Sealed electrical terminals containing adhesive flow inhibitors

Abstract

To provide an easy and cost-effective encapsulating electrical terminal and method that encapsulate a ring terminal and other types of terminals.SOLUTION: An electrical terminal 10 includes a terminal mounting portion 12, a wire mounting portion 14, and a transition portion 16. The wire mounting portion is configured to receive a wire of a cable. The transition portion extends between the terminal mounting portion and the wire mounting portion. A flow barrier 20a is provided on the transition portion near the end of the transition portion. The flow barrier prevents an adhesive / sealant applied to the wire positioned in the wire mounting portion from flowing from the wire mounting portion to the terminal mounting portion.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention is directed to a sealed electrical terminal that prevents adhesive flow from the sealed portion. In particular, the present invention is directed to a sealed electrical terminal that includes a device for preventing the flow of sealant / adhesive from heat shrink tubing used to seal ring terminals and other types of terminals. [Background technology]

[0002] Ring terminals are typically used to attach electrical wires to studs or posts (such as those found on vehicle batteries and other electrical cells) and are manufactured in a variety of types and sizes. Ring terminals typically include a ring portion and a wire attachment / connection portion to which the electrical wire is connected by welding or other means. Non-insulated ring terminals can be crimped or soldered and finished with heat shrink tubing to insulate and protect the connection made between the electrical wire and the wire attachment portion of the terminal. Heat shrink tubing (HST) is a shrinkable plastic tube often used to insulate electrical wires. Within the HST, a separate sealing material can be installed. HST provides abrasion resistance and environmental sealing protection for stranded and solid conductors, connections, splices, and terminals used in a variety of electrical applications. HST can also be used to repair damaged insulation on electrical wires, bundle wires, and create cable entry seals. As mentioned above, HST can be a single-wall system or a multi-wall system, where a multi-wall system includes at least one heat-shrinkable layer and at least one layer of the sealing system. Heat shrink tubing is generally made from fluoropolymers or polyolefins that shrink radially when heated. The process of shrinking the HST is called "recovering" the HST, and the predetermined temperature at which the HST begins to recover is called its "recovery temperature." When the HST recovers, i.e., shrinks, it exerts an inward force on the article surrounding it, which is called the "hoop stress" of the HST. More specifically, hoop stress (also known as circumferential stress) is a force that acts in both directions, circumferentially (perpendicular to both the axis and radius of the object) on every grain of the tube or cylinder wall. The degree of hoop stress is determined by certain HST characteristics such as the type of substrate, wall thickness, degree of crosslinking, and degree of expansion. Hoop stress is also affected by process parameters such as the recovery temperature and degree of recovery.

[0003] Ring terminals currently used in passenger and commercial vehicle or aircraft electrical systems include single and multi-wire configurations. Traditionally, external sealing systems involving the use of heat shrink tubing and adhesive / sealant layers have been used to obtain a watertight seal between and outside the electrical wires attached to the terminal. However, existing sealing systems and methods are unable to adequately seal the electrical wires in a simple and reliable manner. The first problematic issue relates to excessive adhesive or sealant flow or leakage into the ring portion of the ring terminal. The adhesive present in the ring portion can interfere with the metal-to-metal contact required for effective electrical contact, thereby necessitating cleaning of the excess adhesive. The second problematic condition also relates to adhesive or sealant flow or leakage from desired areas, resulting in minimal and uneven distribution of the adhesive or sealant, especially in corners or areas where pressure is increased by the heat shrink tube recovery. This is especially evident when a round shrink tube is shrunk or recovered onto a rectangular or square terminal or board. In such cases, the corners of the terminal, having a rectangular cross section, may exert excessive pressure and cause loss of adhesive or sealant from that area. Loss of adhesive or sealant may provide a path for contaminants and water, affecting the electrical connection between the wire and the terminal. For example, moisture or water may be transported from the ring portion of the terminal to the wire attachment portion of the terminal, then to the attached electrical wire, and then through the welded or crimped interface from one end of the electrical wire to the other, and water may also be transported between the wires and into the terminal.

[0004] To overcome the limitations of sealing systems involving the use of external adhesives and heat shrink tubing, currently used industrial approaches involve multi-component, multi-step processes that are labor intensive and expensive, and therefore there remains a need for a sealing system for use with ring terminals that meets all functional requirements in a simple, reliable, and cost-effective manner. Summary of the Invention [Problem to be solved by the invention]

[0005] It would therefore be advantageous to provide an easily implemented, cost-effective sealed electrical terminal and method for sealing ring terminals and other types of terminals. [Means for solving the problem]

[0006] A solution is provided by an electrical terminal having a terminal attachment portion, a wire attachment portion, and a transition portion. The wire attachment portion is configured to receive a wire of a cable. The transition portion extends between the terminal attachment portion and the wire attachment portion. A flow barrier is provided on the transition portion proximate an end of the transition portion. The flow barrier inhibits adhesive / sealant applied to a wire positioned within the wire attachment portion from flowing from the wire attachment portion to the terminal attachment portion.

[0007] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a ring-shaped electrical terminal including a wire attachment portion, a wire, and a sealing sleeve, shown before being positioned on the wire attachment portion, before the sealing sleeve is recovered, and with an exemplary adhesive spill barrier of the present invention provided on the electrical terminal. [Diagram 2] FIG. 2 is a perspective view of an electrical terminal with a wire inserted and terminated in a wire attachment portion. [Diagram 3] 2 is a perspective view of the electrical terminal of FIG. 1 with the sealing sleeve positioned on the wire attachment portion and the sealing sleeve covering it; [Figure 4] FIG. 3 is a cross-sectional side view taken along line 3-3 of FIG. 2. [Diagram 5] FIG. 2 is a perspective view of an electrical terminal provided with a first alternative embodiment of an adhesive spill barrier; [Figure 6] FIG. 13 is a perspective view of an electrical terminal provided with a second alternative embodiment of an adhesive spill barrier; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] One embodiment is directed to an electrical terminal having a terminal attachment portion, a wire attachment portion, and a transition portion. The wire attachment portion is configured to receive a wire of a cable. The transition portion extends between the terminal attachment portion and the wire attachment portion. A flow barrier is provided on the transition portion proximate an end of the transition portion. The flow barrier inhibits adhesive / sealant applied to a wire positioned within the wire attachment portion from flowing from the wire attachment portion to the terminal attachment portion.

[0010] One embodiment is directed to an assembly of an electrical terminal terminated to a cable. The assembly includes a terminal having a terminal attachment portion, a wire attachment portion for receiving a cable, and a transition portion extending between the terminal attachment portion and the wire attachment portion. A flow barrier is provided on the transition portion near an end of the transition portion. The cable has a wire and an insulating sleeve. A sealing device is provided on the cable and extends over the wire attachment portion of the terminal. The sealing device is a heat shrinkable tube provided with an adhesive / sealant. The flow barrier inhibits the adhesive / sealant from flowing from the wire attachment portion to the terminal attachment portion.

[0011] One embodiment is directed to a method of terminating a cable to an electrical terminal, the method including positioning exposed wires of the cable in a wire attachment portion of the terminal, terminating the exposed wires to the wire attachment portion, moving an adhesive / sealant-loaded heat shrink sealing device over the exposed wires and the wire attachment portion, applying heat to the heat shrink sealing device to cause the adhesive / sealant to flow around the exposed wires at the wire attachment portion and transition portion of the terminal and recover the heat shrink sealing device, and providing a flow barrier to prevent the adhesive / sealant from flowing from the wire attachment portion of the terminal to the terminal attachment portion of the terminal.

[0012] Turning now to the figures, Figure 1 provides an illustration of an electrical terminal 10 that is compatible with the systems, methods, and devices of the present invention. The electrical terminal shown in Figure 1 is a ring-type terminal, however, the systems, methods, and devices of the present invention are 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 Figure 1, the electrical terminal 10 includes a terminal mounting portion 12, a wire mounting portion 14, and a transition portion 16, with the transition portion 16 extending between the terminal mounting portion 12 and the wire mounting portion 14. The terminal mounting portion 12 is configured to connect to a complementary terminal, such as a stud or post, of an electrical device, such as, for example, a battery. The wire attachment portion 14 is configured to connect to a cable 18, 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 10 is shown for illustrative purposes. The terminal attachment portion 12, wire attachment portion 14, and transition portion 16 may have a variety of configurations without departing from the scope of the invention.

[0013] As best seen in Figures 1 and 2, the transition portion 16 of the terminal 10 includes a flow barrier 20. The flow barrier 20 is positioned adjacent the wire attachment portion 14. The flow barrier 20 extends from a first surface or top surface 22 of the transition portion 16 in a direction away from an opposite facing second surface or bottom surface 24 of the transition portion 16. The flow barrier 20 extends from the transition portion 16 in essentially the same direction as the wire attachment portion 14. The flow barrier 20 extends from adjacent a first side 26 of the transition portion 16 to adjacent an opposite second side 28 of the transition portion 16.

[0014] In the embodiment shown in Figures 1-3, the flow barrier 20a is a heat shrink sleeve positioned around the transition 16. The heat shrink sleeve is positioned around the transition 16 and when heat is applied, the heat shrink sleeve recovers to form the flow barrier 20a. The heat shrink sleeve forms a seal with the transition 16. This embodiment is an exemplary embodiment of a flow barrier that is a separate part secured or attached to the terminal.

[0015] 5, the flow barrier 20b is an O-ring positioned about the transition portion 16. The O-ring is positioned about the transition portion 16 and conforms to the transition portion 16 to form the flow barrier 20b. The O-ring is sized such that when inserted onto the transition portion 16, it exerts a compressive force on the transition portion 16 to form a seal with the transition portion 16. This embodiment is an exemplary embodiment of a flow barrier that is a separate piece positioned on the terminal.

[0016] 6, the flow barrier 20c is one or more depressions, peaks, or shoulders stamped from the transition portion 16. This embodiment is an exemplary embodiment of a flow barrier integrally formed with the terminal. However, other configurations of the flow barrier 20 may be used without departing from the scope of the present invention.

[0017] In each of the exemplary embodiments, the flow barrier 20 extends a distance H2 ( FIG. 6 ) from the first surface 22 of the transition portion 16, the distance H2 being less than the height H1 of the wire attachment portion 14. In various exemplary embodiments, the height H2 of the flow barrier 20 is less than one-half the height H1 of the wire attachment portion 14, the height H2 of the flow barrier 20 is less than one-quarter the height H1 of the wire attachment portion 14, the height H2 of the flow barrier 20 is greater than one-quarter the height H1 of the wire attachment portion 14, or the height H2 of the flow barrier 20 is between one-half and one-quarter the height H1 of the wire attachment portion 14.

[0018] In the embodiment shown, the cable 18 has multiple wires 30 with insulating sleeves 32. The wires 30 are exposed at a stripped end 34 of the cable 18. In the embodiment shown, three wires 30 are provided, although other numbers of wires may be used.

[0019] As shown in Figures 1 and 2, a sealing sleeve 40 is provided on the cable 18. The sealing sleeve 40 includes a shrinkable tube 42 positioned inside with a sealant / adhesive 44. The sealant / adhesive 44 may be in the form of a ring, a sleeve, a full circular profile, a semicircular profile, or other profile geometry. The shrinkable tube 42 may be a single layer or multi-layer tube. The shrinkable tube 42 may be a polymeric component that shrinks when heat is applied. Such shrinkable tubes may include, but are not limited to, heat shrinkable tubes or tapes. The term sealant / adhesive includes sealants and adhesives that are viscoelastic materials that have the ability to flow under a suitable stimulus, such as, but not limited to, temperature and / or pressure. Examples of such materials are hot melt adhesives and butyl mastic. The sealant / adhesive 44 is disposed within the shrink tube 42 near or adjacent the leading edge 46 of the shrink tube 42. The sealant / adhesive 44 can be a high viscosity sealant / adhesive, such as a sealant / adhesive having a viscosity greater than 20 Pa·s at an installation temperature that correlates to a specified or rated temperature. The sealant / adhesive 44 can be a low viscosity sealant / adhesive, such as a sealant / adhesive having a viscosity less than 20 Pa·s at an installation temperature that correlates to a specified or rated temperature. The sealant / adhesive 44 can also be a combination of a low viscosity sealant / adhesive and a high viscosity sealant / adhesive. The sealant / adhesive 44 has a flow behavior such that it conforms to the surface of the wire attachment or to the surface of multiple wires while allowing the sealant / adhesive 44 to efficiently displace air within the cable 18 that is intended to be sealed to provide a robust seal.

[0020] In use, the exposed wire 30 at the stripped end 34 of the cable 18 is placed into the wire attachment portion 14 of the terminal 10. Insertion of the wire 30 into the wire attachment portion 14 continues until a portion of the wire 30 engages the flow barrier 20 of the transition portion 16. The flow barrier 20 provides a wire stop to prevent further insertion of the wire 30 into the wire attachment portion 14. This prevents the wire 30 from being inserted into and interfering with the terminal attachment portion 12.

[0021] With the exposed wire 30 properly positioned within the wire attachment portion 14 of the terminal 10, as shown in Figure 2, the wire attachment portion 14 is terminated to the wire 30. In the embodiment shown, the wire attachment portion 14 is crimped to the wire, although other termination methods may be used.

[0022] With the exposed wires 30 properly terminated to the wire attachment portion 14, the sealing sleeve 40 is moved over the exposed wires 30 and wire attachment portion 14. Heat is then applied to the sealing sleeve 40. When heat is applied after placement of the shrink tube 42 over the electrical terminal 10 (e.g., 30 seconds in an infrared oven or other period of time), the sealant / adhesive 44 melts and flows into the exposed wires 30 of the cable 18, filling any voids that may be present. The shrink tube 42 shrinks to enclose the exposed wires 30 and the wire attachment portion 14 of the electrical terminal 10 (as shown in FIG. 3), thereby essentially sealing the melted sealant / adhesive 44 within the shrink tube 42.

[0023] During the heating process, the flow barrier 20 positioned near the leading edge 46 of the shrink tube 42 cooperates with the sealant / adhesive 44 to block and substantially inhibit flow or leakage of the sealant / adhesive 44 toward the terminal attachment portion 12, thereby reducing or preventing problematic contamination of the terminal attachment portion 12 by the sealant / adhesive 44. In some instances, a small amount of the sealant / adhesive 44 may make its way to the terminal attachment portion 12, but such an amount is insignificant to the function of the electrical terminal 10.

[0024] During the heating process, the flow barrier 20 also blocks and substantially inhibits the flow or leakage of the sealant / adhesive 44 away from the exposed wire 30, the transition section 16, and the wire attachment section 14 of the cable 18. Retaining the sealant / adhesive 44 within the desired area allows the sealant / adhesive 44 to flow properly and evenly around the exposed wire 30, the transition section 16, and the wire attachment section 14 to provide a proper seal. As shown in FIG. 4, the sealant / adhesive 44 is provided around the wire 30 and the transition section 16, including the first surface 22, the second surface 24, the first side 26, the second side 28, and the corners 29 therebetween. The controlled and even flow of the sealant / adhesive 44 prevents contaminants and / or water from affecting the electrical connection between the wire 30 and the terminal 10.

Claims

1. A terminal mounting portion (12); a wire attachment portion (14) for receiving a wire (30) of a cable (18); a transition portion (16) extending between the terminal attachment portion (12) and the wire attachment portion (14); a flow barrier (20a) disposed on said transition portion (16) adjacent an end of said transition portion (16), said flow barrier (20a) being a separate part from said electrical terminal (10); the flow barrier (20a) being a heat shrink sleeve secured to the electrical terminal (10) and positioned around the transition portion (16); the flow barrier (20a) is provided such that a side closer to the wire attachment portion (14) faces a front end of the wire (30) of the cable (18), and the side of the flow barrier (20a) closer to the wire attachment portion (14) is a side away from the terminal attachment portion (12); The flow barrier (20a) inhibits adhesive / sealant (44) applied to the wire (30) positioned within the wire attachment portion (14) from flowing from the wire attachment portion (14) to the terminal attachment portion (12). Electrical terminal (10).

2. The electrical terminal (10) of claim 1, wherein the flow barrier (20a) acts as a wire stop to properly position the wire (30) within the wire attachment portion (14).

3. The electrical terminal (10) of claim 1, wherein said electrical terminal (10) is a ring terminal.

4. The electrical terminal (10) of claim 1, wherein a height (H2) of the flow barrier (20a) is less than a height (H1) of the wire attachment portion (14).

5. The transition portion (16) A first surface (22); a second surface (24) facing opposite said first surface (22); a first side (26) and a second side (28) connecting said first surface (22) and said second surface (24), respectively; The flow barrier (20a) comprises:

2. The electrical terminal (10) of claim 1, wherein the adhesive / sealant (44) provided around the wire (30) and around the transition portion (16), including the first surface (22), the second surface (24), the first side (26), the second side (28), and the corners (29) therebetween, is positioned around the transition portion (16) to inhibit flow from the wire attachment portion (14) to the terminal attachment portion (12).

6. An electrical terminal (10) as described in claim 1, wherein a portion of the flow barrier (20a) that is arranged to face the front end of the wire (30) extends in a direction intersecting the axial direction of the wire mounting portion (14).

7. A method of terminating a cable to an electrical terminal (10), comprising the steps of: Positioning exposed wires (30) of a cable (18) within the wire attachment portion (14) of said electrical terminal (10); terminating the exposed wires (30) to the wire attachment portion (14); moving a heat shrinkable sealing device (40) carrying an adhesive / sealant (44) over the exposed wires (30) and the wire attachment portions (14); applying heat to the heat shrinkable sealing device (40) to cause the adhesive / sealant (44) to flow around the exposed wires (30) and recover the heat shrinkable sealing device (40); providing a flow barrier (20a) adjacent said wire attachment portion (14) facing a front end of said exposed wire (30) of said cable (18) to prevent said adhesive / sealant (44) from flowing from said wire attachment portion (14) of said electrical terminal (10) to said terminal attachment portion (12) of said electrical terminal (10); the side of the flow barrier (20a) closer to the wire attachment portion (14) is the side away from the terminal attachment portion (12); the flow barrier (20a) is a separate part from the electrical terminal (10) and the heat shrinkable sealing device (40); the flow barrier (20a) is a heat shrink sleeve secured to the electrical terminal (10) and positioned about a transition portion (16) extending between the terminal attachment portion (12) and the wire attachment portion (14).

8. The method of claim 7, wherein the flow barrier (20a) acts as a wire stop to properly position the exposed wire (30) within the wire attachment portion (14).

9. The transition portion (16) A first surface (22); a second surface (24) facing opposite said first surface (22); a first side (26) and a second side (26) connecting said first surface (22) and said second surface (24), respectively; The flow barrier (20a) comprises:

8. The method of claim 7, wherein the adhesive / sealant (44) provided around the exposed wires (30) and around the transition portion (16), including the first surface (22), the second surface (24), the first side (26), the second side (28), and the corners (29) therebetween, is positioned around the transition portion (16) to inhibit flow from the wire attachment portion (14) to the terminal attachment portion (12).

Images