Patent Description:
As a new construction method, air-blown laying is very popular in developed countries with high labor costs. With the promotion of European and American operators, more and more telecom companies and construction teams around the world are used to laying optical fiber cables in this way. Therefore, how to ensure the stable performance and affordable price of the optical fiber cable during the process of air-blown laying has become a problem that many optical fiber cable companies think about.

During the sheathing process of the existing air-blown optical fiber cable, the sheath material will crystallize after being extruded, causing the optical fiber cable to shrink in the water tank, then the aramid material of the strengthening layer will produce part of excess length, and at the same time, the optical fiber will also produce part of excess length. The excess length of the aramid fiber leads to a decrease in the tensile performance of the optical fiber cable, and the excess length of the optical fiber causes macrobending of the optical fiber in the tube, which increases the loss of the optical fiber cable.

Moreover, during the process of air-blowing construction of the air-blown optical fiber cable, high-pressure gas is used to suspend the optical fiber cable in the micro-tube. When the optical fiber cable itself is propelled by the driver, the high-speed flowing gas carries the optical fiber cable forward together. When the optical fiber cable encounters situations such as turning, it will inevitably contact the inner wall of the micro-tube to form a friction, which hinders the high-speed advancement of the optical fiber cable.

At present, the traditional central tube-type air-blown optical fiber cable mainly relies on the sheath material to reduce the surface friction of the optical fiber cable. However, due to the large gap between the basic materials of China and the materials of world-class enterprises, there is not much room for improvement of the materials themselves. However, redesigning the optical fiber cable from the aspect of structure itself has strong operability. The surface friction F=µ*p*S, if the material is determined, µ is determined, and if the construction equipment is determined, p is determined. Adjusting the contact area between the optical fiber cable and the micro-tube can directly change the surface friction of the optical fiber cable during the process of construction. Therefore, how to change the surface friction of the optical fiber cable during the process of construction through adjusting the contact area between the optical fiber cable and the micro-tube has become an urgent problem to be solved.

<CIT> discloses a superfine anti-termite air-blown optical cable and a fabrication method thereof. <CIT> discloses an ultra-miniature air-blown optical cable. <CIT> discloses an optical cable structure suitable for air blowing installation and a manufacturing method thereof. <CIT> discloses a full-dry air-blowing micro optical cable.

The invention is defined in claim <NUM>, and provides an air-blown optical fiber cable so as to solve the problem in the related art that the optical fiber cable has a large contact area with the inner wall of the micro-tube when the optical fiber cable encounters situations such as turning, resulting in a large friction and hindering the high-speed advancement of the optical fiber cable.

According to the invention, an air-blown optical fiber cable is provided, comprising:.

The strengthening layer of the present application is mesh-shaped, so that at least a partial region of the outer jacket forms a drag reduction structure, and the protrusions and the recesses of the drag reduction structure are alternately connected to each other, and the recesses extend into the mesh of the strengthening layer, which increases the resistance of the airflow during the process of the construction of the air-blown optical fiber cable, and has a stronger drive for the air-blown optical fiber cable. The first gaps that are formed between every two adjacent protrusions and a recess located therebetween are not in contact with a micro-tube, and merely the protrusions are in contact with the micro-tube, which reduces the contact area between the outer jacket and the micro-tube, and reduces surface friction of the optical fiber cable. The second gaps are formed between every two adjacent recesses and a protrusion located therebetween, and the strengthening layer extends into the second gaps and is connected to the protrusions, the drag reduction structure formed on the outer jacket reduces the ability of the molecular chain ordering of the outer jacket material to make the crystallinity of the outer jacket reduce, thereby reducing the excess length of the air-blown optical fiber cable and making the performance more stable.

In some embodiments, each of the recesses is connected to the loose tube. The strengthening layer is wrapped between the loose tube and the outer jacket, and the recesses of the loose tube and the drag reduction structure are integrated at the mesh position of the strengthening layer, so that the strengthening layer and the outer jacket will not slide relative to each other during the process of construction traction, the structure is more reliable, and the stretching of the optical fiber cable is reduced.

In some embodiments, there are a plurality of drag reduction structures, and the plurality of the drag reduction structures are distributed at intervals along an axial direction of the loose tube, and the drag reduction structures are in a shape of an annular surrounding along a circumferential direction of the loose tube. The annular-shaped drag reduction structure can reduce the surface friction in the circumferential direction of the optical fiber cable.

In some embodiments, there are a plurality of drag reduction structures, and the plurality of the drag reduction structures are distributed at intervals along a circumferential direction of the loose tube. The strip-shaped drag reduction structure can reduce the surface friction in an axial direction of the optical fiber cable.

In some embodiments, the drag reduction structures are in a shape of a spiral surrounding along an axial direction of the loose tube. The spiral drag reduction structure can reduce the surface friction in a spiral direction of the optical fiber cable.

In some embodiments, all of the outer jacket forms the drag reduction structure. Through extruding the entire outer jacket, the outer jacket forms a drag reduction structure that is compatible with the mesh-shaped strengthening layer, so that the contact area between the outer jacket and the micro-tube is greatly reduced, thereby greatly reducing the surface friction of the optical fiber cable, and the method of one-time extrusion molding can be adopted to save working hours.

In some embodiments, the drag reduction structure is formed through extruding the outer jacket.

In some embodiments, the protrusion is in a shape of a square or hemisphere. Through designing the structure of the protrusion, the surface friction of the optical fiber cable can be further improved, for example, the contact surface between the hemispherical protrusion and the micro-tube is smoother, and the contact area is smaller, which can have a better effect of reducing the surface friction of the optical fiber cable.

In some embodiments, the portion of the loose tube wrapped by the strengthening layer accounts for no more than <NUM>% of the loose tube. Through designing the structure of the protrusion, the surface friction of the optical fiber cable can be further improved, for example, the contact surface between the hemispherical protrusion and the micro-tube is smoother, and the contact area is smaller, which can have a better effect of reducing the surface friction of the optical fiber cable.

In some embodiments, the cable core comprises a plurality of optical fibers.

The beneficial effects brought by the technical solution provided by the present application comprise: the strengthening layer of the present application is mesh-shaped, so that at least a partial region of the outer jacket forms a drag reduction structure, and the protrusions and the recesses of the drag reduction structure are alternately connected to each other, and the recesses extend into the mesh of the strengthening layer, which increases the resistance of the airflow during the process of the construction of the air-blown optical fiber cable, and has a stronger drive for the air-blown optical fiber cable. The first gaps that are formed between every two adjacent protrusions and a recess located therebetween are not in contact with a micro-tube, and merely the protrusions are in contact with the micro-tube, which reduces the contact area between the outer jacket and the micro-tube, and reduces surface friction of the optical fiber cable. The second gaps are formed between every two adjacent recesses and a protrusion located therebetween, and the strengthening layer extends into the second gaps and is connected to the protrusions, the drag reduction structure formed on the outer jacket reduces the ability of the molecular chain ordering of the outer jacket material to make the crystallinity of the outer jacket reduce, thereby reducing the excess length of the air-blown optical fiber cable and making the performance more stable.

The present application provides an air-blown optical fiber cable, due to the strengthening layer of the present application is mesh-shaped, so that at least a partial region of the outer jacket forms a drag reduction structure, and the protrusions and the recesses of the drag reduction structure are alternately connected to each other, and the recesses extend into the mesh of the strengthening layer, which increases the resistance of the airflow during the process of the construction of the air-blown optical fiber cable, and has a stronger drive for the air-blown optical fiber cable. The first gaps that are formed between every two adjacent protrusions and a recess located therebetween are not in contact with a micro-tube, and merely the protrusions are in contact with the micro-tube, and the second gaps are formed between every two adjacent recesses and a protrusion located therebetween, and the strengthening layer extends into the second gaps and is connected to the protrusions, therefore, the first gaps reduce the contact area between the outer jacket and the micro-tube, and reduce surface friction of the optical fiber cable. The drag reduction structure formed on the outer jacket reduces the ability of the molecular chain ordering of the outer jacket material to make the crystallinity of the outer jacket reduce, thereby reducing the excess length of the air-blown optical fiber cable and making the performance more stable.

In order to better illustrate the technical solution in the embodiments of the present application, the following will briefly introduce the drawings needed in the description of the embodiments, and it is obvious that the drawings in the following description are part of embodiments of the present application, for those of ordinary skill in the art, other drawings may also be obtained based on these drawings without any inventive effort.

In the figure: <NUM>-cable core; <NUM>-optical fiber; <NUM>-loose tube; <NUM>-strengthening layer; <NUM>-outer jacket; <NUM>-drag reduction structure; <NUM>-protrusion; <NUM>-recesse; <NUM>-the first gap; <NUM>- the second gap.

In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without inventive efforts shall fall within the protection scope of the present application.

As shown in <FIG>, an embodiment of the present application provides an air-blown optical fiber cable, which comprises a cable core <NUM>, a loose tube <NUM>, a strengthening layer <NUM> and an outer jacket <NUM>. The cable core <NUM> comprises a plurality of optical fibers <NUM>, the loose tube <NUM> is sleeved outside the cable core <NUM>, and the optical fibers <NUM> can be loosely placed in the loose tube <NUM>. The loose tube <NUM> is a tube made of polypropylene or nylon that protects the optical fibers <NUM> from internal stress and external side pressure, with an outer diameter of <NUM>±<NUM> and an inner hole of <NUM>±<NUM>. Fiber paste is filled in the loose tube <NUM> to prevent longitudinal water seepage in the loose tube <NUM>. The strengthening layer <NUM> is mesh-shaped and is wrapped around the loose tube <NUM>. The outer jacket <NUM> is wrapped around the strengthening layer <NUM>, and the material of the outer jacket <NUM> is polyethylene, nylon and other materials. The method of extrusion molding is adopted, the wall thickness of the outer jacket <NUM> is <NUM>±<NUM>, and the outer diameter is <NUM>±<NUM>. At least a partial region of the outer jacket <NUM> forms a drag reduction structure <NUM>, the drag reduction structure <NUM> comprises a plurality of protrusions <NUM> and a plurality of recesses <NUM>, the protrusions <NUM> protrudes toward the direction away from the loose tube <NUM>, and the recesses <NUM> protrudes toward the direction close to the loose tube <NUM>. The protrusions <NUM> and the recesses <NUM> are alternately connected to each other, and each of the recesses <NUM> extends into the mesh of the strengthening layer <NUM>. The first gaps <NUM> are formed between every two adjacent protrusions <NUM> and a recess <NUM> located therebetween, the first gaps <NUM> do not contact a micro-tube, and merely the protrusions <NUM> contact the micro-tube, such that a contact area between the outer jacket <NUM> and the micro-tube is reduced, thus reducing the surface friction of an optical fiber cable. The second gaps <NUM> are formed between every two adjacent recesses <NUM> and a protrusion <NUM> located therebetween, and the strengthening layer <NUM> extends into the second gaps <NUM> and is connected to the protrusions <NUM>.

The principle of changing the surface friction of the optical fiber cable during the process of construction by the air-blown optical fiber cable in the embodiment of the present application is as follows:
The strengthening layer <NUM> in the embodiment of the present application is mesh-shaped, so that at least a partial region of the outer jacket <NUM> forms a drag reduction structure <NUM>, and the protrusions <NUM> and the recesses <NUM> of the drag reduction structure <NUM> are alternately connected to each other, and the recesses <NUM> extend into the mesh of the strengthening layer <NUM>, which increases the resistance of the airflow during the process of the construction of the air-blown optical fiber cable, and has a stronger drive for the air-blown optical fiber cable. The first gaps <NUM> are formed between every two adjacent protrusions <NUM> and a recess <NUM> located therebetween, the first gaps <NUM> do not contact a micro-tube, and merely the protrusions <NUM> contact the micro-tube, such that a contact area between the outer jacket <NUM> and the micro-tube is reduced, thus reducing the surface friction of an optical fiber cable. The second gaps <NUM> are formed between every two adjacent recesses <NUM> and a protrusion <NUM> located therebetween, and the strengthening layer <NUM> extends into the second gaps <NUM> and is connected to the protrusions <NUM>. The drag reduction structure <NUM> formed on the outer jacket <NUM> reduces the ability of the molecular chain ordering of the outer jacket <NUM> material to make the crystallinity of the outer jacket <NUM> reduce, thereby reducing the excess length of the air-blown optical fiber cable and making the performance more stable.

Optionally, each of the recesses <NUM> is connected to the loose tube <NUM>. The strengthening layer <NUM> is wrapped between the loose tube <NUM> and the outer jacket <NUM>, and the recesses <NUM> of the loose tube <NUM> and the drag reduction structure <NUM> are integrated at the mesh position of the strengthening layer <NUM>, so that the strengthening layer <NUM> and the outer jacket <NUM> will not slide relative to each other during the process of construction traction, the structure is more reliable, and the stretching of the optical fiber cable is reduced.

Optionally, as shown in <FIG>, there are a plurality of drag reduction structures <NUM>, and the plurality of the drag reduction structures <NUM> are distributed at intervals along an axial direction of the loose tube <NUM>, and the drag reduction structures <NUM> are in a shape of an annular surrounding along a circumferential direction of the loose tube <NUM>. The annular-shaped drag reduction structure <NUM> can reduce the surface friction in the circumferential direction of the optical fiber cable.

Optionally, as shown in <FIG>, there are a plurality of drag reduction structures <NUM>, and the plurality of the drag reduction structures <NUM> are distributed at intervals along a circumferential direction of the loose tube <NUM>, and the drag reduction structures <NUM> are in a shape of a strip. The strip-shaped drag reduction structure <NUM> can reduce the surface friction in the axial direction of the optical fiber cable.

Optionally, the drag reduction structures <NUM> are in a shape of a spiral surrounding along an axial direction of the loose tube <NUM>. The spiral drag reduction structure <NUM> can reduce the surface friction in the spiral direction of the optical fiber cable.

Through setting different distributions of the drag reduction structures <NUM>, the air-blown optical fiber cables with different requirements are adapted, and the matching air-blown optical fiber cables are used according to the specific requirements for reducing the surface friction of the air-blown optical fiber cables.

Preferably, all of the outer jacket <NUM> forms the drag reduction structure <NUM>. The drag reduction structure <NUM> is formed through extruding the outer jacket <NUM>. Through extruding the entire outer jacket <NUM>, the outer jacket <NUM> forms a drag reduction structure <NUM> that is compatible with the mesh-shaped strengthening layer <NUM>, so that the contact area between the outer jacket <NUM> and the micro-tube is greatly reduced, thereby greatly reducing the surface friction of the optical fiber cable, and the method of one-time extrusion molding can be adopted to save working hours.

Further, the protrusion <NUM> is in a shape of a square or hemisphere. Through designing the structure of the protrusion <NUM>, the surface friction of the optical fiber cable can be further improved, for example, the contact surface between the hemispherical protrusion <NUM> and the micro-tube is smoother, and the contact area is smaller, which can have a better effect of reducing the surface friction of the optical fiber cable.

Further, the portion of the loose tube <NUM> wrapped by the strengthening layer <NUM> accounts for no more than <NUM>% of the loose tube <NUM>. The strengthening layer <NUM> adopts aramid fiber material for interweaving to form a network structure, which is closely attached to the loose tube <NUM> and forms a whole with the loose tube <NUM>. The coverage of the weaving is no more than <NUM>%, so the proportion of the protrusions <NUM> of the drag reduction structure <NUM> will not exceed <NUM>%, which can reduce the contact area between the drag reduction structure <NUM> and the microtube by at least <NUM>%. The weaved mesh-shaped structure avoids the tensile strain caused by the excess length of the aramid fiber, which can improve the mechanical properties of the optical fiber cable.

Further, the cable core <NUM> comprises a plurality of optical fibers <NUM>, and the optical fibers <NUM> are single-mode or multi-mode optical fibers for single or multi-channel communication, a total of <NUM>, and is distinguished by blue, orange, green, brown, gray, white, red, black, yellow, purple, pink and turquoise.

In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", etc. are based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, instead of indicating or implying that the pointed device or element must have a specific orientation, be configured and operated in a specific orientation, therefore it cannot be understood as a limitation of the present application. Unless otherwise clearly specified and limited, the terms "installation", "connected" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; further can be a mechanical connection, or an electrical connection; further can be directly connected, or indirectly connected through an intermediate medium, or can be the internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above-mentioned terms in the present application can be understood according to specific circumstances.

It should be noted that relational terms such as "first" and "second" are only for distinguishing one entity or operation from another entity or operation in this the present application, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only comprises those elements, but also comprises those that are not explicitly listed, or further comprises elements inherent to the process, method, article, or device. If there are no more restrictions, the elements defined by the sentence "comprising a. " does not exclude the existence of other same elements in the process, method, article, or device comprising the elements.

Claim 1:
An air-blown optical fiber cable, comprising:
a cable core (<NUM>);
a loose tube (<NUM>), which is sleeved outside the cable core (<NUM>);
a strengthening layer (<NUM>), which is mesh-shaped and is wrapped around the loose tube (<NUM>);
an outer jacket (<NUM>), which is wrapped around the strengthening layer (<NUM>), at least a partial region of the outer jacket (<NUM>) forms a drag reduction structure (<NUM>), and the drag reduction structure (<NUM>) comprises a plurality of protrusions (<NUM>) and a plurality of recesses (<NUM>), wherein the protrusions (<NUM>) and the recesses (<NUM>) are alternately connected to each other, and each of the recesses (<NUM>) extends into the mesh of the strengthening layer (<NUM>); first gaps (<NUM>), which are formed between every two adjacent protrusions (<NUM>) and a recess (<NUM>) located therebetween; and second gaps (<NUM>), which are formed between every two adjacent recesses (<NUM>) and a protrusion (<NUM>) located therebetween, and the strengthening layer (<NUM>) extends into the second gaps (<NUM>) and is connected to the protrusions (<NUM>).