MULTILAYERED TETHER LINK FOR LIFTGATE FIELD OF THE INVENTION The present invention relates to a tether component and method of manufacturing the tether component, which is implemented in a liftgate for an automobile. BACKGROUND OF THE INVENTION One of the current trends in the automobile industry is to lower vehicle weight to help achieve better fuel economy, thus helping to meet fuel economy standards and to offset the higher fuel prices. Another trend is that there is a broader range of vehicle models, which in turn reduces the volume of vehicles produced on a per model basis. Liftgates are traditionally made from stamped steel panels that are heavy and have a high tooling cost and are susceptible to corrosion. Sheet Molding Compound (SMC) is an alternative to steel for the inner and outer panels of the liftgate. Using SMC has several manufacturing concerns related to the material and process. Steel and SMC liftgates have a mass penalty over thermoplastics. There are also styling restrictions with traditional sheet metal and SMC components. In certain applications where liftgates are made from composite materials. Tethers made from steel are used to strengthen the liftgate and help maintain the integrity of the liftgate upon impact. The use of steel tethers can be difficult to 1 attach and increase the assembly complicity. It is therefore desirable to design liftgates that have tether systems that are easier to assemble, require less attachment points and still provide the desired level of strength to the liftgate while allowing for maintaining the integrity of the liftgate upon impact.

Over molded ends are sometimes used in flexible tether arrangements such as with belt materials or wires to help the fibers of the tether in such a way that the integrity and strength of the individual fibers is preserved. However, overmolding processes are costly and time consuming because of added tooling and labor costs during manufacture. It is further a desirable to provide a tether system that is flexible and is connected to the liftgate panel through apertures without the necessity of overmolding. It is also desirable to provide a tether system that has failure modes, such as a controlled release failure mode.

It is desirable to develop lower cost tethers that would reduce or eliminate overmolding to the tether belt material but still provide the desired performance. Therefore, it is a goal to provide a lightweight, consistent failure mode tether using more readily available materials to keep costs down.

SUMMARY OF THE INVENTION

The present invention relates to a multilayered tether link for a vehicle tether implemented in a molded vehicle liftgate. The tether has two ends and connects to a vehicle part using a folded wedge section and a folded section of the tether. There is a folded wedge section formed by a tether belt material being sinuously being folded about at least one wedge portion. The tether belt material and the at least one wedge portion are sewn together with at least one stich to form a layered construction. The layered construction has a hole is formed through the layered construction for attachment to a vehicle part.

The multilayered tether link further includes a folded section having a plurality of layers of sinuously folded tether belt material folded adjacently to form a plurality of layers. The folded section further includes at least one stich connecting the plurality of layers together. Also provided is a hole formed through the center of the folded section for attachment to a vehicle part. The vehicle part can be any component of the liftgate and can include the liftgate inner panel, wiper motor housing, support brackets, outer panel of the liftgate, latch mounting bracket or latch actuator housing.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

Fig. 1 is a rear elevational view of a liftgate inner panel having a multilayered tether link connected thereon. Fig. 2 is an enlarged rear elevational view of the multilayered tether link end of the present invention installed on a liftgate of a vehicle.

Fig. 3 is a cross-sectional side elevation view of a folded wedge section of the multilayered tether link in accordance with the present invention.

Fig. 4 is a cross-sectional side elevation view of a folded section of the multilayered tether link in accordance with the present invention.

Fig. 5 is top side perspective view of wedge portion.

Fig ,6A is a top cross-sectional view of a prior art overmolded tether link connected to a vehicle part.

Fig. 6B is a top cross-sectional view of a multilayered tether link connected to a vehicle part in accordance with one embodiment of the invention.

Fig. 6C is a top cross-sectional view of a multilayered tether link connected to a vehicle part in accordance with another embodiment of the invention.

Fig. 7 is a top plan view of a tether according to one embodiment of the invention.

Fig. 8A is an enlarged perspective view of an alternate tether according to an alternate embodiment of the invention.

Fig. 8B is an enlarged perspective view of an alternate tether according to an alternate embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description of the preferred embodiments are merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

Referring now to Fig. 1 there is shown a structural inner panel 100 of a vehicle liftgate. The structural inner panel 100 has an outside surface 112 and an inner surface. The structural inner panel 100 is covered by an outer panel or outer panels (not shown) that have an exterior show surface. The liftgate structure, and the structural inner panel 100 are made of composite material, however, it is within the scope of this invention for different materials to be used such as aluminum, manufactured diecast, metal, etc. The structural inner panel 100 has a lower perimeter surface area 116 extending across substantially the entire width of the structural inner panel 100. The structural inner panel 100 also includes a wiper motor housing recess 118 for holding a wiper motor. Also included is a plurality of brackets including a left side bracket 120, a center lower bracket 122 and a right side bracket 124. It is within the scope of this invention for a greater or fewer number of brackets to be implemented depending on the particular application. The plurality of brackets are connected to the outside surface 112 of the structural inner panel 100. Each of the plurality of brackets also include one or more friendly holes 126, which are apertures through the respective brackets that allow for a tether 12 to pass through. The friendly holes 126 each have a curled edge that creates a smooth edge to prevent any snagging of the tether 12 material. The tether 12 includes two ends each for connecting the tether 12 to a vehicle part, which in the current embodiment of the invention is a wiper motor housing 128 in the wiper motor housing recess 118. The tether 12 is positioned through each of the friendly holes 126 of each of the plurality brackets 120, 122, 124.

While the present embodiment of the invention depicts the tether 12 as being routed through various bracket members, it is within the scope of this invention for the friendly holes 126, to be formed with the structural inner panel 100, thereby eliminating the need for different brackets 120, 122, 124. Additionally, the placement of the brackets 120, 122, 124 are located in predetermined tether reinforcement zones, which are areas on the structural inner panel 100 that are determined to be structurally stronger areas of the liftgate than the portions of the inner panel not located in the tether reinforcement zones. The tether reinforcement zones are best for placement of connections for the tether 12. The structural reinforcement zones allow for the tether 12 to span areas of the composite liftgates that are structurally weaker and will benefit from having the tether 12 passing across the weaker area to be connected to the tether reinforcement zones of the liftgate. The location of the tether reinforcement zones can vary depending upon the design of the liftgate. Factors such as shape, material thickness, material makeup and the dimensions of the liftgate can have an effect on the location of the tether reinforcement zone. Routing the tether 12 between each tether reinforcement zones causes the tether 12 to cross weaker areas of the liftgate to create a type of safety net that will hold the structural inner panel together in the event of breaking of the structural inner panel in the weaker areas between the tether reinforcement zones.

The tether 12 has a specialized construction forming part of a multilayered tether link that is shown in figures 2-5, 6B and 7 will now be described in greater detail. The tether 12 has two ends 14a, 14b that connect to a vehicle part 16 using a folded wedge section 18 and a folded section 20 of the tether 12. The folded wedge section 18 is formed by a tether belt material 22 being sinuously being folded about at least one wedge portion, which the present embodiment of the invention uses two wedge portions 24a, 24b. Each wedge portion 24a, 24b is preferably a polymer plastic material such as a thermoplastic olefin material. The tether belt material 22 can be any suitable material, however, in one embodiment of the invention the tether belt material 22 is polyester or mylar material.

As shown the tether 12 has an end 14a that is folded about wedge portion 24a, while end 14b is folded about wedge portion 24b. The wedge portions 24a, 24b are used in the present embodiment of the invention, but they are optional and in some embodiments of the invention they are not used due to the requirements of a particular design. For example, Fig. 6C shows a multilayered tether link 200 with a tether 202 that has a first folded section 204 and a second folded section 206 are connected to a vehicle part 216. Both the first folded section 204 and second folded section 206 do not have any wedge portions that are present in the multilayered tether link 10 embodiment shown in Fig. 6B.

Referring back to Figs. 1-5, 6B and 7, the tether belt material 22 and the two wedge portions 24a, 24b are sewn together with at least one stich to form a layered construction 26. The layered construction 26 has a hole 28 formed through the layered construction 26 for attachment to a vehicle part 16. The hole 28 is formed ultrasonically using heat knife that prevents fraying. The hole 28 is configured to allow a fastener 29 to pass through the layered construction 26 for connecting the tether 12 to the vehicle part 16. The wedge portions 24a, 24b are designed to transfer the force loads between the tether 12 and the stitching in a more consistent manner. Each of the two wedge sections 24a, 24b include a widened end portion 30 and a flat portion 32. The widened end portion 30 has a round cross-section and the tether belt material 22 wraps around the radius the widened end portion 30 when forming the layered construction 26. This helps to eliminate a flat edge in the area where the tether belt material 22 wraps around the wedge section 24a, 24b, which if a flat edge were present could cut the tether belt material 22 and cause failure when force is exerted on the multilayered tether link 10 during a vehicle accident.

The multilayered tether link 10 further includes a folded section 20 having a plurality of layers of sinuously folded tether belt material folded adjacently to form a layered construction 33. In a preferred embodiment the belt material 14 of the folded section is wound in sinusoidally upon itself to provide an ‘s’ type arrangement. The folded section further includes at least one stich connecting the plurality of layers together. Also provided is a hole 34 formed through the center of the layered construction 33 for attachment to the vehicle part 16. The hole 34 is formed ultrasonically using heat knife that prevents fraying. The vehicle part 16 can be any component of the liftgate and can include the liftgate inner panel, wiper motor housing, support brackets, outer panel of the liftgate, latch mounting bracket or latch actuator housing.

The vehicle part 16 can be any component of a liftgate for a vehicle and can include the liftgate inner panel, wiper motor housing, support brackets, outer panel of the liftgate, latch mounting bracket or latch actuator housing. Regarding the tether belt material 22, Suitable tether belt materials are selected from the group of woven materials including polyester, nylon, aramid fibers including para- phenylene-terephtalamide, each alone or in combination.

The multilayered tether link 10 is connected to the vehicle part 16 it will provide controlled release of the tether 12 upon experiencing force of an impact of accident. The controlled release of the tether 12 is provided by the combination of the folding of the tether belt material 22 in the area of the folded wedge section 18 and the at least one stich forming the layered construction 26 of the folded wedge section 18, and the folded section 20 and the at least one stich forming the layered construction 33. Referring now to Fig. 7 the stich details on the tether 12 are shown and described. The folded wedge section 18 has at least one stich 36 generally shown. The at least one stich 36 includes two tight stich sections 38a, 38b that are joined at opposing ends by two load transfer stich sections 40a, 40b. Similarly, the folded section 20 has at least one stich 42 generally shown. The at least one stich 42 includes two tight stich sections 44a, 44b that are joined at opposing ends by two load transfer stich sections 46a, 46b. During an adverse event such as a vehicle crash where force is applied to the tether 12, forces act on each tight stich section 38a, 38b, 44a, 44b with each load transfer stich section 40a, 40b, 46a, 46b transferring load between the respective tight stich section 38a, 38b, 44a, 44b in order to control the unravelling of the tether 12 and to maximize the absorbance of unwanted forces.

The multilayered tether link 10, 200 shown in Figs. 1-5, 6b, 6C and 7 provide a significant packaging and force absorption advantage over applications the use an overmolded tether. For example, Fig. 6A shows a prior art overmolded tether 300 connected to the liftgate. As shown the overmolded portions of the tether 300 has overmolded connection features that have a stack height A. Fig. 6B shows that the tether 12 has a stack height B for the folded wedge section 18 and a stack height C for the folded section 20. Both the stack height B and stack height C are much smaller than the stack heigh A attained using the tether 300 with overmolding. The tether 10, 200 have a distinct packaging advantage over tether 300.

Referring now to Figs 8A and 8B an alternate tether 400 design is shown. The tether 400 has a loop end 404 with an aperture formed by a loop of the tether material. An eyelet end 406 of the tether 400 has an aperture for receiving a fastener for connecting the tether 400 to a vehicle part. During connection, the eyelet end 406 is passed through the loop end 404 and secured to the vehicle part. A stopper fold 407 on the eyelet end is created by folding the tether belt material and stitching it together. The loop end 404 is held in place between the stopper fold 407 and the fastened down eyelet end 406.

The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the essence of the invention are intended to be 5 within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.