WO1991011012A1

WO1991011012A1 - Flexible synthetic plastic conduit

Info

Publication number: WO1991011012A1
Application number: PCT/US1990/002881
Authority: WO
Inventors: Robert L. Heimann; Wayne L. Soucie; David R. Webb
Original assignee: Orscheln Co.
Priority date: 1990-01-05
Filing date: 1990-05-29
Publication date: 1991-07-25
Also published as: AU6431790A

Abstract

A cable assembly includes a force-transmitting inner core member (1), and an outer flexible synthetic plastic sleeve member (2) including an annular inner portion (4) containing a bore (6) having a smooth wall surface and within which the core member (1) is mounted for longitudinal displacement. A plurality of integral helical rib portions (8) extend radially outwardly from the outer periphery of the inner portion (4), which rib portions (8) extend longitudinally in a spaced helical arrangement about the inner portion (4). In one embodiment, an annular outer synthetic plastic protective layer (10) is arranged concentrically about the inner portion (4) and extends radially inwardly to fill the spaces between the helical ribs (8) in a second embodiment, the annular outer layer (2') is tubular, thereby defining helical noise-baffling passages (16) between the helical ribs (8').

Description

FLEXIBLE SYNTHETIC PLASTIC CONDUIT

Specifica ion

Statement of the Invention

This invention relates to a cable assembly for mechanical control cable installations, such as push-pull cables, throttle cables and the like, including a flexible synthetic plastic outer sleeve member having an annular inner portion containing a bore for slidably receiving a force-transmitting inner member, a plurality of integral helical rib portions extending radially outwardly from the outer periphery of the sleeve inner portion, and a protective annular outer portion arranged concentrically about the helical rib portions.

Brief Description of the Prior Art

The use of synthetic plastic materials in the manufacture of automotive and industrial control cable assemblies, is known in the patented prior art. For example, the Kramer patent No. 3,930,419 discloses the use of high molecular weight thermoplastics including acrylonitrile-butadiene- styrene terpolymers, acetal resins, acrylic resins, cellulosic resins, fluoroplastics, ionomers, methylpentene resins, nylons, polyester resins, polyphenylene ethers, polyallomers, polycarbonates, polyethylene, polyimides, polypropylene, modified polystyrenes, polysufones, polyvinyl chloride, and many others. Especially preferred are thermoplastic polyester resins of the diol terephthalate type, and special mention is made of poly(1,4-butylene terephthalate) .

The use of polybutadiene therephthalate is disclosed in Kuzunishi No. 4,451,303, the use of polyphenylene sulfide is taught by Coule No. 4,075,158 and the use of polyuimides is taught by Boldebuck et al. No. 4,255,471, among others.

In the Fukuda patent No. 4,112,708, the outer sleeve member of a cable assembly is disclosed which is formed of polyamid, polyacetal, polyallylate, polyester, polyethylene, polyfluorocarbon, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene-copolymer, polypropylene or the like. A liner member is provided having an inner periphery formed with a plurality of helically-spiraled lubricant grooves, and an outer periphery formed with a plurality of depressed portions which run the whole length of the liner.

The present invention was developed to provide an improved cable assembly that is stronger, more durable and having a synthetic plastic outer sleeve member that is less expensive to produce than the known cable assemblies, and which has a greatly increased operating life. Summary of the Invention

Accordingly, a primary object of the present invention is to provide a cable assembly including flexible synthetic plastic outer sleeve member having an annular inner portion containing a bore for slidably receiving a force-transmitting inner member, a plurality of integral helical ribs extending radially outwardly from the outer periphery of, and longitudinally relative to, said sleeve inner portion, and a protective annular oute portion arranged concentrically about said helical rib portions. In one embodiment, the protective outer portion is extruded concentrically about, and completely fills the spaces between, the helical rib portions. In a second embodiment, the protective outer portion is tubular and engages only the outermost surfaces of the rib portions, thereby to define helical noise-baffling passages between the helical ribs, which reduce weight while distributing bending and compressive stresses over reduced cross-sections. This construction reduces intraplanar stresses allowing for the use of higher strength engineering polymers while maintaining flexibility.

Another object of the invention is to provide a flexible synthetic plastic mechanical control housing for, but not limited to, push-pull application cable routing comprised of a smooth inner member supporting bore surrounded by helically radiating tensile/compressive load-bearing splines encased within a protective synthetic plastic jacket.

Another object is to provide a novel flexible synthetic plastic guide conduit, and more particularly, to a flexible conduit for housing linear unidirectional, reciprocating, or rotating cable assemblies, and for providing a superior support structure fabricated by a cost effective process. A protective outer sleeve is connected with radially disposed helical ribs on the annular inner portion and extending longitudinally the length of the sleeve while rotating circumfer- entially, thereby redistributing tensile and compressive loading forces induced by bending of th conduit evenly over the radially spaced splines. This integral assembly eliminates the problems of movement and distortion inherent with conventional conduit while prohibiting the crushing effect of compressive forces inherent with reciprocating cabl assemblies induced by operating sequences or installation, handling, shipping, and the like, while the extrusion of the exterior membrane offers protection from detrimental compounds found in the application environment.

The present invention provides a cost effectiv alternative to solid plastic construction by using high molecular weight engineering thermoplastic extruded to a configuration retaining an extremely high strength-to-weight ratio capable of being fabricated to any required length.

Another object is to provide a product capable of being bent without regard to direction by incorporating internal rib structural elements extending the length of the assembly which by virtu of their radial juxtaposition produce a structure sufficiently rigid to retain a circular orifice while sustaining lateral and columnar loadings.

Still another object is to provide through the use of HM engineering thermoplastics, inherently self lubricating, an extruded tubular product of continuously smooth bore whereby a similar coated inner member may slide freely, thereby maximizing the potential of a barrier film lubrication system using minimal material amounts.

A further object is to supply an exceptionally strong platform for anchoring organic polymeric end-fittings so molded as to mechanically interlock with the conduit while eliminating heat scoring requirement and laywires prevalent in previous constructions that might possibly damage the molds used to fabricate said end-fittings.

A further object resides in the provision of substrate capable of meeting a constant changing contact area and distributive or disruptive forces by varying the rate of helical twist and/or the height of the radially disposed splines. Additional modifications may be easily accomplished with selective usage of outer synthetic plastic layers for thermal, electrical, corrosive, shock, chemical and other unspecified protection as may be required.

A still further object is to reduce to a minimum or eliminate any backlash transmission by the cable structure resulting from the movement differential between the core element and outer protective structure by uniting these two substructures together in a single cohesive product

Yet another object is to provide for a cable assembly of particularly silent operation by utilizing the internal baffling inherent in this design, while the protective outer coating reduces noise generated by the vibration induced in an automotive environment.

Yet another object of this invention is to provide a component producible at extremely cost effective levels by replacing slow conventional out-dated technology with high speed precision extrusion processes monitored and controlled throug sophisticated statistical process control data acquisition equipment as demanded by current world class industrial standards.

Brief Description of the Drawings

Other objects and advantages of the invention will become apparent from a study of the following specification, when viewed in the light of the accompanying drawing, in which:

Fig. 1 is a side elevational view, with certai parts broken away, of a first embodiment of the cable assembly of the present invention;

Fig. 2 is a sectional view taken along line 2- of Fig. 1; Fig. 3 is a detailed side elevational view of the inner portion of the outer sleeve member of the apparatus of Fig. 1;

Fig. 4 is a sectional view taken along the line 4-4 of Fig. 3;

Fig. 5 is a side elevational view of a second embodiment of the cable assembly of the present invention; and

Fig. 6 is a sectional view taken along line 6-6 of Fig. 5.

Detailed Description

Referring first more particularly to Figs. 1-4, the cable assembly — which is suitable for various mechanical control cable applications such as push-pull cables, throttle control cables or the like — includes a flexible tubular outer sleeve member 2 having a continuous annular inner portion 4 containing a bore having a smooth wall surface 6. On its outer periphery, the inner portion is provided with a plurality of radially outwardly extending helical rib portions 8 that extend helically longitudinally of the inner portion, as shown in Fig. 1 and 3. This inner portion is formed of a relatively hard synthetic plastic material, such as the product NORYL GTX 910 produced by the General Electric Company, or other suitable polymeric material.

Formed (preferably by extrusion) concentrically about the inner portion from a flexible, relatively soft protective corrosion-resistant synthetic plastic material (preferably TPR, a thermoplastic rubber, or SANTOPRENE, produced by Monsanto or othe suitable polymeric thermoplastic material) is a protective outer cable portion 10. In this embodiment, this protective outer portion completel fills the spaces between the helical ribs, as shown in Fig. 2.

Arranged for longitudinal sliding movement within the bore of the flexible outer sleeve 2 is a inner force-transmitting metal core member 12, such as a unitary rod-like member or a stranded member formed from metal strands, as is known in the art. Preferably, the core member is coated with a layer 14 of self-lubricating material (such as nylon or a polyester) compatible with the material from which the annular inner portion 4 is formed.

It will be seen that the inner annular portion 4 and the helical ribs 8 impart strength to the outer sleeve member and that the outer annular portion 10 protectively covers the inner portion against corrosion moisture, ice, mud, sand and othe impurities.

Referring now to the embodiment of Fig. 5 and 6, the flexible outer synthetic plastic sleeve member 2 ' has an annular inner portion 4 ' having a smooth inner wall surface 6 ' , a plurality of integral radially-outwardly extending helical rib portions 8 ' , and a generally tubular outer portion 10' integral with the outer extremities of the helical rib portions 8 ' , thereby to define between the helical ribs a plurality of helical noise- baffling chambers 16. Preferably the sleeve 2' is formed by extrusion from a flexible relatively hard synthetic plastic material, such as NORYL GTX 625 produced by General Electric Company, with the inner, helical rib and outer portions being integral.

Arranged for sliding movement within the bore 6' contained in the annular inner portion 4' is the convention metal inner core member 12 ' for transmitting tensile force to the associated load means.

While the preferred forms and embodiments of the invention have been illustrated and described as required by the Patent Statutes, it is apparent, of course, that, various modi ications could be made in the described apparatus.

Claims

WHAT IS CLAIMED IS:

1. A cable assembly for mechanical control systems, comprising:

(a) a flexible tubular outer sleeve member, including:

(1) a continuous annular synthetic- plastic inner portion containing a bore having a generally cylindrical wall surface;

(2) a plurality of helical rib portions integral with, and extending radially outwardly from the outer periphery of, said annular inner portion, said helical rib portions extending helically longitudinally of said annular inner portion and having the same pitch; and

(3) a protective annular synthetic plastic outer portion arranged contiguously about said helical rib portions; and

(b) an inner force-transmitting core member arranged for coaxial longitudinal displacement within the bore of said annular inner portion.

2. Apparatus as defined in Claim 1, wherein said annular outer portion is formed by extrusion about said annular inner portion and fills the spaces between said helical rib portions.

3. Apparatus as defined in Claim 2, wherein said annular inner portion and said helical rib are formed by extrusion.

4. Apparatus as defined in Claim 3, wherein said protective outer portion and said inner and helical portions are formed from different relatively soft and relatively hard synthetic plastic materials, respectively.

5. Apparatus as defined in Claim 1, wherein said outer portion is generally tubular and is in engagement with the outer extremities of said helical rib portions, thereby to define between said rib portions noise-deadening helical passages in said outer sleeve member.

6. Apparatus as defined in Claim 5, wherein said annular inner, helical rib and annular outer portions are integral.

7. Apparatus as defined in Claim 1, wherein the bore wall surface of said inner portion is smooth, and further wherein said inner force-transmitting core member is coated with a self-lubricating material.