 12 to provide bend protection to the electrical connector 10.

[0017] A second example of an electrical connector is shown generally at 30 in FIG. 2. The electrical connector 30 includes an outer housing 32 and a cable 34 extending out of one end of the outer housing 32. The other end of the outer housing 32 has extending from it an insert 36 that may have an insert body 38, typically made of a metal or a plastic material, and conductors 39 received in cavities at the free end of the insert 36. As shown in this example the outer housing 32 further includes a pair of flexible push tabs 40, only one is shown in FIG. 2, on opposite sides of the outer housing 32 that are used to control retaining latches 42 on opposite sides of the insert 36 that are used to retain the electrical connector 30 in position when an electrical connection is made. So constructed, the electrical connector 30 may be a so-called male electrical connector operable by sliding the insert 16 into a complementary cavity of a mating female electrical connector to make an electrical connection. The female electrical connector will have corresponding structure to receive the retaining latches 42 to hold the electrical connector 30 in place. A commercial example of this type of electrical connector 30 is the HARTING iX Industrial® electrical connector.

[0018] FIG. 3 shows the electrical connector 30 installed in a typical environment in which the insert 36 is received in an opening in a housing wall 50 and is securely latched into a female electrical connector 52 having a mating shape. The retaining latches 42, not shown, secure the electrical connection 36 in place. The female electrical connector 52 can be mounted onto a circuit board 54 or other structure, or may have a cable extending therefrom. A gap 56 can be seen between the outer housing 32 and the housing wall 50 when the electrical connector 30 is latched in place. The pair of flexible push tabs 40 on opposite sides of the outer housing 32 can be pressed inward to control the retaining latches42, not shown, used to retain the electrical connector 30 in position when an electrical connection is made so that the electrical connector 30 can be removed and inserted.

[0019] As shown in FIG. 4, in at least some implementations, a coating 60 is applied over all or part of the outer housing 12, 32, and a portion of the cable 14, 34, if desired, and a portion of the insert 16, 36, if desired. The coating 60 may be applied as a liquid elastomeric (e.g. rubber) composition that air-dries / cures into a flexible, solid elastomeric coating that is waterproof, e.g. hydroscopic. Commercial examples of such liquid rubber compositions include Plasti Dip® available from the Plasti Dip International in Blaine, Minnesota USA and similar liquid rubber composition products from Star brite, Inc. in Fort Lauderdale, Florida USA.

[0020] In at least some implementations, the liquid rubber compositions are formulated to cure by air-drying at room temperature into a solid elastomeric, flexible rubber coating that is waterproof. The method comprises applying the liquid rubber composition to the outer housing, 12 or 32, and may include covering a portion of the insert body 18, 38 with a protective covering. The protective covering can comprise, by way of non-limiting examples, a tape, sleeve or another covering as discussed below, and it may be arranged to prevent the liquid rubber composition from getting into or onto the electrical connections / conductors, and / or to keep the rubber composition from getting on at least part of the insert body 18, 38. The application can be accomplished in any of a number of ways, for example, by dipping, spraying, pouring or brushing the liquid rubber composition onto the desired locations.

[0021] In at least some implementations, the process involves dipping the entire electrical connector, 10 or 30, into the liquid rubber composition and then removing it andletting it partially air-dry / cure for a first period of time until an outer surface of the liquid rubber composition outer coating has dried and while an inner portion of the coating is still not dried / cured and is still flowable. Then the protective covering is removed from the insert body 18, 38, and the liquid rubber composition outer coating 60 is manipulated to move the outer coating 60 toward and into any gaps between the insert body 18, 38 and the outer housing 12, 32. This inhibits or prevents liquid intrusion into the electrical connector 10, 30 between the outer housing 12, 32 and the insert body 18, 38. The liquid rubber composition outer coating may also be manipulated to create a seal that surrounds a portion of the insert body 18, 38, and is against the outer housing 12, 32. The seal may be designed to fill the gap 56 shown in FIG. 3, for example, between the housing wall 50 and the electrical connector 30 when it is in place. The outer coating of liquid rubber composition is then allowed to fully air-dry / cure thereby providing a waterproof outer coating on the electrical connector, that substantially inhibits or prevents intrusion into the connector 10, 30 of liquid that contacts the connector 10, 30.

[0022] The results of the disclosed process are shown in FIG. 4 and FIG. 5 for the electrical connectors 10, 30 of FIG. 1 and FIG. 2, respectively. In FIG. 4 the electrical connector 10 has been treated with an application of the liquid rubber composition that forms an outer coating 60 over the outer housing 12 and optionally the thickened section 22 and part of the insert body 18. The manipulation of the partially dried outer coating 60 as discussed above is used to create a seal 64 around the insert body 18 and against the outer housing 12. If desired, additional coatings of the liquid rubber composition can be applied at the thickened section 22 to form a thicker outer coating 62 providing additional bend protection. In FIG. 5, the electrical connector 30 has been treated with an applicationof the liquid rubber composition as described with formation of the seal. The liquid rubber composition forms an outer coating 70 over the outer housing 32 and the flexible push tabs 40. The outer coating 70 may include a portion 72 that extends over the cable 34. The manipulation of the partially air-dried / cured liquid rubber composition outer coating 70 as discussed above is used to create a seal 74 around the insert body 38 and against the outer housing 32. If desired additional coatings of liquid rubber composition can be applied at the cable 34 to form a thicker outer coating 72 providing additional bend protection.

[0023] As described above, a portion of the insert body 18, 38 can be received in a tape, sleeve or other cover during the application of the liquid rubber composition. FIG. 6 and Fig. 7 show alternative protective coverings. In FIG. 6 a protective cap shown at 80 can be used with the electrical connector 10 of FIG. 1. The cap 80 is closed at one end and, in use, is put over the insert body 18 prior to application of the liquid rubber composition. This prevents the liquid rubber composition from filling the cavities in the insert body 18 during the application process and during the partial air-drying / curing step of the method. Then the cap 80 is removed and the liquid rubber composition outer coating 60 is further manipulated to form the seal 64. The cap 80 itself can be designed to manipulate the partially dried / cured outer coating 60 to form the seal 64, such as by pressing the cap toward the outer housing 12 to press some of the coating 60 against the outer housing and in a gap between the outer housing 12 and the insert body 18. And FIG. 7 shows a protective cap 90 that can be used with the electrical connector 30 of FIG. 2, in the same manner as cap 80 with electrical connector 10.

[0024] In a first working example, a liquid rubber composition comprising Plasti Dip® was applied to an electrical connector 30, as shown in FIG. 2 to achieve a product like thatshown in FIG. 5. A piece of water sensitive tape was first applied to the outer housing 32 and then a protective tape was applied to a portion of the insert body 38. The electrical connector 30 was then dipped into the Plasti Dip® for a few seconds and then removed and allowed to partially air-dry / cure for 1 hour at room temperature of about 25 °C, in this example. Then the protective tape was removed and the partially dried / cured liquid rubber composition outer coating 70, which had a cured outer surface and uncured inner portion, was pressed against the insert body 38 and against the outer housing 32 to form a seal 74 and the liquid rubber composition outer coating 70 was allowed to air-dry / cure for another 3 hours at about 25 °C. Then, to test for waterproofing the electrical connector 36 was inserted into a mating electrical connector and 1 liter of water was poured over the connection from different angles. Then the waterproof outer coating 70 was removed and the water sensitive tape was examined, it showed no entry of water. In addition, the retaining latches 42 functioned as normal prior to removal of the coating 70. The waterproof outer coating 70 had a thickness of less than 0.3 millimeter and thus it did not increase the footprint of the electrical connector 30 by more than 0.6 millimeters.

[0025] In a second working example an electrical connector 30 as shown in FIG. 2 was utilized again with the liquid rubber composition Plasti Dip®. The same process as above was followed with an additional step. After the first application of the liquid rubber composition and partial air drying / curing additional liquid rubber composition was applied onto an area of the cable 34 to create a thickened portion 72 on the cable 34 for additional bend protection.

[0026] The viscosity of the liquid rubber composition can be manipulated by use of solvents such as, by way of non-limiting examples, xylene, naphtha, trimethylbenzenes,“mineral spirits”, and toluene at levels of up to, for example, 10% by volume based on the total volume. Thinned liquid rubber compositions have a lower viscosity and the increased flowability can be helpful in creating thinner outer coating layers if desired. Preferably, the liquid rubber composition has a viscosity of from 70 to 80 Krebs Units (KU) at a temperature of from 15 to 25 degrees Celsius. Using the liquid rubber composition Plasti Dip®, this can be achieved by thinning the initial composition with 5% by volume of Xylene.

[0027] The drying times for the stages of the process and the manipulation period can vary. For example, the first period for drying can comprise 1.5 to 2 hours, preferably 2 hours. The manipulation time range to form the seal can range from 2 hours to 2 hours and 15 minutes. The final drying time preferably ranges from 4 to 4.5 hours. The coatings produced according to the present disclosure provide a waterproof electrical connector having a rating of IP64.

[0028] While described above as allowing the coatings to dry or cure at room temperature, it is possible to use an elevated temperature to speed up the drying / curing process, if desired. Preferably, the elevated temperature does not exceed 60 Celsius, which is the temperature limit of many electrical connectors. The manipulation process described above can be automated utilizing slides that move the connector relative to a jig that engages the coating 60, 70, or by a robotic arm with a suitable end effector which may mimic the shape of the caps 80, 90, or the like. The method and coatings achieved may be used on a wide variety of electrical and signal pass through connectors, beyond the examples shown in the drawings, as will be readily understood by a person of ordinary skill in this art in view of this disclosure.

[0029] While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention.

[0030] All terms used in the claims are intended to be given their broadest reasonable construction and their ordinary meanings as understood by those skilled in the art unless an explicit indication to the contrary is made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.

Claims

CLAIMS:What is claimed is:

1. An electrical connector comprising: an electrical connector having an outer housing and an electrical connector extending out of an end of the outer housing; and a waterproof outer coating applied to said outer housing, said waterproof outer coating comprising a liquid rubber composition that has been air dried into a solid elastomeric outer coating and that has been pressed into gaps at portions of the outer housing.

2. The electrical connector as recited in claim 1, wherein the waterproof outer coating has a thickness over the outer housing of 0.3 millimeters or less.

3. The electrical connector as recited in claim 1, wherein the electrical connector further comprises a cable extending out of an end of the outer housing and wherein the waterproof outer coating covers a portion of the cable.

4. The electrical connector as recited in claim 3, wherein the waterproof outer coating covering the portion of the cable has a thickness that is greater than a thickness of the waterproof outer coating covering the outer housing.

5. The electrical connector as recited in claim 3, wherein the waterproof outer coating covering the portion of the cable has a thickness of greater than 0.3 millimeters.

6. The electrical connector as recited in claim 1, wherein the electrical connection includes an insert body and the waterproof outer coating further comprises a seal that surrounds a portion of the insert body adjacent to the outer housing.

7. The electrical connector as recited in claim 1, wherein the waterproof outer coating encloses the outer housing.

8. A method of providing a waterproof coating to an electrical connector comprising the steps of: a) providing an electrical connector having an outer housing and an insert extending out of an end of the outer housing; b) providing a liquid rubber composition that is air curable; c) applying the liquid rubber composition to at least the outer housing to form an outer coating on the outer housing; d) allowing the applied liquid rubber composition to air cure for a first period of time sufficient for formation of an air cured surface on the outer coating; e) manipulating a portion of the outer coating at the end of the outer housing adjacent to the insert to form a seal between the insert and the outer housing; and f) allowing the applied liquid rubber composition to air cure for a second period of time.

9. The method as recited in claim 8, wherein step c) comprises forming an outer coating having a thickness of 0.3 millimeters or less.

10. The method as recited in claim 8, wherein the first period of time in step d) ranges from 1.5 to 2 hours.

11. The method as recited in claim 8, wherein the second period of time in step f) ranges from 4 to 4.5 hours.

12. The method as recited in claim 8, wherein in step b) the liquid rubber composition is combined with up to 10% by volume of a solvent.

13. The method as recited in claim 12, wherein the solvent is selected from the group consisting of xylene, naphtha, trimethylbenzenes, mineral spirits, toluene and mixtures thereof.

14. The method as recited in claim 8, wherein step a) further comprises providing an electrical connector having a cable extending out of the outer housing and step c) further comprises applying the liquid rubber composition to a portion of the cable to form an outer coating on the cable.

15. The method as recited in claim 14, wherein step c) further comprises applying the liquid rubber composition to a portion of the cable to form an outer coating on the cable that is thicker than the outer coating on the outer housing.

16. The method as recited in claim 15, wherein in step c) the thickness of the outer coating on the cable is greater than 0.3 millimeters.

17. The method as recited in claim 8, wherein in step b) the liquid rubber composition has a viscosity of from 70 to 80 Krebs Units at a temperature of from 15 to 25 degrees Celsius.

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