DE3032319A1 - INDUCTIVE COUPLER - Google Patents

Description

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Inductive coupler

The invention relates to an inductive coupler a first inductive coupling part, which on a rod-shaped core center piece between core end pieces clamped first winding carries, and with a second inductive coupling part, which on the inside a hollow cylindrical support, a core center piece with one between core end pieces carries second winding, the first inductive coupling part for inductive coupling in the second inductive coupling part is pluggable.

Inductive coupling plugs for the transmission of electrical Energy is often used in environments in which metallic contact is not possible is possible. For example, inductive couplers of this type are used when the sparking occurs in an explosive atmosphere must be suppressed. Such inductive couplers are widely used Also used in underwater areas, e.g. for oil extraction in the underwater area close to the coast.

the

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The functionality of the inductive coupler is based on the transformation principle using alternating currents, i.e. by electromagnetic induction, the magnetic field of a primary winding A voltage is generated in a secondary winding without the need for mechanical contacts will. In its simplest form, such an inductive coupler consists of two C-shaped core parts, which are provided with a winding in the area of the yoke. When the end faces of the C-shaped cores are brought together are, in principle, the transformation property is given. When using suitable electrically insulating materials and anti-corrosive materials can thus make electrical Contact connection can also be established in the underwater area.

If such with their end faces opposite one another inductive couplers are used for signal or data transmission, there is an undesirable result high drop in transmission frequency response with relatively small gaps between the two coupler parts.

It. Another inductive coupler is also already known from British Patent 1,366,134 in which an outer coupler part with a winding is arranged coaxially over an inner coupler part with a winding is. The signal source is on the outer winding, which is the primary winding, whereas the load is connected to the inner winding and thus the secondary winding. If with one such a structure the inner winding on which the load is attached is withdrawn, the primary

current

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current so extreme that a termination can be used must in order to avoid burning through the primary winding. Alternatively, it has been suggested to use the primary winding to connect an auxiliary circuit, which has a large number of inductances and capacitances includes to form a tuned circuit with the primary winding. If now the secondary winding part is pulled out, this tuned circle experiences a detuning, with which the Current in the primary circuit can be reduced significantly.

It is an object of the invention to provide an improved inductive coupler of the coaxial type create, taking auxiliary circuits from discrete components can be avoided and an axial displacement of the two coupling parts against each other in remains in a limited range without significant influence on the transmission frequency response.

According to the invention, this object is achieved in that the first winding has first connecting lines (122) is connected as the primary winding, and that the second winding via second connecting lines (170) is connected as a secondary winding.

These measures of the invention are used in an inductive coupler, the two coaxially overlapping Has coupling connector, the core parts of which are aligned with one another and a magnetic Close the flow circle when plugged together. The first coupling connector includes to support the first inductive coupling part a rod on which the core end pieces and a primary winding supporting

Center piece

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Core center piece is arranged. The second coupling plug has a hollow cylindrical support, on the inner surface of which the second inductive coupling part is attached, which also consists of core end pieces and a core center piece carrying the secondary winding consists. The first coupling plug can be plugged into the second coupling plug, the two inductive coupling parts are radially opposite one another.

According to a further embodiment of the invention it is provided that the inductance L ^ of the primary winding for the plugged-together coupling plugs is greater than the inductance L for the coupling plugs that are not plugged together. The ratio L: L should not be greater than five times the ratio I ₀ : I, where I is the reflected load current and I.

L R LX

is the primary magnetizing current. The core pieces are made according to one embodiment of the invention Ferrite made.

To ensure that an axial misalignment of the two inductive coupling parts is not essential The invention provides for a further embodiment that the transmission frequency response drops the axial length of the core end pieces for the primary winding is greater than the axial length of the core end pieces for the secondary winding is.

Such an inductive coupler constructed according to the features of the invention can be used both for power transmission as well as for data and signal transmission, if for example a Data sensor is connected to one winding and a data receiver is connected to the other winding.

the

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The advantages and features of the invention also emerge from the following description of exemplary embodiments in conjunction with the claims and the drawing. Show it:
5

Fig. 1 shows an inductive coupler according to the prior art with opposite one another Coupling surfaces,

Fig. 2 transmission frequency responses for the coupler

according to Fig. 1,

3 shows another known inductive coupler

according to the state of the art, 15

4 shows a basic illustration of the coupler

according to the invention,

5 shows an equivalent circuit diagram for the primary winding of the coupler,

6 is a vector diagram for explaining the

Current ratios of the primary side of the coupler,

Fig. 7 is a section through a preferred embodiment of the invention, wherein the coupling connector are separated

8 shows a section through the preferred embodiment the invention according to FIG. 7 with

plugged together coupling plugs,

Fig. 9

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FIGS. 9 and 10 are partially cut perspective views of the coupling plugs according to FIG. 7 and 8,

11 shows the circuit diagram for a data transmission system in which a coupling plug according to FIG the invention is used,

12 shows the course of the transmission frequency response of the coupling plug in the data transmission system

according to Fig. 11,

13 shows an axial section through another embodiment of the invention. 15th

The prior art coupler 10 shown in FIG. 1 consists of two housings 12 and 13, in each of which a C-shaped core 15 or 16 is housed, which the corresponding windings 18 and 19 wears. The cores are carried by the surrounding medium, such as water during underwater use Cover plates 21 and 22 protected from stainless steel.

the

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3032313

The windings 18 and 19 are electrically connected to supply cables 24 and 25, via which the data and information exchange takes place. Such inductive couplers are extremely sensitive to the Transmission frequency response as a function of changes in the distance between the two housings 12 and 13. In FIG. 2, for example, such a transmission frequency response is recorded, the Curve 30 represents the course of the transmission frequency response for the case that there is no gap between the two housings matched to one another. In contrast, curve 31 shows a deteriorated transmission frequency response in the event that the two housings are about 0.078 cm apart. From the It can be seen from the curves that at a frequency of 100 kHz the drop is about 2 dB, but the Decay at lower frequencies increases much more strongly.

In Fig. 3, an inductive coupler 39 is shown as it is in the prior art for use in explosive Atmospheres is known. An outer cylindrical part 34 is at the two ends with inward directed flanges 35 and 36, and carries a winding 38 inside. This cylindrical part with the flanges represents the outer part of the core with which an inner part 40 of the core cooperates, wherein the flanges 35 and 36 are opposed to disc-shaped core portions 41 and 42, which through a cylindrical web 43 are connected to one another. The winding 45 is arranged on this web 43.

The inductive coupler is used to transfer power from a source 47 to a load 48 through the windings 35

38 and

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38 and 45 to transfer. The winding 38 is connected to the source and the winding 45 is connected to the load and represent the primary and secondary windings of the inductive coupler. 5

In this construction, if the inner part 40 is removed for the purpose of severing the electrical connection there is a considerable increase in the current flowing in the primary circuit, so that instead of of the withdrawn core part, a closure must be used as an alternative. Given the need the insertion of a termination, in the inductive coupler according to FIG. 3, an auxiliary circuit 50 be provided, which comprises an inductor 51 in series with a second inductor 52, the on the other hand is connected to the winding 38, and in which further a capacitance 53 from the connection point of the two inductances 51 and 52 also leads to winding 38. The inductors and the capacitance are dimensioned in such a way that when an inner part 40 is used, the primary circuit is matched to the supply frequency, and that a withdrawn inner part 40 a frequency detuning results, which significantly reduces and limits the current in the primary circuit.

The inductive coupler according to the invention is based on the type described in FIG. 3, however, neither the insertion of a termination nor the Provision of an auxiliary circuit is necessary.

The principle of power transmission with the measures according to the invention is shown in FIG. Of the 35

inductive

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inductive coupler according to FIG. 4 comprises an inner core part 60 with enlarged end sections 60 and 61, the enlargement in the axial direction corresponding to the length W and the winding 63 having a length /. A cylindrical outer core part 67 with flange-like ends 68 and 69 is arranged coaxially to the inner core part. Between these flange-like ends there is a winding 70 with a length Z ' , the flange-like ends in turn having a length W ¹ .

The unequal length of the axial end sections on the one hand and the windings on the other hand leave a limited one axial displacement of the inner and outer core parts against each other without significantly affecting the transmission properties.

The end portions of both the inner core part 60 and the outer core part 67 are magnetic River connection with each other. Means are also provided to connect the inner winding 63 to the energy source 74 and the outer winding 70 to connect a load 75. Compared to the known embodiment according to FIG. 3, this represents a reversal of the connections to the source and the burden.

A simplified equivalent circuit for the primary winding is given in FIG. 5 and comprises a parallel connection an inductance L with a resistance R. The primary current I consists of the magnetizing current

I through the inductance and the reflected load-L

current IR through the resistor R together.

FIG. 6 shows a vector diagram for the currents according to FIG. 5. The vector represents I.

the reflected load current and the vector I den

Ll

Magnetizing current

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Magnetizing current through the inductance L. The primary current I thus results from the size of the resulting Vector. In a preferred embodiment, the core parts are made of a ferrite, so that there are minimal core losses, which are therefore also not shown. With unmatched Coupler does not flow any reflective load current, so in this case the primary current is derived from the current by the inductance L, which is described in FIG. 6 with the vector I ".

The inner or primary winding 63 has a certain inductance K. in the matched state and a significantly lower inductance L deviating therefrom when there is no matching. If it is ensured that the ratio of the reflected load current to the magnetizing current I '· I is equal to the ratio

Xv LJ.

L: L, then there is no significant change in the primary current with respect to the amplitude, rather it remains essentially constant, both for the adapted and the non-adapted operation of the inductive coupler. Thus, the vector I _p according to FIG. 6 has essentially the same size for the adapted operation as the vector I _T ″ in the absence of adaptation. In an example test setup with 40 turns each for the primary winding and the secondary winding as well as a ferrite core, the inductance for the winding of the inner core part in the matched state was of the order of magnitude of 4.8 mH and in the non-matched state a value of about 360 uH. This results in a value of 13.3: 1 for the ratio LL.

In practice, this value would be 13.3: 1 slightly larger than the desired ratio of the reflected load

Stromes

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Current to the magnetizing current, and there is more Primary windings would cause an increase in copper losses, v / o through a coupler with slightly lower efficiency. Because of this, the ratio of the reflected load current is chosen for the magnetizing current so that it is of the order of 5: 1. Since this is not corresponds exactly to the ratio L: L, the current increases slightly in the decoupled state in the primary circuit namely by a factor of only 2.5 (13.3: 5 = 2.6). This. Is fully acceptable and indeed an increase in the primary current by a factor of 5, based on the primary current in the adapted state, still be fully acceptable.

The basic structure according to FIG. 4 represents the primitive form of a coaxial coupler. inductive coupler constructed according to the features of the invention is shown in FIGS. 7 to 10, on which the following description is based.

An inductive coupler 80 according to FIG. 7 comprises two coupling plugs 82 and 83, of which the coupling plug 82 is provided with the inner core part 86 and the other coupling plug 83 with the outer core part 87. An inner bracket 90 has an elongated rod 91 on which the inner core portion 86 is mounted is. For ease of manufacture, the inner core part preferably consists of three separate ferrite pieces namely the end pieces 94 and 95 and a middle piece 96 around which the primary winding 97 is placed is. The entire arrangement is held in the desired position with the aid of an end cap 104,

Which

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which is fastened to the rod 91 with the aid of a screw 105.

An outer protective sleeve 110 is screwed onto the inner holder 90 at the end 111, on which with An end cap 114 is attached by means of screws 113. Through the inner bracket 90 and the End cap 114, a free space 118 is enclosed, in which an anchoring element 120 is preferably by filling this free space with a synthetic resin such as polyurethane.

The electrical connection cable 122 is constructed as a coaxial cable and is fed through the end cap 114. The outer shield 123 and the inner conductor 124 are connected to corresponding connection elements 125 and 126, the inner conductor 124 being guided through the anchoring element 120. One end of the primary winding 97 ^ t is connected to the connection element 125 via a conductor path which runs through a groove 130 in the center piece 96 and through a groove 131 in the end piece 94 and opens into an opening 132 on the inner holder 90. The other end 97 is connected to the second connection element 126 via a corresponding path which leads via grooves 130 ¹ and 131 'and an opening 132 ¹ .

The coupling plug 83 is provided with an end cap, which with the help of screws 152 to a Plastic cylinder 154 is screwed on. This plastic The cylinder 154 has a recess 155 on the inside into which the outer core part 87 is inserted can be, being on one shoulder of the Aus-35

taking

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reception is fixed lying in the axial direction.

For easier assembly, the outer core part is also made up of three parts, namely the two end pieces 160 and 161 and a middle piece 162. This middle piece carries the winding 165, inserted between the two end pieces and 161. The outer core part 87 is made with the help of a Guide ring 16 8 held in position, which is on the front end of the plastic cylinder 154 is screwed on and has a conical and rounded front edge 169. This formation of the front edge makes it easier to insert the coupling plug into the protective sleeve 110 of the other coupling plug facilitates and at the same time an exact positioning of the outer one The core part is ensured.

A connection cable also designed as a coaxial cable 170 is connected with the outer shield 171 to a connection element 172. Of the Inner conductor 174 runs through an anchoring element 175 to the second connection element 176. The anchoring element 175 is also held in place by a molding compound 178 such as polyurethane held. One end of the winding 165 is connected to the connecting element 172 and the other end the winding is connected to the connection element 176.

To lock the coupling plugs 82 and 83, a plurality of notches 184 are in the interior of the end cap 150 provided. As can be seen from Fig. 8, the notches 184 have locking cams 185, which in a annular recess 186 on the inside of the

Protective sleeve

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Engage protective sleeve 110. They are held in this position by the spring preload of the spring 188. With this type of locking, the two coupling plugs can act on the cables 122 and 170 Tensile forces are not disengaged. A development ring is used to release the coupling connector actuated a variety of development pens 191 which extend through corresponding openings in the end cap 150. These development pens 191 each have a locking notch 195, which push the locking cams back when the development ring 190 is pulled off, so that they come out of engagement with the circumferential recess 186. In this position the two coupling plugs can be separated. The removal of the unlocking ring 190 is made possible by end stops 197 limited at the front end of the development pins 191. In the completely withdrawn In the position of the unlocking ring, the notches 184 are pushed back against the pressure of the spring 188 so that that the two coupling plugs can be re-engaged with one another without difficulty can.

When the unlocking ring 190 is moved forward in the withdrawn state of the coupling plug, engages the catch 184 into the catch notch 195 of the associated unlocking pin 191. Even in this condition the two coupling plugs can be plugged into each other and locked together, as one on the The inclined surface 200 attached to the front edge of the protective sleeve 110 moves the locking cams 185 back and allows the two coupling plugs to be plugged into one another.

if

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If the coupling plugs are used underwater, there is a possibility that foreign bodies will get inside of the disconnected coupling plug. It can be mud, sand or algae, etc. Precautions are therefore taken to ensure that the surfaces of the cooperating clamping parts are wiped off can be. For this purpose, on the one hand, between the plastic cylinder 154 and the guide ring 168 an annular disk 204 and on the other hand an annular disk 206 between the rod 91 and the end cap 104 be used. These ring disks are preferably made of a resilient, rubber-like material Material made as it is known for this purpose. Because the washer 204 on the inner surface the protective sleeve 110 comes into engagement during insertion and lies against it in a sealing manner, are also Openings 210 and 211 are provided in the protective sleeve to remove the water in the coupling plug when Put together to let out. A hole is correspondingly made in the plastic cylinder 154.

In

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In Fig. 11 is an application for the inductive Coupler according to the invention shown. It is about the transmission of information between two different places. A television camera 240 is used as the information source, from which the recorded signals are to be transmitted to a monitor 241 at a remote location. In addition Cables 243 and 244 are used, which are connected to one another with the aid of an inductive coupler 245 according to FIGS. 7 to 10 are connected.

The coupling of the television signals to the inductive coupler 245 takes place via an emitter follower circuit 250, the output impedance of which is very small and, for example, less than 10 ohms. In the event of information transfer it does not matter whether the inner winding or the outer winding of the coupler as Primary winding is used. When the coupler on the output side via a conventional coaxial cable is equipped with a wave impedance of 50 ohms, there is a constant equalizing resistance at the end of the cable 252 is provided, which is used to increase the signal for high frequencies. This balancing resistor This is followed by an amplifier stage 254 and a compensation circuit 256 for low frequencies.

Finally, the signal is fed into amplifier stages 258 and 260 further amplified, and with the aid of a feedback arrangement in amplifier 260 an additional one To effect frequency compensation for high frequencies. The signal processed in this way is then brought to the display on the monitor 241.

In the transmission frequency response shown in FIG. 12, the dashed curve 264 identifies the Fre-35

quenzgang

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quenzgang in the event that the television signal is applied directly to the monitor via the inductive coupler will. It can be seen from the diagram that there is a strong drop below about 500 Hz and above sets about 2 MHz. For high quality television pictures, however, video frequencies of about 60 Hz to at least about 3 MHz are required for transmission. The solid curve 265 characterizes a transmission frequency response via a circuit arrangement according to FIG. 11, in which both the low and high frequencies experience an increase in order to achieve the desired transmission frequency response to reach.

13 is another embodiment of the invention shown, in which with the help of coaxial inductive couplers a variety of circuits to each other can be coupled or uncoupled from each other. This inductive coupler includes a Piston 270, which at one end with a first inductive coupling part 272 and next to it with a second inductive coupling part 273 is provided. The two coupling parts 272 and 273 are both magnetic as well as being electrically isolated from one another by inserting a plastic insert 274 in between. Of the The first coupling part is provided with the winding 276 and the second coupling part with the winding 277.

In a corresponding manner are in an external mounting element, which is the housing 287 of a device can be, further inductive coupling parts 280 and 281 are provided next to one another, these Coupling parts are in turn magnetically and electrically separated from one another by insulation 285. These 35

outer

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outer third and fourth inductive coupling parts have windings 282 and 283.

The outer coupling parts are arranged on the inner surface of a bore in the housing 287 into which the piston 270 can be used. This piston 270 has on its opposite the inductive couplers Side a stop shoulder 292, which ensures that when the piston 270 is inserted, the position of the inductive Coupling parts corresponds to the optimal position radially to one another.

The embodiment shown in Fig. 13 is for the transmission of power from a plurality of power sources when appropriately applied to a variety of loads target. In the same way, this embodiment can also be used to transmit information and data serve, indefe the primary winding of the inductive coupler with sensors and the secondary winding of the inductive coupler is correspondingly connected to evaluation instruments. Of course you can With such a structure, one inductive coupler for the power transmission and the other also inductive couplers can be provided for data or signal transmission.

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Claims (5)

Claims O Inductive coupler with a first inductive coupling part which carries a first winding clamped between core end pieces on a rod-shaped core center piece and with a second inductive coupling part which carries a core center piece with a second winding located between core end pieces on the inside of a hollow cylindrical support, the first being inductive Coupling part for coupling can be plugged into the second inductive coupling part,
characterized, - That the first winding (63) is connected as a primary winding via first connecting lines (122) is, - And that the second winding (70) is connected as a secondary winding via second connecting lines (170) is. 20th 130013/1276 - 2 - WS217P-2156 2. Inductive coupler according to claim 1, characterized in that - That the primary winding (63) has a first inductance L in the assembled state of the coupling parts and has a second lower inductance L when the coupling parts are disconnected, - and that the inductive coupler is constructed in such a way that the ratio L ,,: L "is less than the five- M U times the ratio I: I, where I is the K Ll K current reflected by the load and I the magnetizing current the primary winding is. 3. Inductive coupler according to claim 2, characterized in that the ratio I: I am about 5. R Ll 4. Inductive coupler according to one of claims 1 to 3, characterized in that ferrite is used to adjust the ratios of the inductances and the currents for the core material will. 5. Inductive coupler according to one or more of claims 1 to 4, characterized in that the axial length (W, W ¹ ) of the core end pieces used for setting the ratio of inductances and currents for the primary circuit is different from the length for the secondary circuit is. 130013/1276