JP2014229639A - Structure for fixing solar cell output cable to connection box and fixing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure for fixing a solar cell output cable to a connection box with high water-tightness and at a low cost, and a fixing method.SOLUTION: In a fixing structure of a solar cell output cable, a distal end portion of a solar cell output cable which is peeled over two stages is covered with an elastic cylindrical bush so as to cover an outer side face of an exposed insulation coating body. A connection box includes an outer wall bored with an introduction hole for inserting the distal end portion of the solar cell output cable and an inner wall opposing the outer wall. The inner wall includes a through hole to pass the bush covering the insulation coating body. Narrowed portions are provided within the through hole of the inner wall, and the solar cell output cable is inserted into the connection box until an outer side face of the bush covering the insulation coating body is held between the narrowed portions. Between the outer wall and the inner wall, the solar cell output cable is fixed by a fixture so as to be prevented from moving relatively to the connection box.

Description

  The present invention relates to a cable fixing structure and a fixing method to a connection box of a solar cell output cable for extracting electric power from a solar cell module. More specifically, the present invention relates to a cable fixing structure and fixing method that are excellent in water tightness and can be fixed easily and inexpensively in fixing a solar cell output cable to a connection box.

The electrical output of the solar cell module is connected from the solar cell module to the power conditioner connection box via an output cable laid between them. In a normal installation method, a certain number of solar cell modules are connected in series to a cable with a connector attached to a junction box attached to the module, and then a power conditioner is connected with a long cable with a connector called an extension cable. Connect to the connection box. In addition, there is an installation method in which modules are connected in parallel. In that case, a parallel connection box corresponding to the number of parallel connections is used. In some cases, a backflow prevention box is incorporated in the circuit.
Hereinafter, in the present invention, the connection box refers to a junction box, a multi-connection box, a backflow prevention box, and the like, and the solar cell output cable refers to an output cable attached to the connection box.

  Solar cell modules installed on the roof and outdoors, their connection boxes, and the solar cell output cables attached to the connection boxes are placed in an environment with a large temperature and humidity difference due to changes in day and night, season, etc. It is exposed to the risk of electrical insulation being destroyed by condensation. For this reason, the connection box, the solar cell output cable, and the connection portion between the solar cell cable and the connection box must have sufficient waterproof performance to protect the electrical insulation, and the drip-proof level required for cable connectors for automobiles etc. In addition, a higher level of watertightness that can withstand a submergence test at a depth of 1 m and a more severe immersion voltage test is desired.

  As for the watertight structure of the connection box and its internal connection parts and the solar cell output cable mounting part attached to it, in the case of the method of filling the inside of the box with a silicone sealant, the outer material of the solar cell output cable used In the case of a vinyl chloride resin, the adhesiveness at the interface with the cable sheath is good, so that the necessary watertight performance can be obtained without any special efforts.

  However, the proportion of cable sheath materials that use polyolefin resins such as polyethylene, polypropylene, and polymethylpentene instead of vinyl chloride resin is increasing due to concerns about the generation of dioxins during combustion. However, unlike vinyl chloride resins, polyolefin-based resins have poor adhesion to silicone-based sealants, and it is difficult to obtain sufficient watertight performance with only sealants. Interfacial detachment occurs only by slight movement at the interface of the bonded portion, and watertightness is easily impaired. For this reason, peeling occurs at the bonding interface due to the fine movement of the cable bonding portion due to the linear expansion due to the external force or thermal change to the cable of the cable mounting portion, the watertight state is broken, and the water is immersed. As a result, there may occur a case where an electric leakage fire accident due to poor insulation occurs.

  Therefore, in the case of a connection box using a solar cell output cable having a cable sheath of polyolefin resin, even if the silicone sealant is filled inside, the adhesion between the silicone sealant and the cable sheath is weak, The interface peels off due to fine movement of the cable due to the external force on the cable or the thermal expansion of the cable, and the watertight state is broken. There is a danger of causing a fire accident due to poor insulation due to the ingress of water.

  For this reason, the outer surface of the olefin resin outer shell using a base material having an adhesive property with a silicone sealant and an adhesive tape having good adhesion, such as butyl tape, is wound around the cable outer shell, or the adhesiveness with the polyolefin outer shell resin is improved. There has been proposed a method of increasing water tightness by applying a primer agent for enhancing the outer surface of a cable (see Patent Document 1).

However, in the above method, the cable is flexible but has a certain degree of rigidity. Therefore, when a strong external force is applied to the cable, if the cable sheath at the interface with the silicone sealant slightly moves, interface peeling occurs. The risk of breaking water tightness is inevitable.
Therefore, reliability is not sufficient as a method for preventing water from entering the connection box.

  In addition, there is a method using a cable gland as a means for obtaining a highly reliable cable and watertightness of the mounting through hole portion of the connection box. This is a method of obtaining a watertight performance by covering a cable sheath with a rubber bush and tightening the inner and outer surfaces of the rubber bush in the mounting through-hole portion simultaneously and strongly with screw parts (see Patent Document 2).

  However, since the cable gland has a screw shape, the structure is complicated, so the manufacturing cost is high, and fixing is performed by rotating the screw, so it is not quick and simple. There is a problem that the cost becomes high.

  Therefore, there is a need for a fixing structure and a fixing method that are excellent in waterproofness for the connection box of the solar cell output cable to the connection box at a simpler and lower cost than the prior art.

JP 2008-066492 A JP 2000-340821 A

  An object of the present invention is to provide a cable fixing structure and a fixing method that are simple and inexpensive and have excellent watertightness in fixing a solar cell output cable to a connection box.

The invention described in claim 1
In the fixing structure of the solar cell output cable for fixing the solar cell output cable composed of the core wire, its insulating covering and outer skin to the connection box,
An inner diameter made of an elastic material is formed at the tip of the solar cell output cable, the core wire projecting in the central axis direction of the cable, and further stripped in a state where the insulating coating is exposed. A cylindrical bush smaller than the outer diameter is covered so that the inner surface of the bush covers the outer surface of the exposed insulating covering,
The connection box is provided with an outer wall in which an introduction hole having a diameter substantially equal to the diameter of the cable sheath for inserting the tip of the solar cell output cable in the insertion direction of the solar cell output cable is opened and an inner wall facing the outer wall. The inner wall is provided with a hole having a diameter smaller than the outer diameter of the bush after being covered with an insulating covering, forming a narrow portion,
The solar cell output cable is inserted into the connection box until at least a part of the outer surface of the bush covered with the insulating covering is sandwiched between the narrow portions,
And between the outer wall and the inner wall, the solar cell output cable is sandwiched and fixed between a part of the connection box and a fixture,
This is a solar cell output cable fixing structure.

  The invention according to claim 2 is the solar battery output cable fixing structure according to claim 1, wherein the inner diameter of the bush is 3 to 40% smaller than the outer diameter of the insulating covering.

  A third aspect of the invention is a solar cell output cable fixing structure according to the first or second aspect of the invention, wherein the bush is made of silicone rubber.

The invention according to claim 4 is a method of fixing a solar cell output cable comprising a core wire, its insulating coating, and a polyolefin-based outer sheath to a connection box,
The connection box is provided with a double wall surface of an outer wall and an inner wall in the insertion direction of the solar cell output cable, and the outer wall is substantially equal to the diameter of the cable jacket for inserting the tip of the solar cell output cable. A through-hole having a diameter is provided, and a circular through-hole is provided on the inner wall through which a bush covered with the insulating coating passes, and an inner diameter of the inner surface of the circular through-hole on the inner wall is insulated. An annular narrow portion having a cross section perpendicular to the central axis of the cable, which is smaller than the outer diameter of the bushing covered by the covering and larger than the outer diameter of the insulating covering, is provided.
Peeling the tip of the solar cell output cable in two steps to expose the core wire and the insulation coating,
A step of covering a double cylindrical bush having an inner diameter smaller than that of the insulating cover and having elasticity so that the outer surface of the exposed insulating cover is covered on the inner cylindrical surface of the bush;
Inserting the solar cell output cable into the connection box until at least a part of the outer surface of the bush covered with the insulating covering is sandwiched between the narrow portions;
Fixing the solar cell output cable between a part of the connection box and the fixture between the outer wall and the inner wall; and
A method for fixing a solar cell output cable.

The present invention will be described in detail below.
The solar cell output cable used in the present invention is a cable for transmitting electric power generated in the solar cell module as described above. Generally, a cable with a rated voltage of 600V is used, but recently, a cable with a rated voltage of 1000 to 1500V has been developed and used for large-scale mega solar power generation.
As the solar cell output cable, a single-core cable having a two-layer coating in which a core wire is covered with an insulating coating layer and the outer side thereof is covered with an outer cover and a cross-sectional shape perpendicular to the central axis is concentric.

As the solar cell output cable, a CV cable having a rated voltage of 600 V, which is permitted for outdoor use in the domestic standard, or an EM-CE cable is used.
The cross-sectional area of the core wire is 2 mm ² , the outer diameter of the insulating layer is 3.5 mm, the outer diameter of the outer skin is 6.4 mm, the cross-sectional area of the core wire is 3.5 mm ² , the outer diameter of the covering layer is 4.0 mm, and the outer diameter of the outer skin is 7 0.0 mm is common. In the case of mega solar, a core with a cross-sectional area of 5.5 mm ² or more may be used.

  As the outer covering material of the solar cell output cable, soft vinyl chloride resin is used for CV cables, and soft polyethylene resin is used for EM-CE cables. Although both have flexibility but are not elastic like rubber and elastomer, they are stiff, so even if a narrow portion as described later is provided, it cannot be easily inserted into the narrow portion. In addition, since the elastic repulsive force is weak, even if it is forced to be inserted, it cannot be in close contact with the inner surface of the narrow part, and even when an external force is applied to the cable, the response speed is slow, so it is sufficient for displacement Since it cannot follow, sufficient watertightness cannot be obtained. In addition, polyethylene resin has poor adhesiveness and does not adhere to the silicone sealant, so that sufficient watertightness cannot be obtained.

Low-priced soft vinyl chloride CV cables are common for solar cell output cables, but EM-CE cables using soft polyethylene resin called eco-cables are increasing due to concerns about dioxin generation during combustion. ing.
Recently, cables (PV-CC, CQ, QQ) for high voltage solar cells with a rated voltage of 1000-1500V dedicated for solar cells have been standardized along with the spread of mega solar. Cross-linked polyethylene resin / A cross-linked polyolefin resin is used. High-voltage solar cell cables are less flexible and have better adhesion to silicone sealants than conventional CV cables and EM-CE cables with a rated voltage of 600V. difficult.
The present invention can be used for a CV cable and an EM-CE cable, but is also useful for a high voltage solar cell cable having a cross-linked polyolefin-based outer sheath.

  In order to connect the solar cell output cable to the connection box, the end of the cable is exposed to a length where the core wire can be electrically connected, and then the insulation coating layer is exposed for the required length, in a so-called two-stage peeled state. Used.

  A cylindrical elastic bush having an inner diameter smaller than that of the insulating coating is covered with a portion where the outer surface of the insulating coating at the tip of the two-stage stripped solar cell output cable is exposed.

  The inner diameter of the bush used in the present invention is preferably 3 to 40% smaller than the outer diameter of the insulating coating, and more preferably 5 to 30% smaller. If the inner diameter of the bush is too small compared to the outer diameter of the insulation coating, it will be difficult to cover the bush on the insulation coating, and if the inner diameter is too large, that is, the inner diameter of the bush will be too close to the outer diameter of the insulation coating. For example, the inner side surface of the bush is weakened in the force of tightening the outer side surface of the insulating covering body due to its elasticity, and it becomes difficult to maintain watertightness.

  The outer diameter of the bush used in the present invention is not particularly limited, but it is preferable that the outer diameter of the cable sheath is substantially smaller than or smaller than the outer diameter of the cable sheath after the bushing is covered with the insulating covering.

  The bush used in the present invention has a cylindrical shape, and the term “cylindrical shape” as used herein refers to a shape in which a penetrating columnar cavity having a common axis is provided inside a column. This is because this shape is the simplest and the manufacturing cost is low. However, even if at least one of the outer and inner surfaces is rugged, as long as the watertightness is not impaired, the inner surface is tapered and inclined with respect to the shaft. )

  The axial length of the bush is not limited, but in order to maintain a stable watertight structure, the length is preferably 0.5 to 5 times the outer diameter of the insulating covering. In order to make the overall connection structure compact, the length is preferably 0.5 times or more and 2 times or less.

The bush used in the present invention is preferably made of a material having rubber elasticity and satisfying electric insulation, heat resistance, creep resistance and the like.
This is because it can be covered with an insulating coating layer larger than the inner diameter, and can be pressed with a narrow portion described later to maintain a watertight structure. The bush used in the present invention is preferably harder than an eraser and softer than an automobile tire, and preferably has a durometer hardness of 40 to 60 as defined in JIS K 6253. As the material of the bush, rubber (including elastomer) such as urethane, nitrile, chloroprene, ethylene, butyl, fluorine, silicone (organic polysiloxane) can be used.

  The elongation at normal temperature is preferably 100 to 600% and the tensile strength is preferably 5 to 16 MPa. The temperature range that can function as an elastic body is preferably −40 ° C. to 90 ° C., and when soldering the core wire, it is more preferable that it can withstand 200 ° C. even for a short time. In order to satisfy such requirements, silicone rubber and fluororubber are preferable in terms of performance. However, since fluororubber is expensive and silicone rubber is relatively inexpensive, silicone rubber is particularly preferable.

  As such a bush, a silicone rubber molded by injection molding, extrusion molding or the like can be used. The crosslinking may be performed at any time as long as the physical properties are satisfied.

  From the exposed side of the core wire of the solar cell output cable, the cylindrical bush made of a material having an inner diameter smaller than that of the insulating coating body and having elasticity is applied to the portion where the outer surface of the insulating coating body is exposed. Pass the core wire through the cavity of the bush, then hold the inner surface of the bush so that it is approximately equidistant from the axis of the solar cell output cable, and place the end surface of the bush against the end surface of the insulation covering on the side where the core wire is exposed. By pushing in the direction parallel to the axis of the battery output cable, the bush extends with rubber elasticity, so that the bush can be covered on the insulating coating. It is preferable to cover the bushing until the end surface of the bush comes into contact with the end surface of the outer cover of the solar cell output cable peeled off in two steps. This step may be performed manually or by a machine.

As described above, in the present invention, the connection box refers to various connection boxes that are required to be waterproof for outdoor use, such as junction boxes, parallel connection boxes, and backflow prevention boxes.
The connection box for forming the fixing structure of the present invention includes an outer wall having an introduction hole having a diameter substantially equal to the diameter of the cable sheath for inserting the tip of the solar cell output cable, and an inner wall facing the outer wall. A through hole is provided.
The introduction hole needs to have a diameter that does not allow a gap as much as possible so that the cable sheath of the solar cell output cable can pass through and the axis of the cable does not shake. The shape of the opening may be a polygon or an ellipse, but the solar cell output cable has a circular cross section, and is preferably circular. The diameter of the solar cell output cable is preferably approximately the same as or slightly larger than the solar cell output cable jacket. In order to suppress vibration due to an external force of the output cable, it is preferable to provide an introduction hole penetrating the outer wall integrated with the connection box from the viewpoint of mechanical strength and ease of manufacture.

  In the connection box, an inner wall is provided on the inner side of the fixed portion, on the extension of the central axis of the solar cell output cable with respect to the introduction hole, at an opposed position, and the inner wall is covered with an insulating covering. A through-hole through which the bush having elasticity is passed is provided. The outer wall and the inner wall are preferably parallel to each other, and more preferably orthogonal to a straight line connecting the center of the introduction hole and the center of the through hole provided in the inner wall. In order to increase the fixing force of the cable, the cable may be bent or meandered between the introduction hole of the outer wall and the through hole of the inner wall, but the connection box becomes larger and the cost increases. It is preferable that the axis | shaft of the solar cell output cable in between becomes short linear form, and is orthogonal to an outer wall and an inner wall. The inner wall has a function of separating the live part that connects electricity passing through the core wire from the other outside.

  The inner wall is provided with a through-hole having an inner diameter portion smaller than the outer diameter of the bush after being covered with the insulating cover, and forms a narrow portion with respect to the bush covered with the insulating cover. The inlet of the through hole in the inner wall may have the same diameter as the through hole in the outer wall. Although a narrow part may be formed by putting another member in the through hole of the inner wall, the protrusion directed toward the central axis of the cable that continues to the entire circumference of a partial section in the cable axial direction of the inner side surface of the through hole of the inner wall It is preferable that a circular hole is formed by the outer periphery in which the tips of the protrusions are continuous, and that the bush is inserted into the bush after being covered with the insulating covering, and is narrow. That is, it is preferable that the diameter of the inner side surface of the middle part of the through hole is small to form a narrow part. Moreover, in order to make it easy to pass the bushing covered by the insulation coating body through the narrow portion, it is preferable that a taper is provided from the entrance of the through hole of the inner wall to the narrow portion. The bush after being covered with the insulating cover is pressed toward the central axis of the solar cell output cable at the narrow portion. In order to sufficiently exert the pressing effect by the narrow portion, it is preferable that the tip of the protrusion is narrow enough not to damage the bush.

  The solar cell output cable with the core material exposed and the insulation coating covered with the bushing is inserted through the introduction port, and the bush after the second opening is covered with the insulation coating is the central axis at the narrow portion. The solar cell output cable is fixed to the connection box by a fixing tool at the fixing part after being pushed in the direction and pressed to the position where the outer surface of the bush is constricted (deformed without breaking). The

Between the said outer wall and the said inner wall, the fixing | fixed part which suppresses the said solar cell output cable toward the center axis direction of a solar cell cable from upper and lower, right and left is provided. This is because if the bush is merely sandwiched between the narrow portions as described above, the watertightness may be broken when an external force is applied so that the position of the cable changes with respect to the connection box.
Therefore, in the present invention, in order to maintain sufficient watertightness, the movement of the solar cell output cable in the direction perpendicular to the cable axis at the introduction port of the outer wall is restricted, and then the bush is formed in the through hole of the inner wall. In addition to being held by the narrow portion, the solar cell output cable is further fixed by a fixing portion for fixing the output cable to the connection box.

  The fixing part is for fixing the output of the solar cell output cable during construction and subsequent use without transmitting it to the inside of the connection box. And it is for keeping at a fixed position also in the axial direction, and the outer skin of the solar cell output cable inserted from the introduction port is pressed evenly so as not to be eccentric toward the axial center It is preferable that it can be pinched and fixed. Moreover, it is preferable that the fixing with the fixing tool can be easily and quickly performed. Fixing by the fixing tool is not limited, and the fixing tool is locked to the connection box, and the fixing tool and the fixing tool may be paired to fix the cable, but the connection box holds the solar cell output cable. It is preferable to have a receiving part and to fix the cable by sandwiching it between the fixture and the receiving part.

  In order to perform the fixing easily and quickly, it is preferable to fix with a fixture that can be locked to the connection box. After inserting the solar cell output cable from the introduction hole of the connection box, the structure can be locked in a pressed state so that the fixing tool bites into the outer shell of the solar cell output cable (deforms it into a constricted state) It is preferable that As a fixture having a locking piece, a clamp made of resin or the like having a protrusion contacting the solar cell output cable toward the central axis on the surface in contact with the solar cell output cable is fixed to the cable. It is also excellent in workability.

  The length of the fixed part in the axial direction should be long in order not to transmit the cable deflection to the inside, but it must also be housed in a compact structure, so it must be at least 3 times the cable diameter. Is preferred.

In the present invention, by providing a fixing portion between the introduction hole for inserting the solar cell output cable of the connection box and the through hole of the inner wall, the deformation of the bush due to the external force to the solar cell output cable is three-dimensional X , Y, and Z can be suppressed and water tightness can be maintained.
Although it is difficult to completely lose the influence of the external force on the cable on the bush, water tightness can be sufficiently ensured if the pressure can be sufficiently suppressed by the elasticity of the pressed bush.

  The material of the connection box and fixture used in the present invention has flexibility and strength, weather resistance, heat resistance, hot water resistance, electrical insulation, flame retardancy, adhesion to silicone potting agents, moldability, etc. Resin having GF reinforced polyamide (GF-PA), polycarbonate (PC), modified polyphenylene ether (m-PPE), GF reinforced polybutylene terephthalate (GF-PBT), GF reinforced polyethylene terephthalate (GF-PET), etc. Engineering plastic is preferred, and amorphous polyarylate (PAR), polysulfone (PSF), polyethersulfone (PES), polyphenylene sulfide (PPS), polyetherimide (PEI). Among these, PES, PPS, modified polyphenylene ether (m -PPE) is preferred , Modified polyphenylene ether (m-PPE) is, performance, productivity, the balance of price particularly preferred.

  The present invention is intended for mechanical watertight fixing of the cable, and the electrical connection for flowing power, which is the original purpose, is crimped by crimping the core wire to a metal connector or the like inside the connection box, screwed, They are connected by a normal method such as soldering.

  After all of the necessary cable cores are connected, a silicone potting agent or the like is usually poured into the connection box, solidified and sealed. If necessary, the lid is covered and protected. In addition, the fixture of the said fixing | fixed part can also be attached at the appropriate timing which fixes a cable to a connection box.

  According to the fixing structure of the first aspect, the solar cell output cable is fixed to the connection box easily and inexpensively with good water tightness.

  According to the fixing structure of the second aspect, since the inner diameter of the bush is 3 to 40% smaller than the outer diameter of the insulation coating body, the bush is easily covered with the insulation coating body, and the inner surface of the bush is outside the insulation coating body. Watertightness is easily maintained because the side surface is appropriately tightened by its elasticity.

  According to the fixing structure described in claim 3, since the bush is made of silicone rubber in the fixing structure described in claim 1 or 2, it is inexpensive and excellent in waterproofness and durability.

  According to the fixing method of the fourth aspect, the fixing is simple and quick, and after fixing, the watertight structure is maintained and the waterproof property is excellent.

It is a perspective view which shows the main body 1 of the connection box (parallel connection box) of Example 1. FIG. (A) is the top view which looked at the right part of FIG. 1 of the main body 1 of the connection box of Example 1 from the top. (B) is the figure of the hole 11 and the hole 12, and the annular protrusion 50 in the hole 12 seen from the side of the outer end wall 101 on the extension of AA. It is the figure of the front-end | tip part which peeled two steps | paragraphs of the solar cell output cable. (A) is a perspective view, (b) is sectional drawing cut | disconnected by the plane which passes along the axial center of a cable. It is a figure of the state which covered the bush to the resin coating body of the front-end | tip part which peeled off the solar cell output cable two steps. (A) is a perspective view, (b) is sectional drawing cut | disconnected by the plane which passes along the axial center of a cable. It is a figure of the clamp of Example 1. (A) is a front view. (B) is a side view. (C) is a top view. (D) is a bottom view. In Example 1, a solar cell output cable covered with a bush is inserted into the lower right portion of the connection box and fixed with a clamp. Then, in the BB portion of FIG. 1, the plane is perpendicular to the central axis of the solar cell output cable. It is sectional drawing cut | disconnected. In Example 1, a solar cell output cable covered with a bush is inserted into the lower right part of the connection box and fixed with a clamp, and then the outer wall 103 including the axis of the solar cell output cable is attached to the AA portion of FIG. It is sectional drawing cut | disconnected by the parallel plane. The state of bending when the solar cell output cable is bent in the left-right direction after the first immersion withstand voltage test is performed on the connection box to which the solar cell output cable is fixed in Example 1 is shown. It is a drawing substitute photograph. In the first embodiment, the connection box to which the solar cell output cable is fixed is bent after the first immersion withstand voltage test, and the solar cell output cable is bent in the vertical direction before the second immersion. It is a drawing substitute photograph.

FIG. 1 is a perspective view showing a main body 1 of a connection box. The outer shape is a rectangular parallelepiped shape, and four cables can be connected.
The main body of the connection box according to the first embodiment is an injection-molded product made of m-PPE resin, and is bilaterally symmetric and vertically symmetric when viewed from above the perspective view. Therefore, since the other three cables are fixed in the same manner, the fixing structure and the connecting method for fixing one solar cell output cable 2 to the lower right part of the main body of the connection box will be described first, and then the whole will be described. explain.

Fig.2 (a) is the top view seen from the upper side of FIG. 1 with respect to the right part of the main body 1 of the connection box which is embodiment of this invention. Hereinafter, the respective directions of up, down, left, and right are assumed to be performed based on FIG. FIG. 2B is a diagram illustrating a state in which the hole 11 and the hole 12 as viewed from the side of the outer end wall 101 on the extension of AA and the annular protrusion 50 are visible in the hole 12.

  The outer end wall 101 that is the outer wall of the right front portion of the main body 1 of the connection box has a uniform thickness, and the outer end wall 101 has a solar cell output cable as an introduction hole through which the solar cell output cable 2 is passed. A through-hole 11 having a slightly larger diameter substantially equal to the diameter of the outer skin 21 is provided, and is opposed to the outer end wall 101 from the outer end wall 101 having the through-hole 11 toward the inside of the connection box body 1 in parallel with the outer end wall 101. An inner wall 102 is provided. The inner wall 102 has a uniform thickness. A through hole 12 having a center at a position corresponding to the center of the through hole 11 is formed in the inner wall 102. Both the outer end wall 101 and the inner wall 102 are orthogonal to a straight line connecting the center of the through hole 11 and the center of the through hole 12. This is because the connection box can be made compact and is preferable for fixing the solar cell output cable 2.

  A part of the inner surface of the through-hole 12 is integrally formed with a protrusion 50 having a trapezoidal cross-sectional shape with a narrowed extension toward the center of the through-hole 12 continuously over the entire circumference of the inner surface. A cylindrical cavity having the trapezoidal upper bottom portion as a side surface is a narrow portion 16 against which the bushing covered with the insulating covering is inserted. That is, the diameter of the inner side surface of the middle portion of the through hole 12 is reduced by the protrusion 50 to form the narrow portion 16. The cross-sectional shape of the annular protrusion 50 is shown in FIG. From the entrance of the through-hole 12 to the narrow portion 16 is tapered and corresponds to the hypotenuse of the trapezoidal cross section, but it is easy to insert the bushing covered with the insulating covering.

The inside 17 of the connection box between the through hole 11 and the through hole 12 is provided with a cable lower support portion 13 that is a part of an integral bottom portion of the connection box and serves as a cable receiving portion. The gap 131 is provided on both sides thereof.
In addition, a recess 19 for housing the lid 70 is provided across the upper inner side surface and the wall surface 104 of the interior 18 of the connection box body 1 in which the conductive connection portion is accommodated.

  The interior 18 that houses the conductive connection portion of the connection box body 1 has a bottom surface over the entire surface, and a conductive material 60 made of a copper plate for electrical conduction is provided on the bottom surface for conductive connection to the solar cell output cable 2. Is attached. A barrel 61 for soldering to the core wire 23 of the solar cell output cable 2 is provided at the end of the conductive material 60. The conductive material 60 is fixed to the connection box 1 by a fastener 191 provided on the bottom wall 105 inside the connection box body 1 (details are omitted).

FIG. 3 shows the tip of the solar cell output cable 2 peeled off in two steps. a) is a perspective view, and b) is a cross-sectional view cut along a plane passing through the axial center of the cable.
The solar cell output cable has a cross-linked polyolefin-based resin coated as an outer cover, and the outer diameter of the outer cover 21 is 6.4 mm. An insulating covering 22 made of a crosslinked polyethylene resin and having an outer diameter of 3.5 mm is provided on the inner side, and a core wire 23 is provided on the inner side. The core wire uses copper, and the cross-sectional area of the core wire is 2 mm ² .
When connecting the solar cell output cable to the connection box, the tip of the solar cell output cable 2 was stripped in a so-called two-stage using a commercially available peeling machine as shown in FIG.

  A bush 3 made of silicone rubber was placed on the insulating covering 22 of the solar cell output cable 2 peeled off in two steps. The bush was made of silicone rubber having a hardness of A56, an elongation of 460%, and a tensile strength of 9.51 MPa, and a cylindrical shape having an inner diameter of 3 mm, an outer diameter of 6 mm, and a length of 5 mm. In order to cover the solar cell output cable 2 with the bush peeled off in two steps, the core wire is passed through the hollow portion of the bush from the exposed side of the core wire 23, and then the inner surface of the bush is approximately equidistant from the axis of the solar cell output cable 2 By holding the end face of the bushing against the end face of the insulation coating 22 on the side where the core wire is exposed and pushing it in a direction parallel to the axis of the solar cell output cable 2, the bushing has rubber elasticity and extends. The bush was put on the insulating coating 22. The bushing was covered until the end face of the bush was in contact with the end face of the outer skin 21 of the solar cell output cable 2 peeled off in two steps.

  FIG. 4 is a view showing a state in which a bushing is put on the resin coating at the tip of the solar cell output cable peeled off in two steps. a) is a perspective view, and b) is a cross-sectional view cut along a plane passing through the axial center of the cable.

Next, a description will be given of attaching the solar cell output cable 2 having the bush 3 covered with the insulating covering 22 to the lower right portion of the main body 1 of the connection box of FIG.
First, the solar cell output cable 2 with the bush 3 covered with the insulating covering 22 is pushed from the tip on the core wire side into the 6.5 mm diameter through hole 11 provided in the outer end wall 101 at the lower right side of the main body 1 of the connection box. Pass through. Further, a part of the bush 3 covering the solar cell output cable 2 passes through the through hole 12 provided in the inner wall of the main body 1 of the connection box, and the end surface of the outer skin 21 of the solar cell output cable 2 reaches the surface 14 of the inner wall 102. I pushed it in.

  Here, an annular protrusion 50 is formed inside the through hole 12 so as to narrow the hole diameter in a ring shape, and the narrow portion 16 having a diameter of 5.6 mm is formed. The bush 3 that covers the insulating covering 22 of the solar cell output cable 2 is pressed by the narrow portion 16 in the axial direction of the solar cell output cable 2 and deforms. Due to the elastic repulsive force, the inner surface of the through-hole 12 opened in the inner wall 102 at the lower right side of the main body 1 of the connection box and the surface where the outer surface of the insulating covering 22 of the solar cell output cable 2 contacts the inner surface of the bush 3. As a result, the outer surface of the bush 3 is pushed to form a watertight structure.

Next, in order to fix the solar cell output cable 2 to the connection box from the upper side of FIG. 1 of the main body 1 of the connection box, it was fixed with a clamp as a fixture. The clamp 4 is an injection-molded product made of m-PPE resin and has appropriate elasticity as described below.
The clamp 4 has a symmetrical front shape as shown in FIG. 5 (a), and the length (depth) is a side view of FIG. (B), a top view of FIG. (C), and a view of FIG. As shown in the bottom view, the distance between the outer end wall 101 at the lower right of the connection box body 1 and the inner wall 102 facing the same is 7 mm, and the width (the distance between side surfaces 46 and 46 described later) is the connection box body 1. 10 mm, which is substantially equal to the distance between the inner surface of the outer wall 103 and the inner surface of the partition 104.

  As shown in FIG. 5 (a), the clamp 4 has an upper inner peripheral surface 41 for holding a solar cell output cable having a radius substantially equal to the outer skin 21 of the cable 2, a lateral inner peripheral surface 42, leg portions 43, 43, It has the latching | locking parts 44 and 44 provided in the leg parts 43 and 43, the upper surface 45 for pushing the clamp 4 in from the top, and the side surfaces 46 and 46. As shown in FIG.

  Further, as shown in FIGS. 5 (a), 5 (d) and 7, the clamp 4 has a semi-annular shape at the inner surface end of the upper inner peripheral surface 41 and the lateral inner peripheral surface 42 on the side in contact with the solar cell output cable 2. Protrusions 47 and 47 are provided. This is because, even if an external force is applied in a direction parallel to the axis of the solar cell output cable, the protrusion bites into the cable sheath and does not move the cable in the direction parallel to the axis.

  FIG. 6 shows a clamped state after inserting the two-stage stripped end of the solar cell output cable 2 with the bushing 3 covered with the insulating covering 22 through the through-hole 11 and the through-hole 12 at the lower right of the main body 1 of FIG. 4 shows a cut surface in a plane perpendicular to the axis of the solar cell output cable 2 passing through the position BB shown in FIG.

  As shown in FIG. 6, the distance between the outer convex surface of the locking portion 44 provided on the legs on both sides and the outer convex surface of 44 is such that the inner surface of the outer wall 103 of the main body 1 of the connection box and the partition wall 104 are Although it is parallel to the outer wall 103 but wider than the interval with the inner surface of the partition wall, when the clamp 4 is pushed in, it bends inward due to its elasticity, and the respective locking portions 44, 44 are connected to the connection box body 1. The outer wall 103 and the partitioning wall 104 are locked to the recesses 103-1 and 104-1 provided at the lower part. As a result, the clamp 4 is locked and fixed to the main body 1 of the connection box with the solar cell input / output cable 2 interposed therebetween.

  The solar cell output cable 2 includes an upper inner peripheral surface 41 of the clamp 4 from the upper surface in the fixing portion 17 between the through hole 11 on the outer end wall of the main body 1 of the connection box and the through hole 12 provided on the inner wall. The side surface is a lateral inner peripheral surface 42, and from the bottom, the outer skin 21 of the solar cell output cable 2 is pressed and pinched by the cable lower support portion 13 of the connection box 1 main body, and is fixed so that the axis does not shake. As described above, the solar cell output cable 2 is further prevented from shifting in the axial direction of the solar cell output cable 2 by the circumferential projections 47, 47 provided on the inner surface of the clamp 4.

  FIG. 7 shows the state in which the bush 3 is constricted at the narrow portion by passing through the through hole 12 at the tip of the solar cell output cable 2 in which the bush 3 is covered with the insulation coating 22 on the main body 1 of the connection box of FIG. After being inserted until the clamp 4 is pushed in and fixed as described above, it passes through the position A-A shown in FIG. 1 and is cut along a plane parallel to the outer wall 103 including the axis of the solar cell output cable 2. A cross-sectional view is shown.

  The end surface of the cable outer skin 21 is in contact with the surface 14 of the inner wall 102 provided with the through hole 12. The core wire 23 of the solar cell output cable 2, the insulating cover 22, and the bush 3 covered by the insulating cover 22 pass through the through-hole 12 provided in the inner wall and pass through the inside 18 of the main body 1 of the connection box of FIG. In. Here, the bush 3 covered with the insulating cover 22 is deformed by being pressed in the axial direction of the solar cell output cable 2 by the annular protrusion 50 provided on the inner periphery of the through hole 12, and has elasticity. Thus, the inner peripheral surface of the bush 3 and the outer peripheral surface of the insulating cover 22 are in close contact with each other. And the outer peripheral surface of the bush 3 and the inner peripheral surface of the through-hole 12, and especially the protrusion part 50 are closely_contact | adhered. Therefore, water does not enter the inside 18 of the main body 1 of the connection box along the outer periphery of the solar cell output cable 2, and a watertight structure is formed.

  As shown in FIGS. 6 and 7, the solar battery output cable 2 is provided on the inner wall with the cable outer skin restrained by the inner peripheral surface of the through hole 11 provided in the outer end wall at the lower right portion of the main body 1 of the connection box. The insulating cover covered with the bush is constrained by the formed through-hole 12, and the cable fixing portion 17 is provided between the through-hole 11 and the through-hole 12, and the cable skin is connected to the inner surface of the clamp 4. Since the solar cell output cable 2 is pressed and fixed between the cable support 13 provided on the main body 1 of the connection box so that the axis of the solar cell output cable 2 is not displaced, the solar cell output cable 2 is attached to the connection box. On the other hand, even if stress is applied in a direction away from the axis, the cable shaft does not deviate from the center in the vertical and horizontal directions. Even if stress in the axial direction of the cable is applied, the projections 47, 47 provided on the clamp 4 are pressed and pressed so as to bite the outer skin of the solar cell output cable 2 in the axial direction of the cable 2. The cable is not displaced in the direction parallel to the axis.

  Therefore, according to the present fixing structure, after being fixed by the fixing portion, the solar cell fixed to the connection box 1 even during the installation and connection work of the solar cell output cable 2 to the connection box or during subsequent use. Even if an external force is applied to the output cable 2 in the direction in which the cable shaft sways or parallel to the shaft, the watertight structure is maintained.

  In the inside 18 of the connection box main body 1, the core wire 23 is conductively connected by soldering to a barrel 61 formed by bending a conductive material 60 made of a copper plate for energization provided in the inside 18.

  At the other three locations on the connection box body 1, that is, at the upper right, upper left, and lower left in FIG. 1, the solar cell output cable with the soft polyethylene resin sheath is fixed by the above method, and the four solar cell output cables are connected. After conducting conductive connection to the box body 1, a curable silicone resin usually used for the inside 18 of the connection box body 1 (Shin-Etsu Chemical Co., Ltd., two-component room temperature curing silicone, Shin-Etsu Silicone (registered trademark) KE-200F) After injecting and curing, the lid 70 was put on for protection. The lid 70 was locked and fixed to the connection box body.

  Next, in order to confirm the insulation performance of the connection box in which the four solar cell output cables obtained above were connected to the connection box, the following immersion withstand voltage test was performed.

  In the immersion withstand voltage test method, the leakage current value is inspected and measured by two continuous immersion tests. The first time, a connection box to which the solar cell output cable is connected is connected to a neutral detergent solution (47% surfactant, (Sodium alkyl ether sulfate ester, alkylhydroxysulfobetaine, alkylamine oxide, alkylglycoside) is completely submerged in an aqueous solution containing 3%, and a voltage (1000 VAC) is applied between one of the solar cell output cables and the aqueous solution. The leakage current was measured. If the leakage current was 1 mA or less, it was continuously applied for 12 hours. In the meantime, when the leakage current value exceeded 1 mA, the withstand voltage test was automatically stopped, and in this case, the test was rejected.

  Next, the second time, the test product that passed the first test is pulled up from the aqueous solution, and the four solar cell output cables connected to the connection box in the wet state are left, right, up and down with respect to the connection box. And then repeatedly forcibly bent 90 degrees each time, and then submerged again in an aqueous solution containing 3% of the above neutral detergent solution, and the immersion withstand voltage test was conducted in the same manner as in the first time. Judgment was made. The photograph in the state bent in the left-right direction and the up-down direction is shown in FIGS.

  The results of the immersion current test of the connection box to which the four solar cell output cables obtained in Example 1 were connected passed both the first time and the second time.

(Comparative Example 1)
Except not fixing using a clamp in Example 1, the solar cell output cable was connected to the connection box like Example 1, and the immersion current test was done similarly to the above. The first immersion current test was acceptable, but the second immersion current test was unsuccessful because the test was automatically stopped because of a leakage immediately after the start of the immersion withstand voltage test.

(Comparative Example 2)
In Example 1, instead of using a silicone rubber bush, a solar cell output cable was connected to the connection box in the same manner as in Example 1 except that a butyl rubber tape was wound around the entire circumference of the insulating cover, and dipped in the same manner as above. An energization test was conducted. Although the first immersion current test was acceptable, the second test was automatically stopped because the current leaked in the middle and failed.

The solar cell output cable fixing structure and fixing method of the present invention can be effectively used for connecting the solar cell output cable and the connection box between the solar cell module and the power conditioner connection box.

DESCRIPTION OF SYMBOLS 1 Connection box 10 Connection box main body 11 Through-hole 12 Through-hole 13 Cable support part 131 Space | gap 17 Cable fixing | fixed part 18 Inside 19 Lid for lid | cover 101 Outer end wall 102 Inner wall 103 Outer side wall 104 Partition wall 105 Bottom wall 191 Fastener 2 Solar cell Output cable 21 Cable sheath 22 Insulation sheath 23 Core wire 3 Bush 4 Clamp 41 Upper inner peripheral surface 42 Horizontal inner peripheral surface 43 Leg portion 44 Locking portion 50 Projection portion 60 Conductive material 61 Barrel 52 Core wire 70 Lid

Claims (4)

In the fixing structure of the solar cell output cable for fixing the solar cell output cable composed of the core wire, its insulating covering and outer skin to the connection box,
An inner diameter made of an elastic material is formed at the tip of the solar cell output cable, the core wire projecting in the central axis direction of the cable, and further stripped in a state where the insulating coating is exposed. A cylindrical bush smaller than the outer diameter is covered so that the inner surface of the bush covers the outer surface of the exposed insulating covering,
The connection box is provided with an outer wall in which an introduction hole having a diameter substantially equal to the diameter of the cable sheath for inserting the tip of the solar cell output cable in the insertion direction of the solar cell output cable is opened and an inner wall facing the outer wall. The inner wall is provided with a hole having a diameter smaller than the outer diameter of the bush after being covered with an insulating covering, forming a narrow portion,
The solar cell output cable is inserted into the connection box until at least a part of the outer surface of the bush covered with the insulating covering is sandwiched between the narrow portions,
The solar cell output cable fixing structure is characterized in that the solar cell output cable is sandwiched and fixed between a part of the connection box and a fixture between the outer wall and the inner wall.   The solar cell output cable fixing structure according to claim 1, wherein an inner diameter of the bush is 3 to 40% smaller than an outer diameter of the insulating covering.   The structure for fixing a solar cell output cable according to claim 1 or 2, wherein the bush is made of silicone rubber. A method of fixing a solar cell output cable consisting of a core wire, its insulating covering and outer skin to a connection box,
The connection box is provided with a double wall surface of an outer wall and an inner wall in the insertion direction of the solar cell output cable, and the outer wall is substantially equal to the diameter of the cable jacket for inserting the tip of the solar cell output cable. A through hole having a diameter is provided, and the inner wall is provided with a hole having a diameter smaller than the outer diameter of the bush after being covered with an insulating covering, forming a narrow portion,
Peeling the tip of the solar cell output cable in two steps to expose the core wire and the insulation coating,
A step of covering a double cylindrical bush having an inner diameter smaller than that of the insulating cover and having elasticity so that the outer surface of the exposed insulating cover is covered on the inner cylindrical surface of the bush;
Inserting the solar cell output cable into the connection box until at least a part of the outer surface of the bush covered with the insulating covering is sandwiched between the narrow portions;
Fixing the solar cell output cable between a part of the connection box and the fixture between the outer wall and the inner wall; and
The fixing method of the solar cell output cable characterized by including.