JP5384202B2 - X-ray CT system - Google Patents

Description

  The present invention relates to an X-ray CT apparatus, and more particularly to a technique for performing non-contact power transmission between a gantry fixing part and a rotating part.

  An X-ray CT apparatus is used for diagnosis by reconstructing and displaying a tomographic image of a subject based on X-ray projection data at various angles acquired by irradiating the subject with X-rays. It is. Many X-ray CT apparatuses include an X-ray tube that irradiates the subject with X-rays, an X-ray detector that is disposed opposite to the X-ray tube and acquires X-ray projection data, the X-ray tube, and the X-ray tube A line detector is mounted, and a rotating unit that rotates around the subject is provided. In order to drive the X-ray tube and the X-ray detector mounted on the rotating unit, it is necessary to supply power to the rotating unit from a gantry fixing unit that rotatably supports the rotating unit.

  In many X-ray CT apparatuses, a slip ring is used to supply power from a gantry fixing unit that rotatably supports the rotating unit to the rotating unit. However, since the slip ring rotates the rotating part while bringing the metal ring and the metal brush into contact with each other, wear powder is generated due to wear of the metal ring and the metal brush, and maintenance work such as removal of the wear powder is required. Therefore, Patent Document 1 discloses an X-ray CT apparatus including a power transmission unit that transmits power in a non-contact manner by using electromagnetic induction as a power transmission unit instead of a slip ring.

  The power transmission unit disclosed in Patent Document 1 includes a fixed-side winding wound around a gantry fixing unit, a fixed-side iron core disposed in the vicinity of the fixed-side winding, and a rotation wound around a rotating unit. It has the structure which has a side winding and the rotation side iron core arrange | positioned in the vicinity of the said rotation side winding.

Japanese Patent Laid-Open No. 7-204192

  With the shortening of imaging time using X-ray CT devices and the increase in size of X-ray detectors, the output of X-ray tube devices has been increasing, and the power consumed by X-ray tube devices has also increased. doing. Furthermore, there has been a demand for further shortening of the photographing time by increasing the rotation speed of the rotating part. In addition to reducing the weight of the rotating part body, the power transmission part for supplying power to the rotating part is also reduced in size and weight. Therefore, there is a demand for higher output.

  However, in order to reduce the size and increase the output of the power transmission unit that transmits power in a non-contact manner, it is necessary to apply a current of about 20 to 100 A with a frequency of about 20 kHz to 100 kHz to the fixed side winding and the rotation side winding. . In addition, it is necessary to provide a gap in the non-contact power transmission unit, and the alternating magnetic flux φ leaks from the gap, and the leakage flux interlinks the fixed-side winding and the rotation-side winding to generate an eddy current in the winding. Generated power loss (copper loss). Furthermore, the skin effect (a phenomenon in which current flows only on the surface of the conductor) accompanying the increase in the frequency significantly increases the AC resistance in the windings, resulting in a large copper loss. Since this copper loss reaches several kW and hinders improvement in power transmission efficiency of the X-ray CT apparatus, it is desired to reduce the copper loss.

  The present invention has been made in view of these problems, and an object of the present invention is to reduce the copper loss of the fixed-side winding and the rotating-side winding when power is transmitted in a non-contact manner by using electromagnetic induction. An object of the present invention is to provide an X-ray CT apparatus capable of performing the above.

In order to solve the above problem, the rotating part imaging mechanism consisting of the X-ray source and the X-ray detector is rotated around the subject, a gantry for rotatably supporting the rotating portion, said from the gantry An X-ray CT apparatus including a power transmission unit that transmits power to a rotation unit, wherein the power transmission unit includes an annular fixed-side winding unit disposed on the gantry side, and a rotation unit. while it is arranged, and a rotary side coil portion of the annular disposed opposite to the fixed-side winding part, the fixed-side winding part and the rotating winding part comprises a sheet winding X-ray CT apparatus.

  ADVANTAGE OF THE INVENTION According to this invention, the copper loss of the fixed side coil | winding and rotation side coil | winding at the time of transmitting electric power by non-contact by electromagnetic induction can be reduced.

1 is an overall configuration block diagram of an X-ray CT apparatus according to a first embodiment to which the present invention is applied. It is a figure for demonstrating the structure of the electric power transmission part of Embodiment 1 of this invention. It is a figure for demonstrating the structure of the sheet | seat winding of Embodiment 1 of this invention. It is a figure which shows the relationship between the frequency of a copper wire, and skin depth. It is a figure for demonstrating the eddy current in the electric power transmission part of Embodiment 1 of this invention. It is a chart figure for eddy current and eddy current loss calculation. It is a figure of the conditions of sheet winding applicable to the electric power transmission part of Embodiment 1 of the present invention. It is a figure which shows the simulation conditions of the electric power transmission part in the X-ray CT apparatus of Embodiment 1 of this invention. It is a figure which shows the result of the simulation about the eddy current loss in the electric power transmission part of Embodiment 1 of this invention. It is a figure which shows the result of the simulation about the eddy current loss in the electric power transmission part of Embodiment 1 of this invention. It is a figure for demonstrating schematic structure of the electric power transmission part in the X-ray CT apparatus of Embodiment 2 of this invention. It is a figure for demonstrating schematic structure of the electric power transmission part in the X-ray CT apparatus of Embodiment 3 of this invention. It is a whole block diagram of the X-ray CT apparatus of Embodiment 4 of this invention. It is a figure for demonstrating schematic structure of the electric power transmission part in the X-ray CT apparatus of Embodiment 4 of this invention.

  Hereinafter, an example of an embodiment to which the present invention is applied will be described with reference to the drawings. However, in the following description, the same components are denoted by the same reference numerals, and repeated description is omitted.

<Embodiment 1>
(overall structure)
FIG. 1 is an overall configuration block diagram of an X-ray CT apparatus according to a first embodiment to which the present invention is applied. The X-ray CT apparatus of Embodiment 1 irradiates the subject 105 with X-rays from various angles, measures the distribution of the X-ray dose transmitted through the subject 105, and reconstructs the subject 105 reconstructed based on the measurement result. A tomographic image is displayed. The X-ray CT apparatus of the present embodiment is divided into a fixed side and a rotating side. The fixed side includes a gantry fixing unit 100 and a console 300. The rotating side includes a rotating unit 200. Yes. The rotating part 200 is supported rotatably with respect to the gantry fixing part 100.

  The gantry fixing unit 100 includes a power supply 30 and an inverter 34. The rotating unit 200 includes a high voltage transformer 37, a high voltage rectifier 38, an X-ray tube 39, and an X-ray detection unit 40. Between the gantry fixing unit 100 and the rotating unit 200, there are a power transmission unit 102 and non-contact signal transmitting means 108 for transmitting electric power from the gantry fixing unit 100 to the rotating unit 200. The console 300 includes an image processing device 46 and an image display device 47.

  The power supply 30 generates a DC voltage, and includes a commercial AC power supply 31, a converter 32 that converts the voltage of the AC power supply 31 into a desired DC voltage, and a smoothing capacitor 33 that smoothes the output voltage of the converter 32. ing. The inverter 34 converts the DC voltage output from the converter 32 into a high-frequency AC voltage. The output of the inverter 34 is transmitted to the rotating unit 200 by the power transmission unit 102 and input to the high voltage transformer 37. The high voltage transformer 37 boosts the input AC voltage. The high voltage rectifier 38 rectifies the output voltage of the high voltage transformer 37 and converts it into a direct high voltage.

  The X-ray tube 39 irradiates the subject 105 with X-rays by being supplied with the DC voltage output from the high voltage rectifier 38. X-rays that have passed through the subject 105 enter the X-ray detection unit 40. The X-ray detection unit 40 detects X-rays transmitted through the subject 105 and amplifies the detected signal. The X-ray detection unit 40 is disposed to face the X-ray tube 39 and detects a dose distribution of transmitted X-rays. 42 and a preamplifier 43 for amplifying the detection signal from the detector 42. X-ray irradiation and detection are performed while the X-ray tube 39 and the X-ray detection unit 40 provided in the rotation unit 200 rotate, so that transmission X at various angles (360 ° around the subject 105) is transmitted. Dose distribution can be measured.

  The non-contact signal transmission means 108 transmits the detection signal of the X-ray detection unit 40 from the rotation unit 200 to the gantry fixing unit 100, and includes a rotation-side transmission device 107 and a fixed-side reception device 106. The detection signal received by the fixed receiving device 106 is transmitted to the image processing device 46. The image processing device 46 generates a tomographic image of the subject 105 by reconstructing the transmitted detection signal. The image display device 47 displays a tomographic image or the like generated by the image processing device 46, and is a known television monitor, for example.

  The power transmission unit 102 includes a fixed-side winding 2 disposed on the gantry fixing unit 100 and a rotation-side winding 4 disposed on the rotating unit 200. The fixed side winding 2 is connected to an inverter 34, and the rotation side winding 4 is connected to a high voltage transformer 37. The rotation side winding 4 is arranged in the vicinity of the fixed side winding 2. With this arrangement, when an alternating current flows through the fixed-side winding 2, an alternating magnetic flux φ is generated around the fixed-side winding, and the rotating-side winding 4 interlinking with the alternating magnetic flux φ is subjected to electromagnetic induction. This is a so-called rotary transformer configuration in which voltage is induced and electric power is transmitted. A detailed configuration of the power transmission unit 102 will be described below.

(Power transmission unit configuration)
FIG. 2 is a diagram for explaining the configuration of the power transmission unit according to the first embodiment of the present invention, and FIG. 3 is a diagram for explaining the configuration of the sheet winding according to the first embodiment of the present invention. In particular, FIG. 2A is a bird's-eye view of the power transmission unit 102 viewed from the rotation axis direction of the rotation unit 200, and FIG. 2B is a cross-sectional view taken along the line AA in FIG. It is sectional drawing. 3A is a cross-sectional view of the sheet winding shown in FIG. 2B, and FIG. 3B is a configuration diagram of the sheet winding of the first embodiment. However, in the following description, the case where the sheet winding forming the fixed side winding 2 and the rotation side winding 4 is formed of copper will be described, but the material of the sheet winding is not limited to copper, Other conductive materials may be used. However, when a material other than copper is used for the sheet winding, a conductive material having a resistivity ρ = 2.65 × 10 ⁻⁸ (Ω · m) or less of aluminum is preferable.

  The rotating side of the power transmission unit 102 rotates in the direction of the arc 201 shown in FIG. The power transmission unit 102 according to the present embodiment includes a fixed-side iron core 1 and a rotating-side iron core 3 in addition to the fixed-side winding 2 and the rotating-side winding 4 described above.

  The fixed-side winding 2 is arranged in the gantry fixing part 100, the rotation-side winding 4 is arranged in the rotating part 200, and in order to allow the rotating part 200 to rotate smoothly with respect to the gantry fixing part 100, the fixed-side winding A gap 5 is formed between the wire 2 and the rotation side winding 4. The fixed-side iron core 1 and the rotary-side iron core 3 are arranged in the vicinity of the fixed-side winding 2 and the rotating-side winding 4, respectively, and are fixed so that the rotating part 200 can rotate smoothly with respect to the gantry fixing part 100. A gap 6 is formed between the side iron core 1 and the rotation side iron core 3. An insulating sheet 7 is provided between the turns of the fixed winding 2 and between the fixed winding 2 and the fixed iron core 1. An insulating sheet 7 is also provided between the turns of the rotation side winding 4 and between the rotation side winding 4 and the rotation side iron core 3.

The fixed-side winding 2 and the rotation-side winding 4 are sheet windings, and are disposed horizontally in the grooves of the fixed-side iron core 1 and the rotation-side iron core 3. By using the sheet winding can reduce the eddy current loss W _e generated by the leakage magnetic flux phi _a of the gap 5 and a gap 6, it is possible to reduce copper loss in the winding.

  That is, as shown in FIG. 2A, in the power transmission unit 102 according to the first embodiment, a pair of fixed-side iron core 1 and rotating-side iron core 3 having a flat annular shape are opposed to each other with a predetermined gap 6. It becomes the composition arranged. At this time, in the first embodiment, as shown in FIG. 2 (b), concave portions (grooves) along the circumferential direction are formed on the opposing surface sides of the fixed-side iron core 1 and the rotary-side iron core 3, respectively. It has a configuration. In each recess, a sheet winding formed in a spiral shape from the bottom surface side toward the opening portion side is arranged. Further, in the first embodiment, as is apparent from FIG. 2B, the length in the radial direction (hereinafter referred to as the width) of the sheet windings serving as the stationary winding 2 and the rotating winding 4 is fixed. The length is substantially the same as the length in the radial direction of the recesses of the iron core 1 and the rotating iron core 3.

  Further, the heights of the fixed side winding 2 and the rotation side winding 4 formed by the sheet winding are the heights of the peripheral edges of the iron cores 1 and 3 (radially inner end and radially outer end). The height), that is, smaller than the depth of the recess. By adopting such a configuration, the distance 5 between the regions in which the sheet windings are formed (the fixed winding 2 and the fixed winding 2) rather than the gap 6 when the fixed iron core 1 and the rotating iron core 3 are arranged to face each other. The gap between the rotation side winding 4 and the rotation side winding 4 is increased.

  The pair of fixed-side iron cores 1 (including the rotation-side winding 4) and the rotation-side iron core 3 (including the fixed-side winding 2) formed in this way are connected to the rotation center axis of the rotation-side iron core 3 and the rotating portion 200. The rotating side iron core 1 is arranged in the rotating part at a position where it coincides with the rotation center axis, and the fixed side iron core 1 is arranged in the gantry fixing part 100 at a position facing the rotating side iron core 3.

  In the cross-sectional view shown in FIG. 2B, the thickness t of the sheet winding 4 and the thickness of the insulating sheet 7 are the same for the sake of explanation, but from the thickness t of the sheet winding 4 In addition, by forming the insulating sheet 7 thin, it is possible to reduce the height of the fixed-side iron core 1 and the rotating-side iron core 3, so that the power transmission unit 102 can be further reduced in size.

  Moreover, in the electric power transmission part of Embodiment 1, the ease of manufacture is also mentioned as another effect. In sheet winding, a copper plate can be cut into an annular shape (ring shape), the copper plates are insulated with an insulating sheet 7 or the like, and then the ends of the cut copper plates are connected by brazing or the like. Therefore, by arranging the manufactured winding as the fixed-side winding 2 and the rotating-side winding 4 in the grooves of the fixed-side iron core 1 and the rotating-side iron core 3, the winding work at the time of manufacture becomes unnecessary and workability is improved. It is possible to improve. That is, as illustrated in FIG. 3A, in the power transmission unit 102 of the first embodiment, a thin C-shaped copper plate 401 for forming a sheet winding is disposed so as to overlap with the insulating sheet 7. One end of the C-shaped copper plate 401 and the other end of the C-shaped copper plate 401 disposed in the upper layer are sequentially electrically connected via a connection portion 402. As described above, in the fixed side winding 2 and the rotation side winding 4 of the first embodiment, the C-shaped copper plates 401 are sequentially connected to form a spiral shape from the bottom surface side of the concave portion of each iron core toward the opening surface side. A sheet winding is formed. With such a configuration, the sheet winding 4 can be divided and formed, so that workability can be improved. However, you may use the sheet | seat winding | winding 4 formed continuously toward the opening surface side from the bottom face side of the recessed part of each iron core. Further, in the formation of the fixed-side winding 2 and the rotation-side winding 4 in the first embodiment, when the C-shaped copper plate 401 having the same shape is overlapped, as shown in FIG. The copper plate 401 is rotated so as to be sequentially shifted clockwise or counterclockwise at the center position. By adopting such a configuration, one end of the C-shaped copper plate 401 disposed on the lower side, that is, the bottom surface side of the recess, and the C-shaped copper plate 401 disposed so as to overlap the C-shaped copper plate 401. This facilitates connection with the other end. At this time, the insulating sheet (not shown) arranged between the C-shaped copper plate 401 arranged in an overlapping manner is configured such that an opening is formed at a position where the C-shaped copper plate 401 is connected. The special effect that the connection of the C-shaped copper plate 401 arrange | positioned through an insulating sheet can be made easy can be acquired.

  However, in the fixed side winding 2 and the rotation side winding 4 of the first embodiment, as shown in FIG. 3B, the C-shaped copper plate 401 is a thin copper foil having a cross-sectional shape of width H and thickness t. It is formed with a copper plate. As will be described in detail later, the width H and the thickness t of the copper plate 401 are appropriately determined according to the power required for the power transmission unit 102.

  Furthermore, since the surface area of the winding in the sheet winding is larger than that in the litz wire, the cooling effect by heat conduction and heat transfer can be increased. If a sheet having good thermal conductivity is used for the insulating sheet 7, heat conduction between the turns of the sheet winding can be increased, which is advantageous in terms of thermal design.

(Explanation of effect)
In general, in order to reduce the skin effect and eddy current loss, a bundle wire called a litz wire is often selected as a winding used in a device that generates a high-frequency leakage magnetic flux. As described in Japanese Patent Publication (hereinafter referred to as Reference 1), it is known that even with a litz wire, the AC resistance increases as the frequency increases. In particular, since the X-ray CT apparatus needs to pass a large current of several hundreds A, the cross sectional area of the current must be increased in order to reduce the resistance of the winding.

When using litz wire, it is necessary to increase the number of strands or increase the strand diameter, but even if the strand diameter is increased, the current that is energized is the skin effect. There is no point in enlarging the strand diameter while only flowing about δ. When the angular frequency is ω, the magnetic permeability μ, and the conductivity σ, the skin depth δ is expressed by the following equation (1).

  For example, when the wire material is copper, the skin depth δ at a frequency of 100 kHz is about 0.2 mm, as is clear from the diagram showing the relationship between the frequency of the copper wire and the skin depth in FIG. In order to pass a current of about 400 A to the winding, about 2000 strands must be twisted. However, when the number of strands reaches about 2000, as described in Reference Document 1, even if an attempt is made to lower the resistance value, a phenomenon occurs that the AC resistance value is saturated.

FIG. 5 is a diagram for explaining eddy currents in the power transmission unit according to the first embodiment of the present invention. FIG. 6 is a chart for calculating eddy currents and eddy current losses. FIG. 5 and FIG. based on 6 to describe the effect of reducing the eddy current loss W _e in the power transmission unit of the first embodiment using the sheet winding. However, FIG. 5A is a diagram for explaining eddy current when a conventional litz wire is used for the power transmission unit, and FIG. 5B is a diagram when the sheet winding is used for the power transmission unit. It is a figure for demonstrating an eddy current.

As shown in FIG. 5 (a), when using Litz wire as the winding, the leakage magnetic flux phi _a wire wound interlinked flow eddy current i. At this time, the impedance Z of the litz wire is expressed by the following equation (2).

Here, in the case of the litz wire, since the strand diameter is thin, the resistance R is dominant in the impedance to the eddy current i. On the other hand, the electromotive force e generated when entering the leakage magnetic flux phi _a becomes the following equation (3).

Thus, over-current i flowing through the leakage magnetic flux phi _a becomes the following equation (4).

From this equation (4), it can be seen that the eddy current i is proportional to the frequency. Further, the eddy current loss _{W e} is the formula (5) below.

Thus, in the case of using Litz wire in the windings, as shown in equation (4), an eddy current i caused by the leakage magnetic flux phi _a is proportional to the frequency f. Accordingly, as shown in Equation (5), the eddy current loss W _e is proportional to the square of frequency f. As a result, the high frequency under causes an eddy current loss W _e is increased, it is impossible to just reduce the copper loss.

On the other hand, as shown in FIG. 5 (b), even when using sheet winding as the winding, the leakage magnetic flux phi _a wire wound interlinked flow eddy current i. At this time, the impedance Z in the sheet winding is expressed by the following equation (6).

Here, in the case of the sheet winding, due to the large area to leakage flux phi _a, the impedance is an inductance L is dominant for eddy currents i. On the other hand, the electromotive force e generated when entering the leakage magnetic flux phi _a becomes the following equation (7).

Thus, over-current i flowing through the leakage magnetic flux phi _a becomes the following equation (8).

From this equation (8), it can be seen that the eddy current i is proportional to the frequency. Further, the eddy current loss _{W e} is the following equation (9).

Thus, when using the sheet winding as winding, it is possible to increase the area for leakage flux phi _a, as shown in equation (6), the impedance is dominated by inductance L to the eddy current i It becomes the target. Accordingly, as shown in equation (7) to (9), since the eddy current i caused by the leakage magnetic flux phi _a is independent of the frequency f, the eddy current loss W _e becomes independent of the frequency f, even in a high frequency under Copper loss can be reduced.

Here, Electrology B, 109, 8, pp. 339-346 (1989) as in (hereinafter Reference 2 hereinafter), in order to eddy current loss _{W e} have become irrelevant to the frequency f, the coefficient shown in the following equation (10) alpha 1 or less Therefore, the thickness t and width H of the sheet winding must be selected.

Here, ρ is the resistivity of the sheet winding. In a situation where the resistivity ρ and the frequency f are fixed, α is a coefficient that determines the ratio between the thickness t and the width H of the sheet winding. Eddy current loss W _e in the case of placing the sheet winding in uniform magnetic field B comprising a frequency f is expressed by the following equation (11).

  Here, Q (α) is an eddy current loss coefficient. FIG. 6 is an excerpt from Reference 2. The horizontal axis is α, and the vertical axis is the eddy current loss coefficient Q (α). When α = 1, the eddy current loss coefficient Q (α) is low, and it can be seen that the eddy current loss can be reduced by selecting the thickness t and the width H of the sheet winding so that α ≦ 1.

Since the thickness t of the sheet winding has a skin effect, it is appropriate to set it to about twice the skin depth δ, and therefore, the following equation (12) is obtained.

If the width H of the sheet winding is t = 2δ and is substituted into equation (10) so that α ≦ 1, the following equation (13) is obtained. In order to match the unit system, ρ [μΩ · cm] = 10 ⁸ / σ in the equation (10).

  If the thickness t and the width H of the sheet winding represented by Expression (12) and Expression (13) are selected, eddy current loss can be reduced. Therefore, also in the electric power transmission part of Embodiment 1, the sheet | seat winding of the range shown by Formula (12) and Formula (13) is used.

FIG. 7 is a diagram of sheet winding conditions applicable to the power transmission unit according to the first embodiment of the present invention. In particular, when the winding material is copper (σ = 58 × 10 ⁶ S / m), the formula This is a result of calculating the thickness t and the width H of the sheet winding by changing the frequency f using (12) and the equation (13). From FIG. 7, it can be seen that at a frequency of 100 kHz, the thickness of the sheet winding must be 0.4 mm or less and the width must be 42 mm or more.

  The inventors have confirmed through simulation that the use of sheet windings for the stationary winding 2 and the rotating winding 4 can reduce eddy current loss at high frequencies compared to the litz wire and copper loss. . Hereinafter, the effect of reducing copper loss by simulation will be described in detail.

FIG. 8 is a diagram showing simulation conditions for the power transmission unit in the X-ray CT apparatus according to the first embodiment of the present invention. FIGS. 9 and 10 are simulations for eddy current loss in the power transmission unit according to the first embodiment of the present invention. It is a figure which shows the result. In particular, FIG. 7A is a cross-sectional view and a simulation condition of the power transmission unit when a litz wire is used, and FIG. 7B is a diagram of the power transmission unit when a sheet winding having a width H = 56 mm is used. 7C is a cross-sectional view and simulation conditions, and FIG. 7C is a cross-sectional view and simulation conditions of the power transmission unit when a sheet winding having a width H = 96 mm is used, and FIG. 7C is a width H = 156 mm. It is sectional drawing and simulation conditions of the electric power transmission part at the time of using a sheet | seat winding. FIG. 10 is a diagram showing the copper loss of the power transmission unit using the sheet winding shown in FIG. 9 and 10, the vertical axis represents the copper loss W _Cu and the horizontal axis represents the frequency f.

In the simulations shown in FIGS. 8A to 8D, assuming that the same power is supplied to the litz wire and the sheet winding, the fixed winding 2 is set to 1200 ampere turns, and the rotation winding 4 Is set to -1200 amp turn. The cross-sectional area S1 is 23.5 [mm ² ], but considering the space factor of the winding, in the case of the litz wire, the winding space of the iron core, that is, the depth of the recess in which the winding is formed. Is set larger.

As is clear from FIG. 9, as the frequency increases in the litz wire, the copper loss W _Cu also increases to the right, and a copper loss W _{Cu of} about 32 kW is generated at a frequency of 100 kHz. On the other hand, in the case of the sheet winding, the copper loss W _Cu is kept low even when the frequency is high, and only a copper loss W _Cu of about 1.8 to 4.2 kW is generated at a frequency of 100 kHz. As is clear from the simulation results, in the power transmission unit according to the first embodiment using the sheet winding, the copper loss W _Cu can be significantly reduced, so that the frequency of the current supplied to the fixed-side winding The power transmission unit can be reduced in size. Further, as is apparent from FIGS. 8A to 8D, by using a sheet winding as the winding, the space factor of the winding occupying the volume of the recessed portion formed in the fixed side iron core and the rotation side iron core. As a result, it is possible to further reduce the size of the power transmission unit.

On the other hand, as shown in FIG. 10, when the thickness t of the sheet winding as a winding remains t = 0.42 mm and the winding width H is increased to 56 mm, 96 mm, and 156 mm, FIG. ) To (d), it is necessary to increase the winding space of the iron core, that is, the width of the recess. Further, as shown in FIG. 10, in the case of a sheet winding having a width H = 56 mm, the copper loss W _Cu = 2.6 kW at the frequency f = 20 kHz is the copper loss W _Cu = 4.5 kW at the frequency f = 120 kHz. In the case of a sheet winding with a width H = 96 mm, the copper loss W _Cu = 1.4 kW when the frequency f = 20 kHz is the frequency f = 120 kHz, the copper loss W _Cu = 2.6 kW, and the width H = 156 mm of the sheet winding. an increase of copper loss _W Cu = 2.0 kW, it can be seen that the suppressed are lower than the increase of the litz wire of copper loss _W Cu = 1.1 kW frequency f = 120 kHz when the frequency f = 20 kHz in the case At the same time, it hardly depends on the frequency. Further, as shown in FIGS. 8B to 8D, the DC resistance in the case of a sheet winding having a width H = 56 mm is R = 15.3 (mΩ), and the sheet winding having a width H = 96 mm is used. The DC resistance in the case is R = 8.1 (mΩ), and the DC resistance in the case of the sheet winding with the width H = 156 mm is R = 5.5 (mΩ), which is proportional to the width H of the sheet winding. It can be lowered. As a result, even if the width H is increased in the sheet winding, the copper loss W _Cu does not increase as in the case of the litz wire. Therefore, even when a large current is applied, the width H should be increased. It becomes possible to obtain a special effect that becomes possible. However, it provided that the copper loss _{W Cu} is the sum of the direct current loss _{W dc} and eddy current loss _{W e.}

  From the above results, by forming the fixed side winding 2 and the rotation side winding 4 with sheet windings, it is possible to prevent an increase in the copper loss of the windings even when the frequency is increased. It is possible to cope with higher frequency and higher output of the line CT apparatus.

  As described above, in the X-ray CT apparatus of the first embodiment, the annular fixed side winding portion disposed on the gantry side forming the power transmission portion, the rotating portion, and the fixed side Since the annular rotation side winding portion disposed opposite to the winding portion is formed by using sheet windings, the AC current supplied to the rotation side winding portion has a higher frequency. However, it is possible to reduce the copper loss in the fixed-side winding portion and the rotation-side winding portion, and the power transmission portion can be reduced in size. By using sheet windings for the fixed-side winding portion and the rotating-side winding portion, the space factor of the windings in the volume of the recesses formed in the fixed-side iron core and the rotating-side iron core can be improved. Therefore, it is possible to further reduce the size of the power transmission unit.

<Embodiment 2>
FIG. 11 is a diagram for explaining a schematic configuration of the power transmission unit in the X-ray CT apparatus according to the second embodiment of the present invention. In particular, FIG. 11A shows the power transmission unit viewed from the rotation axis direction of the rotation unit. 11 (b) is a cross-sectional view of the AA cross section of FIG. 11 (a) seen from the direction of the arrow, and FIG. 11 (c) is a view of the sheet winding shown in FIG. 11 (b). It is sectional drawing. However, the X-ray CT apparatus of the second embodiment is the same as the X-ray CT apparatus of the first embodiment except for the fixed side winding and the rotating side winding that constitute the power transmission unit. Therefore, in the following description, the fixed side winding and the rotation side winding in the power transmission unit will be described in detail.

  As shown in FIG. 11, in the power transmission unit 102 of the second embodiment, in order to increase the width H of the sheet winding, the sheet winding is folded in the middle, and the fixed side winding 2 and the rotation side winding 3 are connected. It is composed. With such a configuration, even with the fixed side iron core 1 and the rotary side iron core 3 having a limited winding space, the sheet winding can be folded and arranged, and the width H is larger than that of the first embodiment. Can be increased. The eddy current loss can be reduced by using the sheet winding as in the first embodiment. In FIG. 11, the sheet winding is folded once, but a plurality of folding may be performed.

  That is, in the power transmission unit 120 of the second embodiment, as shown in FIG. 11A, a pair of annular fixed side iron cores 1 and a rotary side iron core 3 each having a flat annular shape have a predetermined gap 6. The configuration in which the concave portions (grooves) along the circumferential direction are formed on the opposed surfaces of the fixed side iron core 1 and the rotary side iron core 3 are the same as in the first embodiment. . At this time, in the second embodiment, as is apparent from FIG. 11B, the length in the radial direction (the width of the sheet winding) of the sheet winding serving as the fixed winding 2 and the rotation winding 4 is fixed. The side iron core 1 and the rotary iron core 3 are formed to be larger than the radial lengths of the recesses, and are folded back at half the radial length of the sheet winding. FIG. 11 (c) shows the sheet winding at this time, and the structure is folded back at a position half the length of the sheet winding in the radial direction (width direction) along the extending direction of the sheet winding. Accordingly, a sheet winding having a thickness t having a width H twice that of the sheet winding according to the first embodiment can be formed within the same width of the recess as that of the first embodiment. However, two or more C-shaped thin copper plates 401 shown in FIG. 3B are used as one set, and the outer peripheral portion or the inner peripheral portion of each set of copper plates 401 is electrically connected, so that FIG. A sheet winding equivalent to the sheet winding shown in c) can be formed.

  At this time, in the second embodiment, by inserting the insulating sheet 7 between the folded sheet windings, electrical contact of the sheet windings associated with the folding is prevented, and the thickness t of the sheet winding is the electrical contact. Is prevented from being doubled. When securing the same number of turns as in the first embodiment, the height of the fixed side winding 2 and the rotation side winding 4, that is, the height (depth) of the recess can be doubled. Become.

  Also in the second embodiment, the heights of the fixed-side winding 2 and the rotation-side winding 4 formed by the sheet winding are the peripheral edge heights (radially inner end portions) of the respective iron cores 1 and 3. And the height of the outer end in the radial direction), that is, lower than the depth of the recess. By adopting such a configuration, the distance 5 between the regions in which the sheet windings are formed (the fixed winding 2 and the fixed winding 2) rather than the gap 6 when the fixed iron core 1 and the rotating iron core 3 are arranged to face each other. The gap between the rotation side winding 4 and the rotation side winding 4 is increased.

  As a result, in the X-ray CT apparatus according to the second embodiment, in addition to the effects of the X-ray CT apparatus according to the first embodiment, a larger current than that in the X-ray apparatus according to the first embodiment can be supplied to the rotating unit.

  In the cross-sectional view shown in FIG. 11C, the thickness t of the sheet winding 4 and the thickness of the insulating sheet 7 are the same for the sake of explanation, but from the thickness t of the sheet winding 4 In addition, by forming the insulating sheet 7 thin, it is possible to reduce the height of the fixed-side iron core 1 and the rotating-side iron core 3, so that the power transmission unit 102 can be further reduced in size. Furthermore, by using the insulating sheet 7 thinner than the thickness of the insulating sheet 7 between the sheet windings, the folded sheet windings are insulated so that the fixed-side winding 2 formed by the sheet windings is used. And the height of the part of the rotation side coil | winding 4 is suppressed, and the electric power transmission part is reduced in size. However, the thickness of the insulating sheet 7 is not limited to this. For example, the insulating sheet 7 having the same thickness may be used, and furthermore, the insulating sheet 7 is thicker than the thickness of the insulating sheet 7 between the sheet windings. The sheet 7 may be used to insulate the folded sheet windings.

<Embodiment 3>
FIG. 12 is a diagram for explaining a schematic configuration of the power transmission unit in the X-ray CT apparatus according to the third embodiment of the present invention. In particular, FIG. 12A shows the power transmission unit viewed from the rotation axis direction of the rotation unit. 12 (b) is a cross-sectional view of the AA cross section of FIG. 12 (a) viewed from the direction of the arrow, and FIG. 12 (c) is a view of the sheet winding shown in FIG. 12 (b). It is sectional drawing. However, the X-ray CT apparatus of the third embodiment is the same as the X-ray CT apparatus of the first and second embodiments except for the fixed side winding and the rotation side winding that constitute the power transmission unit. Therefore, in the following description, the fixed side winding and the rotation side winding in the power transmission unit will be described in detail.

  As shown in FIG. 12, in the power transmission unit 102 of the third embodiment, in order to increase the width H of the sheet winding, the sheet winding is wave-shaped, and the fixed side winding 2 and the rotation side winding 3 Is configured. By adopting such a configuration, the width H of the sheet winding can be made larger than that in the first embodiment, and the cross-sectional area through which a current is passed can be made larger. The eddy current loss can be reduced by using the sheet winding as in the first embodiment.

  That is, in the power transmission unit 120 according to the third embodiment, as shown in FIG. 12A, a pair of annular fixed side iron cores 1 and a rotary side iron core 3 each having a flat annular shape have a predetermined gap 6. The configuration in which the concave portions (grooves) along the circumferential direction are formed on the opposed surfaces of the fixed side iron core 1 and the rotary side iron core 3 is the same as that of the first embodiment. At this time, in the third embodiment, as shown in FIG. 12 (b), unevenness extending in the extending direction of the sheet winding is formed, and the sheet winding of the fixed winding 2 and the rotating winding 4 is formed. The actual length in the radial direction (the width of the sheet winding) is configured to be larger than the length in the radial direction (the width of the recess) of the recesses of the fixed side iron core 1 and the rotation side iron core 3. FIG. 12 (c) shows the sheet winding at this time, and the extending direction of the sheet winding so that corrugated irregularities are arranged in the radial direction (width direction) of the sheet winding. A sheet winding having a thickness t having a width H wider than that of the sheet winding according to the first embodiment within the width of the same concave portion as that of the first embodiment. It becomes possible to form. At this time, as shown in FIG. 12B, the height of the portions of the fixed side winding 2 and the rotation side winding 4 is set by arranging the sheet windings so that the concave and convex positions arranged above and below coincide with each other. Can be lowered.

  Also in the third embodiment, the heights of the portions of the fixed side winding 2 and the rotation side winding 4 formed by the sheet winding are the peripheral edge heights (radially inner end portions) of the respective iron cores 1 and 3. And the height of the outer end in the radial direction), that is, lower than the depth of the recess. By adopting such a configuration, the distance 5 between the regions in which the sheet windings are formed (the fixed winding 2 and the fixed winding 2) rather than the gap 6 when the fixed iron core 1 and the rotating iron core 3 are arranged to face each other. The gap between the rotation side winding 4 and the rotation side winding 4 is increased. As a result, in the X-ray CT apparatus according to the third embodiment, in addition to the effects of the X-ray CT apparatus according to the first embodiment, a larger current than that in the X-ray apparatus according to the first embodiment can be supplied to the rotating unit.

  Further, the sheet winding of the third embodiment is folded back in the middle in the width direction like the sheet winding of the second embodiment (the configuration in which the outer peripheral portion or the inner peripheral portion is connected when the sheet winding is formed of a thin copper plate) In this case, the width of the sheet winding formed within the limited width of the recess can be further increased.

<Embodiment 4>
(overall structure)
FIG. 13 is an overall configuration block diagram of an X-ray CT apparatus according to Embodiment 4 of the present invention. As is apparent from FIG. 13, the X-ray CT apparatus of the fourth embodiment heats the stator coil 62 for rotationally driving a rotating anode (not shown) included in the X-ray tube 39 and the cathode included in the X-ray tube 39. In order to transmit power to the heating transformer 61, a power transmission unit 112 of a different system from the power transmission unit 102 shown in the first embodiment is provided. This power system includes a power source 50, an inverter 54, a ring-shaped transformer (rotary transformer) 112, rectifiers 55 and 56, smoothing capacitors 57 and 58, inverters 59 and 60, a heating transformer 61, and a stator. A coil 62 is provided. However, the power source 50 includes a commercial AC power source 51, a converter 52 that converts the voltage of the AC power source 51 into a desired DC voltage, and a smoothing capacitor 53 that smoothes the output voltage of the converter 52.

  The power source 50 and the inverter 54 have the same configuration as the power source 30 and the inverter 34, although the output power is different from that of the power source 30 and the inverter 34. Therefore, detailed description is omitted. The rectifiers 55 and 56 are well-known devices that convert an AC voltage input via the power transmission unit 112 into a DC voltage. The smoothing capacitors 57 and 58 are for smoothing the ripple of the output voltage from the rectifiers 55 and 56 so as to approach the DC voltage. The inverters 59 and 60 convert the output voltage from the smoothing capacitors 57 and 58 into a high-frequency AC voltage and output it to the stator coil 62 and the heating transformer 61, respectively.

  In addition, the power transmission unit 112 includes a fixed side winding 111 disposed on the gantry fixing unit 100 and a rotation side winding 113 disposed on the rotating unit 200. The fixed side winding 111 is connected to the inverter 54, and the rotation side winding 113 is connected to the rectifiers 55 and 56. The rotation side winding 113 is disposed in the vicinity of the fixed side winding 111.

(Power transmission unit configuration)
Next, FIG. 14 is a diagram for explaining a schematic configuration of the power transmission unit in the X-ray CT apparatus according to the fourth embodiment of the present invention. Hereinafter, the details of the power transmission units 102 and 112 will be described based on FIG. The configuration will be described. 14A is a bird's-eye view of the power transmission unit 102 viewed from the direction of the rotation axis of the rotation unit 200, and FIG. 14B is a cross-sectional view taken along the line B-B in FIG. It is sectional drawing. However, in the following description, a case will be described in which the sheet winding for forming the fixed side windings 2 and 111 and the rotation side windings 4 and 113 is formed of copper, but the material of the sheet winding is limited to copper. There may be other conductive materials. Further, an arc-shaped arrow shown in FIG. 14A indicates the rotation direction of the rotating unit 200.

  13A is a diagram of the power transmission unit 102 and the power transmission unit 112 as viewed from the direction of the rotation axis of the rotation unit 200, and FIG. 13B is a cross-sectional view taken along the line B-B in FIG. It is the figure seen from. The rotating part 200 rotates in the direction of the arc of the arrow in FIG.

  As shown in FIG. 13A, in the fourth embodiment, the power transmission units 102 and 112 for two systems are provided, and the power transmission unit 112 includes the fixed-side winding 111 and the rotation-side winding described above. In addition to 113, a fixed iron core 8 and a rotating iron core 9 are provided. As long as the alternating magnetic flux φ1 generated around the fixed-side winding 2 and the alternating magnetic flux φ2 generated around the fixed-side winding 111 do not interfere with each other, it is possible to transmit power independently in each power system. .

  The fixed side winding 2 and the rotation side winding 4 of the power transmission unit 102 of the present embodiment, and the fixed side winding 111 and the rotation side winding 113 of the power transmission unit 112 are sheet windings as in the first embodiment. In the power transmission unit 102, the fixed side iron core 1 and the rotary side iron core 3 are disposed horizontally in the groove. The same applies to the power transmission unit 112, and the power transmission unit 112 is disposed horizontally in the grooves of the stationary iron core 8 and the rotating iron core 9. It is the same as in the first embodiment that the eddy current loss can be reduced by using the sheet winding.

  That is, as shown in FIG. 14 (a), in the X-ray CT apparatus of the fourth embodiment, a pair of annular fixed-side iron core 8 and a rotary-side iron core 9 having a plate-like toroid shape form a power transmission unit. The power transmission unit 11 is formed on the outer peripheral side of 102. The rotating side iron core 8 and the fixed side iron core 9 constituting the power transmission unit 112 are configured to face each other with a predetermined gap 10. At this time, as shown in FIG. 14B, similarly to the power transmission unit 102, also in the power transmission unit 112, the opposing surface side of the fixed side iron core 8 and the rotation side iron core 9 are respectively along the circumferential direction. In this configuration, a concave portion (groove) is formed. In each recess, a sheet winding formed in a spiral shape from the bottom surface side toward the opening portion side is arranged. At this time, as is apparent from FIG. 14B, the length in the radial direction of the sheet winding serving as the fixed-side winding 111 and the rotation-side winding 113, that is, the width of the sheet winding is determined by the fixed-side iron core 8 and the rotation. The side iron core 9 is formed to be shorter than the length of the concave portion in the radial direction.

  Further, the heights of the fixed side winding 111 and the rotation side winding 113 formed by the sheet winding are the same as the power transmission unit 102, and the peripheral edge heights of the respective iron cores 8 and 9, that is, the depths of the recesses. It becomes the structure formed smaller than this. By adopting such a configuration, the distance 11 between the regions in which the sheet winding is formed (the fixed winding 111 and the fixed winding 111) rather than the gap 10 when the fixed iron core 8 and the rotating iron core 9 are arranged to face each other. The gap between the rotation side winding 113 and the rotation side winding 113 is increased.

  As with the power transmission unit 102, first, the sheet winding of the power transmission unit 112 is also cut out in a ring shape, and then the copper plates are insulated from each other by the insulating sheet 12 or the like. Thereafter, the end portions of the cut copper plates are electrically connected by brazing or the like to form a sheet winding. Therefore, for example, compared with a configuration in which the manufactured winding is arranged as the fixed-side winding 111 and the rotating-side winding 113 in the groove portions of the fixed-side iron core 8 and the rotating-side iron core 9, the winding work at the time of manufacture becomes unnecessary. Workability can be improved.

  As described above, in the X-ray CT apparatus of the fourth embodiment, the power supply system for supplying the X-ray tube 39 with a voltage for accelerating thermionic electrons and the other two power supply systems are independent of each other. 30 and 50, and power transmission units 102 and 112 corresponding to the power sources 30 and 50, respectively, so that in addition to the effects of the X-ray CT apparatus of the first embodiment described above, the rotation can be performed more efficiently. The special effect that electric power can be supplied to the unit 200 can be obtained.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment of the invention. However, the invention is not limited to the embodiment of the invention, and various modifications can be made without departing from the scope of the invention. It can be changed.

DESCRIPTION OF SYMBOLS 1, 8 ... Fixed side iron core, 2, 111 ... Fixed side coil | winding, 3, 9 ... Rotation side iron core 4, 113 ... Rotation side coil | winding, 5, 11 ... Fixed side coil | winding Distance between wire and rotation side winding 6, 10 ... Gap, 7, 12 ... Insulating sheet, 30, 50 ... Power source 31, 51 ... AC power source, 32, 52 ... Converter 33 , 53, 57, 58 ... smoothing capacitors 34, 54, 59, 60 ... inverter, 37 ... high voltage transformer 38 ... high voltage rectifier, 39 ... X-ray tube, 40 ... X-ray detector 42 ... detector 43 ... preamplifier 46 ... image processing device 47 ... image display device 55, 56 ... rectifier 61 ... heating transformer 62 ..Stator coil, 100 ... Fixing base part 102, 112 ... Power transmission part, 105 ... Subject 1 6 ... fixed side receiving device, 107 ... rotating side transmitting device 108 ... non-contact signal transmission means, 200 ... rotating part, 300 ... console 401 ... C-shaped copper plate, 402 ... Connection part (brazing part)

Claims (3)

An imaging mechanism including an X-ray source and an X-ray detection unit rotates a rotating unit that rotates around the subject, a gantry unit that rotatably supports the rotating unit, and transmits electric power from the gantry unit to the rotating unit. An X-ray CT apparatus including a power transmission unit,
The power transmission unit is arranged in an annular fixed-side winding unit disposed on the gantry unit side, and in an annular rotation disposed in the rotating unit and opposed to the fixed-side winding unit. Side winding part,
The fixed-side winding portion and the rotation-side winding portion include an iron core having a concave portion along a circumferential direction on the surface side facing each other, and a sheet winding disposed in the concave portion ,
The X-ray CT apparatus , wherein the sheet winding is arranged to be folded once or more in the radial direction of the fixed side winding portion and the rotation side winding portion so as to be accommodated in the recess . The X-ray CT apparatus according to claim 1,
The sheet winding is formed such that corrugated irregularities are formed in the radial direction of the fixed-side winding portion and the rotating-side winding portion, and the corrugated irregularities are arranged to coincide with each other. X-ray CT apparatus. The X-ray CT apparatus according to claim 1 or 2,
An X-ray CT apparatus comprising a plurality of the power transmission units, wherein each power transmission unit is arranged in a radial direction .

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