JP2007218789A - Torque detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque detector capable of readily mounting a holding ring, made of synthetic resin, at a suitable position. <P>SOLUTION: The torque detector includes a magnetic circuit forming member, provided on a rotating body to which torque is applied, a magnetism-collecting ring for collecting magnetic flux generated by the member, a detecting part for detecting the torque applied to the rotating body based on density of the magnetic flux collected by the ring, and the holding ring 7, made of synthetic resin having a flange 71 attached via a bolt 9 for holding the magnetism collecting ring and the detecting part. The flange 71 is equipped with an insertion hole 73, into which the bolt 9 is inserted and a tube 74 fixed to a position that is separated apart from the insertion hole 73 and is more rigid than the holding ring 7. The diameter of a hole of the tube 74 is made smaller than that of the insertion hole 73 so that at least a part of the flange 71 can be surely attached at a suitable position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a torque detection device that detects torque applied to a rotating body.

  As a torque detection apparatus, it describes in patent document 1, for example. The torque detection device of Patent Document 1 is juxtaposed in the axial direction so as to be separated from the outer periphery of a magnetic circuit forming member provided on a rotating body having an input shaft and an output shaft connected by a torsion bar. Two magnetic flux collecting rings that collect the magnetic flux generated by the magnetic flux collecting ring, a detecting unit that detects torque applied to the rotating body based on the density of the magnetic flux collected by each of the magnetic flux collecting rings, and a flange, and the magnetic flux collecting ring And a synthetic resin holding ring held by molding the detection portion, and after attaching the flange to the housing with a bolt in a state where the holding ring is inserted into the aluminum housing, the rotating body is placed inside the housing. The magnetic circuit forming member is arranged inside the magnetism collecting ring.

  The housing has a through hole penetrating in two directions and supporting the rotating body, an insertion hole into which the holding ring is inserted, and two screw holes formed on both sides of the insertion hole. In addition, the attachment portion of the holding ring is provided with first and second insertion holes corresponding to the screw holes, and the two bolts inserted through the first and second insertion holes are screwed. By tightening on the hole, the attachment portion is attached and the holding ring is attached to the housing.

In addition, since the torque detection device mounted on the electric power steering device for a vehicle is easily affected by electromagnetic noise generated by a speaker or the like, the detection unit and calculation processing of a detection signal detected by the detection unit are performed. A controller composed of a microprocessor is connected by a conductive wire covered with an electromagnetic shielding member. A ground wire having a terminal is connected to the electromagnetic shielding member of the conducting wire, and the terminal of the ground wire is attached to a vehicle body or a housing by bolts.
Japanese Patent Laid-Open No. 2005-265587

  However, in the torque detection device configured as in Patent Document 1, since the two screw holes provided in the aluminum housing are drilled by a tool such as a tap, a highly accurate screw hole (inner diameter and hole). The two insertion holes provided in the attachment part of the retaining ring made of synthetic resin are formed by the mold for forming the retaining ring. Compared with this, it is not possible to obtain a highly accurate insertion hole (inner diameter and distance between holes). Therefore, when a plurality of torque detection devices are assembled, variation occurs in the attachment position of the retaining ring. Then, after the retaining ring is attached to the housing, when the rotating body is inserted into the housing and the magnetic circuit forming member provided on the outer periphery of the rotating body is disposed inside the magnetism collecting ring, There is a possibility that the magnetic circuit forming member is biased with respect to the center of the magnetism collection ring due to variations in the attachment position, and may come into contact with the inner peripheral surface of the magnetism collection ring.

  In addition, in a torque detection device used in an electric power steering device, when the holding ring is formed of an insulating synthetic resin in order to reduce the size and improve the productivity, electromagnetic shielding is performed in the vicinity of the holding ring. In order to ground the member, a member such as a bolt dedicated to grounding is necessary.

The present invention has been made in view of such circumstances, and a main object of the present invention is to provide a torque detection device capable of reducing variations in the attachment position of the synthetic resin retaining ring.
Another object is to provide a torque detector that can easily connect a conductor covered with an electromagnetic shielding member to a ground.

  A torque detector according to a first aspect of the present invention is disposed around the outer periphery of a magnetic circuit forming member provided on a rotating body to which torque is applied, and a magnetic flux collecting ring for collecting magnetic flux generated by the magnetic circuit forming member, and the magnetic flux collecting device A detection unit that detects torque applied to the rotating body based on the density of magnetic flux collected by the ring, and an attachment unit that is attached to an appropriate object by a bolt, and holds the magnetic collection ring and the detection unit In the torque detection device including the retaining ring made of synthetic resin, the attachment portion is fixed to an insertion hole through which the bolt is inserted, and a portion separated from the insertion hole, and is a cylinder that is harder than the holding ring. The hole diameter of this cylinder is smaller than the said insertion hole, It is characterized by the above-mentioned.

  The torque detector according to a second aspect of the present invention is characterized in that the cylindrical body is longer than the length of the attachment portion in the bolt insertion direction.

  A torque detector according to a third aspect of the present invention is arranged around the outer periphery of a magnetic circuit forming member provided on a rotating body to which torque is applied, and a magnetic flux collecting ring for collecting magnetic flux generated by the magnetic circuit forming member, and the magnetic flux collecting device A detection unit that detects torque applied to the rotating body based on the density of magnetic flux collected by the ring, a conductive wire that is connected to the detection unit and is covered with an electromagnetic shielding member, and is attached to an appropriate object with a bolt. A torque detection device including a retaining ring made of synthetic resin that holds the magnetism collecting ring and the detection unit, wherein the attachment unit includes an insertion hole through which the bolt is inserted, and the insertion unit. The conductive cylinder is fixed to a position separated from the hole and is harder than the holding ring, and the hole diameter of the conductive cylinder is smaller than the insertion hole, and is connected to the electromagnetic shielding member and the conductive cylinder. A ground wire is provided.

  According to the first aspect of the present invention, the cylindrical portion that is harder than the retaining ring is fixed to the attachment portion of the retaining ring made of the synthetic resin at a position separated from the insertion hole. It can be processed with high accuracy. Therefore, the holding ring can be attached to an appropriate position by the bolt inserted into the cylinder, and the holding ring is attached by inserting another bolt into the insertion hole in the state of being attached at the appropriate position as described above. Therefore, variation in the attachment position can be reduced.

  According to the second aspect of the present invention, when the bolt is inserted into the cylindrical body and the attachment portion is attached and attached by the bolt, the cylindrical body can be attached and deformation due to the attachment force of the attachment portion can be achieved. Can be prevented.

  According to the third aspect of the invention, since the conductive cylinder that is harder than the retaining ring is fixed to the attachment portion at a location separated from the insertion hole, the hole of the conductive cylinder is processed with high accuracy by a tool such as a tap. be able to. Therefore, the holding ring can be attached to an appropriate position by a bolt inserted into the conductive cylinder, and the holding ring can be attached by inserting the bolt into the insertion hole in such a state attached at the appropriate position. Therefore, the variation in the attachment position can be reduced.

  In addition, a ground wire is connected to the conductive cylinder of the attachment portion, and one end of the conductive cylinder can be brought into contact with an appropriate object formed of a conductive material such as aluminum. By inserting and attaching the bolt, the electromagnetic shielding member of the conducting wire can be easily grounded.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
Embodiment 1
1 is a longitudinal front view of a state in which the torque detection device according to the present invention is incorporated in a housing, FIG. 2 is a longitudinal side view of the state in which the torque detection device is incorporated in a housing, and FIG. 4 is an exploded perspective view of a part of the torque detection device, FIG. 5 is a schematic exploded perspective view showing the configuration of the torque detection device, and FIG. 6 is an explanation of a magnetic circuit generated when the rotating body rotates in one direction. FIG.

  The torque detection device A is disposed around the outer periphery of the magnetic circuit forming member 4 included in the first rotating body 2 and the second rotating body 3 that are coaxially connected by the torsion bar 1, and the magnetic circuit forming member 4 is Two magnetic flux collecting rings 5 and 5 that collect the generated magnetic flux, a detection unit 6 that detects torque applied to the first rotating body 2 based on the density of the magnetic flux collected by the magnetic flux collecting rings 5 and 5, and magnetism A housing 8 that surrounds the circuit forming member 4 has a flange 71 attached by bolts 9, 9. A holding ring 7 that holds the magnetism collecting rings 5, 5 and the detection unit 6, and an outer periphery of the holding ring 7. And a magnetic shielding plate 10 to be covered. The magnetic circuit forming member 4 is disposed around the outer periphery of the first rotating body 2, the plurality of permanent magnets 41 and the outer periphery of the permanent magnet 41, and is fitted on the second rotating body 3. It consists of two fixed magnetic rings 42 and 42.

  The permanent magnet 41 is a multipolar magnetized ring in which N poles and S poles are alternately magnetized at a plurality of circumferential positions, and is externally fixed to the outer peripheral portion of the first rotating body 2. .

  The magnetic rings 42, 42 extend from the two annular plate portions 42 a, 42 a facing each other in the axial direction of the second rotating body 3 and the inner peripheral portions of the annular plate portions 42 a, 42 a so as to approach each other. Comb teeth 42b and 42b, and the magnetic flux density between the magnetic rings 42 and 42 is changed by rotating relative to the permanent magnet 41. The comb teeth 42b and 42b are arranged at equal intervals so as to alternately mesh with each other in the circumferential direction, and the magnetic rings 42 and 42 are molded with a synthetic resin material in a state where the comb teeth 42b and 42b alternately mesh with each other. It has become.

  The magnetism collecting rings 5 and 5 extend radially outward from one place in the circumferential direction, have a cylindrical shape having convex pieces 5a and 5a disposed on both sides of the detection unit 6, and the convex pieces 5a and 5a It is comprised so that magnetic flux may gather. In addition, the detection unit 6 is molded with a synthetic resin material in a state where the detection unit 6 is disposed between the convex pieces 5a and 5a to form a molded body. Further, the magnetic flux collecting rings 5 and 5 are formed by molding a magnetic plate such as an iron plate, and are arranged apart from each other in the axial direction.

  The retaining ring 7 holds the magnetism collecting rings 5 and 5 by molding the magnetism collecting rings 5 and 5 with a synthetic resin material. The retaining ring 7 has a through hole 7a corresponding to the inner peripheral surface of the magnetism collecting rings 5 and 5, and the magnetism collecting rings 5 and 5 are fitted and fixed to the through hole 7a. The holding ring 7 has both end surfaces 7b and 7b in the axial direction, a substantially semicircular outer peripheral surface 7c, and two extending outer surfaces 7d and 7d extending in a tangential direction from the substantially semicircular outer peripheral surface 7c. The peripheral surface between both end faces 7b and 7b is substantially U-shaped, the extending side of the extending outer surfaces 7d and 7d is a rectangular cross section, and the rectangular shape is at the extending end of the extending outer surfaces 7d and 7d. Are formed integrally with a synthetic resin material. The flange 71 and the square cylinder 72 projecting from the center of the flange 71 and containing the detection circuit board 11 are integrally formed.

  The flange 71 as the attachment portion is provided with an insertion hole 73 through which the bolt 9 is inserted on one side of the rectangular tube portion 72, and is made of a metal harder than the holding ring 7 on the other side of the rectangular tube portion 72. The cylindrical body 74 is fixed.

  The cylindrical body 74 is disposed together with the magnetic flux collecting rings 5 and 5 and the detection unit 6 in the cavity of the molding die, and is integrally molded by injecting a synthetic resin material into the cavity. The cylindrical body 74 is formed by integrally molding a hole processed with high accuracy, or fixed by integral molding, and then processing the hole with high accuracy using a tool such as a tap. This hole processing has a smaller diameter than the insertion hole 73 and a slightly larger diameter than the bolt 9, in other words, a hole diameter that allows the bolt 9 to be inserted without rattling. Further, the cylindrical body 74 is formed to be slightly longer than the length of the flange 71 in the bolt insertion direction, and this longer portion projects outward from the surface of the flange 71.

  The insertion hole 73 is formed larger in diameter than the bolt 9 so that a gap is formed between the insertion hole 73 and the peripheral surface of the bolt 9.

  A detection circuit board 11 connected to the detection unit 6 is attached in the rectangular tube part 72, and a conducting wire 12 is connected to the detection circuit board 11.

  The detection unit 6 includes a Hall element whose electrical characteristics (resistance) change according to a change in magnetic flux density generated between the convex pieces 5a and 5a of the magnetic flux collecting rings 5 and 5, and the convex piece of the magnetic flux collecting rings 5 and 5 The detection signal is changed according to the change of the magnetic flux density generated between 5a and 5a, and the detection signal is given to the detection circuit board 11. In addition to the Hall element, the detection unit 6 only needs to have a magnetosensitive element whose electrical characteristics (resistance) change due to the action of a magnetic field, such as a magnetoresistive element (MR element). Not.

  The magnetic shielding plate 10 has a substantially U shape corresponding to the substantially semicircular outer peripheral surface 7c and the extended outer surfaces 7d and 7d, and is formed of a flexible nonmagnetic material such as a silicon steel plate. Further, at both ends of the magnetic shielding plate 10, locking pieces that are locked by caulking are provided in the recesses formed in the extended outer surfaces 7d and 7d.

  The housing 8 as an appropriate object is provided with a cylindrical portion 81 surrounding the magnetic circuit forming member 4, a mounting seat 82 for attaching the retaining ring 7, and a mounting seat 82, which protrudes from one outer peripheral portion of the cylindrical portion 81. A through-hole 83 having a rectangular cross section for passing through the seating 82 in the radial direction and disposing the holding ring 7 in the cylindrical portion 81, and a fitting groove that continues to the through-hole 83 and curves in correspondence with the holding ring 7 84 (see FIG. 2).

  The attachment seat 82 is formed in a rectangular ring shape corresponding to the flange 71, and the screw seat 85 is provided with two screw holes 85 and 85 corresponding to the holes of the insertion body 73 and the cylindrical body 74.

  In the torque detection device A configured as described above, the holding ring 7 is inserted into the cylindrical portion 81 from the through hole 83 penetrating the attachment seat 82 of the housing 8, and the holding ring 7 is engaged with the fitting groove 84. As a result, the position of the retaining ring 7 in the cylindrical portion 81 is determined, and the flange 71 is brought into contact with the seat 82. In this state, the bolt 9 is inserted into the cylindrical body 74 of the flange 71, the bolt 9 is tightened into the screw hole 85, the bolt 9 is inserted into the insertion hole 73 of the flange 71, and the bolt 9 is tightened into the screw hole 85. By doing so, the flange 71 is attached, and the holding ring 7 is attached to the attachment seat 82. In this case, since the hole of the cylindrical body 74 is formed with high accuracy and has a smaller diameter than the insertion hole 73, the displacement of the holding ring 7 with respect to the bolt 9 tightened in the screw hole 85 is prevented. The holding ring 7 can be fixed at an appropriate position. Further, since the insertion hole 73 has a larger diameter than the hole of the cylindrical body 74 and there is a gap between the insertion hole 73 and the peripheral surface of the bolt 9, even when there is a dimensional error in the insertion hole 73 with respect to the screw hole 85, the insertion hole 73. The bolt 9 inserted through can be securely fastened to the screw hole 85.

  After attaching the torque detection device A to the housing 8 as described above, the rotating bodies 2 and 3 having the magnetic circuit forming member 4 provided on the outer peripheral portion, the bearing 14 for rotatably supporting the rotating bodies 2 and 3 and the like Is inserted and supported in the housing 8 from the axial direction of the housing 8, and the magnetic circuit forming member 4 is disposed inside the magnetism collecting rings 5 and 5 so as to be capable of relative rotation. In this case, since the holding ring 7 is attached to the mounting position 82 by the bolts 9 and 9 inserted through the cylindrical body 74 and the insertion hole 73, the magnetic circuit forming member 4 is attached to the magnetism collecting rings 5 and 5. It can be arranged at an appropriate position.

  FIG. 7 is a cross-sectional view showing a state in which the torque detection device is mounted on the electric power steering device. The torque detection device A configured as described above is mounted on, for example, an electric power steering device for a vehicle. This electric power steering apparatus includes an input shaft 20 (first rotating body 2) connected to a steering wheel, and an output shaft 21 (second rotating body 3) coaxially connected to the input shaft 20 by a torsion bar 1. A housing 22 that surrounds the input shaft 20 and the output shaft 21 and rotatably supports the input shaft 20 and the output shaft 21 by the three bearings 14, and an electric motor 23 for steering assistance attached to the housing 22; A reduction mechanism 24 that transmits the rotational force of the drive shaft of the electric motor 23 to the output shaft 21, the torque detection device A, the detection circuit board 11 of the torque detection device A, and the drive circuit of the electric motor 23 are connected by a lead 12. And a control unit (not shown) using a microprocessor. The detection unit 6 detects the rotational torque applied to the input shaft 20 by steering the steering wheel by the twist generated in the torsion bar 1, and the detection torque is converted into a voltage signal by the detection circuit board 11 and then controlled from the lead 12. The electric motor 23 is driven and controlled by an instruction signal output from the control unit and the output shaft 21 rotates via the speed reduction mechanism 24.

Embodiment 2
FIG. 8 is a cross-sectional view showing the configuration of the torque detection device according to the second embodiment. The torque detection device A of this embodiment has conductivity and uses a conductive cylinder 75 that is harder than the retaining ring 7 in place of the cylinder 74, and is further connected to the detection circuit board 11 and electromagnetic shielding member 12a. And a ground wire 15 connected to the electromagnetic shielding member 12a and the conductive cylinder 75.

  The conducting wire 12 includes a plurality of lead wires 12b, a net-like electromagnetic shielding member 12a that covers the lead wires 12b, and an insulating member 12c that covers the electromagnetic shielding member 12a, and an end portion of the electromagnetic shielding member 12a. Is connected to the ground wire 15. A terminal 16 having a through hole through which the bolt 9 is inserted is connected to the tip of the ground wire 15.

  The conductive cylinder 75 has conductivity, is formed of a metal material harder than the retaining ring 7, and has an end surface having a size corresponding to the terminal 16. The conductive cylinder 75 is disposed together with the magnetism collecting rings 5 and 5 and the detection unit 6 in the cavity of the molding die, and is integrally molded by injecting a synthetic resin material into the cavity. In addition, the conductive cylinder 75 is formed by integrally molding a hole processed with high precision, or after being fixed by integral molding, the hole is processed with high accuracy by a tool such as a tap. This hole processing is provided with a through-hole that is smaller in diameter than the insertion hole 73 and slightly larger in diameter than the bolt 9, in other words, that allows the bolt 9 to be inserted without rattling. Further, the conductive cylinder 75 is formed to be slightly longer than the length of the flange 71 in the bolt insertion direction, and this long portion protrudes from the surface of the flange 71 to the outside.

  9 and 10 are enlarged cross-sectional views of the conductive cylinder portion. As means for providing an end face of a size corresponding to the terminal 16, the conductive cylinder 75 is formed with a larger diameter than the annular terminal 16 in FIG. 9, and a flange 75a having a larger diameter than the annular terminal 16 is provided in FIG. It is. The conductive cylinder 75 is formed of a conductive material. However, a conductive layer may be provided on the surface of a half formed of a non-conductive material. It is good also as a structure which provided the conductive layer in the part.

In the torque detection device A configured as described above, the holding ring 7 is inserted into the cylindrical portion 81 from the through hole 83 penetrating the attachment seat 82 of the housing 8, and the holding ring 7 is engaged with the fitting groove 84. As a result, the position of the retaining ring 7 in the cylindrical portion 81 is determined, and the flange 71 is brought into contact with the seat 82. In this state, the terminal 16 of the ground wire 15 is brought into contact with one end face of the conductive cylinder 75, the bolt 9 is inserted into the terminal 16 and the conductive cylinder 75, the bolt 9 is fastened to the screw hole 85, and the flange The bolt 9 is inserted into the insertion hole 73 and the bolt 9 is fastened to the screw hole 85, whereby the flange 71 is attached and the holding ring 7 is attached to the attachment seat 82. In this case, since the other cross section of the conductive cylinder 75 is in contact with the mounting seat 82 of the housing 8 formed of a conductive material such as aluminum, the electromagnetic shielding member 12a is connected to the ground wire 15, the terminal 16, and the conductive cylinder. 75 and the housing 8 can be grounded to the vehicle body. Further, since the hole of the conductive cylinder 75 is formed with high accuracy and is formed with a smaller diameter than the insertion hole 73, the displacement of the holding ring 7 with respect to the bolt 9 fastened to the screw hole 85 is prevented. And the retaining ring 7 can be fixed at an appropriate position. Further, since the insertion hole 73 has a larger diameter than the hole of the conductive cylinder 75 and there is a gap between it and the peripheral surface of the bolt 9, the insertion hole 73 even when there is a dimensional error in the insertion hole 73 with respect to the screw hole 85. The bolt 9 inserted through 73 can be securely fastened to the screw hole 85.
Since other configurations and operations are the same as those in the first embodiment, common parts are denoted by the same reference numerals, and detailed descriptions thereof and descriptions of operations and effects are omitted.

  In the embodiment described above, the insertion hole 73 and the cylindrical body 74 are provided in the flange 71 as the attachment portion. However, in addition to the configuration in which the cylindrical body 74 is provided in place of the insertion hole 73, that is, two spaced apart. It is good also as a structure which provided the cylinders 74 and 74 in one location.

  In the embodiment described above, the cylindrical body 74 is longer than the length of the flange 71 as the attachment portion in the bolt insertion direction, or other than the length of the attachment portion in the bolt insertion direction. It is good also as a structure provided with the cylinder 74. FIG.

  Further, the torque detection device A according to the present invention may be used for devices other than the electric power steering device in addition to the electric power steering device.

It is a vertical front view of the state which built the torque detection apparatus which concerns on this invention in the housing. It is a vertical side view of the state which incorporated the torque detection apparatus which concerns on this invention in the housing. It is an expanded sectional view of the important section of the torque detector concerning the present invention. It is the perspective view which decomposed | disassembled some torque detection apparatuses which concern on this invention. It is a typical exploded perspective view showing the composition of the torque detector concerning the present invention. It is explanatory drawing of the magnetic circuit which generate | occur | produces when a rotary body rotates to one direction. It is sectional drawing which shows the state with which the torque detection apparatus which concerns on this invention was mounted in the electric power steering apparatus. It is sectional drawing which shows the structure of Embodiment 2 of the torque detection apparatus which concerns on this invention. It is an expanded sectional view of the conductive cylinder part of the torque detector according to the present invention. It is an expanded sectional view of the conductive cylinder part of the torque detector according to the present invention.

Explanation of symbols

2 1st rotating body (rotating body) 3 2nd rotating body (rotating body) 4 Magnetic circuit formation member,
5 magnetism collecting ring, 6 detecting section, 7 holding ring, 71 flange (attaching section), 73 insertion hole,
74 cylinders, 75 conductive cylinders, 8 housings (objects), 9 bolts, 12 conductors,
12a Electromagnetic shielding member, 15 Ground wire

Claims (3)

  Based on the magnetic flux collecting ring arranged around the outer periphery of the magnetic circuit forming member provided on the rotating body to which torque is applied and collecting the magnetic flux generated by the magnetic circuit forming member, and the density of the magnetic flux collected by the magnetic collecting ring A detection unit that detects torque applied to the rotating body, and a holding ring made of a synthetic resin that has a mounting unit that is attached to an appropriate object by a bolt and holds the magnetism collecting ring and the detection unit. In the torque detector, the attachment portion includes an insertion hole through which the bolt is inserted, and a cylindrical body that is fixed to a place separated from the insertion hole and is harder than the holding ring, and the hole diameter of the cylindrical body Is a smaller diameter than the insertion hole.   The torque detection device according to claim 1, wherein the cylindrical body is longer than a length of the attachment portion in a bolt insertion direction. Based on the magnetic flux collecting ring arranged around the outer periphery of the magnetic circuit forming member provided on the rotating body to which torque is applied and collecting the magnetic flux generated by the magnetic circuit forming member, and the density of the magnetic flux collected by the magnetic collecting ring A detector that detects torque applied to the rotating body; a conductor that is connected to the detector and is covered with an electromagnetic shielding member; and an attachment that is attached to an appropriate object by a bolt. In the torque detection device comprising a magnetic ring and a synthetic resin retaining ring that retains the detection portion, the attachment portion is fixed to an insertion hole through which the bolt is inserted, and a location separated from the insertion hole, A torque characterized by comprising a conductive cylinder harder than the holding ring, the hole diameter of the conductive cylinder being smaller than that of the insertion hole, and a ground wire connected to the electromagnetic shielding member and the conductive cylinder. Detection device.

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