JP2009027007A - Reactor core and reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reactor core capable of preventing peeling at a bonding portion of core members and a gap plate by reducing thermal stress at the bonding portion, and capable of effectively suppressing the leakage of magnetic flux generated at the bonding portion, and to provide a reactor provided with the reactor core. <P>SOLUTION: The reactor core is composed of a plurality of core members 1 and 1 having magnetism, and a gap plate 2 located between adjoining core members 1 and 1, and having non-magnetism, wherein opposing faces of the core members 1 and opposing faces of the gap plate 2 are fixed through an adhesive layer 3. The core member 1 is formed so that cross sections of the opposing faces of the core member 1 are smaller than those of cross sections of other parts of the core member 1. The gap plate 2 is formed so that cross sections of the opposing faces of the gap plate 2 are approximately equal to those of the cross sections of the opposing faces of the core member 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a reactor core and a reactor, and more particularly, to a reactor core in which a core material forming a reactor core and a gap plate hardly peel off and a reactor including the reactor core.

  When the reactor core is formed of a plurality of core materials, a ceramic gap plate serving as a spacer is interposed between adjacent core materials, and the gap plate and the core material are bonded and fixed with an adhesive. It is common.

  By the way, when the reactor including the reactor is mounted in an engine room of a hybrid vehicle or the like, in such an application, under a cold cycle environment within a range of about −40 ° C. to 150 ° C. due to a change in the use environment. Therefore, in the reactor core in which the gap plate is interposed, there is a problem that peeling is likely to occur at the bonding portion between the core material and the gap plate. As shown in FIG. 20, the opposing surfaces of the conventional core materials a and a and the gap plate b are both formed flat, and the thickness of the adhesives c and c between them is inevitably at any part. It is the same thickness, and the outer peripheral portion of the reactor core is more susceptible to the thermal cycle, and the difference in thermal expansion between the core material a, the gap plate b, and the adhesive c is greater at the outer peripheral portion. The major factor is that the adhesive layer is easily peeled off due to repeated thermal stress. In addition, the shear stress which arises in this adhesive bond layer becomes large, so that the thickness of an adhesive bond layer is small.

  Therefore, by increasing the thickness of the adhesive layer, it is possible to increase the durability against the thermal cycle. On the other hand, the thickness of the adhesive layer having low rigidity is increased to increase the static strength of the reactor core itself ( (Rigidity) will be reduced.

  By the way, Patent Document 1 discloses a reactor core that can sufficiently secure the spread area and thickness of the adhesive in order to effectively prevent the peeling of the adhesive portion described above. Specifically, in a structure in which a gap spacer is interposed between core materials, a protrusion that abuts against the core material is formed on the adhesive surface of the gap spacer with the core material. By filling the gap with the fixing adhesive, an adhesive layer having a predetermined thickness dimension is formed over the entire surface of the core material.

JP 2006-135018 A

  According to the reactor disclosed in Patent Document 1, it is possible to form an adhesive layer having a predetermined thickness over the entire area of the end face of the core material. However, the above-described problem, that is, peeling at the outer peripheral portion of the reactor core where peeling is most remarkable cannot be effectively suppressed.

  In addition, how to reduce the so-called leakage magnetic flux, in which the magnetic flux leaks outward from the end of the core material, is an important issue. The leakage magnetic flux interlinks with the coil formed on the outer periphery of the coil, which leads to heat generation of the coil, or so-called EMI failure (electromagnetic noise or interference that hinders the normal functioning of the device). Cause.

  The present invention has been made in view of the above-described problems, and can reduce peeling at the portion by reducing the thermal stress at the bonding portion between the core material and the gap plate, and can occur at the bonding portion. An object of the present invention is to provide a reactor core capable of effectively suppressing leakage magnetic flux and a reactor including the reactor core.

  In order to achieve the above object, a reactor core according to the present invention is formed of a plurality of magnetic core materials and a non-magnetic gap plate interposed between adjacent core materials. In the reactor core in which the opposing surface of the surface and the gap plate is fixed via an adhesive layer, the core material has a smaller cross-sectional area of the opposing surface than the cross-sectional area of other portions of the core material The gap plate is characterized in that the cross-sectional area of the facing surface is formed with substantially the same dimension as the cross-sectional area of the facing surface of the core material.

  As a measure for effectively reducing the thermal stress at the bonded portion between the core material and the gap plate, particularly the end portion (outer peripheral side), the present inventors have determined the cross-sectional area of the facing surface of the core material to the gap plate. The cross-sectional area of the other part of the core material is formed to be smaller than the cross-sectional area of the gap plate, and the cross-sectional area of the gap plate facing the core material is also formed with the same dimension as the cross-sectional area of the facing surface of the core material And it discovered that a thermal stress could be reduced effectively by connecting these through an adhesive bond layer, and a magnetic flux leakage could also be controlled effectively.

Here, as one embodiment of the reactor core, two U-shaped cores are arranged to face each other with a space therebetween, and a plurality of rectangular cores (or I-shaped cores) are disposed between the U-shaped core and the I-shaped core. And a gap plate formed of ceramic such as alumina (Al ₂ O ₃ ) or zirconia (ZrO ₂ ) is interposed between the I-type cores, and the core material and the gap plate are heat resistant. Reactors are formed by bonding and fixing with a high epoxy resin adhesive or the like.

  The core material is formed from a powder magnetic core formed by pressing soft magnetic powder or a laminated steel plate formed by laminating electromagnetic steel sheets. In the present invention, the core material is formed from a powder magnetic core particularly from the viewpoint of formability. preferable. Examples of the soft magnetic metal powder include iron, iron-silicon alloy, iron-nitrogen alloy, iron-nickel alloy, iron-carbon alloy, iron-boron alloy, iron-cobalt alloy, iron-phosphorus. An alloy-based alloy, an iron-nickel-cobalt-based alloy, and an iron-aluminum-silicon-based alloy can be used, and an insulating coating made of a silicon resin or the like is formed on the surface of the alloy to produce a soft magnetic powder.

  As a form in which the cross-sectional area of the surface facing the gap plate of the core material is formed to be smaller than the cross-sectional area of the other part of the core material, one of them is that the end is formed in a step shape. The cross-sectional area of the opposite surface is smaller than the cross-sectional area of other parts, and the other is that the end is a truncated pyramid or truncated cone And the cross-sectional area of the facing surface is smaller than the cross-sectional area of the other part. In the former case, for example, it can be formed in one or two stages.

  Further, as a form of the adhesive layer, the end portions of the two adhesive layers (for example, the first adhesive layer) on both sides of the gap plate are the second adhesive layer straddling the end portions of the gap plate. It is connected and the outer surface of this adhesive bond layer has fallen from the outer surface of the core material, or the form which is substantially flush with the outer surface of a core material can be mentioned.

  As another form of the adhesive layer, the ends of the two adhesive layers on both sides of the gap plate are connected by an adhesive straddling the end of the gap plate in a fillet shape, The form which the top surface part has fallen from the outer surface of the core material, or is substantially flush with the outer surface of the core material can be mentioned. Here, the fillet shape means a dome shape or a curved shape.

  By using the reactor described above and forming a reactor in which a coil is formed on the outer periphery of the core, it is possible to particularly reduce the thermal stress at the end of the bonded portion between the magnetic core material and the gap plate. This effectively leads to the prevention of peeling. Furthermore, it has been proved that leakage magnetic flux can be effectively suppressed by adopting the above-described configuration of the connecting portion. Therefore, the present reactor is particularly suitable for a hybrid vehicle that requires high cooling durability (particularly difficulty in peeling off the end of the core material bonding portion).

  As can be understood from the above description, according to the reactor of the present invention, the thermal stress at the bonded portion between the core material and the gap plate can be reduced by an extremely simple structure such as forming the end portion of the core material in a step shape. Both reduction and suppression of leakage flux can be realized.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an embodiment of an I-type core constituting a reactor core according to the present invention, FIG. 2 is a perspective view of an adhesive portion between the I-type core of FIG. 1 and a gap plate, and FIG. It is a longitudinal cross-sectional view of the adhesion part of FIG. FIG. 4 is a perspective view of another embodiment of the I-type core constituting the reactor core of the present invention, and FIG. 5 is a perspective view of still another embodiment of the I-type core constituting the reactor core of the present invention. FIG. 6 is a longitudinal sectional view of a bonding portion between the I-type core and the gap plate of FIG. FIG. 7 a is a longitudinal sectional view of an example having the adhesive portion of FIG. 2 and a resin mold formed on the outer periphery thereof, and FIG. 7 b is a longitudinal sectional view of a comparative example.

  FIG. 1 shows an I-type core 1 having magnetism that constitutes a reactor core of the present invention. The I-type core 1 is manufactured by press-molding magnetic powder and annealing as necessary. The I-type core 1 has an adhesive surface 11 that is bonded to a gap plate (not shown) via an adhesive. One step 12 is formed on the upper and lower ends. In addition, when the surface on the opposite side to the adhesion surface 11 of the I-type core 1 becomes an adhesion surface, the same level | step difference part is formed also in the upper and lower ends of this surface.

  FIG. 2 shows a state in which two I-type cores 1 shown in FIG. 1 are prepared, arranged opposite to each other, a gap plate 2 is interposed therebetween, and both are bonded and fixed via an adhesive layer 3. .

  In the figure, two adhesive layers 3, 3 between the gap plate 2 and the adhesive surface 11 of the I-type core 1 are connected by an adhesive fillet end 3 a straddling the gap plate 2. Further, from FIG. 3 which is a longitudinal sectional view, the top portion of the fillet end portion 3a is adjusted to a level that does not protrude vertically from the upper end surface or the lower end surface of the I-type core 1. The level is adjusted to be flush with the upper or lower surface.

  FIG. 4 shows another embodiment of the I-type core. The I-type core 1A is an endless stepped portion 13 in contrast to the stepped portions formed at the upper and lower ends in the I-type core 1, and the stepped portions are formed at all four end sides. It is. In each of the I-type cores 1 and 1A, the bonding surface 11 is formed in a small cross section compared to other portions of the core, and a step is formed on all or a part of the end of the core bonding surface facing the gap plate. The part is formed. By providing this step portion at the end of the core where the adhesive surface is likely to be peeled off by a cooling and heating cycle, the generated shear stress on the core adhesive surface can be reduced as compared with a conventional core that does not have a step portion. Furthermore, by providing the step portion, the leakage magnetic flux from the core end can be effectively reduced, and the coil heat generation can be reduced by reducing the interlinkage area between the leakage magnetic flux and the coil. In addition, by adopting a structure in which the adhesive layers on both sides of the gap plate are connected by the fillet end of the adhesive at the end of the gap plate, the effect of reducing the generated shear stress and leakage can be achieved as compared with the case where only the stepped portion is provided. It has also been demonstrated that the magnetic flux reduction effect is even more pronounced.

  FIG. 5 shows still another embodiment of the I-type core. In this I-type core 1B, taper portions 14 are formed from four end sides toward an adhesive surface 11 having a relatively small cross section instead of forming a stepped portion, and the shape toward the adhesive surface 11 is a truncated pyramid shape. Is the core. This core is also expected to have the effect of reducing the generated shear stress on the bonding surface and the effect of reducing the leakage magnetic flux since the core end is cut off in the same manner as the I-type cores 1 and 1A.

  In addition to the core form shown in FIG. 5, an I-type core having a truncated conical shape toward the bonding surface 11 may be used.

  6, the two I-type cores 1 </ b> B and 1 </ b> B shown in FIG. 5 are opposed to each other, the gap plate 2 is interposed therebetween, and both are bonded with an adhesive layer 3 having a fillet end 3 a as in FIG. 3. The structure of the junction is shown.

  FIG. 7a shows a resin mold body made of potting resin on the outer periphery of the I-type core 1, 1 ′ having a step portion (core having steps on both bonding surfaces), the gap plate 2, and the adhesive layer 3 connecting them. 4 shows a part of the reactor core in which 4 is formed. On the other hand, a conventional structure (having a conventional I-type core) for comparison with this is shown in FIG. 7b, and a gap plate b between the I-type cores a and a is bonded by an adhesive layer c.

  As can be seen from FIGS. 7a and 7b, in the conventional core having no step at the core end, if the fillet end c1 that connects the adhesive layers is provided, the thickness of the resin mold body d at that portion becomes thin. In addition, cracks are likely to occur in the resin mold body, and this can easily cause a short circuit by allowing entry of water from the outside.

  As mentioned above, although the form of several I type cores and the effect were described, the U-core which abbreviate | omits illustration performs the same process of providing a level | step-difference part, etc. on the adhesive surface with an I type core. These U-type core and I-type core are prepared to form a reactor core (not shown). Specifically, two U-type cores, a plurality of I-type cores arranged with a space therebetween, and between the U-type core and the I-type core and between the two I-type cores. A reactor plate is formed from a gap plate and an adhesive layer having a fillet end portion for bonding the gap plate and the core, and the plan view is formed in a horizontally long annular shape as a whole. A magnetic circuit is formed in the annular direction.

Both the U-shaped core and the I-shaped core are formed from a powder magnetic core formed by press-molding soft magnetic powder. The gap plate is formed of a nonmagnetic material ceramic such as alumina (Al ₂ O ₃ ). Further, the adhesive layer is formed of an epoxy resin adhesive or the like.

  A coil in which a conducting wire is wound is formed in a straight section in the longitudinal direction of the reactor core to form a reactor (not shown). This reactor comprises the power converter device mounted in vehicles, such as a hybrid vehicle, for example.

[Thermal stress analysis and results of an example in which a step is provided at the core end and an adhesive fillet end is provided, and a comparative example of a conventional structure]
The present inventors made a three-dimensional FEM analysis model having a structure in which a core having a stepped portion and a gap plate shown in FIG. FEM thermal stress analysis was performed using both analysis models, with an analysis model having a structure in which the core has no step and the adhesive layer has no fillet end as a comparative example.

  Here, the temperature dependency of the strength of the adhesive layer of the epoxy adhesive used in this example is shown in FIG. Table 2 shows the material property values set in the thermal stress analysis. Further, an outline of the analysis model is shown in FIG. In FIG. 9, the overall model M is composed of a core analysis model M1, a gap plate analysis model M2, and an adhesive layer analysis model M3.

As a result of the temperature dependency of the adhesive strength, a test piece of 1.6 × 25 × 100 mm was prepared with aluminum (A2024P), and the adhesive area of the test piece was set to 12.5 × 25 mm ² . It is the result of setting the thickness to 0.1 mm, setting the curing condition in a 120 ° C. atmosphere for 60 minutes, placing each temperature environment, and performing a tensile test at a pulling speed of 5 mm / min.

In the analysis model diagram of FIG. 9, the thickness of the adhesive layer: δ is 0.05 mm.
The analysis model for one core shown in FIG. 9 was combined into the analysis model shown in FIG. 10, and the analysis model for the joint structure shown in FIG. 3 was created. Note that the end shape of the adhesive in this analysis is not a fillet shape because of the model creation, and the cross section is a horizontally long rectangular shape.

  In the figure, various analysis models are created by varying the width of the stepped portion: b, the thickness of the adhesive end portion: t, and the thickness of the stepped portion: d, and the influence of these factors on the thermal stress results. Verified. Outlines of the joints of these various analysis models are shown in FIGS. In addition, the constraint conditions of each analysis model were set to free constraints with 6 degrees of freedom.

  12A to 12G show the thermal stress analysis results of the respective analysis models, and the shear stress results in the YZ direction of the adhesive under the condition of −40 ° C. FIG. 13 is an enlarged view showing the FEM analysis result on the right side of the analysis model in more detail. In addition, it means that the smaller the absolute value of the MAX value of the shearing force and the MIN value in the figure, the smaller the shear stress generated on the bonding surface, and thus the greater the stress reduction effect. means.

  In FIG. 13, for example, FIG. 13a, d, FIG. 13b, d, or FIG. Both of these combinations are in the case where the width of the stepped portion: b is the same, and the thickness of the adhesive end portion: t is doubled (or 0.5 times).

  Comparing the analysis results for each combination, it can be seen that when the width of the stepped portion: b is the same, the difference in shear strength hardly occurs even if the thickness of the adhesive end portion: t changes.

  Next, each of FIG. 13a, b, c or FIG. 13d, e, f is compared. In both of these combinations, the thickness of the adhesive end portion: t is the same, and the width of the stepped portion: b is, for example, twice in FIG. 13b and three times in FIG. 13c. Yes.

  By comparison, it can be seen that the greater the width of the stepped portion, b, the smaller the shearing stress that is generated, resulting in a bonded structure that is less prone to peeling. However, if the width of the stepped portion “b” becomes too large, the rigidity of the entire reactor core will be reduced this time. Therefore, the optimum width of the stepped portion should be set in consideration of these factors.

  FIG. 14 is an analysis result under the condition of 150 ° C. and corresponds to FIG. 13 in the case of −40 ° C.

  From the figure, although the value of the generated shear stress is different even under a temperature environment of 150 ° C., the tendency, that is, the thickness of the adhesive end portion: t changes when the width of the stepped portion: b is the same. Even so, the conclusion that the difference in shear strength hardly occurs and that the generated shear stress decreases as the width b of the stepped portion increases is the same.

[Magnetic field analysis and results to verify the effect of core step shape on magnetic properties]
Based on the analysis described above, the present inventors have found that the thermal stress is reduced by providing a step at the end of the core, particularly by providing a step at the end of the core, and providing a connecting portion of the adhesive layer at the step. Demonstrated. Here, the effect of the stepped portion (change in shape) provided at the end of the core on the magnetic characteristics (inductance) of the reactor core and the degree of leakage flux are verified by analysis.

  Here, the core material constituting the analysis model is formed from magnetic powder of Fe-3% Si, and the relationship between the magnetic field and the magnetic flux density is shown in FIG.

  FIG. 16 shows a three-dimensional analysis model of a reactor core composed of a U-shaped core, an I-shaped core, and a coil. Here, the mesh size of each model is 1 mm for both the I-type core and U-type core, the coil is 2 mm, the air 1 is 5 mm, the air 2 is 20 mm, the gap length is 2.1 mm, and the number of turns of the coil is 70 turns. Yes.

  Further, the shape of the stepped portion at the core end was variously changed from that shown in FIGS. FIG. 17g shows a conventional core structure model without a stepped portion, and FIG. 17h shows a conventional structure, but a comparative example model is used as an R-processed (chamfered) core structure instead of a stepped portion at the end. .

  The magnetic field analysis results in each model are shown in FIGS. 18a shows the analysis results of FIGS. 17a and 17d, FIG. 18b shows the analysis results of FIGS. 17b and e, FIG. 18c shows the analysis results of FIGS. 17c and f, FIG. 18d shows the analysis results of FIG. FIG. 17 shows the analysis results of FIG. 17h, and both show the magnetic flux density distribution.

  From the same figure, it can be seen that the magnetic flux interlinked with the coil has a lower magnetic flux region interlinked with the coil in the analysis result of each example model compared to the analysis result of the comparative example model. This is because by providing a step at the end of the core, the leakage flux starting point moves away to the opposite side of the coil, so that the top of the leakage flux route is drawn to the opposite side of the coil. As a result, it can be concluded that the low magnetic flux region is linked to the coil. From this result, the magnetic flux density linked to the coil is reduced by providing the step portion at the end of the core, so that the amount of heat generated by the coil can be reduced. Further, the leakage magnetic flux itself is reduced, which leads to a reduction in loss.

  FIG. 19 is an analysis result showing the relationship between the current (superimposed current) and the inductance of each example and each comparative example.

  For example, in a hybrid vehicle, the range of about 0 to 200 (A) is targeted as the current superimposed current range.

  Although the inductance is reduced by providing a step at the end of the core material as compared with the conventional structure, both the standard value at 0A and the standard value at 161A are satisfied, and there is no problem. It is settled by decline.

  On the other hand, for example, the thermal stress (shear stress) of the adhesive layer in a low temperature environment of −40 ° C. varies depending on the width of the stepped portion, but is reduced to about 74 to 78%. By providing the stepped portion, it is possible to effectively reduce the thermal stress without substantially reducing the inductance characteristics.

  As described above, the reactor core to which the structure of the magnetic core according to the present invention and the joint portion between the magnetic core, the adhesive layer, and the gap plate are applied has a markedly improved peel resistance at the bonded portion. Therefore, it is suitable for application to a recent hybrid vehicle or the like used in a severe heat cycle environment.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

It is a perspective view of one embodiment of the I type core which constitutes the reactor core of the present invention. It is a perspective view of the adhesion part of the I type core of FIG. 1, and a gap board. It is a longitudinal cross-sectional view of the adhesion part of FIG. It is a perspective view of other embodiment of the I-type core which comprises the reactor core of this invention. It is a perspective view of further another embodiment of the I type core which constitutes the reactor core of the present invention. It is a longitudinal cross-sectional view of the adhesion part of the I-type core of FIG. 5 and a gap board. (A) is the longitudinal cross-sectional view of the Example which has the adhesion part of FIG. 2, and the resin mold was formed in this outer periphery, (b) is a longitudinal cross-sectional view of a comparative example. It is a graph which shows the temperature dependence of the adhesive bond layer intensity | strength of the epoxy adhesive used in the present Example. It is the figure explaining the outline | summary of the analysis model used by the thermal-stress analysis of the adhesion part of a core material and a gap board. It is a figure explaining the part to change in the structure of the adhesion part of an analysis model. (A)-(g) is each a front enlarged view of the analysis model from which the structural form of an adhesion part differs, (h) is a schematic diagram of the whole analysis model. (A)-(g) is the figure which showed the analysis result (YZ shear stress) of each model of (a)-(g) of FIG. 11 on the conditions of -40 degreeC, respectively, (h) is a shear stress. It is explanatory drawing regarding the magnitude | size of. (A)-(g) is the analysis result which showed the shear stress of the right side surface in the analysis result of FIG. 11 in detail, respectively. (A)-(g) is the figure which showed the analysis result (YZ shear stress) of the right side surface of each model of (a)-(g) of FIG. 13 on 150 degreeC conditions, respectively. It is the graph which showed the magnetic field analysis result of the rear anchor. It is the figure explaining the outline | summary of the magnetic field analysis model. (A)-(h) is each a front enlarged view of the analysis model from which the structural form of an adhesion part differs, (a)-(f) is an Example model, (g), (h) is a comparative example. It is a model. (A) is the analysis result of (a), (d) of FIG. 17, (b) is the analysis result of (b), (e) of FIG. 17, (c) is (c), (c) of FIG. FIG. 18 shows the analysis result of f), (d) shows the analysis result of (g) in FIG. 17, and (e) shows the analysis result of (h) in FIG. It is a graph which shows the analysis result regarding the inductance characteristic of each model of FIG. It is the longitudinal cross-sectional view which showed the structure of the adhesion part of the conventional core material and a gap board.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,1 ', 1A, 1B ... I type core, 11 ... Adhesion surface, 12 ... Step part, 13 ... Endless step part, 14 ... Taper part, 2 ... Gap board, 3 ... Adhesive layer, 3a ... Fillet edge 4, resin mold body, M ... analysis model, M1 ... core analysis model, M2 ... gap plate analysis model, M3 ... adhesive layer analysis model

Claims (5)

A core material having a plurality of magnets and a non-magnetic gap plate interposed between adjacent core materials, the opposing surface of the core material and the opposing surface of the gap plate being interposed via an adhesive layer In the fixed Reach Turkey,
The core material has a cross-sectional area of the facing surface that is formed in a smaller dimension than a cross-sectional area of the other part of the core material,
The gap plate is a reactor core in which the cross-sectional area of the facing surface is formed with the same dimension as the cross-sectional area of the facing surface of the core material.   2. The reactor core according to claim 1, wherein the core material has a stepped end, and a cross-sectional area of an opposing surface thereof is smaller than a cross-sectional area of another portion.   The core material has an end formed into one shape of a truncated pyramid shape or a truncated cone shape, and the cross-sectional area of the opposing surface is smaller than the cross-sectional area of other portions. The reactor according to claim 1.   The ends of the two adhesive layers on both sides of the gap plate are connected by a second adhesive layer straddling the ends of the gap plate, and the outer surface of the adhesive layer falls from the outer surface of the core material. The reactor core according to any one of claims 1 to 3, wherein the reactor core is substantially flush with an outer surface of the core material. A reactor in which a coil is formed on the reactor core according to any one of claims 1 to 4, and an outer periphery thereof is resin-molded.

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