EP3304570A1

EP3304570A1 - Low-noise special transformer

Info

Publication number: EP3304570A1
Application number: EP16734034.8A
Authority: EP
Inventors: Wladimir Weigandt; Hans-Dieter MÜLLER
Original assignee: Manfred Schmelzer GmbH
Current assignee: Manfred Schmelzer GmbH
Priority date: 2015-06-04
Filing date: 2016-06-06
Publication date: 2018-04-11
Anticipated expiration: 2036-06-06
Also published as: WO2016193958A1; EP3304570B1

Abstract

The invention relates to a temperature resistant special transformer having excellent structure borne sound and/or airborne sound behaviour at the same time as a small, extremely flat construction and excellent overall efficiency. According to the invention, the transformer windings are distributed over three chambers as linearly consecutive, aligned coils having a single centrosymmetric primary coil (20) and two further coils (10, 30), electrically interconnected as a secondary winding, the coils being mechanically linked to one another in a chain. Such a transformer has a significantly lower input current in idle than in the lowest intended capacitive loading condition. In addition, the aforementioned advantageous acoustic characteristics are further improved by means of a special encapsulation of the transformer in an associated housing. The invention also relates to a method for producing the transformer at optimal cost and to the use of such a transformer in the automotive sector.

Description

Low-noise special transformer

introduction

The invention relates to a working with low frequency electrical transformer.

The invention is in particular a special transformer with extremely good structure-borne sound and / or airborne sound in unusually elongated and extremely flat design because of an available or intended installation space.

The very low structure-borne noise and airborne sound behavior lies over an extended ambient temperature range according to so-called MIL or "automotive" specifications below the low limit values, as they are customary in industry, for example in the automotive sector.

In idle mode, a transformer constructed in accordance with the invention should have a substantially lower input current than the value of the primary input current at a minimum specified capacitive load.

Furthermore, the invention relates to methods for cost-optimal production of such a transformer.

State of the art and its disadvantages

For reasons of literacy, it is common to provide electric machines and transformers with the shortest possible magnetic flux paths. Associated coils may have comparatively large surfaces or volumes. As an appropriate reminder, the phrase "iron short, copper long" is occasionally quoted. For this reason, regular transformers tend to have a rather compact, cubic design. Transformers for special applications may have a different shape. An example of this is the so-called Tesla Transformer, as it is known with its preferred pyramidal shape, for example, from the patent US 1, 1 19,732.

No transformer construction known from the patent or other literature appears to meet the requirements placed on the subject matter of the invention. Standard transformers are either

- to wide,

too high or

too expensive

for the intended application. Other known types of transformers, either of their shape and dimensions, performance class, cost or noise emissions, are not suitable for realizing the functions as is possible with a miniature transformer according to the invention.

As far as can be seen, a transformer according to the invention is neither offered commercially nor used in the military field. For comparison, the following patent literature is cited, which is considered to be particularly close prior art: a) CN 201 163564 Y, inventor: Li

Title: Miniature transformer iron core / winding structure

This document cites in the abstract a miniature transformer with low noise. As far as can be seen from the drawing, this is a completely normal transformer with E and I core laminations. b) US7218198, inventor: Pilniak et al.

Title: Coil form

Among other things, this document cites E-shaped core parts and, in contrast to the present invention, is based on metallic separating plates between axially aligned coils. Object of the invention and associated solution

The invention has for its object to provide a transformer having all the following properties in combination, namely:

is of miniaturized design and has cross-sectional dimensions of a few square centimeters

powered with input voltages in the 5 volt range and delivering output voltages in the 100 volt range or greater at idle with a much lower primary current than is the case with minimum capacitive load

characterized by extremely low airborne and / or structure-borne noise emissions, both at idle and at nominal load

- Has a good overall efficiency

has particularly good temperature and climate resistant performance characteristics

This object is achieved by a special transformer with carefully matched mechanical, electrical, magnetic and thermal properties and values, namely transformer windings, which are distributed as linearly successive, flushing spools on wide baffles nd, wherein egg nzi ge centrally symmetrically arranged primary coil and two other, as Sekudärwickl ung interconnected coils in mechanically concatenated (concatenated) construction are available, the length of the transformer does not exceed 8 times the height, the degree of height of the transformer maximum 13 mm and the volume of the transformer including an associated housing is limited to 130 cubic centimeters, preferably only 60 cubic centimeters. An essential part of the solution continues to be that the existing bobbins are all aligned coincidentally axially along their longitudinal axes and are mechanically chained together adhering to predefined rotational positions about the longitudinal axis, preferably by means of uniform, highly symmetrical shaped clip-connection devices.

A further aspect of the solution consists in a method for producing such a transformer, which comprises the following method steps: a) winding and provision of coils on bobbin, which preferably have the same cross-sectional dimensions and snap-in (activatable) clip devices b) generating a combined Mechanically integral coil set by stringing together three or more such coils by means of said clip devices in the direction of the coil axes c) Completing the transformer by alternately inserting ferromagnetic core material in said one-piece coil set and then attaching the coil set to the transformer core thus formed

figure description

The invention will be explained in detail with reference to the drawings. It shows : Fig. 1 is a schematic plan view of a transformer according to the invention

Fig. 2 is a schematic perspective proportionate view

Fig. 3 is a perspective complete view

Fig. 4 is a schematic view of the invention

Arrangement and method relating to the mechanical concatenation of transformer coils

5 is a phasor diagram for illustrating the

complex-valued current / voltage ratios

6 is a side view and a plan view of a

preferred encapsulated embodiment of the invention

A transformer according to the invention with the required service characteristics consists, as shown in schematic form in FIG. 1, of a special transformer core and special transformer coils.

The transformer coils according to the invention consist of at least three individual coils 10, 20 and 30. These are arranged axially aligned and produce in this way the exceptionally unusually large ratio of length to cross section (width times height) of the transformer.

If necessary, a transformer according to the invention is equipped with further axially aligned coils. The centrally symmetrically arranged coil 20 is preferably used as a primary coil, while coils 10 and 30 preferably function as secondary coils. Preferably, coils 10 and 30 are electrically connected in series. They then generate in combination not only in a conventional manner a desired secondary voltage, but also in a innovative way a relatively large leakage inductance.

The feeding of the primary voltage takes place via the connection contacts 21, 22, while the output of the contactor is in contact with the secondary voltage, e.g. via the terminal contacts 1 1 and 32 takes place, wherein the terminal contacts 12 and 31 are then electrically connected (not shown) and the individual secondary voltages of coils 10 and 30 are thus added in the correct phase.

Another essential aspect of the invention is the use of completely uniform highly symmetrical and elongated bobbins. These are provided in a conventional manner as needed with different Wickelungen made of enamel-insulated wire.

The arrangement and spacing of the three (if necessary, more) provided coils an increased leakage flux is generated compared to conventional transformers, whereby the desired performance properties of the invention even come about, namely least possible body and scarf lable and defi ned generation egg ner increased output voltage at the intended electrical load.

Also by the shape of the transformer core 40 with extremely elongated ED sheet metal parts with a relatively wide cross yoke, the leakage flux is increased in accordance with the invention desired, without regard to desired overall efficiency and No-load current special disadvantages arise.

As can be seen, according to the invention a transformer length is preferred which is more than four times, preferably more than five times the width of the transformer. At the same time a transformer height can be provided in this way, which is only less than a sixth, preferably less than one-eighth of the transformer length. As a result, a particularly flat for his power class in the watt range transformer is provided with very low production costs.

The required electrical properties of the transformer according to the invention are also realized inexpensively by using only commercially available cheapest transformer sheet materials, ie only in cold-rolled or grain-oriented design. It is therefore not necessary to use expensive special materials such as ferrite, high nickel or amorphous metals in order to provide the highest quality of service properties, and according to the innovation, this can be dispensed with.

For better visualization, Fig. 2 shows a transformer according to the invention comparable to Fig. 1 in a diagrammatic perspective view, but partially assembled. without primary coil 20.

It will be seen that both the iron flow path volume and the arrangement of the existing coils are in a relatively highly elongated form, and thus this arrangement is very different from typical forms of general small and medium power transformer construction. It is understood that the connection contacts 1 1, 12, etc., if necessary, can be provided with contact pins, solder lugs or other connection means.

To protect such an arrangement against mechanical or climatic influences, it is inserted into a capsule or shell made of suitable plastic and, if necessary, coated with a potting compound. The advantageous dimensional ratios of the invention essentially remain the same and result in a highly flexible, miniaturized transformer of low-noise and low-noise design.

Furthermore, it is shown in Fig. 2 that the transformer core 40, 41 is advantageously made of sheets of ED cut. The sheets are also held together with rivets of suitable design, or with a bond, or with a suitable form-fitting connection, also to meet the acoustic requirements. The transverse yoke of said sheets of transformer core is held relatively wide, approximately twice as wide as a leg width.

A particularly advantageous embodiment of the invention (English: Best mode of invention) is shown in Fig. 3. The bobbins shown (10 ', 20', 30 ') allow a particularly compact and efficient construction. A special aspect of the invention relates to the arrangement and orientation of the pin-shaped contact terminals 1 1, 12, etc., which have to save space alternately to the left and to the right side; nevertheless, the bobbins are uniformly highly symmetric and of identical shape. The modular arrangement of coils in a transformer designed according to the invention is particularly suitable for automation and, in a further optimized embodiment of the invention, results in even lower production costs.

This is done by individual coils in the axial direction, each lined up with an associated clip-connection device and assembled into a one-piece coil set (clipped). It does not matter whether a solvable or a permanent connection of the coils is desired to the integral coil set or not.

The principle of the axially directed connection of transformer coils is shown in FIG. Each of the schematically shown coils 110, 120, 150 with electrical connection elements 111, 112, etc. has one or more clip or latching devices 115, 116 for a positive connection. The clip or Verrastungsvorrichtungen can in a variety of shapes, for example in the manner of tongue and groove, are performed and are shown in Fig. 4 only schematically and in the simplest form to suggest the principle.

From Fig. 5 it follows that this transformer according to the invention is well suited to achieve a higher operating voltage on capacitive loads than is specified in the fundamentally known way by the Wndungszahlverhältnis of secondary and primary coils alone. Pointer sizes with the index 21 refer to an inductive load case, while pointer sizes with the index 22 refer to a capacitive load case.

At an inductive load with comparably large complex-worth Wderstand only a secondary AC voltage with the size of the pointer U21 is generated. In the case of a capacitive load is a secondary AC voltage of the size of the pointer U22. This is in any case greater than pointer U21 due to the capacitive and leakage-related vectorial variable 122 * (R + jXs). (jXs denotes leakage flux impedance with inductive or capacitive load). The invention is therefore less suitable for inductive components that are to be operated with a relatively high nominal voltage. Accordingly, the transformer according to the invention can be operated in an innovative manner as needed and by selecting a suitable frequency of the primary voltage (operating frequency) also in the vicinity of the associated electrical resonance. That is, it can provided capacitive loads despite the small size of the transformer with relatively high operating voltages and power, so that Wrkstromverluste fall less significant and good overall efficiency of the relevant electrical circuit can be achieved. The above design features and dimensions of the transformer according to the invention help in a special way to be able to energize a downstream intended, substantially capacitive load of a few hundred nano Farad or more.

The mentioned electrical or magnetic design of the invention also has an innovative effect that the primary-side current at idling is substantially (at least 70%) smaller than compared to the operation of the transformer at the lower limit of such intended load-range. The invention is therefore particularly suitable for a downstream load in the form of an electrochromic or LCD shading device in the sense of sun protection. Such a sunscreen or a corresponding shading device is mentioned, for example, in claim 7 of DE19962115A. A particularly important embodiment of the invention with optimum suitability for the automotive market is shown in FIG. It is explained how a built-up according to the described method in multi-chamber technology and with a matched to the capacitive load high leakage inductance transformer to achieve the lowest structure-borne noise and airborne noise in a plastic housing with open top mounting device and is shed. - In a somewhat more elaborate method of preparation, the bottom of the plastic housing can also be provided with a thin layer of potting compound. After curing of this layer, the transformer body is inserted and then finally wrapped with potting compound.

According to the invention and with reference to FIG. 6, the best results are obtained if, when the transformer is installed in the plastic housing, the following design features are fulfilled:

1. no contact of the transformer body with the

sidewalls

2. lowest possible direct bearing surface of the inserted

Transformer body on the housing bottom, with a total bearing surface (reference numeral 34) from zero to less than 150 mm ** 2

3. defined minimum distance of the coil surface to

Caseback (less than 3 mm)

4. Using an elastic potting compound with

following main features:

Shore - Hardness A35 or smaller

Shore hardness damping behavior almost constant over the operating temperature range, at the same time

moistureproof encapsulation of the transformer body The very small housing 160, shown substantially to scale in FIG. 6, has a height of only 13 mm (reference numeral 13) and is open at the top. The illustrated symmetrical spacing of the transformer body 180 to the sides of the housing (end faces 162, longitudinal sides 164) is in the millimeter range between 0.5 and 5 mm and has considerable significance for the advantageous noise behavior of the invention. Likewise, the already mentioned spacing of the transformer body to the housing bottom 166, as shown in Fig. 6, of significant importance according to the invention. Advantageously, the bobbins 10 ^' , 20 ^' , 30 ^'have nubs or foot-like spacer elements 34, with which the column bodies are placed on the floor panels (optionally on a layer of encapsulant), such as shown in Fig. 6. The spacing elements according to the invention have a support surface of each max. 16 mm ** 2 and in total less than 150 mm ** 2.

For the embedding of the transformer body in the housing, the already mentioned potting compound 170 is provided, which tuned to the acoustic target values of the invention and having a Shore A hardness of less than 35 comparatively good elasticity, but also suitable damping properties. Due to the above-described careful coordination of the mechanical, electrical and magnetic parameters of each other, the transformer according to the invention developed at each point of the mounting surface of the transformer housing nurge ri nge sound accelerations. Based on the operating frequency, the sum of the harmonics of the sound accelerations in the frequency range up to 1000 Hz is less than 0.40 m / sec ** 2. List of reference numbers:

10 coil, secondary coil

10 'bobbin

11, 12 terminal contact, winding connection

13 Dimensions

20 coil, primary coil

20 'bobbin

21, 22 connection contact, winding connection

30 coil, secondary coil

30 'bobbin

31, 32 connection contact, winding connection

34 spacer element

40, 41 transformer core

110 coil

111 connection element

112 connection element

115 clip or latching device,

116 clip or latching device,

120, ...., 150 coils

160 housing

170 potting compound

180 transformer body

Claims

Claims: 1.

Electric transformer for operation in the extended temperature range between -40 ° C and +130 ° C,

characterized in that the transformer windings are distributed as linearly successive, axially aligned coils on three chambers, while a single centrally symmetrically arranged primary coil (20) and two other, as a secondary winding together mengeschalteten Coil (1 0, 30) in mechan isch chained construction ; the overall length of the transformer does not fall short of 8 times the overall height and the maximum height of the transformer is 13 mm. Second

Low-noise, encapsulated in a housing transformer with a volume of less than 130 cubic centimeters, a generated at all points on the surface of the transformer housing sound acceleration, which does not exceed the value of 0.40 m / sec ** 2 in the load range of 5 to 15 watts output power and is based on the sum of all existing at operating frequency harmonics in the frequency range from 0 to 1000 Hz.

Third

Transformer according to claim 2, having a construction volume of less than 60 cubic centimeters.

4th

Transformer according to one of the preceding claims, characterized in that the primary-side current at idle of the transformer is at least 70% smaller than compared to an intended load case with a capacitive load of more than 100 Nano Farad

5th

Transformer according to one of the preceding claims, characterized in that the existing bobbin (10 ', 20', 30 ') all coincident axially aligned coincidentally along their longitudinal axes and adhering to two 180 ° offset predefined rotational positions about the longitudinal axis by means of a uniform clip connection Devices (115, 116) are mechanically chained together.

6th

Transformer according to one of the preceding claims, characterized in that bobbin (10 ', 20', 30 ') with spacer elements (34) are provided, wherein a single bearing surface of a spacer element is less than 16 mm ** 2.

7th

Transformer according to one of the preceding claims, characterized in that the ferromagnetic transformer core (40, 41) consists only of grain-oriented or cold-rolled transformer sheet. 8th.

Use of a transformer according to one of the preceding claims for feeding an output-side substantially capacitive load.

9th

Use of a transformer according to claim 8 for feeding an electronic LCD or electrochromic sunscreen or an electronic shading device.

10th

Use of a transformer according to claim 9 for actuating a sunshade in an automobile. 11th

Method for producing a transformer, characterized by the following method steps:

- Winding and provision of coils on bobbin (10 ', 20', 30 '), which preferably have the same cross-sectional dimensions and in the axial direction snap-clip devices (115,116)

Producing a combined mechanically integral coil set by mechanically stringing together three or more such coils by means of said clip devices in the direction of the coil axes

- Completing the transformer by inserting a transformer core (40, 41) made of ferromagnetic core material in said one-piece coil set and attaching the one-piece coil set to the transformer core. 12th

The method of claim 11, wherein the bottom of a housing (160) covered by potting compound, the transformer body (180) after the partial or complete curing of the potting compound in the housing with all-round spacing of the housing inside inserted, and then with said potting compound (170) um- and overflowing.