IMPROVED CAPACITOR WITH CONTROLLED IMPEDANCE

Abstract: A capacitor with controlled impedance, consisting in a reel obtained from the winding of foils/strip implicating in overlap alternated at least: a metallic conductor sheet/foil/strip (a); a first dielectric insulating foil/film/strip (b), metallized (b') from the side opposed to the adjacent metallic conductor sheet/foil/strip (a); a second dielectric insulating foil/film/strip (c).

Description: improved capacitor with controlled impedance The object of this invention is a capacitor with controlled impedance. The invention founds particular even if not exclusive application into systems of ignition for i.c. motors. In prior art the characteristics of this capacitors are disclosed in the IT83490A/87 and lT-83491A/87 in the name of same applicant. These solutions foresee a new integrated sets of capacitors in which capacity and inductive effect is integrated in a single device (foil/strip reel). This capacitor is conveniently used in spark generation for i.c. motors as suggested from the Italian patent application IT-83490A/87, by means of coaxial insertion inside the high voltage circuit, said integrated inductive-capacitor. In this solution is disclosed the winding of metallic conductor strip with an insulating dielectric strip foreseen even the possibility to use stratified metallized plastic strip (stratification). An object of the present invention is to to embody an improved inductive-capacitor with metallized plastic strips. This and others aims will reached with the present innovation as claimed solving the problems exposed by capacitor with controlled impedance, consisting in a reels obtained from the winding of a package of leaves implicating in overiap alternated at least: - a metallic conductor sheet/foil/strip; - a first dielectric insulating foil/film/strip, metallized from the side opposed to the adjacent metallic conductor strip; - a second dielectric insulating foil/film/strip. One border of metallization of said first dielectric insulating strip being conductively placed in short-circuit by metallization of the head of the respective reel remaining insulated said metallic conductor sheet/foil/film/strip. In order to ailow the electric linkage the following elements are provided: - a first electric conductor with capacitive effect, linked to said metallization in head; - at least a second electric conductor from an internal extremity of the said metallic conductor sheet/foil/strip; - at least a third electric conductor from the exterior opposed extremity of said metallic conductive sheet/foil/strip. With this solution is obtained an inductive-capacitor able to operate in integrated inductive-capacitive function particularly useful in i.c. sparking devices. Being allowed to reduce the respective encumbrance and costs of the entire device, by automatic coaxial insertion of the inductive-capacitor inside the spark high tension winding These and others advantages will appear from the next itemized description of preferentials solutions with the enclosed drawings the particulars of execution have not to be considered limitative but by way of example only. Figure 1 represents a schematic outlook view in axial section of the device of this invention. Figure 2 represents a partial magnified view of the winded set of layers and of the respective linkage to the reel head metallization Figure 3 represents a schematic view of an example of electric schema of the device for i.c. motors ignition. With reference to figure 1 it can be pointed out that the winding having function of inductor and capacitor as for the invention is composed of three strips alternately disposed respectively: - a metallic conductor sheet/foil/strip (eg. aluminium, a); - a first dielectric foil/film/strip (Eg. plastic material film of polypropylene b), metallized on the opposed surface (b'); - a second dielectric insulating foil/film/strip (Eg. film of polypropylene (c)). As for this invention the metallic sheet strip (a) is shorter than metallized dielectric foil/film/strip (b'). In order after winding in reels to allow reel head metallization (d) to short-circuit the respective edges of dielectric metallized foil/strip (b'). The electric terminals will be the following: 1) head conductor metallization (d); 2) electric linkage to the internal extremity of the winded metallic conductor sheet/foil/strip (a); 2') electric linkage to the external extremity of said winded metallic conductor sheet/foil/strip (a), being destined the last two to explicate the inductive function. Making reference to Fig.3 it can be pointed out that setting the device as represented in Fig.1 (A) is coaxially inserted into a spark high tension induced winding (3-B), in order to deliver spark in a plugs of ignition (4). In this way the device can function in simple and very reiiable mode foreseen to link the terminals (1, 2, 2') of the device of which to the present invention with: - a generator (G) with respective internal resistance (R), - across two breaker means connected in serial (Eg. diodes, SCR, etc. I, I') operatively linked in order that when one (the first) closes the second open or viceversa (P); - with the contrivance that the terminal (1) of the metallized head is linked between the respective opposed switches (I, I'), and the respective terminals (2, 2') of the metallic conductor sheet/foil/strip (a) linked from one side to said second switch into respective linkage in serial (I') and from the other to said generator (G). Naturally into the ambit of this exemplificative circuit numerous variations can be made.

Claims: CLAIMS 1. A capacitor with controlled impedance, consisting in a reels obtained from the winding of a package of leaves implicating in overlap alternated at least: - a metallic conductor sheet/foil/strip (a); - a first dielectric insulating foil/film/strip (b), metallized (b') from the side opposed to the adjacent said metallic conductor sheet/foil/strip (a); - a second dielectric insulating foil/film/strip (c). 2. An inductive-capacitor as claimed in claim 1., characterized in that said metallization (b') of the dielectric foil/film/strip (b), is short-circuited on the winded boundary in by metallization of the respective head reel (d) leaving said conductive alternate metallic conductor sheet/foil/strip (a) insulated from said head metallization (d). 3. An inductive-capacitor as claimed in claim 1., characterized in that it is structured with at least three electric linkages: - a first electric conductor (1) linked to the said head metallization (d); - at least a second electric conductor (2) from an extremity more or less internal of the said metallic conductor sheet/foil/strip (a) into respective reels (A); - at least a third electric conductor (2') from the opposed extremity more or less exterior in respective reel (A) of the said metallic conductor sheet/foil/strip (a). 4. An inductive-capacitor as claimed in claim 1., characterized in that it is structured with at least three electric linkages: - a first electric conductor (1) linked to the said head metallization (d); - a second electric conductor (2) from an internal extremity of the said conductive metallic winded sheet/strip (a) into respective reels (A); - a third electric conductor (2') from the opposed external extremity in said reel (A) of the said conductive metallic winded sheet/strip (a). 5. An inductive-capacitor as claimed in claim 1., characterized in that it is associated with a induced coaxial high tension winding (B). 6. An inductive-capacitor as claimed in claim 1., characterized in that it is integrated in an i.c. motor ignition device. 7. An inductive-capacitor as claimed in claim 1., characterized in that said insulation of said metallic conductor sheet/foil/strip (a) from the respective head metallization (d) is realized by means of being shorter then said metallized dielectric foil/film/strip (d).

Inventors: BIONDI ASTORRE, TURA DANTE, BIONDI, ASTORRE, TURA, DANTE
Applicants: DUCATI ENERGIA SPA, DUCATI ENERGIA S.P.A.
Application year: 1989
Main classification: H01G4
IPC codes: F02P3, H01F27, H01G4