DE2211222A1 - Oil-encapsulated return transformer arrangement - Google Patents

Description

L '- \ J \ J

- CJ,

MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD. Osaka, Japan

Oil-encapsulated flyback transformer arrangement

The invention relates to an oil-enclosed flyback transformer arrangement with a tightly closed container, in the flyback transformer is included.

The object of the invention is to provide an oil-encapsulated flyback transformer arrangement to create at which the oil pressure inside a tightly closed container with temperature changes is hardly subject to fluctuations and in addition hardly any stray capacities can occur. ■ ■

In a known oil-immersed flyback transformer arrangement If the sealed container for the return drain sfornator is made of metal, the side walls bulging and bulging can when the volume of oil in the closed container increases or decreases due to temperature changes of the oil. However, here it comes from the stretching and contraction movements

209839/0837

movements of the metal cause fluctuations in capacitance between the Winding and the metal container and the sound of the flyback transformer therefore, cannot be kept at a normal level. This excessive clinking can, for example, lead to a "reduction of the stepped-up output voltage. Especially for gate directions where a high-voltage rectifier diode is provided is, the capacitance between the diode and the metal container can increase the internal loss of the diode, irregularities in the voltage carried by the diode, etc., which can lead to premature failure of the diode. Want to remedy this deficiency, one must find a container of extreme use high rated load.

Another shortcoming of the conventional oil-immersed return line trän sf ο rma to rano rdnunge η consists in the fact that with a decrease the insulation distance between the high-voltage output terminal or the low voltage output terminal and the metal container die Bauweiee of the devices is correspondingly more complicated if one ensure the voltage load capacity of the relevant connections want.

The invention, which aims to eliminate the above deficiencies, shall be based on preferred embodiments below will be described with reference to the accompanying drawings. Show in it:

Fig. 1 shows an embodiment of the invention in longitudinal section *

2 shows a sectional view of an oil-encapsulated return transformer arrangement according to a further embodiment of the invention;

Fig. 3 is a diagram showing the relationships between the changes in the internal oil pressure and the ratio of the total volume V of the internal parts of the flyback transformer assembly to the capacity V ^ of the closed container; and

4 is a diagram showing the relationships between changes in internal oil pressure and the ratio cJ / β des

combined

209839/0837

combined coefficient of thermal expansion O for the volume of the overall arrangement including the insulating oil zürn coefficient of thermal expansion ß for the volume of the closed container.

Reference is first made to FIG. 1, in which the reference number 1 denotes a closed container made of plastic, which has side walls 2 made of a plastic material reinforced with long glass fibers and a base plate 3 and a top cover 4 made of an unreinforced plastic material. The thickness of the base plate 3 and the upper cover 4 is accordingly three to five times the thickness of the side walls 2. On the underside of the upper cover 4 is fastened by metal fittings 6 in a flyback transformer 5, while an upper voltage connection 7 and other connections 8 and a connecting piece 9 for closing an oil filling opening can be formed in one piece with the upper cover 4 in the production process. The upper cover 4 i ⁸ ^ fitted in a sealing manner into the container 1 and these parts are also firmly connected to one another, for example with the aid of epoxy resin. The return transformer 5 is immersed in insulating oil 10 ′ and the breathing activity of the container when the oil volume changes takes place on the side walls 2.

In the context of the invention it is provided that the closed container is made of plastic, and further that the temperature-related Changes in volume of that filled in the closed container Insulating oil by a sufficiently measured margin between the temperature-dependent changes in the capacity of the sealed Container and the temperature-dependent volume changes of the inner arrangements is taken into account, so that from the volume changes of the oil inside the sealed container prevailing oil pressure is reduced.

In other words, the original volume of the insulating oil is designated by V ₀ , the coefficient of thermal expansion for the volume of the insulating oil in relation to the original volume (v) by o (, the original capacity of the closed container by V _ß , the coefficient of thermal expansion for the. Capacity of the container in relation to the original capacity

209839/0837

(Y _n ) with ß, the original total volume of the internal arrangements, C

So including the ferrite core, the Eupfer wires, the insulating oil, etc., with Υ _φ and the coefficient of thermal expansion for the total volume of the internal arrangements in relation to the original volume (V_) with O ₁ , the following relationship generally applies

and it still applies

V = Y + V (2)

CO T ^K '

Should an internal oil pressure effect as a result of temperature changes to be avoided on the closed container, so must the relationship

Y _c (l + ßT) = Y ₀ (1 + rfT) + T _T (1 +? T) (3)

apply, where T denotes the temperature changes. From the above Equations (2) and (3) thus result in the ratio Υ_ / Υ-, to

In Pig. 3 are the relationships between the on the locked Internal oil pressure acting on the container and the ratio VJv obtained according to equation (4). shown graphically, with revealed these relationships from the experiments carried out. How out Fig. 3 shows, the internal oil pressure changes only slightly, if the ratio Vm / V «exceeds the value of 70 percent, this may show a certain deviation from equation (4).

Turning on the other hand the above conditions to the equation (4), then the relations between give the result of temperature changes on the closed container acting oil pressure and the ratio of the combined thermal expansion coefficient E for the volume of accommodated in the sealed container overall arrangement including the insulating in relation to the original volume to the coefficient of thermal expansion ß for the capacity of the closed container in the

209839/0837

in the form shown in Fig. 4, where ο by the equation

given is. It can be seen from this figure that the changes in the internal oil pressure which occur with changes in temperature are only small when the above ratio of the two thermal expansion coefficients obeys the condition J / β = 2. In this case, i.e. if the relation J '/ ß ^ 2 holds, the condition ν - /? - = 70 ° / o can also be met at the same time. Although the volume, the coefficient of thermal expansion, etc. differ depending on the construction of the flyback transformer, these differences are so small that they can be neglected with regard to the economy, etc. of the oil-immersed flyback transformer arrangement.

The invention provides oil-immersed flyback transformer arrangements in which the above conditions are taken into account, and a further embodiment of the invention will now be described with reference to FIG. In this figure, reference numeral 11 denotes a group consisting of epoxy resin, a closed container with a capacity of 225 cm TMCL a thermal expansion coefficient of 5 x ^10/0 C, with the reference number is also composed of epoxy resin cover part and denoted at the reference numeral 13 is a in.den closed container 11 recorded flyback transformer with a ferrite core I4, a coil I5 and a (ni, ch, t, .represented) bobbin. The reference number l6 denotes a quantity of metal oxide filled between the ferrite core I4 and the coil I5 with a volume of 60 cm, the reference number 17 denotes a high-voltage diode arranged in the closed container 11 and the reference number 18 denotes a high-voltage diode between the flyback transformer 13 and the high-voltage diode I7 Spacer element, this spacer element 18 being made of polypropylene and intended to prevent the transfer of heat to the high voltage diode 17. Lead wires I9 and 20 are led through a high-voltage connection 21 and low-voltage connections 22 to the outside. Reference numeral 23 denotes the filled through an oil filling hopper 24 and the

inner space

209839/0837

Insulating oil filling the interior of the closed container 11, this insulating oil being silicone oil with a (volume-related) thermal expansion coefficient of 9, Ox 10 / C, while the reference number 25 denotes a cap made of synthetic resin for sealing the filling opening 24. The total volume of the internal arrangements including the ferrite core 14, the coil 15, the lead wires I9 and 20, the stand element 18, the amount of metal oxide 16 and the high voltage diode 17 amounts to 205 cm and the (volume-related) coefficient of thermal expansion has the value 1.5 x 10 "/ ⁰ C

Tests have shown that the change in the oil pressure inside the container in the embodiment with that described above Build-up amounts to almost zero at a temperature difference of 50 C.

In tests carried out with an oil-encapsulated recirculation transformer arrangement, which was constructed very similarly to that of the second embodiment, the only difference being that the capacity of the closed container was 170 cm and the amount of metal oxide was not 16, could also be determined that a temperature difference of 50 ⁰ C caused almost no change in the oil pressure inside the container.

In the above-described embodiments, the ratio becomes the combined coefficient of thermal expansion for the volume of the internal assemblies housed in the closed container including the insulating oil in relation to the original volume to the coefficient of thermal expansion for the capacity of the closed container with respect to its original Holding capacity at a value below 2.0, so that the differences caused by temperature changes in the oil pressure prevailing inside the container almost to zero, so that there is still no risk of oil loss due to seepage and the like exist and stray capacitance can hardly occur, since the closed container 11 is made of epoxy resin, which means

209839/0837

indicates that the walls of the closed container 11 , ■ the coil 15 and the other parts can be provided close to one another. As a result, the device is kept smaller and more compact overall and the amount of insulating oil required is reduced, so that the temperature-related fluctuations in the insulating oil volume are counteracted and changes in the operating behavior of the return oil converter are prevented. Ba stray capacitances ^{: in} addition, can hardly occur, the voltage load capacity of the high-voltage diode 17 is not reduced, which thus has a favorable effect on the operational reliability of the high-voltage diode 17. The second embodiment also allows the terminals 21 and 22 to be constructed more simply, and the internal insulation can also be simplified. It should also be emphasized that a respiratory mechanism or the possibility of "breathing" the container can be dispensed with. While the metal containers of the conventional devices are made of paramagnetic materials such as brass or aluminum, the container used for the device according to the invention is made of epoxy resin and can therefore be manufactured easily and without major manufacturing costs.

As can be seen from the above, there is the locked Container in the oil-encapsulated return transformer arrangement made of plastic and the return flow created by the invention transformer is included in the sealed container, which gives the following advantages:

(1) Changes in oil volume cannot change that in the transformer Coil caused stray capacitance so that a normal level of ringing can be maintained.

(2) The stray capacitance caused in the diode is far less than in the case of using a metal container and the generation of heat the diode is also small. The voltage carried by the diode is kept practically at a constant value, so that the operational reliability of the diode is noticeably increased.

(3) Since the container is made of plastic, the creepage distance can of the high-voltage output connection considerably

■ -_. "^;'Ssert

209839/0837

Bert, so that the possibility of a breakdown in the High voltage circuit as a result of a flashover, etc. with complete Security is turned off.

(4) Thanks to the use of reinforced plastic as the material for the container, it has a significantly increased resistance to fatigue fracture, as could otherwise occur as a result of the bulging and bulging of the container side walls caused by changes in the oil volume, since the strength value is reduced to the 10- up to 50 times the strength of a container made entirely of a conventional plastic.

(5) Ia is the approximate coefficient of thermal expansion of the plastic The same as the one who eats oils, practically no effective change can be made Oil volumes occur which lead to an oil pressure effect on the container could lead. For this reason, the oil pressure inside the container has a better hermetic seal compared to a metal container considerably less.

In addition, it is characteristic of the invention that d & S is the ratio o / ß of the combined coefficient of thermal expansion £ for the volume of the entire internal arrangements accommodated in the closed container, including the insulating oil, to the coefficient of thermal expansion β for the fit of the closed container at a value below 2, 0 is held, so that the invention provides the following advantages

(1) The oil pressure inside the container depends on temperature changes hardly influenced, and leakage of oil or the like is therefore not to be feared, which means that a better hermetic quality Sealing is achieved.

(2) Since stray capacitance can hardly occur, the walls of the closed container, the coil and the other parts can be close to each other, so that the device can be made smaller and more compact.

(3) Since the volume of the insulating oil is hardly influenced by temperature changes the operating behavior of the fiüoklauf-

traneforma tor s

209839/0837

transformer not and the operational reliability of the high-voltage diode is also increased as a result.

(4) It enables the ports to be made simpler and eliminates the need for a respiratory mechanism, and also simplifies internal insulation. The device thus has
a simple structure and does not require a great deal of manufacturing effort.

■ ', "*' B ^V

209839/0837

Claims (6)

Claims ! .encapsulated flyback transformer arrangement, characterized by a sealed container (1; 11) made of plastic, whereby in this closed container (l * 11) a flyback transformer (5 * 13) and insulating oil (10; 23) encompassing transformer arrangement is recorded. 2. Oil-immersed flyback transformer arrangement, characterized by a closed container (l) made of plastic, wherein the side walls (2) of this container (l). from one with a fiber material Reinforced plastic are made, with a return transformer (5) and insulating oil (10) engaging in the container (1) Transformer assembly is added and wherein the container (l) respiratory activity in response to changes in oil volume can be actuated on the side walls (2). 3 Oil-encapsulated return transformer arrangement, characterized by a value below 2.0. Of the ratio <JJq of the combined coefficient of thermal expansion ü for the volume of the entire inner arrangements (5, 6, 10) accommodated in a sealed container made of plastic (lj 11) 15-20, 23) including the insulating oil (lO »23) in relation to its original volume to the coefficient of thermal expansion β for the capacity of the closed container (l» 11) in relation to its original capacity. 4. Oil-encapsulated flyback transformer arrangement according to claim 1, characterized characterized in that the insulating oil (10; 23) is silicone oil acts. 5 · Oil-immersed flyback transformer arrangement according to claim 1, characterized characterized in that the locked container (lj 11) made of epoxy resin consists. 6. oil-encapsulated flyback transformer arrangement according to claim 1, characterized characterized in that a filling material (18) is inserted between the closed container (ll) and the return transformer (13). 209839/0837 Blank page