CN112017854B

CN112017854B - Inductance device and manufacturing method thereof

Info

Publication number: CN112017854B
Application number: CN202011001234.XA
Authority: CN
Inventors: 李宁; 任文; 廖胜峰; 罗健
Original assignee: Guangzhou Shiyuan Electronics Thecnology Co Ltd
Current assignee: Guangzhou Shiyuan Electronics Thecnology Co Ltd
Priority date: 2020-09-22
Filing date: 2020-09-22
Publication date: 2022-08-23
Anticipated expiration: 2040-09-22
Also published as: CN112017854A

Abstract

The embodiment of the application relates to an inductance device and a manufacturing method thereof. The inductance device comprises an inductance coil and two magnetic cores, wherein the two magnetic cores are vertically superposed in a mode that the opening positions of the two magnetic cores correspond to each other, and the inductance coil is wound on center pillars of the two magnetic cores; the magnetic core structure comprises two magnetic cores and is characterized in that a gap is formed between the center pillars of the two magnetic cores, a structural part is arranged in the gap, one or more chambers are enclosed between the structural part and the center pillars of the two magnetic cores, and the volume of air contained in each chamber is stretched or compressed by magnetic field force generated by the center pillars of the magnetic cores in working. The inductance device of the embodiment of the application can reduce the vibration of the magnetic core of the inductance device and reduce the noise generated inside the inductance device.

Description

Inductance device and manufacturing method thereof

Technical Field

The embodiment of the application relates to the technical field of inductors, in particular to an inductance device and a manufacturing method thereof.

Background

With the development of intelligent technology, electronic products in various industries cannot be used without switching on a switching power supply, and the switching power supply is used as a high-efficiency power supply device, and the application of the switching power supply is concerned. And transformers, inductors and the like are indispensable inductance devices in the switching power supply. In a circuit of a switching power supply, an inductor is connected to a semiconductor device such as a switching tube or a diode, and when the switching power supply operates, magnetic core vibration and large noise are generated due to a change in electromagnetic force caused by a change in a magnetic circuit.

Inductance device produces the center pillar that vibration and noise are the most serious generally the magnetic core, and traditional scheme generally is to carry out the point glue at the center pillar of magnetic core, glues the effect that the existing cushion effect of existing cushion force also has two lamella magnetic cores of bonding, and traditional scheme utilizes the adhesive to glue and alleviates the influence of the electromagnetic force of magnetic core center pillar to the magnetic core as damping material, but this kind of mode is limited to the effect of electromagnetic force, because the instability of adhesive is great, especially also can change the cushioning effect to the electromagnetic force after the solidification. This approach may not be sufficient to achieve the desired results for different applications.

Disclosure of Invention

The embodiment of the application provides an inductance device and a manufacturing method thereof, which can reduce the vibration of a magnetic core of the inductance device and reduce the noise generated inside the inductance device.

In a first aspect, an embodiment of the present application provides an inductive device, including:

the inductor comprises an inductance coil and two magnetic cores, wherein the two magnetic cores are vertically superposed in a way that the opening positions correspond to each other, and the inductance coil is wound on the middle columns of the two magnetic cores;

two be provided with the clearance between the center pillar of magnetic core, be provided with the structure in the clearance, the structure and two enclose into one or more cavities jointly between the center pillar of magnetic core, every the structure of cavity makes the volume of the air that holds in this cavity receive the magnetic core center pillar tensile or compression that the magnetic field force that produces produced in work influences, the produced reaction force of air by tensile or compression that holds in the cavity offsets the produced electromagnetic force of magnetic core center pillar in work.

Optionally, the structural member includes one or more sub-structural members, and the one or more sub-structural members and the center pillars of the two magnetic cores together enclose one or more chambers.

Optionally, the chamber includes a closed chamber, and an inner space of the closed chamber is closed relative to the outside.

Optionally, the chamber includes a non-sealed chamber, and the non-sealed chamber is provided with an air inlet passage connected with the outside.

Optionally, the air inlet channel is a void inside the substructure material.

Optionally, the air inlet channel is a gap formed by the sub-structural member.

Optionally, the width of the air inlet passage is smaller than the width of the structural member surrounding the chamber to which the air inlet passage belongs.

Optionally, the ratio of the width D of the air inlet channel to the width D of the structural member enclosing the chamber of the air inlet channel is greater than 1/10 and less than 1/5.

Optionally, the shape of the sub-structure is annular, and when the sub-structure comprises a plurality of sub-structures, the plurality of sub-structures are nested in the gap.

Optionally, the structural member is made of an elastic material.

Optionally, the structural member is made of a viscoelastic material, or the structural member is fixed to the gap by a viscous material.

Optionally, the structural member is an epoxy resin adhesive.

In a second aspect, an embodiment of the present application provides a method for manufacturing an inductive device, including the following steps:

superposing the two magnetic cores up and down in a mode that the opening positions correspond;

arranging a structural member in a gap between the center pillars of the two magnetic cores, wherein the structural member and the center pillars of the two magnetic cores jointly enclose one or more chambers, each chamber is structured such that the volume of air contained in the chamber is stretched or compressed by the center pillars of the magnetic cores under the influence of magnetic field force generated in operation, and the reaction force generated by stretching or compressing the air contained in the chamber counteracts the electromagnetic force generated by the center pillars of the magnetic cores in operation;

and winding an inductance coil around the center posts of the two magnetic cores.

In the embodiment of the application, a structural member is arranged in a gap between center pillars of two magnetic cores which are stacked up and down, and one or more chambers are enclosed between the structural member and the center pillars of the two magnetic cores, the chambers are structured such that the volume of air contained in the chambers is stretched or compressed by magnetic field force generated by the center pillars of the magnetic cores in operation, when the air contained in the chambers is compressed, the air forms a reaction force for being compressed in a "resisting way", and when the air contained in the chambers is stretched, the air also forms a reaction force for being stretched in a "resisting way", and the reaction force generated by the air contained in the chambers can counteract the electromagnetic force generated by the center pillars of the magnetic cores in operation, so as to play a role of buffering the electromagnetic force, reduce vibration of the magnetic cores and reduce noise generated inside an inductance device.

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Drawings

FIG. 1 is a schematic diagram of column dispensing in a magnetic core according to an example of the prior art;

FIG. 2 is a schematic diagram of an inductive device provided in an exemplary embodiment;

fig. 3 is a schematic diagram of structural components of an inductive device provided in an exemplary embodiment;

FIG. 4 is a schematic illustration of a center leg and structural member of a magnetic core when the magnetic core provided in one exemplary embodiment is stacked one on top of the other;

FIG. 5 is a schematic diagram illustrating the buffering action of the enclosed air provided in an exemplary embodiment;

FIG. 6 is a schematic illustration of the buffering action of the enclosed air provided in one exemplary embodiment;

fig. 7 is a schematic diagram of structural components of an inductive device provided in an exemplary embodiment;

fig. 8 is a schematic structural member of an inductive device provided in an exemplary embodiment;

fig. 9 is a flow chart of a method of manufacturing an inductive device provided in one exemplary embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

It should be understood that the embodiments described are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without any creative effort belong to the protection scope of the embodiments in the present application.

The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the embodiments of the present application. As used in the examples of this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the application, as detailed in the appended claims. In the description of the present application, it is to be understood that the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not necessarily used to describe a particular order or sequence, nor are they to be construed as indicating or implying relative importance. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

Further, in the description of the present application, "a plurality" means two or more unless otherwise specified. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.

A conventional inductor device is generally composed of two magnetic cores, each of which includes a center pillar and two side pillars, the two magnetic cores are stacked up and down with the opening positions thereof corresponding to each other, and an inductor coil is wound around the center pillars of the two magnetic cores to form the inductor device.

In the embodiment of the present application, the inductance device may specifically be an inductor, or one of inductors in a transformer.

Fig. 1 is a schematic structural diagram of one of the magnetic cores, and as shown in fig. 1, the height of the center pillar of the magnetic core is smaller than the heights of the two offset pillars at both sides of the center pillar, so that the two magnetic cores have a narrow air gap between the stacked center pillars, the air gap is used for reducing magnetic permeability, and the air gap can avoid magnetic saturation phenomenon under large ac signals or dc offsets, thereby better controlling inductance.

Inductance device produces the center pillar that vibration and noise are the most serious generally the magnetic core, as shown in fig. 1, traditional scheme generally is to glue at the center pillar of magnetic core, glues the effect that the existing buffer force of existing effect also has two lamella magnetic cores of bonding, can reduce the electromagnetic force and do work to the magnetic core to reach the effect of subducing the noise. However, the hardness of the hardened rubber is high, and the buffering effect on high-frequency vibration force is limited.

In view of this technical problem, the present application provides an inductance device, as shown in fig. 2, in an exemplary embodiment, the inductance device includes an inductance coil (not shown), a magnetic core 1 and a magnetic core 2, the magnetic core 1 includes a center pillar 11, the magnetic core 2 includes a center pillar 21, and the magnetic core 1 and the magnetic core 2 are stacked on top of each other in a manner that the opening positions correspond to each other. The core 1 and the core 2 may be any structural type core having a center pillar, such as an E-type core, an EE-type core, an EQ-type core, a PQ-type core, an EFD-type core, an ECR-type core, and the like, and in the embodiment of the present invention, the core 1 and the core 2 are exemplified as the EQ-type core.

In fig. 2, the magnetic core 1 further includes two legs 12 on both sides of the center leg 11, and the magnetic core 2 further includes two legs 22 on both sides of the center leg 21, the two legs 12 of the magnetic core 1 and the two legs 22 of the magnetic core 2 abutting when stacked.

A gap 3 is arranged between the center column 11 of the magnetic core 1 and the center column 21 of the magnetic core 2, and the inductance coil is wound around the center column 11 of the magnetic core 1 and the center column 21 of the magnetic core 2.

In the embodiment of the present application, it may be that the center leg 11 of the magnetic core 1 has a length less than two side legs 12, and the center leg 21 of the magnetic core 2 has a length less than two side legs 22, thereby forming the gap 3. In other examples, the length of the center leg of only one of the magnetic cores may be smaller than the lengths of the two side legs, and the length of the center leg of the other magnetic core may be the same as the lengths of the two side legs.

The gap 3 is internally provided with structural members which jointly enclose one or more chambers with the

center pillars

11 and 21 of the

magnetic core

1 and 2, and each chamber is structured such that the volume of air contained in the chamber is stretched or compressed by the magnetic field force generated by the center pillars of the magnetic core during operation.

In the embodiment of the present application, the structural member may be any structure made of a material having no electrical conductivity or magnetic conductivity, and the structural member functions to surround one or more chambers with the pillars in the two magnetic cores, so that air contained in each chamber can be stretched or compressed by magnetic force generated by the pillars in the magnetic cores during operation. When the air contained in the chamber is compressed, the air forms a reaction force for resisting the compression, and when the air is stretched, the air also forms a reaction force for resisting the stretching, and the reaction force generated by the air contained in the chamber can counteract the electromagnetic force generated by the center pillar 11 of the magnetic core 1 and the center pillar 21 of the magnetic core 2 in operation, so as to play a role in buffering the electromagnetic force, reduce the vibration of the magnetic core and reduce the noise generated inside the inductance device.

In a specific example, the volume of air to be contained in the chamber is stretched or compressed by the magnetic field force generated in operation by the legs of the core, which together with the

legs

11 and 21 of the

cores

1 and 2 define one or more chambers, which may be closed chambers.

As shown in fig. 3, fig. 3 is a schematic view of a structural member in an example, in fig. 3, the structural member 4 is in a ring shape and is disposed on a surface of the center pillar 21 of the magnetic core 2, and when the magnetic core 1 and the magnetic core 2 are stacked up and down in a manner that the opening positions thereof correspond to each other, the structural member 4, the center pillar 11 of the magnetic core 1 and the center pillar 21 of the magnetic core 2 enclose a closed circular region, and an inner space of the closed circular region is sealed from the outside. In a preferred example, the center point of the closed circular region coincides with the axial centers of the center leg 11 of the core 1 and the center leg 21 of the core 2.

As shown in fig. 4, fig. 4 is a schematic structural view of the core leg 11, the structural member 4 and the core leg 21 when the magnetic core 1 and the magnetic core 2 are stacked one on top of the other in the example of fig. 3, and it can be seen from fig. 4 that a certain amount of air is sealed in the annular structural member 4. This part airtight air is used for playing the effect of buffer force, works the magnetic field force that the magnetic core center pillar produced in the work, plays the purpose of offsetting effort to the realization reduces the purpose of magnetic core noise.

As shown in fig. 5 and 6, fig. 5 and 6 illustrate the principle of the closed air acting as a buffer force under different working conditions.

In the example of fig. 5, when the upper magnetic core 1 generates downward attraction force during operation, the annular structural member 4 contains sealed air, and this air volume is compressed, and the air generates upward supporting force to form a reaction force for "resisting" the compression, so as to counteract the downward force of the magnetic core 1, and thus achieve the buffering effect.

In the example of fig. 6, when the upper magnetic core 1 generates upward pulling force in operation, the air volume is stretched due to the enclosed air in the annular structural member 4, and the air generates downward suction force to form a reaction force for "resisting" the stretching, so as to counteract the upward force of the magnetic core 1, and thus achieve the buffering effect.

In other examples, when the lower magnetic core 2 generates a similar magnetic field force during operation, the air enclosed in the annular structural member 4 can achieve the same buffering effect, and will not be described herein again.

In the example of fig. 3 to 6, the number of the cavities is one, which is equivalent to that the structural member includes one sub-structural member, and in other examples, the structural member may further include a plurality of sub-structural members, and a plurality of the cavities are defined between the plurality of sub-structural members and the center pillars of the two magnetic cores.

As shown in fig. 7, in the example of fig. 7, the core includes 3 ring-shaped sub-structural members nested inside each other, and 3 chambers are defined between the 3 sub-structural members and the center pillars of the two magnetic cores, and preferably, the center point of each chamber coincides with the axial center of the center pillars of the two magnetic cores.

In other examples, the number of the sub-structures may be other, and the shape of the cavity is not limited to a circle, and may be a polygon or an irregular shape.

In the above specific example, the chamber is a closed chamber, the inner space of the chamber is closed relative to the outside, and when the reaction force is formed by the air closed in the chamber being compressed or stretched for "resisting", the reaction force is too strong, new noise may be generated, so that, in a preferred embodiment, the chamber further comprises a non-closed chamber, the non-closed chamber is provided with an air inlet channel connected with the outside, so that when the reaction force is formed by the air closed in the chamber being compressed for "resisting", the compressed air can overflow from the non-closed chamber, and when the reaction force is formed by the air closed in the chamber being stretched for "resisting", the outside air can be timely replenished into the non-closed chamber, so that the reaction force is not too strong.

In some examples, when the number of chambers includes a plurality of chambers, all the chambers may be closed chambers, all the chambers may be non-closed chambers, or a part of the chambers may be closed chambers and a part of the chambers may be non-closed chambers.

In one example, the air inlet passage of the chamber may be a void within the material of the sub-structure, for example, when the sub-structure is made of foam, sponge, or other foaming material, a large number of voids are present within the material, and the voids constitute the air inlet passage of the chamber.

In other examples, the air inlet passage may be a gap formed by the sub-structure when there are no substantial voids within the sub-structure material. As shown in fig. 8, a ring-shaped sub-structural member 41 is included, and the sub-structural member forms a gap 411, and the gap 411 is an air inlet of a cavity enclosed by the sub-structural member 41 and the center pillars of the two magnetic cores. In other examples, the air inlet passage may also be a gap between the sub-structure and the legs of the two magnetic cores.

When the diameter of the air inlet passage is too large, the electromagnetic force generated by the magnetic core in operation to receive air in the chamber is greatly reduced, and therefore, in one example, the width D of the air inlet passage is smaller than the width D of the structural member surrounding the chamber to which the air inlet passage belongs. In a preferred example, the ratio of the width D of the air inlet channel to the width D of the structural member enclosing the chamber in which the air inlet channel is located is greater than 1/10 and less than 1/5.

In the embodiment of the present application, when the structural member is made of an inelastic material, the inductance component mainly cancels the electromagnetic force generated by the magnetic core center pillars by the reaction force formed by the air in the chamber enclosed between the structural member and the two magnetic core center pillars, and in a preferred embodiment, in order to further reduce the vibration and noise caused by the electromagnetic force generated by the magnetic core center pillars, the structural member is made of an elastic material.

When the structural member is made of the elastic material, the elastic material has a buffering effect on vibration caused by electromagnetic force, and the electromagnetic force acting on the magnetic core can be reduced, so that noise is reduced. In combination with the cavity in the embodiment of the present application, when the structural member in the example of fig. 5 is made of an elastic material, when the upper magnetic core 1 generates a downward attraction force during operation, because there is closed air in the annular structural member 4, the volume of the air is compressed, and the air is compressed to "resist" and form a reaction force, an upward supporting force is generated, so that the downward action force of the magnetic core 1 is counteracted, and at the same time, the upper magnetic core 1 generates a downward attraction force during operation and also compresses the structural member 4, so that the volume of the cavity surrounded by the structural member 4 is reduced, and the closed air in the structural member is further compressed, thereby generating a stronger reaction force, generating a stronger upward supporting force, and achieving a better buffering effect.

In the example of fig. 6, when the upper magnetic core 1 generates an upward pulling force in operation, because there is closed air in the annular structural member 4, the air volume will be stretched, and the air will form a reaction force in order to "resist" the stretching, so as to generate a downward suction force, which will cancel the upward force of the magnetic core 1, and at the same time, the upper magnetic core 1 generates an upward pulling force in operation and also stretches the structural member 4, so that the volume of the cavity enclosed by the structural member 4 is increased, and the closed air in the structural member is further stretched, so as to generate a stronger reaction force, and generate a stronger downward suction force, which has a better buffering effect.

Preferably, in order to fix the structural member between the two legs of the magnetic core more conveniently, the structural member is made of a viscoelastic material, or the structural member is fixed to the gap by an adhesive material, in other cases, when the structural member is made of a non-viscoelastic material, the structural member may be directly placed in the gap.

When the structural member is made of a viscoelastic material, the structural member can be epoxy resin glue, in the embodiment of the application, when the dispensing shape is annular, the dispensing amount is better controlled, and compared with the traditional dispensing method, the dispensing amount is better consistent.

In the embodiment of the present application, the structural member may be specifically made of a non-newtonian fluid material such as a foaming material with a property of having a high elasticity/molding material, various systems/hardness glue, a silicone/rubber system material, a foam/sponge, or the like, or a TPU, and the embodiment of the present application is not limited to a specific material type.

Embodiments of the present application further provide a method for manufacturing an inductive device, as shown in fig. 9, in an exemplary embodiment, the method includes the following steps:

s901: superposing the two magnetic cores up and down in a way that the opening positions correspond;

s902: arranging a structural member in a gap between the center pillars of the two magnetic cores, wherein one or more chambers are formed by the structural member and the center pillars of the two magnetic cores, and the structure of each chamber enables the volume of air contained in the chamber to be stretched or compressed by magnetic field force generated by the center pillars of the magnetic cores in operation;

s903: and winding an inductance coil around the center posts of the two magnetic cores.

In an exemplary embodiment, the structural member includes one or more sub-structural members, and the one or more sub-structural members and the center pillars of the two magnetic cores together enclose one or more chambers.

In an exemplary embodiment, the chamber includes a closed chamber having an inner space closed with respect to the outside.

In an exemplary embodiment, the chamber includes a non-hermetic chamber provided with an air inlet passage connected with the outside.

In an exemplary embodiment, the air inlet passage is a void within the substructure material.

In an exemplary embodiment, the air inlet passage is a gap formed by the sub-structure.

In an exemplary embodiment, the width of the air inlet passage is smaller than the width of the structural member enclosing the chamber in which the air inlet passage is located.

In an exemplary embodiment, the ratio of the width D of the air inlet passage to the width D of the structural member bounding the chamber in which the air inlet passage is located is greater than 1/10 and less than 1/5.

In an exemplary embodiment, the sub-structure is in the shape of a ring, and when the sub-structure comprises a plurality of sub-structures, the plurality of sub-structures are nested in the gap.

In an exemplary embodiment, the structural member is made of an elastic material.

In an exemplary embodiment, the structural member is made of a viscoelastic material, or the structural member is fixed to the gap by a viscous material.

In an exemplary embodiment, the structural member is an epoxy glue.

It is to be understood that the embodiments of the present application are not limited to the precise arrangements described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the embodiments of the present application is limited only by the following claims.

The above-mentioned embodiments only express a few embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, without departing from the concept of the embodiments of the present application, several variations and modifications can be made, which all fall within the scope of the embodiments of the present application.

Claims

1. An inductive device, comprising:

a gap is arranged between the center pillars of the two magnetic cores, a structural part is arranged in the gap, one or more chambers are enclosed by the structural part and the center pillars of the two magnetic cores together, the structure of each chamber enables the volume of air contained in the chamber to be stretched or compressed by the center pillars of the magnetic cores under the influence of magnetic field force generated in work, and the electromagnetic force generated in the work of the center pillars of the magnetic cores is counteracted by the reactive force generated by stretching or compressing the air contained in the chamber;

the structural part comprises one or more sub-structural parts, and one or more chambers are formed by the one or more sub-structural parts and the center pillars of the two magnetic cores in a surrounding mode; the chamber comprises a non-closed chamber, and the non-closed chamber is provided with an air inlet channel connected with the outside; the air inlet channel is a notch formed by the sub-structural part; the width of the air inlet channel is smaller than that of a structural member which encloses the chamber of the air inlet channel.

2. The inductive device of claim 1, wherein:

the ratio of the width D of the air inlet channel to the width D of the structural member enclosing the cavity of the air inlet channel is greater than 1/10 and less than 1/5.

3. The inductive device of claim 1, wherein:

the shape of the substructure is annular, and when the substructure comprises a plurality of substructures, the plurality of substructures are nested and arranged in the gap.

4. An inductive device according to any one of claims 1 to 3, characterized in that:

the structural member is made of an elastic material.

5. The inductive device of claim 4, wherein:

the structural member is made of a viscoelastic material, or the structural member is fixed to the gap by a viscous material.

6. The inductive device of claim 5, wherein:

the structural member is epoxy resin glue.

7. A method of manufacturing an inductive device, comprising the steps of:

superposing the two magnetic cores up and down in a way that the opening positions correspond;

arranging a structural member in a gap between the center pillars of the two magnetic cores, wherein the structural member and the center pillars of the two magnetic cores jointly enclose one or more chambers, each chamber is structured such that the volume of air contained in the chamber is stretched or compressed by the center pillars of the magnetic cores under the influence of magnetic field force generated in operation, and the reaction force generated by stretching or compressing the air contained in the chamber counteracts the electromagnetic force generated by the center pillars of the magnetic cores in operation; the structural part comprises one or more sub-structural parts, and one or more cavities are enclosed between the one or more sub-structural parts and the center pillars of the two magnetic cores; the chamber comprises a non-closed chamber, and the non-closed chamber is provided with an air inlet channel connected with the outside; the air inlet channel is a notch formed by the sub-structural part; the width of the air inlet channel is smaller than that of a structural member which encloses the cavity of the air inlet channel;