DE602004012751T2 - Rod-shaped core choke, ballast and method of manufacture - Google Patents

Abstract

A rod core choke, for use e.g. in an electronic ballast of a fluorescent lamp, includes: a core (4) in the form of a rod having long and narrow solid shape, a sheath (bobbin 3) of an electrically insulating material surrounding said core (4) and a wire winding (2) around the said sheath (3), whereby said sheath (3) mutually insulates said core (4) and said wire winding (2). According to a preferred embodiment of the invention, said core is in form of a rod having parallelepiped shape.

Description

Field of the invention

The The present invention relates to so-called "choke coils".

reactors become present for suppression of interferences z. B. used in motors of household appliances to radio frequency interference with radios, television equipment and the like. To prevent. Lamp reactors are also in electronic Rescue fluorescent lamps inserted, with the intention of the lamp current to limit, especially during the switch-on phase to prevent rapid destruction of the circuit.

Description of the Related State of technology

A rod core choke coil for suppressing interference is e.g. In DE-A-42 41 604 disclosed. There is disclosed a rod core choke coil including a coil having various numbers of layers along the rod core portion.

The Winding is enclosed by an insulated wire, which is wound directly on the ferrite core: Such an arrangement is present also in so-called "drum" core choke coils used, as they z. B. used in compact lamps for low-power applications become. Usually a copper wire winding is used, which by two pins, the on the opposite surfaces the drum itself are glued, electrically connected. Of the Drum core simplifies the direct winding of a copper wire around the ferrite core while the turns laterally between two ferrite disks, which at the end provided by the core is limited.

These Prior art arrangement has a number of disadvantages on.

First, when the wire is wound directly around the ferrite core, around one To provide perfect insulation, the ferrite must not from the Type of low conductivity his and his for The winding wire used must have good insulation properties.

One currently disadvantage encountered, in particular with drum ferrite cores, is that the paint of the copper wire easily in the connection points the winding and the pins breaks. This is usually due to the sharp Causes edges that have the end plates of the ferrite core.

This Disadvantage can somehow be alleviated by the whole inductor is dipped in a paint bath. This step improves the Coil insulation and attaches the wire to the flange, causing dangerous Wire scraping on the ferrite is prevented. Such an extra However, processing involves additional costs and could not too complete lead to satisfactory results.

The choke coil to properly connect to the associated circuit is another factor that must be considered. For example disclosed DE-A-195 20 858 schematically a plastic or metal cap for SMD attachment of a rod core choke coil. Said cover has a quadrangular shape which allows the inductor to be laid flat on a printed circuit board, while the flat surfaces serve as electrical contact points for pre-galvanized wire ends for use, e.g. B. with automatic Schwalllötgeräten serve.

The publication US 2002/079999 discloses an electrodeless fluorescent lamp comprising a coil including a cylindrical ferrite core, a plastic coil, and a conductive, insulated wire wound around a portion of the coil. The spool includes a base and a slot portion having grooves for guiding the wire around the spool.

The publication GB 2 073 500 (closest prior art) discloses a rod core choke coil according to the preamble of claim 1 and a method of manufacturing the same according to the preamble of claim 15.

Subject and Summary of the Invention

• – eine Kerngestalt einschließen, welche auf der einen Seite eine einfache Bauweise und Struktur, wohingegen auf der anderen Seite eine vielseitige technische Lösung darstellt,
• – keine bedeutenden Veränderungen in der Auslegung der bedruckten Leiterplatten einschließen, an welche die Drosselspule angeschlossen werden soll, z. B. in der elektronischen Hauptbettung für eine fluoreszierende Lampe im niedrigen Leistungsbereich,
• – Größenbegrenzungen erfüllen während sie eine technische Leistung auf demselben Niveau gegenwärtiger Drosselspulen absichern, und
• – keine spezifischen Beschränkungen, was die Leitfähigkeit des Kernferrits und der Isolationsmerkmale des Wicklungsdrahts auferlegen.

Despite the effort attested by the prior art discussed above, the need for inductors is still felt, including:

• - include a core shape, which on the one hand is a simple construction and structure, while on the other hand represents a versatile technical solution,
• - do not include significant changes in the design of the printed circuit boards to which the choke coil is to be connected, e.g. In the main electronic bed for a low power fluorescent lamp,
• - Meet size limits while ensuring a technical performance at the same level of current inductors, and
• No specific restrictions on the conductivity of the core ferrite and the insulation properties of the winding wire.

Of the The object of the invention is to provide a choke coil, which satisfies these outstanding needs.

According to the present Invention is this object by the means of a choke coil which has the features of the claims which follow, wherein such claims constitute an essential part of the disclosure of the invention. The The invention also relates to an electronic rescue, which Such a choke coil and a method such as such inductors to manufacture.

The Arrangement described herein comprises a plastic sheath (coil), which encases the ferrite core to prevent the insulation between the Winding wire and the core to ensure. In this way no strict requirements are placed on the ferrite of the core, while the insulation features of the wire are not a critical issue.

By the use of such a plastic spool can easily with the pins Ends of the winding with respect to soldering z. B. to a printed circuit board (PCB) soldered become. This while an exact, fixed position of the pins and an exactly orthogonal Orientation to the PCB level, which is the insertion of the pins into the PCB receiving holes simplified, guaranteed becomes. A preferred pin arrangement allows the winding wire at both ends (both to the PCB or in the opposite direction) to solder: this is advantageous in that it allows the overall height / thickness to reduce the choke coil.

In the execution, which is shown herein, the ferrite core has a simple geometry (in practice a long and narrow solid shape) and the ends The winding are made by flange with which the coil the ends are limited and exactly along the core in position brought. Ferrite cores with a simple long and narrow solid Can shape simply in large numbers made by simplifying the industrial manufacturing process be while the amount of waste products is minimized and without any noticeable changes in the PCB layout. Additionally, one may be in cross section rectangular shape simply the space available on the PCB, with the length of the core remaining unchanged and where z. As the width is reduced and the height, if only space in the vertical Direction exists, is enlarged. The above, in a given volume, around the room, which claimed on a printed circuit board (PCB) (eg occupied) will reduce.

• – einen Kern in Gestalt einer Stange, welcher eine lange und schmale Gestalt hat,
• – einen Mantel (Spule) aus einem elektrisch isolierenden Material, welches den Kern umgibt, und
• – eine Drahtwicklung um den Mantel, wobei der Mantel den Kern und die Drahtwicklung gegenseitig isoliert.

A preferred embodiment of the invention is thus a rod core choke, which includes:

• A core in the form of a rod, which has a long and narrow shape,
• A jacket (coil) made of an electrically insulating material surrounding the core, and
• A wire wrap around the jacket, with the jacket isolating the core and the wire coil from each other.

Preferably the core has an approximately rectangular shape Cross-section and the jacket closes axial boundary structures a to the core at a fixed axial position in the jacket to keep. Still preferably, the coat essentially has the shape of a tubular body, which has a closed end, with such a closed end of the shell forms an abutment, which is an axial displacement of the core with respect to the jacket beyond the abutment position prevented against the closed end.

In In a particularly preferred embodiment, the jacket has an open End on the opposite side of the closed end, the core slidably insertable into the jacket through the open end; the open end of the shell has an associated entity (e.g. a tooth). This arrangement prevents axial displacement of the core, which is introduced into the sheath from the open end of the sheath, while the possible Lack of use of an adhesive is missing.

always even more preferably, the jacket is provided with flange formations, which a Längsendbegrenzungsgebilde for the Forming wire winding.

Advantageous includes the choke coil wire connecting pins and the coat closes Attachments to store the connecting pins, while the Wire winding allows is to be soldered to one of the ends of each of the pins.

Brief description of the drawings

The Invention will now be described, by way of example only, with reference to the appended drawings of the drawings, in which

1 is a schematic perspective view of a choke coil according to the invention,

2 two parts a) and b), which respectively the front and side views of the core of the choke coil of 1 represent

3 again the two parts referred to as a) and b) including, respectively, a longitudinal cross-sectional view and end view of the coil of Choke coil of 1 are and

4 is exemplary of a typical mounting arrangement of the choke coil of 1 on a printed circuit board (PCB).

Detailed description of a preferred embodiment the invention

In the 1 and 4 The attached drawings refer to reference characters 1 as a whole, a rod core choke coil for use z. As a lamp choke coil included in an electronic rescue of a fluorescent lamp (not shown).

The lamp choke coil 1 is essentially of a copper wire winding 2 which involves a plastic spool 3 is wound, which is a ferrite core 4 in it, so that the coil 3 (and the winding 2 ) the core 4 enclose.

How better in 2 is shown is the core 4 typically in the form of a small rod of ferrite, which has a long and narrow solid shape.

According to one preferred embodiment of Invention is the solid state in the shape of a parallelspat.

Typically, the core has 4 almost a rectangular cross section (with dimensions of 3 x 3.5 mm being a typical case) with a length in the range of 14 mm. Of course, these quantitative data are merely exemplary and should not be interpreted in a limiting sense of the scope of the invention.

adjustments could by those skilled in the art, without departing from the scope of the invention become.

As best in the views of 3 can be viewed is the coil 3 essentially enclosed by an approximately tubular body of plastic material (as well as PBT) of a generally cup-like shape. Otherwise stated, the coil is 3 preferably in the form of a tubular body having a rectangular, ie almost rectangular cross-sectional shape. The tubular body of the coil 3 is completely or partially at one end 3a closed and at the opposite end 3b open. In this way, the core can 4 in the coil 3 by longitudinal sliding of the core 4 in the coil 3 , starting from the open end 3b to the end of the core 4 , which was first inserted into the coil against the closed end 3a pushes, be introduced.

After inserting the core, hold a small plastic nose 30 at the open end 3b the coil 3 by preventing any relative longitudinal movement of the coil (and winding 2 which is wound around there) and the core 4 , the core 4 safe in the coil 3 , The core 4 becomes longitudinal between the closed end 3a , the coil 3 and the nose 30 limited. Typically, the nose is heat deformed to the opposite end of the core 4 lock.

This arrangement is advantageous to any noisy mechanical resonance frequency during reactor operation and any variation in inductor inductance due to various relative positions of the ferrite core 4 and the winding 2 which are around the coil 3 is bound to be avoided.

As an example of a general reference, in the case of inductors 1 which correspond to the arrangement described herein and which had 465 windings and 530 windings (corresponding to the inductance values of 2.7 mH and 3.3 mH, respectively), it was found that a 1% (one percent) change in the number of Turns leads to a change in the inductance value in the range of 2% (two percent). Such a number of turns is reasonably sufficient to compensate for any variation in the mechanical / magnetic parameter of the choke coil.

This Feature appears in direct comparison with making conventional Choke coils, which closed magnetic circuits with E-shaped cores (so-called e-choke coils) advantageous in that it allows any adaptive air gap core system in the manufacturing process, as it is usually used to desired inductance to achieve in inductor production lines to dispense. This contributes significantly for simplicity and cost reduction.

reference characters 31 in 3 denote two flanges (or sets of flange formations) attached to the ends of the tubular body of the coil 3 to be provided. These flanges serve as lateral boundary walls or stoppers for the two ends of the winding 2 , wherein it any unwanted relative longitudinal sliding of the winding 2 and the coil 3 prevent.

As is well known, the mutual position of the core and the winding greatly affects the inductance value of the choke coil and its current saturation level, with the best magnetic coupling between the core and the winding being achieved when total longitudinal overlap is achieved. A low relative axial change Between the core and the winding reduces such a coupling and the inductance as well as the current saturation level.

The arrangement described herein guarantees an exact location and position of the core 4 in the coil 3 (Over the Endbegrenzungsgebilde, which by the closed end 3a and the tooth structure 30 While it also guarantees that, once inserted into the coil 3 , the core 4 a well-defined axial position to the coil 3 holds.

The end flanges of 31 the coil 3 in turn, ensure an accurate axial position of the winding 2 in relation to the coil 3 and thus in relation to the core 4 by also ensuring that this accurate axial position is maintained over time. This while also obstructing the winding wire from coming into contact with any sharp edge as possibly from the ferrite core 4 being represented. Any scratching of the wire insulation by the ferrite is thus reliably prevented.

An extension 32 typically in the form of additional flanges, which are from the flanges 31 in a plane perpendicular to the plane of the flanges 31 protrude, allow easy positioning of the metal pins 33 which are at the ends of the coil 3 to be provided. There is also the possibility of a third pen 33 to in another recording / extension 32bis for an auxiliary winding (autotransformer) introduce. Such metal pins serve as contact pins of the choke coil winding (s) to a printed circuit board (PCB) 5 as in 4 shown. In particular shows 4 a choke coil 1 , which is mounted on a PCB together with various other electronic components (collectively referred to as 6 ), which usually in an electronic rescue of a z. B. fluorescent lamp are included.

The pin layout described allows easy insertion of a pen on one side of the printed circuit board 5 and soldering this on the opposite side of the printed circuit board 5 , In addition, such an arrangement results in a low cross-section of the choke coil, which can thus be mounted very close and with reduced "height" with respect to the PCB plane.

The arrangement shown allows asymmetric positioning of the two pins 33 , which also allows to develop different Aussteckvarianten, which from the side of the coil 3 , which is required by the pen introduction into the printed circuit board 5 to be used, depend. In actuality, the arrangement shown allows the winding to be soldered to one end of the pin while the pin is inserted into the printed circuit board at the opposite end and vice versa. In addition, such an asymmetric pin layout facilitates easy insertion of the ferrite core into the coil 3 without disability. In reality, in the present prevailing order, the coil is 3 already equipped with the pins when it is assembled with the core.

Inductors, as shown herein have improved thermal performance proved in comparison with drum core coils of the prior art, which is due to a reduced AC resistance and greater thermal Exchange surface to be explained can.

Of course without Damage to the underlying principle of the invention could be the Details of the designs, also significant, in terms of what only described for example was without the scope of the invention as defined by the appended claims will vary, leave.

Claims (15)

A rod core choke comprising: a core ( 4 ) in the form of a rod, which has a long and narrow solid shape, - a sheath (coil - 3 ) an electrically insulating material, which the core ( 4 ), and - a wire winding ( 2 ) around the coat ( 3 ), where the jacket ( 3 ) mutually the core ( 4 ) and the wire winding ( 2 ), characterized in that the core ( 4 ) the shape of a rod, which has a spade, and in that the jacket ( 3 ) with flange formations ( 31 ), which longitudinal boundary formations for the wire winding ( 2 ) form. The choke coil according to claim 1, characterized in that the core ( 4 ) has a rectangular cross-section. The choke coil according to claim 1, characterized in that the core ( 4 ) has a square cross-section. The choke coil according to one of claims 1 or 2 or 3, characterized in that the sheath ( 3 ) axial boundary structures ( 3a . 30 ) to the core ( 4 ) in a fixed axial position in the shell ( 3 ) to keep. The choke coil according to one of the preceding claims, characterized in that the sheath ( 3 ) the shape of a mainly tubular body, which has a closed end ( 3a ) is molded. The choke coil according to claims 4 and 5, characterized in that the closed end ( 3a ) of the jacket ( 3 ) forms an abutment structure which reduces the axial displacement of the core ( 4 ) with respect to the jacket ( 3 ) over the abutment condition against the closed end ( 3a ) prevented. The choke coil according to one of the preceding claims, characterized in that the sheath ( 3 ) the shape of a substantially tubular body, which has a closed end ( 3a ) and an open end ( 3b ) opposite the closed end ( 3a ), where the core ( 4 ) in the coat ( 3 ) over the open end ( 3b ) is slidably insertable. The choke coil according to claim 7, characterized in that the open end ( 3b ) of the jacket ( 3 ) an associated entity ( 30 ) has, to axial displacement of the core ( 4 ) which in the jacket ( 3 ), from the open end ( 3b ) of the jacket ( 3 ) to prevent. The choke coil according to any one of the preceding claims, characterized in that it has end connection pins ( 33 ) of the wire winding ( 2 ) and that the jacket ( 3 ) Attachment structures ( 32 . 32a ) for holding the connecting pins ( 33 . 33a ). The choke coil according to claim 9, characterized in that the fastening structure ( 32 ) of the wire winding ( 2 ) are allowed to be soldered at each of the ends of each of the pins. The reactor according to any one of the preceding Claims, characterized in that the electrically insulating material includes a plastic material. The choke coil according to claim 11, characterized in that that the plastic material is PBT. The choke coil according to any one of the preceding claims, characterized in that the core ( 4 ) is a ferrite core. A rescue for a fluorescent lamp containing the choke coil of any of the claims 1 to 13. A method of manufacturing a rod core choke, the method comprising the steps of: - providing a core ( 4 ) in the form of a rod, which has a long and narrow solid shape, - enclosing the core ( 4 ) with a jacket (coil 3 ) of an electrically insulating material, and - winding a wire ( 2 ) around the coat ( 3 ), where the jacket ( 3 ) mutually the core ( 4 ) and the wire ( 2 ), which around the mantle ( 3 ), insulated, characterized in that the step of providing a core ( 4 ) in the form of a rod, which has a latex shape, and in that the method further comprises providing the shell ( 3 ) with flange formations ( 31 ), which longitudinal end formations for the wire winding ( 2 ) includes.