Patent Description:
Ring terminals are typically used to attach electrical wires to studs or posts (such as those found on vehicle batteries and other batteries) and are manufactured in various types and sizes. Ring terminals typically include a ring portion and a wire attachment/connection portion to which electrical wires are connected by welding or other means. Non-insulated ring terminals can be crimped or soldered and may be finished off with heat shrink tubing to insulate and protect the connection formed between the electrical wires and the wire attachment portion of the terminal. Heat shrink tubing (HST) is a shrinkable plastic tube often used to insulate electrical wires. The HST may have discrete sealant materials installed therein. HST provides abrasion resistance and environmental sealing protection for stranded and solid wire conductors, connections, joints, and terminals used in various electrical applications. HST can also be used to repair damaged insulation on electrical wires, bundle wires together, and to create cable entry seals. As stated above, HST may be a single-walled system or a multi-walled system, wherein the multi-walled system includes at least one heat-shrinkable layer and at least one layer of a sealant system. Heat shrink tubing is commonly manufactured from fluoropolymer or polyolefin, which shrinks radially when heated. The process of shrinking an HST is referred to as "recovering" an HST and the predetermined temperature at which a HST starts to recover is referred to as its "recovery temperature". As an HST recovers, i.e., shrinks, it exerts an inward force against the items it surrounds, which is referred to as the "hoop stress" of the HST. More specifically, hoop stress (also known as cylinder stress) is the force exerted circumferentially (perpendicular both to the axis and to the radius of the object) in both directions on every particle in the tubing or cylinder wall. The degree of hoop stress is determined by certain HST characteristics such as the type of base material, wall thickness, degree of cross-linking, and degree of expansion. Hoop stress is also affected by process parameters such as temperature of recovery and degree of recovery.

Ring terminals currently used with passenger and commercial vehicle or aircraft electrical systems include single-wire and multi-wire configurations. External sealant systems that include the use of heat shrink tubing and an adhesive/sealant layer have been previously used to create a watertight seal in between and outside of the electrical wires attached to the terminal. However, existing sealant systems and methods may not properly seal the electrical wires in a simple and reliable manner. A first problematic issue involves the flow or oozing of excessive adhesive or sealant onto the ring portion of the ring terminal. Adhesive that is present on the ring portion can interfere with the metal to metal contact that is needed for an effective electrical contact, thereby requiring cleaning of the excess adhesive. A second problematic situation also involves the flow or oozing of adhesive or sealant out of the desired area, causing the minimal and uneven distribution of the adhesive or sealant, particularly around corners or areas which the recovery of the heat shrink tubing causes increase pressure. This is particularly evident when round shrink tubing shrinks or recovers onto a rectangular or square terminal or substrate. In such case, corners of the rectangular cross section terminal exerts excessive pressure, causing that area to be lacking in adhesive or sealant material. The lack of adhesive or sealant provides a path for contaminants and water to affect the electrical connection between the wires and the terminals. For example, moisture or water can wick from the ring portion of the terminal onto the wire attachment portion of the terminal, then onto the attached electrical wires, and then from one end of the electrical wires to the other end thereof through the welded or crimped interface; water can also wick from in between the wires and into the terminal.

To overcome the limitations of sealing systems that involve the use of external adhesive and heat shrink tubing, the industrial approach currently used involves a multi-component, multi-step process. This process is labor intensive and expensive; therefore, there is an ongoing need for a sealing system for use with ring terminals that meets all functional requirements in a simplistic, reliable, and cost-effective manner.

<CIT>, on which the preamble of claim <NUM> is based, discloses an electrical terminal comprising a terminal attachment portion, a wire attachment portion for receiving wires of a cable therein, and a transition portion extending between them. An electrical terminal sealing device is positioned over exposed wires of the cable and the wire attachment portion, and comprises a first heat shrinkable tubing with a second heat shrinkable tubing forming a lip structure at one end of the first heat shrinkable tubing wherein the lip structure forms a flow barrier which constrains adhesive from the electrical terminal sealing device applied to the wires positioned in the wire attachment portion from flowing from the wire attachment portion to the terminal attachment portion.

<CIT> discloses an electrical terminal comprising a terminal attachment portion, a wire attachment portion for receiving wires of a cable therein, and a transition portion extending between them. A flow barrier integrally formed with the terminal is provided on the transition portion proximate an end of the transition portion. A heat shrinkable sealing device is positioned over exposed wires of the cable and the wire attachment portion, and the flow barrier constrains adhesive/sealant applied to the wires positioned in the wire attachment portion from flowing from the wire attachment portion to the terminal attachment portion.

<CIT> and <CIT> disclose similar electrical terminals.

<CIT> discloses an electrical terminal with a separate flow barrier that is joined to the terminal by adhesive.

<CIT> discloses an electrical terminal for holding exposed wires of a cable. A heat shrinkable tube is positioned over the ends of the exposed wires and is closed by a sealing member. The exposed wires and the heat shrinkable tube are held by a wire attachment portion of the terminal.

It would be beneficial to provide a sealed electrical terminal and method for sealing ring terminals and other types of terminals which is easy to implement and cost effective.

According to one aspect of the invention there is provided an electrical terminal as claimed in claim <NUM>.

An assembly of the electrical terminal with a cable terminated thereto may be provided wherein the cable has wires and an insulation sleeve.

According to another aspect of the invention there is provided a method of terminating a cable to an electrical terminal as claimed in claim <NUM>.

With reference to the Figures, <FIG> provides an illustration of an electrical terminal <NUM> that is compatible with the systems, methods, and devices of the present invention. The electrical terminal shown in <FIG> is a ring-type terminal; however, the systems, methods, and devices of this invention are also compatible with many other types of electrical terminals such as, for example, spade terminals, hook terminals, flag terminals, push-on terminals, and the like. With reference to <FIG>, electrical terminal <NUM> includes terminal attachment portion <NUM>, a wire attachment portion <NUM> and a transition portion <NUM> which extends between the terminal attachment portion <NUM> and the wire attachment portion <NUM>. The terminal attachment portion <NUM> is configured for connection to a complementary terminal, such as a stud or a post, of an electrical device such as, for example, a battery. The wire attachment portion <NUM> is configured for connection to a cable <NUM>, such as, but not limited to, one or more electrical wires, which may be connected by welding, soldering, crimping or other suitable attachment methods. The particular configuration of the terminal <NUM> is shown for illustrative purposes. The terminal attachment portion <NUM>, the wire attachment portion <NUM> and the transition portion <NUM> may have varied configurations without departing from the scope of the invention.

As best shown in <FIG>, the transition portion <NUM> of the terminal <NUM> includes a flow barrier 20a. The flow barrier 20a is positioned proximate to the wire attachment portion <NUM>. The flow barrier 20a extends from a first or top surface <NUM> of the transition portion <NUM> in a direction away from an oppositely facing second or bottom surface <NUM> of the transition portion <NUM>. The flow barrier 20a extends from the transition portion <NUM> in essentially the same direction as the wire attachment portion <NUM>. The flow barrier 20a extends from proximate a first side surface <NUM> of the transition portion <NUM> to proximate an opposed second side surface <NUM> of the transition portion <NUM>.

As shown in <FIG>, the flow barrier 20a is a heat shrinkable sleeve which is positioned around the transition portion <NUM>. The heat shrinkable sleeve is positioned about the transition portion <NUM> and heat is applied such that the heat shrinkable sleeve is recovered to form the flow barrier 20a. The heat shrinkable sleeve forms a seal with the transition portion <NUM>, and is a separate part which is fixed or attached to the terminal.

In the arrangement shown in <FIG>, which does not form part of the invention as claimed, the flow barrier 20b is an O-ring which is positioned around the transition portion <NUM>. The O-ring is positioned about the transition portion <NUM> and conforms to the transition portion <NUM> to form the flow barrier 20b. The O-ring is dimensioned to apply a compressive force to the transition portion <NUM> when it is applied onto the transition portion <NUM> to form a seal with the transition portion <NUM>. This arrangement is an illustrative arrangement of the flow barrier being a separate part which is positioned on the terminal.

In the arrangement shown in <FIG>, which does not form part of the invention as claimed, the flow barrier 20c is a one or more dimples, peaks or shoulders stamped from the transition portion <NUM>. This arrangement is an illustrative arrangement of the flow barrier being integrally formed with the terminal. However, other configurations of the flow barrier may be used.

In each of the illustrative embodiment and arrangements, the flow barrier 20a, 20b or 20c extends from the first surface <NUM> of the transition portion <NUM> a distance H2 (<FIG>) which is less than the height H1 of the wire attachment portion <NUM>. In various illustrative embodiments, the height H2 of the flow barrier is less than one-half the height H1 of the wire attachment portion <NUM>, the height H2 of the flow barrier is less than one-fourth of the height H1 of the wire attachment portion <NUM>, the height H2 of the flow barrier is greater than one-fourth of the height H1 of the wire attachment portion <NUM>, or the height H2 of the flow barrier is between one-half to one-fourth of the height H1 of the wire attachment portion <NUM>.

In the embodiment shown, the cable <NUM> has a plurality of wires <NUM> with an insulation sleeve <NUM>. The wires <NUM> are exposed at a striped end <NUM> of the cable <NUM>. In the embodiment shown, three wires <NUM> are provided, however, other numbers of wires can be used.

As shown in <FIG>, a sealing sleeve <NUM> is provided on the cable <NUM>. The sealing sleeve <NUM> includes a piece of shrinkable tubing <NUM> with a sealant/adhesive <NUM> positioned inside. The sealant/adhesive <NUM> may be in the form of a ring, sleeve, full circular profile, semi-circular profile, or other profiled geometry. The shrinkable tubing <NUM> can be a single layer or multilayer tubing. The shrinkable tubing <NUM> may be a polymeric component that shrinks on the application of heat. Such shrinkable tubing may include, but is not limited to, heat shrinkable tubing or tape. The term sealant/adhesive includes, but is not limited to, sealants and adhesives which are viscoelastic materials that have an ability to flow under suitable stimulus like temperature and/or pressure. Examples of such materials are hot melt adhesives and butyl mastics. The sealant/adhesive <NUM> is placed within the shrinkable tubing <NUM> adjacent to or proximate a leading edge <NUM> of the shrinkable tubing <NUM>. The sealant/adhesive <NUM> may be a high viscosity sealant/adhesive, such as, for example, sealant/adhesive which has a viscosity that is greater than <NUM> Pa·s at an installation temperature which correlates to a designated or rated temperature. The sealant/adhesive <NUM> may be a low viscosity sealant/adhesive, such as, for example, sealant/adhesive which has a viscosity that is less than <NUM> Pa·s at an installation temperature which correlates to a designated or rated temperature. The sealant/adhesive <NUM> may be a combination of low viscosity sealant/adhesive and high viscosity sealant/adhesive. The sealant/adhesive <NUM> has a flow behavior such that it conforms to the surface of the wire attachment portion or surface of the plurality of wires while allowing the sealant/adhesive <NUM> to displace air efficiently inside the cable <NUM> intended to be sealed to create a robust seal.

In use, exposed wires <NUM> at the stripped end <NUM> of the cable <NUM> are moved into the wire attachment portion <NUM> of the terminal <NUM>. The insertion of the wires <NUM> into the wire attachment portion <NUM> continues until a portion of the wires <NUM> engages the flow barrier attached to the transition portion <NUM>. The flow barrier provides a wire stop to prevent the further insertion of the wires <NUM> into wire attachment portion <NUM>. This prevents the wires <NUM> from being inserted to the terminal attachment portion <NUM> and interfering therewith.

With the exposed wires <NUM> properly positioned in the wire attachment portion <NUM> of the terminal <NUM>, the wire attachment portion <NUM> is terminated to the wires <NUM>, as shown in <FIG>. In the embodiment shown, the wire attachment portion <NUM> is crimped to the wires, but other methods of termination can be used.

With the exposed wires <NUM> properly terminated to the wire attachment portion <NUM>, the sealing sleeve <NUM> is moved over the exposed wires <NUM> and the wire attachment portion <NUM>. Heat is then applied to the sealing sleeve <NUM>. Upon the application of heat (e.g., in an infrared oven for <NUM> seconds or other time period) after installation of the shrinkable tubing <NUM> over the electrical terminal <NUM>, the sealant/adhesive <NUM> melts and flows across the exposed wires <NUM> of the cable <NUM> filling any present air voids. The shrinkable tubing <NUM> shrinks to encapsulate the exposed wires <NUM> and the wire attachment portion <NUM> of the electrical terminal <NUM> (as shown in <FIG>), thereby substantially sealing the melted sealant/adhesive <NUM> within the shrinkable tubing <NUM>.

During the heating process, the flow barrier, which is positioned proximate the leading edge <NUM> of the shrinkable tubing <NUM> cooperates with the sealant/adhesive <NUM> to block and effectively constrain the flow or oozing of the sealant/adhesive <NUM> in the direction of the terminal attachment portion <NUM>, thereby reducing or preventing any problematic contamination of the terminal attachment portion <NUM> by the sealant/adhesive <NUM>. While in some instances a small amount of sealant/adhesive <NUM> may travel onto the terminal attachment portion <NUM>, the amount will be insignificant with regard to the functioning of the electrical terminal <NUM>.

Claim 1:
An electrical terminal (<NUM>) comprising:
a terminal attachment portion (<NUM>);
a wire attachment portion (<NUM>) for receiving wires (<NUM>) of a cable (<NUM>) therein;
a heat shrinkable sealing device (<NUM>) for being positioned over exposed wires (<NUM>) of the cable and the wire attachment portion (<NUM>), the heat shrinkable sealing device (<NUM>) having adhesive/sealant (<NUM>) retained therein;
a transition portion (<NUM>) extending between the terminal attachment portion (<NUM>) and the wire attachment portion (<NUM>),
wherein
the electrical terminal (<NUM>) includes a flow barrier (20a) which is a separate part from the terminal (<NUM>), the flow barrier (20a) being provided on the transition portion (<NUM>) proximate an end of the transition portion (<NUM>), the flow barrier (20a) being a heat shrinkable sleeve fixed to the terminal (<NUM>) and positioned around the transition portion (<NUM>), wherein the flow barrier (20a) constrains the adhesive/ sealant (<NUM>) applied to the wires (<NUM>) positioned in the wire attachment portion (<NUM>) from flowing from the wire attachment portion (<NUM>) to the terminal attachment portion (<NUM>); characterized in that
the flow barrier (20a) is configured to act as a wire stop to prevent the further insertion of the wires (<NUM>) into the wire attachment portion (<NUM>) to properly position the wires (<NUM>) in the wire attachment portion (<NUM>).