US3195020A

US3195020A - High tension impulse transformer

Info

Publication number: US3195020A
Application number: US150795A
Authority: US
Inventors: Willutzki Kurt
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-11-09
Filing date: 1961-11-07
Publication date: 1965-07-13
Anticipated expiration: 1982-07-13
Also published as: GB934091A; DE1232399B

Description

2 Sheets-Sheet 1 Filed Nov. 7, 1961 II 0 III July 13, 1965 K. WlLLUTZKl 3,195,020

HIGH TENSION IMPULSE TRANSFORMER Filed Nov. '7, 1961 2 Sheets-Sheet 2 /N VE/vraQ 444% M fliola.

fl-TTORNE Y United States Patent 17 Claims. (Cl: 317-15162) The invention relates to a high tension impulse transformer for high momentary output, particularly for generating high voltage sparks for igniting fuel/ air mixtures.

For more than 20 years efforts have been made to create an improved ignition with transformed condenser discharges. Of such condenser discharging ignition arrangements the most important advantage expected is the fact that these guarantee a safe ignition regardless of the state of insulation of the spark gap.

This would remove one of the greatest disadvantages of the high voltage (battery or magneto) ignition used at present, namely the unreliable operation, or the complete failure caused by the fouling of the ignition spark gap by Water condensation, fuel condensation, oil and carbonaceous oil precipitates, which are unavoidable in some working conditions.

The reason that these ignition arrangements hitherto have not been adopted in practice, may be due partly to the proposals for the structural arrangement of the material employed and partly to improper application of the guiding principles which have not resulted in practical serviceable ignition arrangements.

The object of the present invention is the production of an improved high tension impulse transfer by means of which a practical serviceable condenser discharging ignition arrangement is possible.

The light tension impulse transformer, according to this invention, is distinguished by the combination of the following characteristics:

(a) The internal primarywinding is disposed on a tubular former with a radial externally arranged flange;

(b) The external secondary winding is disposed in a pot shaped former, which rests in contact with the free end of the primary coil former and surrounds the pn' mary winding, the potshaped former having a depending cylindrical projection which fits into the interior of the primary coil former;

(c) The low voltage ends of the primary and sec ondary windings which preferably are both earthed, are near to the flange of the primary coil former;

(d) The high voltage end of the secondary Winding, is arranged level with the base of the former and is led out through the depending cylindrical projection.

The above mentioned construction has the substantial advantage that, despite a very compact mounting, a high resistance to breakdown is secured, because points in the winding at high potentials can only come into contact with points in the Winding at lower potentials along long leakage paths.

A further important advantage is that the high tension impulse transformer described herein can be easily slid on to the insulating body of a spark plug and connected thereto.

The separate layers of the high voltage winding which is arranged in several layers, preferably have a lesser axial length than the primary winding and are arranged in steps towards the high voltage end.

Each layer of the secondary winding thus extends only over part of the axial length of the winding space, the unwound part being filled with a paperlayer the thicknessof which is similar to the diameter of the wire.

In order to avoid sparking or leakage from layer to 3,195,920 assented July 13, 1965 ICC layer, layers in the second winding wound progressively in the same axial direction, alternate with other layers wound progressively in opposite axial direction.

The primary winding of the high tension impulse transformer preferably consists of plain copper strip, which is wound with interposed insulation in the form of a layer of insulating material on the former. The resistance of the primary winding should be less than the aperiodic limit resistance.

The magnetic circuit of the high tension impulse transformer, described herein, comprises a winding consisting of insulated layers of sheet iron of high permeability, the windings of which can be supported by an internally arranged core, within the winding space of the primary winding, and a further external casing to enclose the high voltage winding.

A further characteristic of the invention is that the secondary winding is surrounded by a high volt-age cylindrical condenser, the inner foil of which is connected with the high voltage end of the secondary Winding whilst the outer foil preferably is earthed.

If the high tension impulse transformer described above is directly mounted on a spark plug, the distance between the ends of the spark plug terminal and the end of the high voltage winding of the transformer can form an auxiliary spark gap.

Further particulars and characteristics of the invention are apparent from the following detailed description of the attached drawings, in which preferred forms of construction of the invention are shown by way of example.

In the drawings accompanying this specification:

FIG. 1 is a diagram showing the switching arrangement of a condenser discharging ignition installation for a four cylinder internal combustion engine.

FIG. 2 is a vertical longitudinal section through a high tension impulse transformer, combined with a spark plug, drawn to a larger scale.

FIG. 3 is a cross section through a part of one layer of the primary winding of the transformer shown in FIGURE 2 considerably enlarged; and

FIG. 4 is a radial section through the secondary winding of the transformer shown in FIG. 2 drawn to a larger scale.

The ignition arrangement diagrammatically shown in FIG. 1 consists of a DC. source, represented by the box 1, supplying electrical current at 450 volts; a contact arrangement 2, shown in a frame of broken lines, which distributes the primary current to four high tension impulse transformers 3, each of which is arranged on a cylinder of an internal combustion engine.

The contact arrangement 2 includes a storage condenser Cl, which can, for instance, have a capacity of 6 ,wf. and provide full operating scope for the ignition installation, i.e., four ignition impulses, without thereby lowering its voltage substantially.

Two further impulse condensers C2 and C3, connected in series, are connected in parallel with the storage condenser Cl. The condensers C2, C3 each may have a capacity of about 0.5 f.

The junction of the two condensers C2, C3 is connected to the casing of the contact arrangement 2, that is, grounded. The other two terminals of the condensers C2, C3 respectively are connected to the ignition distributor contacts K1, K2 and K3, K4.

The high tension impulse transformers 3 are each enclosed in a grounded screen. Each transformer 3 includes a primary winding 4 and a secondary winding 5, a terminal of each of the windings 4 and 5 being earthed.

The high voltage end of each secondary winding 5 is earthed through a storage con-denser 6 and is also con- 3 nected to an electrode of a spark plug 7 having a grounded electrode.

The mode of operation of the ignition arrangement shown in FIG. 1 is obvious to the expert from the circuit. The contacts Kit to K4 are opened and closed in sequence by the ignition distributor. When each contact is closed, one of the impulse condensers C2, C3 is discharged.

When a contact is closed, not only does the discharging current flow from one condenser, but also the charging current of the other condenser flows at the same time through the primary winding of the impulse transformer 3 concerned, thus the initial impulse is doubled. The sequence of connect-ions, as such is known and was proposed as far back as the year 1938 by Hooven.

The structural arrangement of this impulse transformer is shown in FIG. 2, from which it can be seen that it consists of a primary coil former 8, a secondary coil former 9, a primary winding 10, a secondary winding 11, -a high voltage condenser 12, an internal iron core 13, an external iron shell 14 and a transformer casing 15.

The two

coil formers

8 and 9 consists preferably of thermoplastics, those for the lower thermal ranges being made of polyethylene or polyesters and those for higher thermal ranges being made, if necessary, of halogen polymerisates. The production can be carried out by injection moulding.

The primary coil former 8 consists of a tubular part having a radial arranged external flange 16, while the secondary coil former 9 is pot shaped and contacts with the upper face of the flange 16 as well as at the free end of the primary coil former 8, so that an enclosed winding space is provided for the primary winding 10. The base of the secondary coil former 9 is provided with a depending cylindrical projection 17, which fits into the interior of the primary coil former 8.

The upper end of the coil formers is closed by a lid 18, consisting of the same insulating material which lies in contact with the base of the secondary coil former 9 and also serves to centralize the iron shell 14.

The inner iron core 13 is located inside the winding space for the primary winding, the iron core 13 and iron shell 14- consisting of a winding comprising two or more layers of well insulated sheets of high permeability iron.

The low voltage ends of the primary winding and the secondary winding 11 are connected together within the space enclosed by the flange 16 and connected with the earth terminal of the transformer. The high voltage end of the primary winding 10 is arranged within the space enclosed by the flange 16 outside the iron shell 14, taken from the space for the primary winding and connected with the terminal 19, which passes, by means of a glass bushing 20, through the upper cover 21 of the transformer casing.

The high voltage electrode 22 of the secondary winding is located in the depending cylindrical projection 17 of the secondary coil former 9.

In FIG. 2, the high voltage end of the secondary winding 11 is situated at the top and the high voltage connection is, on the one hand, connected with the high voltage electrode 22 and, on the other hand, with the internal foil of the high voltage cylindrical condenser 12, the external foil of which is grounded.

The metal casing is hermetically sealed, the outer boundary of the casing being formed by a cylindrical shell, the upper boundary by the lid 21 with the glass bushing 20, and the lower boundary by the flange 16 or perhaps by the projection 17 with the high voltage electrode 22.

The high voltage electrode 22 of the transformer is so arranged that the distance between it and the corresponding electrode 23 of the sparking plug 24 is about 0.5 to 1.0 mm., in order to provide the auxiliary spark gap required for reliable ignition.

The transformer is mounted in an adapter 25 of pressed sheet iron that has the lower opening 26 which is constructed as a washer to be compressed, when the sparking plug 2'7 is screwed in place, so as to effect perfect contact with the cylinder head 23, thus assuring a proper seat for the transformer and at the same time providing a complete and efficient low resistance metal screen for the high voltage condenser circuit which carries steeply peaked and powerful impulses.

Such an effective screening is necessary in order to render the ignition arrangement entirely free from interference in the decimeter wave range. Further, the described method of fixing renders the ignition arrangement waterproof.

In the upper part of the high voltage transformer there is an evacuated capsule 31, of the kind used in aneroid barometers, to compensate for the change in volume due to heat.

When settling the form of the primary winding 10 its ohmic resistance should be low relatively to its inductive resistance; further, the windings should be closely coupled and well adapted to the load on the secondary side, in relation to the aperiodic limit resistance.

Moreover, the inductive resistance of the primary winding should be large, relatively to the inductive resistance of the connecting cable between the distributor contacts and the impulse transformer.

Taking into account these requirements and the permissible potential in the winding to secure adequate insulation, a two-layer winding with an internal diameter of 20 mm. and a length of 60 mm. was selected. In the interior of the primary winding there is, to act as an iron core, a winding consisting of three or four layers of high permeability iron sheet 0.1 mm. thick, with adequate insulation between the layers.

The winding arranged on this core consists of a strip of copper foil 5 mm. wide and 0.1 mm. thick. This strip of copper foil can be bare if it is insulated with a strip 29 of 30/,u plastics foil 10 mm. wide interwound with it during winding.

This arrangement of the winding is shown diagrammatically in PEG. 3. The insulation between the layer consists of 3 layers of the same plastics foil. In the two layer arrangement with a total of ten turns the winding begins and ends on the face of the flange 16 of the primary coil former.

As on account of the high instantaneous value of the impulse (450 v. a. equals 45 kw.) the electro dynamic stresses in the primary winding are considerable it is advisable to impregnate the insulating foil of the iron core as well as the Winding, prior to the winding with a solvent free, hardening plastics varnish and thereby fix the winding.

This assembly of the primary winding ensures, with suflicient consideration of all other requirements, a minimum of radial expansion of the primary winding.

The construction of the secondary winding is shown in FIG. 4. The secondary winding 11 is shorter than the primary winding 10, and arranged to provide close coupling between each of the layers of the secondary wind- 111g.

The arrangement of the secondary winding is based on the consideration that with a potential of about 20 v. in thewinding, the insulation from turn to turn of ordinary enarnelled wire is sufficient, but that the insulation between the layers is not sufficient without the provision of special means.

The secondary winding lll. also begins at the face of the flange 16 of the primary coil former. For the winding a wire of 0.07 mm. in diameter with a coat of enamel about 0.01 mm. is employed. The 2,000 turns selected here, as an example, are distributed over a total of ten layers.

The first and second layers, the fifth and sixth layers, and the ninth and tenth layers progressively are wound from left to right according to FIG. 4, and have a length of 4.25 cm. each. The third and fourth layers as well as w the seventh and eighth layers are wound in the opposite direction and have a length of 3.45 cm. each.

The maximum potential diflerence between the ends of two adjacent layers that is possible amounts to about kv., starting with volt winding potential. To insulate the layers two foils of plastics, with high penetration resistance are employed.

As an example, a suitable foil is of polyethylene of thickness, which has a penetration resistance of 150 kv./ mm. In each layer the part not occupied by the windings is filled up by a layer 30 of paper having a thickness equal to the diameter of the wire.

Theseparate paper layers are treated in a manner that they do not impede the penetration of the impregnating medium when completing the transformer.

By means of the winding arrangement shown in FIG. 4, not only about 30% of the insulation space, while maintaining equal potential resistance, can be saved, but also the capacity of the winding itself can be considerably reduced compared with one of the usual multi layer coils. From the point of view of construction, this assembly also has the advantage that several coils can be wound on the mandrel of an automatic coil winding machine simultaneously.

The foil 12a on the high tension side of the high voltage condenser 12, consisting of a sheet of copper, is insulated against the uppermost layer of the secondary winding 11 with the same number of layers of insulating material as the layers are insulated, the one from the other, while the number of layers of insulating material between the two condenser foils is determined by the area of these foils and the capacity required (about 40% of the energy content of a working condenser) on the low voltage side, the outer condenser foil preferably being earthed.

The iron shell 14 completes the external enclosure, as also is seen in FIGURE 2, which iron shell, similarly to the iron core 13, is composed of three or four layers of iron sheet having interposed insulating foil.

The above mentioned data show that in the high tension impulse transformer described above, the insulating materials are used far more eiiiciently than is usual in electro technical practice. Therefore, in order to safeguard satislactory operation of the apparatus, the impulse transformer must be constructed very carefully.

Above all, prior to impregnation, all dampness must be removed with the greatest care. The windings must be exposed for asuflicient time to adequate vacuum, and it is advisable to effect a current heating from the interior outwards. it is also obvious that air pockets between dif ferent layers of foil must be avoided, as these, owing to the great electrical strength of field, rapidly destroy the organic insulating substances by ionisation.

To avoid air pockets, the layers of foil tightly wound one over the other, can, before being used, becovered with a material such for instance as petroleum jelly.

The inventionis not limited to the forms of construction described by the way of example, and particularly the particular dimensions stated and also the electrical data are to be considered only as examples. The scope of the present invention is given in the following patent claims:

What I claim is:

1. Ahigh tension ignition transformer for the production of instantaneous impulses, particularly for igniting fuel/ air mixtures, comprising a primary winding wound on an iron core supported by a cylindrical former having an upper end and a lower end, a flange projecting radially outwards from said lower end and forming a base; a secondary winding of multiple layers surrounding the primary winding and supported by a pot shaped former having a lower open portion in contact with said base and whose upper portion is in contact with the upper end of the primary coil former and is provided with a depending cylindrical projection extending inwardly of the primary coil former; the low tension ends of the primary and secondary windings being grounded and being located in proximity to the flange while the high tension end of the secondary winding is disposed in the depending cylindrical projection, one portion of each secondary winding layer being separated by insulation from adjacent layers, another portion of said secondary winding layers being overlapped by a portion of an adjacent overlapping layer, each secondary layer being wound in a direction opposite to the preceding underlapped layer, the last winding layer being joined to the wound capacitor.

2. A high tension ignition transformer for the production of instantaneous impulses, particularly for igniting tuel/ air mixtures, comprising a primary winding wound on aniron core supported by a cylindrical former having an upper open end and a lower end, a flange projecting radially outwards from said lower end and forming a base; a secondary winding of multiple layers surrounding the primary winding and supported by a pot shaped former whose lower open portion is in contact with said base and whose upper portion is in contact with the upper end of the primary coil former and is provided with a depending cylindrical projection extending inwardly of the primary coil former; the low tension ends of the primary and secondary windings being grounded and being located in proximity to the flange while the high tension end of the secondary winding is disposed in the depending cylindrical projection, the separate layers of the secondary winding being shorter in axial extension than the primary winding and being arranged in step-like formation relative to one another, extending towards the high voltage end, one portion of each secondary winding layer being separated by insulation from adjacent layers, another portion of said secondary winding layers being overlapped by a portion of an adjacent overlapping layer, each secondary layer being wound in a direction opposite to the preced-j ing underlapped layer, the last winding layer being joined to the wound capacitor..

3. A high tension ignition transformer for the production of instantaneous impulses, particularly for igniting fuel/ air mixtures, comprising a primary winding wound on an iron core supported by a cylindrical former having an. upper end and a lower end, a flange projecting radially outwards from said lower end and forming a base; a secondary winding of multiple layers surrounding the primary winding and supported by a pot shaped former whose lower portions is in contact with said base and whose upper portion is in contact with the upper end of the primary coil former and is provided with a depending cylindrical projection extending inwardly of the primary coil former; the low tension ends of the primary and secondary windings being grounded and being located in proximity to the flange while the high tension end of the secondary winding is disposed in the depending cylindrical projection, said secondary winding consisting of wire layer portions shorter in axial extension than said wire layer portion being arranged in step-like formation relative toone another the primary winding towards the high voltage end the unwound part of each layer being filled with insulating material, the thickness of which is equal to the thickness of the wire layer portion, one portion of each secondary winding layer being separated by insulation from adjacent layers, another portion of said secondary winding layers being overlapped by'a portion of an adjacent overlapping layer, each secondary layer being wound in a direction opposite to the preceding underlapped layer, the last winding layer been joined to the wound capacitor.

4. A high tension ignition transformer for the production of instantaneous impulses, particularly for igniting fuel/ air mixtures, comprising a primary winding wound on an iron core supported by a cylindrical former having an upper end and a lower end, a flange projecting radially outwards and forming a base; a secondary winding of multiple layers surrounding the primary winding and supported by a pot shaped former having a lower open portion in contact with said base and whose upper portion is in contact with the upper end of the primary coil former and is provided with a cylindrical projection extending inwardly of the primary coil former; the low tension ends of the primary and secondary windings being grounded and being located in proximity to the flange while the high tension end of the secondary winding is disposed in the depending cylindrical projection, said secondary winding consisting of wire layer portions shorter in azial extension than the primary winding said wire layer portions being arranged in step-like formation relative to one another, towards the high voltage end the unwound part of each layer being filled with insulating material, the thickness of which is equal to the thickness of the wire layer portion, and each wire layer of the secondary winding being wound in opposite direction to the direction of its adjacent wire layer so that the direction of winding in the several layers alternates, one portion of each secondary winding layer being separated by insulation from adjacent layers, another portion of said secondary winding layers being overlapped by a portion of an adjacent overlapping layer, each secondary layer being wound in a direction opposite to the preceding underlapped layer, the last winding layer been joined to the wound capacitor.

5. The invention as claimed in claim 3, wherein the wire layers of the secondary winding are separated, the one from the other, over the whole length of the coil by thin layers of insulating material.

6. The invention as claimed in claim 3, wherein the resistance of the primary winding is less than the aperiodic limit resistance and is defined by the formula 4L ye in which R is the resistance in ohms, L, the inductance of the circuit, C the capacity of the circuit.

7. The invention as claimed in claim 3, wherein the primary winding consists of bare copper strip provided with a thin layer of insulating material.

8. The invention as claimed in claim 3, wherein the windings are with synthetic resin varnish.

9. The invention as claimed in claim 3, wherein within the winding space for the primary winding, there is provided a core consisting of insulated layers of sheet iron of high permeability.

10. The invention as claimed in claim 3, wherein the primary and secondary windings are surrounded by an external shell consisting of insulated layers of sheet iron of high permeability.

11. The invention as claimed in claim 3, wherein the primary and secondary windings are surrounded by an external shell consisting of insulated layers of sheet iron of high permeability, said external shell having one end resting on said base of the former for the primary winding and being centralised at the opposite end with a lid of insulating material.

12. The invention as claimed in claim 3, wherein the secondary winding is surrounded by a high tension cylindrical condenser, the inner foil of which is connected with the high tension end of the secondary winding while the outer foil is grounded.

13. The invention as claimed in claim 3, wherein the internal space of the formers being so dimensioned that they can be mounted on the exterior of the insulator of a sparking plug.

14. A high tension ignition transformer for the production of instantaneous impulses, particularly for igniting fuel/ air mixtures, comprising a primary winding wound on an iron core supported by a cylindrical former having an upper end and a lower end, a flange projecting radially outwards and forming a base; a secondary winding of multiple layers surrounding the primary winding and supported by a pot shaped former having a lower open portion in contact with said base, and whose upper portion is in contact with the upper is provided with a cylindrical projection extending inwardly end of the primary coil former and of the primary coil former; the low tension ends of the primary secondary windings being grounded and being located in proximity to the flange while the high tension end of the secondary winding is disposed in the depending cylindrical projection, said secondary winding consisting of wire layer portions, shorter in axial extension than the primary winding said Wire layer portions being arranged in step-like formation relative to one another, towards the high voltage end the unwound part of each layer being filled with insulating material, the thickness of which is equal to the thickness 'of the wire layer portion, the internal space of the formers being so dimensioned that they can be mounted on an exterior of the insulator of a sparking plug, with the high voltage end of the secondary located in the depending cylindrical projection of the secondary coil former being spaced a predetermined distance from the terminal of a sparking plug located in the interior of the former to form an auxiliary spark gap, one portion of each secondary winding layer being separated by insulation from adjacent layers, another portion of said secondary winding layers being overlapped by a portion of an adjacent overlapping layer, each secondary layer being wound in a direction opposite to the preceding underlapped layer, the last winding layer being joined to the wound capacitor.

15. The invention as claimed in claim 3, wherein the transformer is enclosed in an air tight metal casing hermetically sealed and the connection on the high voltage end of the primary winding is carried co-axially through an insulator, out of a casing at the end remote to the sparking plug opening.

16. The invention as claimed in claim 3, wherein an air tight casing for the transformer contains an evacuated capsule.

17. The invention as claimed in claim 3, wherein the external casing of the transformer comprises an annular sheet iron adapter having a bottom flange, and an opening for a sparking plug in said base flange.

References Cited by the Examiner UNITED STATES PATENTS 1,633,047 6/27 James 317-15762 1,869,233 7/32 Welter 336- 2,127,575 8/38 Thompson et al 3l7157.6 2,328,443 8/43 Foster 33669 2,381,782 8/45 Stephens 336--70 2,394,768 2/46 Harkness 317-157.62 2,441,047 5/48 \Wall 317--l57.62 2,445,169 7/48 Frey 336-96 2,941,172 6/60 Sutton 336-92 2,972,713 2/61 Sutton 336- 3,060,353 10/62 Shansky 33690 SAMUEL BERNSTEIN, Primary Examiner.

Claims

1. A HIGH TENSION IGNITION TRANSFORMER FOR THE PRODUCTION OF INSTANTANEOUS IMPULSES, PARTICULARLY FOR IGNITING FUEL/AIR MIXTURES, COMPRISING A PRIMARY WINDING WOUND ON AN IRON CORE SUPPORTED BY A CYLINDRICAL FORMER HAVING AN UPPER END AND A LOWER END, A FLANGE PROJECTING RADIALLY OUTWARDS FROM SAID LOWER END AND FORMING A BASE; A SECONDARY WINGING OF MULTIPLE LAYERS SURROUNDING THE PRIMARY WINDING AND SUPPORTED BY A POT SHAPED FORMER HAVING A LOWER OPEN PORTION IN CONTACT WITH SAID BASE AND WHOSE UPPER PORTION IS CONTACT WITH THE UPPER END OF THE PRIMARY COIL FORMER AND IS PROVIDED WITH A DEPENDING CYLINDRICAL PROJECTION EXTENDING INWARDLY OF THE PRIMARY COIL FORMER; THE LOWER TENSION ENDS OF THE PRIMARY AND SECONDARY WINDINGS BEING GROUNDED AND BEING LOCATED IN PROXIMITY TO THE FLANGE WHILE THE HIGH TENSION END OF THE SECONDARY WINDING IS DISPOSED IN THE DEPENDING CYLINDRICAL PROJECTION, ONE PORTION OF EACH SECONDARY WINDING LAYER BEING SEPARATED BY INSULATION FROM ADJACENT LAYERS, ANOTHER PORTION OF SAID SECONDARY WINDING LAYERS BEING OVERLAPPED BY A PORTION OF AN ADJACENT OVERLAPPING LAYER, EACH SECONDARY LAYER BEING WOUND IN A DIRECTION OPPOSITE TO THE PRECEDING UNDERLAPPED LAYER, THE LAST WINDING LAYER BEING JOINED TO THE WOUND CAPACITOR.