JP2002198238A - Power/signal transmitter for rotary connection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power/signal transmitter for rotary connection, that can surely perform both power supply and two-way high-speed large-capacity signal transmission, can be simplified in structure, reduced in size, and assembled and adjusted easily. SOLUTION: This power/signal transmitter transmits electric power and signals at a rotary connection. This transmitter is provided with first and second cores 10 and 12, which are made of annular ferromagnetic bodies and arranged in such a way that the cores 10 and 12 face each other, with a clearance in between so as to be allowed to make revolving motions relative to each other, about their center axes, first and second coils 14 and 16 respectively incorporated in the cores 10 and 12 so that the coils 14 and 16 face each other, and electrodes 18 and 20 respectively provided on the facing faces of the cores 10 and 12. Consequently, the transmitter transmits electric power by utilizing the electromagnetic induction between the coils 14 and 16 and bidirectionally transmits signals, by utilizing the capacitive coupling between the electrodes 18 and 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for transmitting electric power and a signal at a rotary connection, and more particularly to a device in which a coil is incorporated into a pair of cores which are opposed to each other through a gap and are relatively rotatable. Provide electrodes on the opposite surface,
The present invention relates to a power / signal transmission device of a rotary connection unit that transmits power by electromagnetic coupling between coils and transmits a signal by capacitive coupling between electrodes. This device is not particularly limited, but is useful for, for example, power supply and bidirectional signal transmission between the vehicle body side and the steering side of the self-propelled vehicle.

[0002]

2. Description of the Related Art In recent years, along with the sophistication of self-propelled vehicles such as automobiles or the differentiation from other types of vehicles, various types of steering systems (steering-side (rotating-side) and body-side (fixed-side) have been used. Information is being transmitted. Therefore, various electronic circuits, display devices, and the like have been mounted on the steering side, and electric power for their operation has to be supplied from the vehicle body side to the steering side via the rotary connection portion. In addition, the amount of information transmission increases as the functions become higher and more multi-functional, and there is a demand for high-speed signal transmission and high response performance. For example, an airbag is installed on a steering side and is controlled from a vehicle body side, but is required to operate quickly and reliably at an appropriate timing.

In such a rotary connection, various systems have been developed and used as techniques for transmitting power and signals. In the past, slip rings have been used, but there is a problem of low reliability due to sliding wear and the like, and at present, use of flexible leads is common. However, the direct connection structure using flexible leads is difficult to cope with multiple rotations due to problems such as lead routing and storage, and especially in the case of multi-channel signals, a wide lead is required and miniaturization is required. There are also problems such as difficulty.

In recent years, there has been proposed a method of supplying power by electromagnetic induction using a rotary transformer having a structure in which a coil is incorporated in a pair of magnetic cores which are opposed to each other via a gap and are relatively rotatable. ing. In the power supply by such a rotary transformer, it is desirable to use a rectangular wave drive switching type for high efficiency and to increase the frequency for miniaturization. However, as the frequency increases, core loss (hysteresis loss and eddy Current loss, etc.), a frequency of about several hundred kHz is currently optimal. With a low-speed and small-capacity signal, it is possible to transmit the power transmission waveform by amplitude-modulating the power transmission waveform using the rotary transformer.

However, in high-speed, large-capacity signal transmission, demodulation is difficult even if a signal is applied in the amplitude direction. The reason for this is that the required level of stability and noise immunity generally differ greatly between the power supply level and the signal level. Therefore, the switching waveform for power supply is frequency-modulated or phase-modulated according to the signal, and is demodulated on the secondary side to obtain a signal. A scheme that is also used for signal transmission has been proposed.

[0006]

Generally, in order to modulate with a plurality of high-speed signals, it is necessary to set a higher switching frequency.
The ratio (signal to noise ratio) is improved. On the other hand, it is preferable that the frequency deviation is small in order to ensure the stability of power supply. As described above, there is a conflicting relationship with respect to the frequency deviation, and there is a limit in simultaneously improving the performances of both power transmission and high-speed / large-capacity signal transmission.

Therefore, a system has been proposed in which power is supplied by electromagnetic induction and signal transmission is performed by capacitive coupling (Japanese Patent Laid-Open No. 5-2 / 1993).
01337). Here, a double-cylindrical facing surface is formed on the outer peripheral side of the core pair that performs electromagnetic induction to form a capacitor capacitance, and a coaxial parallel plate-shaped coaxial outer side away from the core pair that performs electromagnetic induction. A configuration in which a facing surface is formed to form a capacitor capacitance is disclosed.

However, as described above, these parts have a portion for forming a capacitor capacitance separately from the pair of cores, so that the structure becomes complicated, the size becomes large, and the portions facing each other with a small gap therebetween are provided. , The assembly and adjustment are complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to ensure reliable power supply and bidirectional high-speed and large-capacity signal transmission, simplify the structure, reduce the size, and easily assemble and adjust the power of the rotary connection. -To provide a signal transmission device.

[0010]

SUMMARY OF THE INVENTION The present invention is an apparatus for transmitting power and signals at a rotary connection, comprising annular ferromagnetic material, opposed to each other through a gap and relatively about a central axis. First and second cores arranged so as to allow a proper rotation operation, first and second coils incorporated in both cores so as to have an opposing positional relationship, and on the opposing surfaces of both cores, respectively. Provided electrodes. The power is
Transmission is performed by electromagnetic induction between coils whose coupling degree is magnetically enhanced by a ferromagnetic core. On the other hand, signals are transmitted bidirectionally by capacitive coupling of electrodes provided on the opposing surfaces of the cores and forming capacitors. Therefore, the device of the present invention is not suitable for high-speed and large-capacity information transmission, since the DC component cannot be transmitted, but can be transmitted more easily as the frequency becomes higher.

In order to enhance the electromagnetic coupling and the capacitive coupling, it is necessary to reduce the gap between the core opposing surfaces as far as the accuracy such as the play of the bearing or the eccentricity of the opposing surfaces is allowed. In this regard, in the device of the present invention, the opposing surface is only one location between the cores, so that assembly and adjustment are easy.

In the present invention, it is preferable that the electrode provided on the core-facing surface is a conductor pattern that is discontinuous (cut) in at least one place without making one round around the central axis. This is because, if the electrodes are continuously arranged on the entire surface, the electrodes operate as a one-turn short ring, so that power transmission loss occurs. If not closed around the rotation axis, no circulating current flows and no loss occurs. Therefore, it is preferable to provide a slight slit-shaped insulating portion that does not affect the facing area.

The first core and the second core have a specific resistance of 1
0 ⁴ Ω · cm equal to or greater than about ferrite material (for example, Ni-Zn
In the case of using a ferrite, an electrode can be formed by directly attaching a conductor layer to the core surface. For the formation of the conductor layer, a thin film forming method such as sputtering or vapor deposition or a plating method can be used. A desired pattern can be formed by selectively forming a conductor layer using a metal mask or the like, or a desired pattern can be formed by physical / chemical etching after forming a conductor layer on the entire surface. . In addition, there are a method of applying a conductive paint by screen printing or the like, or applying a mask, and a method of bonding a patterned metal foil.

When the first core and the second core are made of a magnetic material having a low specific resistance, an insulating layer is provided on the surface of the core, and an electrode is formed by attaching a conductive layer on the insulating layer. . Of course, the configuration is also applicable to a case where the magnetic material has a high specific resistance. As in the case of the formation of the conductor layer, a method such as sputtering, application of an insulating paint, and adhesion of an insulating film can be used for forming the insulating layer.

The electrodes used in the apparatus of the present invention are, in particular,
Preferred is a patterned metal foil adhered to an insulating film. For example, an electrode in which a metal foil is pasted on the entire surface of a thin plastic film in advance is masked and chemically etched to pattern only the metal foil to form an electrode. By attaching the surface of the insulating film to the core facing surface, an electrode insulated from the core is obtained.

In the present invention, the opposing surfaces of the first and second cores may be planes perpendicular to the rotation axis or cylindrical surfaces parallel to the rotation axis. The surface may be a truncated conical surface that is inclined with respect to the surface. The use of the inclined frustoconical surface has the advantage that the area of the core-facing surface can be increased and the capacitance of the capacitor can be increased.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view showing an embodiment of a power / signal transmission device of a rotary connection portion according to the present invention, wherein A is an external appearance in a separated state, B is a longitudinal section, and C is a core The facing surfaces are shown respectively. The present device includes a first core 10 and a second core 10 which are formed of an annular ferromagnetic material, are opposed to each other via a gap, and are arranged so as to allow a relative rotation operation about a central axis oo. The first coil 14 and the second coil 14 incorporated in both cores so as to have a positional relationship facing each other with the core 12.
And the electrodes 18 and 20 formed on the opposing surfaces of both cores, respectively. For example, when incorporated into a steering device of a self-propelled vehicle, one (eg, first core 10) is installed on the vehicle body side (fixed side), and the other (eg, second core 12) is installed on the steering side (rotation side). .

Electric power is transmitted by electromagnetic induction between the first and second coils 14 and 16 whose magnetic coupling is enhanced by the first and second cores 10 and 12 made of ferromagnetic material. On the other hand, the signal is transmitted bidirectionally by capacitive coupling between the electrodes 18 and 20 provided on the opposing surfaces of the cores and forming a capacitor.

The first core 10 and the second core 12 are made of, for example, a soft magnetic ferrite material such as a Ni—Zn system.
It has substantially the same shape with a substantially flat ring shape and a substantially U-shaped cross section in the radial direction, whereby a ring-shaped groove 22 is formed on the core facing surface. First core 10 and second core
The first coil 14 and the second coil 16, which have been wound in a ring a predetermined number of times in advance, are embedded in the respective grooves 22 of the core 12. Here, it is preferable that both coils have a structure of being solidified with resin.

Electrodes 18 and 20 are formed on the core facing surfaces of the first core 10 and the second core 12 (the inner and outer peripheral planes excluding the groove 22). These electrodes 18 and 20 are formed of a conductor pattern that is discontinuous at at least one location without making one round around the central axis oo. The discontinuous portion 24 is a slit-shaped non-conductive portion that has little effect on the facing area. Although one location is provided in the example of FIG. 1, a plurality of locations may be provided, and it is not necessary that the outer peripheral side and the inner peripheral side have the same position. In FIG. 1A, the conductor pattern is hatched for clarity of the electrode shape. Since the conductor pattern is not closed around the rotation axis, no circulating current flows and no loss occurs.

The first core 10 and the second core 12 are N
In the case of a material having a specific resistance of about 10 ⁴ Ω · cm or more such as i-Zn ferrite, an electrode can be formed by directly attaching a conductor layer to the core surface by sputtering or vapor deposition.
A desired conductor pattern is obtained by selectively forming the conductor pattern using a metal mask or by chemically etching after forming a conductor layer on the entire surface. In addition, a method of applying a conductive paint by screen printing or masking, drying, or baking may be used.

When the first and second cores are made of a magnetic material having a low specific resistance, an insulating layer is provided on the core surface, and electrodes are formed on the insulating layer in the same manner as described above. Of course, this method can also be applied when the first and second cores are made of a magnetic material having a high specific resistance.

FIG. 2 is a longitudinal sectional view showing another embodiment of the present invention. The present device also includes a first core 30 and a second core 32 which are made of an annular ferromagnetic material, are opposed to each other through a gap, and are arranged so as to allow relative rotation about a central axis. A first coil 34 and a second coil 36 incorporated in both cores 30 and 32 so as to have a mutually opposing positional relationship, and electrodes formed on opposing surfaces of both cores.

The first core 30 and the second core 32 are combined so that they have a substantially L-shaped cross section in the radial direction, and have a small gap therebetween. Therefore, the core facing surface (reference numeral 3)
7) is a cylindrical surface parallel to the rotation axis oo. The coils 34, 36 are mounted on the L-shaped corners of both cores 30, 32. An electrode is provided on the core facing surface 37 in the same manner as described above. This structure is effective in such an installation situation, even if the dimension in the radial direction is short, if the dimension in the axial direction can be increased, the core facing surface can be widened and the required capacity can be obtained.

FIG. 3 is a longitudinal sectional view showing still another embodiment of the present invention. This device is also basically the same as each of the above embodiments, and is made of an annular ferromagnetic material so that they oppose each other via a gap and allow relative rotation about the central axis. First core 40 and second core 42 arranged
, A first coil 44 and a second coil 46 incorporated in both cores so as to be opposed to each other, and electrodes formed on the opposing surfaces of both cores.

In this example, the core facing surfaces 47 of the first core 40 and the second core 42 are inclined with respect to the rotation axis oo (a truncated conical surface and an inverted truncated conical surface). It is. When viewed in a radial cross section, there is a step-shaped recess at the center (this recess is formed in a circumferential shape), and the coils 44 and 46 are mounted in the recess. An electrode is provided on the core facing surface 37 in the same manner as described above. In this structure, when the dimensions in both the radial direction and the axial direction can be secured to some extent, the slope makes the core-facing surface wider, and the required capacity can be secured.

FIG. 4 is an exploded perspective view of another embodiment of the present invention. The first and second cores and coils may be the same as those in FIG.
Parts are given the same reference numerals. The electrode 50 is an insulating film 52
Consists of a patterned metal foil 54 adhered thereon. A thin plastic insulating film, such as a flexible printed circuit sheet, in which a metal foil is previously adhered to the entire surface, is selectively removed by chemical etching to remove an excess portion and pattern only the metal foil. And FIG.
As shown in (B), an insulated electrode is obtained by attaching the surface of the insulating film 52 to the core facing surface using an adhesive. According to this method, electrodes can be formed on the entire core facing surface (including on the embedded coil). In addition, there are advantages such as easy handling, irrespective of the core material (irrespective of the specific resistance value), and a wide electrode area.

Here, as shown in FIG. 5A, a large number of slit-like electrodeless portions 56 extending in the radial direction are formed alternately from the outer peripheral edge to the inner peripheral side, and conversely, from the inner peripheral edge to the outer peripheral side. . A slit-shaped discontinuous portion (insulating portion) 58 from which the metal foil is completely cut off at only one location is formed. With such a pattern, the flow of the current circulating around the central axis is obstructed, which is effective in reducing the loss. In addition, since only one connection between the electrode and the external circuit is required, the connection work becomes easy.

FIG. 6 shows a circuit example of power transmission and signal transmission using the device of the present invention. The power transmission is performed using an AC waveform (rectangular waveform) generated by the fixed-side oscillation circuit 60.
Is amplified by the power amplifying circuit 61 and an alternating current flows through the primary coil. A magnetic flux proportional to this current is guided to the secondary side by the core, and an electromotive force corresponding to the change of the magnetic flux is induced in the secondary coil on the rotating side, and this is returned to DC by the rectifying and smoothing circuit.
The part of the transformer T including the primary coil, the core, and the secondary coil is configured by a part of the device of the present invention.

In signal transmission, a plurality of signals are converted into serial signals by a multiplexer circuit 70 and an encoder circuit 71 to drive an amplifier 72, and are transmitted from one to the other by capacitive coupling between electrodes. Is amplified to a predetermined signal level by the signal amplifier 73 so as to complement the above, and a plurality of signals are reproduced by the decoder circuit 74 and the demultiplexer circuit 75. By installing two sets of the same circuit configuration, it is possible to transmit signals bidirectionally on the fixed side and the rotating side. The part of the capacitor C by the electrode
It is constituted by the device of the present invention. As shown in FIGS. 1 to 3, when two pairs of electrodes are provided, one electrode pair is used for signal transmission from the fixed side to the rotation side, and the other electrode pair is used for transmission from the fixed side to the rotation side. For signal transmission. Alternatively, they may be connected in common to form a pair of electrodes. At that time, by changing the frequency or sending signals at different timing in time division,
It is possible to multiplex. The electric power for driving the circuit on the rotating side can be supplied from the fixed side in the manner described above. Therefore, power transmission and bidirectional signal transmission can be performed while freely rotating between members that relatively rotate about the rotation axis.

Although the preferred embodiment of the present invention has been described in detail above, it is needless to say that the present invention is not limited to this configuration. The shape of the core, the shape of the core-facing surface, the installation state of the coil, the shape of the electrode, and the like may be appropriately changed depending on the use state and the like. One core and the other core are used in a state where relative rotation is possible, and can be installed not only when one is fixed, but also when both are fixed or both are rotated.

When the device of the present invention is applied to a steering device of an automobile, bidirectional signal transmission is possible while maintaining the degree of freedom of steering rotation, and in particular, airbag signals and shifts requiring quick response are required. Since the transmission of signals and the like is transmitted by a high frequency carrier wave by capacitive coupling, it is possible to easily satisfy the required performance. Since a carrier wave having a high frequency can be used, a large amount of information can be transmitted in addition to quick response, and for example, various information can be displayed by installing a liquid crystal display or the like on a steering wheel. For example, in the case of an airbag device, a large-capacity capacitor for an airbag is incorporated on the steering side, the power transmitted by electromagnetic coupling between the coils is charged in the large-capacity capacitor, and the electric power is transmitted by capacitive coupling between the electrodes. If the airbag is configured to be discharged by the trigger signal, the airbag can be reliably operated at a predetermined timing.

As another example, if the present invention is applied to a contactless charging connector of an electric vehicle or the like, it is not limited to simply supplying charging power. It is also possible to perform charging, and also to quickly acquire various information (for example, sensor information of each part of the vehicle, tachograph information, etc.) stored in the vehicle itself at the time of charging and use the information as maintenance information.

[0034]

Since the present invention is a power / signal transmission device of a rotary connection part configured as described above, power supply and bidirectional high-speed / large-capacity signal transmission can be reliably performed, and the structure is simplified. It is easy to assemble and adjust, and has high reliability because there is no noise or sliding wear as in the case of mechanical connection. Further, since a high-frequency carrier wave can be used for signal transmission due to capacitive coupling, responsiveness is very good, and a large amount of information can be transmitted.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a power / signal transmission device of a rotary connection unit according to the present invention.

FIG. 2 is a longitudinal sectional view showing another embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing still another embodiment of the present invention.

FIG. 4 is an exploded perspective view showing another embodiment of the present invention.

FIG. 5 is an explanatory view of the electrode shape and the core mounting state.

FIG. 6 is an explanatory diagram of a circuit example of power transmission and signal transmission using the device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 1st core 12 2nd core 14 1st coil 16 2nd coil 18, 20 Electrode

Claims (5)

[Claims] 1. A device for transmitting power and a signal at a rotary connection part, comprising a ring-shaped ferromagnetic material, opposed to each other via a gap, and allowing relative rotation about a central axis. The first and second cores arranged in the first and second cores, the first and second coils incorporated in the two cores such that the first and second coils have an opposing positional relationship, and electrodes provided on the opposing surfaces of the two cores, Power is transmitted by electromagnetic induction between
A power / signal transmission device for a rotary connection, wherein a signal is transmitted by capacitive coupling between both electrodes. 2. The power / signal transmission of a rotary connection according to claim 1, wherein the electrode provided on the core facing surface is made of a conductor pattern that is discontinuous at least at one position without making a circuit around the central axis. apparatus. 3. The first and second cores have a specific resistance of 10 ^4.
3. The power / signal transmission device for a rotary connection according to claim 1, wherein the electrode is formed of a conductor layer directly formed on the surface of the core. 4. The power / signal transmission of a rotary connection according to claim 2, wherein the electrode is made of a patterned metal foil adhered to an insulating film, and the insulating film is attached to a surface facing the core. apparatus. 5. The power / signal transmission of the rotary connection according to claim 1, wherein the opposing surfaces of the first and second cores are frustoconical surfaces inclined with respect to the rotation axis. apparatus.