JP5388111B2 - Stirling engine - Google Patents

Description

  The present invention relates to a Stirling engine, and more particularly to a Stirling engine that can convert heat energy into electric energy or the like using exhaust heat as a heat source.

  In recent years, a Stirling engine has attracted attention as a device capable of converting heat energy into electric energy or the like using exhaust heat as a heat source in order to recover heat energy discharged from a ceramic furnace, a waste treatment furnace, or the like.

  As is well known, the basic configuration of a Stirling engine is that a power piston is accommodated in a cylinder, and a displacer piston for moving a working fluid such as air is accommodated in the cylinder. It is configured to move while maintaining a gap, and the one in which these power piston and displacer piston are accommodated in one cylinder is called a one-cylinder type. The power piston and the displacer piston are connected via a crank mechanism, and a mechanical link type (kinematic type) configured to reciprocate on the same axis while maintaining a constant phase difference, and a crank mechanism are required. A free piston type is known, and an example of the former is disclosed in Patent Document 1 below.

  In Patent Document 1, “One of the important methods for obtaining a high-performance Stirling engine is to introduce a working gas into the crank chamber and make the crank chamber into a pressure-resistant structure so that the crank chamber penetrating portion of the rotating shaft The internal friction and the external leakage that are likely to occur when using other seal systems are extremely reduced by using a mechanical seal or by placing a generator in the crank chamber. In order to prevent an increase in weight, the crank chamber needs to be as small as possible.On the other hand, the Lombic crank mechanism having two twin cranks 1 and 2 as shown in FIG. However, since this method has two cranks, the crank chamber becomes large and a compact pressure-resistant structure Is difficult to make. "(Patent Document 1, page 1, lower left column, 14th line to lower right column, 9th line) Phase shift between a single crank with a rotating shaft and a displacer piston arranged in a skewer shape in the cylinder by two linkages extending obliquely upward and obliquely downward from the crankpin, and a power piston An eccentric crank type Stirling engine that is driven up and down with a delay and that can pressurize the entire crank chamber. ”(Patent Document 1, page 1, lower left column, lines 5 to 12) Has been proposed. That is, the “eccentric slider crank mechanism” referred to in mechanics is configured, and in Japanese Patent Application Laid-Open No. H10-318707, two sliders called a cross head and housed in a longitudinal groove and two connecting rods are essential.

  On the other hand, in paragraph [0004] of Patent Document 2 below, “There are three main types of structures for realizing the Stirling cycle: an alpha type, a beta type, and a gamma type. Each space has one power piston, also known as a two-piston type.This method is characterized by a very small dead space because each of the two pistons is completely scavenged in each space. Has been. And in the same paragraph [0007] regarding the same beta type as in Patent Document 1, “Beta type has one power piston on the low temperature side, and the displacer fits in the same cylinder as the power piston and moves while overlapping each other. It is characterized by being capable of complete scavenging. " Furthermore, in paragraph [0008] of Patent Document 2, “The gamma type has one power piston on the low temperature side and the displacer fits in another cylinder. Therefore, the diameter is increased to increase the amount of gas passing through the regenerator. The ratio can be optimized according to the temperature difference. "

  Furthermore, regarding the same beta type as in Patent Document 1, in Patent Document 3, the paragraph [0002] states that “The Stirling engine uses a low-temperature heat source. Reducing mechanical loss due to piston seal and mechanism friction is one of the development issues, ”and described in paragraph [0003],“ The Scotch-Yoke mechanism increases the mass of the reciprocating part of the yoke. There is a problem with the increase in mechanical loss due to contact, the strength and wear resistance of the contact between the crankpin and the yoke, and the clearance between the crankpin bearing and the yoke must be set appropriately to reduce noise and mechanical loss. To provide a Stirling engine that reduces sliding loss and provides a highly reliable Scotch-yoke mechanism as described in the paragraph [0004]. It has been proposed. That is, here, a “cross slider crank mechanism” which is one of the “double mechanism” in mechanics, a so-called Scotch yoke mechanism is configured, and three connecting rods are indispensable.

JP-A-58-25555 JP 2006-118430 A JP 2008-101501 A

  As for the displacer piston in the above-mentioned Patent Document 2, as in a piston support structure in a general internal combustion engine, a connecting member that rotatably supports one end portion on a crank and swingably supports the other end portion in the radial center of the piston. A slider crank mechanism having a rod and using the piston as a slider is employed, but the power piston has a pair of connecting rods disposed on both sides with respect to the center in the radial direction. On the other hand, in the beta type as described in Patent Documents 1 and 3, the connecting rod cannot swingably support the displacer piston and the power piston at the center in the radial direction of each piston. . For this reason, a pair of connecting rods are arranged on both sides with respect to the radial center of the power piston.

  In Patent Documents 1 and 3, as described above, the “eccentric slider crank mechanism” and the “scotch yoke mechanism” are used, respectively, and the apparatus has a complicated structure, a large number of parts, and an expensive apparatus. . However, it is desirable that such a beta type also has a basic structure of a slider crank mechanism having a connecting rod that supports the other end of the power piston so as to be swingable at the center in the radial direction of the power piston. .

  Therefore, the present invention is a Stirling engine in which a power piston arranged coaxially with a displacer piston is configured to reciprocate in the axial direction of the cylinder, and the displacer piston and the power piston are smoothly arranged coaxially with a simple structure. It is an object to provide a Stirling engine that can move.

In order to solve the above problems, a Stirling engine according to the present invention accommodates a displacer piston in a cylinder to form a high temperature space and a low temperature space, and the working fluid in both spaces moves periodically via a regenerator. The displacer piston is reciprocated in the axial direction of the cylinder while a power piston arranged coaxially with the displacer piston is fixed in the Stirling engine configured to reciprocate in the axial direction of the cylinder. A flywheel rotatably supported with respect to the housing, a first crank having a first rotation center at a first offset position with respect to the rotation axis of the flywheel, and one end portion of the first crank rotating to the first crank The other end of the power piston is swingably supported at the center in the radial direction of the power piston. And a first slider crank mechanism having the power piston as a slider, and one end fixed to the displacer piston and the other end extending through the power piston. A slider rod which is disposed and supported by the power piston so as to be slidable on an axis parallel to the reciprocating movement axis of the power piston, and a second rotation at a second offset position with respect to the rotation axis of the flywheel. A second crank having a center, and a second connecting rod that rotatably supports one end on the second crank and swingably supports the other end on the other end of the slider rod. the second slider crank mechanism which the slider rod and slider, arranged on an axis parallel to the reciprocating axis of the power piston, the power Piston and is fixed at one end portion on one side of the displacer piston is obtained by a further comprising a guide rod for supporting the other end portion slidably on the other side of said power piston the displacer piston.

In the above Stirling engine, the fixed position of the guide rod may be set on an axis separated by a distance equal to a radial distance from a position where the slider rod penetrates the power piston to a radial center of the power piston. Further, the slider rod and the guide rod are arranged so that the plane including the slider rod and the guide rod includes the rotation axis of the flywheel, and the plane orthogonal to the plane including the slider rod and the guide rod. It is preferable to arrange the first and second connecting rods so as to swing on the top.

Since this invention is comprised as mentioned above, there exists an effect as described below. That is, the Stirling engine configured as described above includes the first slider crank mechanism and the second slider crank mechanism, and has a simple structure including the first and second connecting rods, and a displacer piston and Smooth operation of the power piston can be ensured, and the power piston can be configured at low cost. In particular, in a so-called beta-type Stirling engine in which two pistons, a displacer piston and a power piston, are housed in a single cylinder, the power piston to which a large pressure is applied by the first slider crank mechanism has its diameter. Since it is supported at the center, it can reciprocate in the axial direction with a stable posture. On the other hand, the displacer piston is not applied with such a large pressure, and the displacer piston does not necessarily need to be supported at the center in the radial direction. Smooth operation can be ensured by supporting the power piston so as to be slidable on an axis parallel to the shaft. In addition, since the guide rod is supported on one of the power piston and the displacer piston so as to be movable in the axial direction, the displacer piston can be reliably prevented from rotating, and the displacer piston can be held in a more stable state. it can.

It is a longitudinal section showing a Stirling engine concerning one embodiment of the present invention. It is a longitudinal cross-sectional view of the Stirling engine which concerns on one Embodiment of this invention by the side view. 1 is an enlarged longitudinal sectional view showing a part of a Stirling engine according to an embodiment of the present invention. It is a skeleton figure of the 1st and 2nd slider crank mechanism in the Stirling engine concerning one embodiment of the present invention. It is a circuit diagram which shows an example of a mounting state and a control circuit when applying this invention to a generator and comprising a Stirling engine generator.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1 and FIG. 2, this embodiment is a mechanical link type (kinematic type) Stirling engine. As shown in FIG. 1, the housing 1 includes a cylinder of the Stirling engine. 10 and a motor generator 2 that functions as an electric motor and a generator are fixed, and both are connected as described later.

  A displacer piston 20 is accommodated in the cylinder 10 to form a high temperature space HS and a low temperature space LS, and the displacer piston 20 moves in the axial direction of the cylinder 10 while the working fluid in both spaces periodically moves through the regenerator 30. The power piston 40 disposed coaxially with the displacer piston 20 is configured to reciprocate in the axial direction of the cylinder 10. 1 shows a state in which the high temperature space HS has a minimum capacity and the low temperature space LS has a maximum capacity, and FIG. 2 shows a state in which the high temperature space HS has a maximum capacity and the low temperature space LS has a minimum capacity. The cylinder 10 is formed by welding a cylinder head 11 and a cylindrical cylinder body 12, and covers the inner wall surface of the cylinder 10 and the outer wall surface of the displacer piston 20 over the entire length of the reciprocating movement locus of the displacer piston 20 in the cylinder 10. The displacer piston 20 is supported so as to be axially movable with respect to the power piston 40 so as to maintain a constant annular gap therebetween.

  The regenerator 30 of the present embodiment is composed of a laminated cylinder having a plurality of metal mesh layers. For example, after a single metal mesh is wound a plurality of times, the winding end is spot-welded to form a laminated cylinder. It is formed. Or it replaces with this and it is good also as using the other member which can make the ensuring of heat storage amount and reduction of ventilation resistance compatible. The regenerator 30 is disposed in the annular gap, and is supported by the cylinder 10 so as to maintain an annular flow path having a constant gap with respect to the working fluid during the reciprocating movement of the displacer piston 20 in the cylinder 10. Yes. The working fluid is a gas, and helium gas is used in this embodiment, but air may be used.

  As shown in an enlarged view in FIG. 3, an annular recess 10 r is formed on the inner wall surface of the cylinder 10, and the regenerator 30 is fitted into the annular recess 10 r, and the full length of the reciprocating movement locus of the displacer piston 20 in the cylinder 10. The displacer piston 20 is slidably supported by the power piston 40 so that a constant gap (clearance d) is maintained in the circumferential direction between the inner wall surface of the regenerator 30 and the outer wall surface of the displacer piston 20. During the reciprocating movement of the displacer piston 20 in the cylinder 10, an annular flow path CP with a constant gap (d) is maintained with respect to the working fluid.

  Further, as shown in FIG. 1, an annular recess 12 r is formed on the outer wall surface of the cylinder body 12, and a support cylinder 13 is disposed so as to cover the annular recess 12 r, and is liquid-tight with respect to the cylinder body 12. It is fixed to. The support cylinder 13 is provided with a cooling medium inflow portion FI and a cooling medium outflow portion FO, and the cooling medium (for example, water) is cooled in the annular space CL defined by the annular recess 12r and the support cylinder 13. It is configured to be introduced from the inflow portion FI and discharged from the cooling medium outflow portion FO, thereby forming a cooler, and a low temperature space LS is formed in the cylinder body 12. On the other hand, the cylinder head 11 is provided with a plurality of heat collecting fins 11f. The cylinder head 11 is heated by a heat source (not shown) through these heat collecting fins 11f, and the high temperature space HS is formed in the cylinder head 11. Is formed. Thus, the regenerator 30 is held in the cylinder 10 so as to be positioned between the high temperature space HS and the low temperature space LS, and the working fluid in both spaces periodically moves via the regenerator 30. However, the displacer piston 20 can reciprocate in the axial direction of the cylinder 10.

  As shown in FIGS. 1 and 2, the cylinder 10 is fixed to the housing 1, and a flywheel 80 is supported on the housing 1 so as to be rotatable around a rotation shaft 81 (the rotation center is indicated by C <b> 2). Yes. A first crank having a first rotation center (indicated by C6) at a first offset position with respect to the rotation shaft 81 (rotation center C2 of the flywheel 80) is a crankshaft portion 82 (rotation center) of the flywheel 80. Part including C2 and C6). One end of the first crank (crankshaft portion 82) including the rotation center C6 is rotatably supported, and the other end is swung to the radial center (indicated by RC) of the power piston 40. A first connecting rod 62 that supports the rocking center (shown by C4) is provided, and a first slider crank mechanism 60 using the power piston 40 as a slider is configured.

  Further, one end portion of the slider rod 50 is fixed to the displacer piston 20 and the other end portion is disposed so as to extend downward in FIG. 1 through the through hole 41 of the power piston 40. Is supported by the power piston 40 so as to be slidable on an axis parallel to the power piston 40. A second crank having a second rotation center (indicated by C7) at a second offset position with respect to the rotation shaft 81 (rotation center C2) of the flywheel 80 is constituted by the link plate 71. One end of the second crank (link plate 71) is rotatably supported (the center of rotation is indicated by C7), and the other end is swingable to the other end of the slider rod 50 (the center of swing is C5). The second connecting rod 72 is provided to support the slider rod 50 (and the displacer piston 20 that moves integrally with the slider rod 50), and the second slider crank mechanism 70 is configured.

  As shown in FIG. 1, bearings (ball bearings) B1 to B4 are mounted at the rotation center and the swing center, and smooth rotation and swing motion are ensured. That is, the large end portion 61 of the first connecting rod 62 is rotatably supported by the protrusion including the rotation center C6 of the crankshaft portion 82 via the bearing B1. On the other hand, the small end 63 of the first connecting rod 62 is swingably supported by the power piston 40 via the bearing B2 and the piston pin 42, and has a so-called semi-floating structure. It is good.

  A link plate 71 that constitutes the second crank is fixed to the protrusion including the rotation center C6 of the crankshaft portion 82 that constitutes the first crank, and the link plate 71 is integrated with the flywheel 80. Rotate to. The link plate 71 is formed in a fan shape as shown in FIG. 2, and is firmly fixed to the flywheel 80 (the crankshaft portion 82) by the two bolts shown in FIG. Further, one end of the second connecting rod 72 is rotatably supported by the link plate 71 via the bearing B3 (rotation center C7), and the other end is supported by the other end of the slider rod 50 via the bearing B4. It is supported at the end so as to be swingable (swing center C5).

  As shown in FIG. 1, a slider rod 50 is fixed to the end of the displacer piston 20. The slider rod 50 penetrates the power piston 40 and can move in the through hole 41 of the power piston 40 in the axial direction. It is supported by. If surface hardening treatment such as DLC (diamond-like carbon) coating is performed in the through hole 41 of the power piston 40 that is the support portion of the slider rod 50, the slider rod 50 and thus the displacer piston 40 are in a stable state. During reciprocating movement of the displacer piston 40 in the cylinder 10, the annular flow path (CP in FIG. 3) having a constant gap with respect to the working fluid can be more reliably maintained. Furthermore, it is preferable to subject the sliding portion between the power piston 40 and the cylinder 10 to a surface hardening treatment by DLC coating or the like.

  FIG. 4 shows the first and second slider crank mechanisms 60 and 70 represented by skeletons. FIG. 4 is a skeleton that is identical to the configuration of FIG. 2, and is indicated by using the reference numerals in FIGS. 1 and 2. As described above, the slider rod 50 is fixed to the displacer piston 20 and moves integrally along the sliding shaft (shown by a broken line in FIG. 4). Therefore, since the sliding axis (broken line) of the slider rod 50 is actually overlapped with the reciprocating movement axis (solid line) of the power piston 40, the broken line and the solid line are on the same line. Is shown offset. The relationship between the first rotation center (C6) and the second rotation center (C7) is that the displacer piston 20 has a phase difference that precedes the power piston 40 by a predetermined crank angle (60 degrees in this embodiment). Is set.

  In the present embodiment, the guide rod 90 is further disposed on an axis parallel to the reciprocating movement axis of the power piston 40, and one end is press-fitted and fixed to the power piston 40. The other end of the guide rod 90 is slidably supported by the displacer piston 20. The above relationship may be reversed, and one end of the guide rod 90 may be press-fitted and fixed to the displacer piston 20 and the other end may be slidably supported on the power piston 40. The guide rod 90 of the present embodiment is fixed on an axis separated by a distance equal to the radial distance from the position where the slider rod 50 penetrates the power piston 40 to the radial center (RC) of the power piston 40. That is, as shown in FIG. 1, the slider rod 50 and the guide rod 90 are arranged so that the central axes of both are equidistant on both sides of the radial center (RC). In particular, the slider rod 50 and the guide rod 90 are arranged so that the plane including the slider rod 50 and the guide rod 90 includes the rotation shaft 81 of the flywheel 80, and the plane including the slider rod 50 and the guide rod 90 (FIG. 1). The first and second connecting rods 62 and 72 are arranged so as to swing on a plane orthogonal to the sheet surface.

  As the power piston 40 moves in the axial direction, the guide rod 90 also moves in the axial direction. However, since the guide rod 90 moves while being slidably supported by the displacer piston 20, it affects the axial movement of the displacer piston 20. The power piston 40 and the displacer piston 20 move independently of each other in the axial direction. In particular, the displacer piston 20 is provided by the guide rod 90 even when a rotational force about the central axis is applied to the displacer piston 20 due to the axial movement of the power piston 40 due to the arrangement of the mechanical components. Independent axial movement can be ensured. However, the guide rod 90 may be omitted as long as the power piston 40 and the displacer piston 20 can ensure independent axial movement.

  The Stirling engine configured as described above is mounted on, for example, the exhaust heat cylinder EX shown in FIG. In this case, it arrange | positions so that the upper and lower sides of FIG. 1 may become reverse. That is, the housing 1 is fixed to the heat exhaust cylinder EX of the heat source, and the Stirling engine is supported in a state where the heat collecting fins 11f of the cylinder head 11 are accommodated therein. The motor generator 2 connected to the flywheel 80 is constituted by, for example, a well-known permanent magnet synchronous motor, and functions as an electric motor and a generator. Will be described later.

  The present embodiment is configured as described above. In a so-called beta-type Stirling engine in which the displacer piston 20 and the power piston 40 are accommodated in a single cylinder 10, a large pressure is applied by the first slider crank mechanism 60. Since the power piston 40 to which is provided is supported at the radial center RC, the power piston 40 can reciprocate in the axial direction with a stable posture. On the other hand, the displacer piston 20 is not applied with such a large pressure, and the displacer piston 20 does not necessarily have to be supported at the center in the radial direction. Smooth operation can be ensured by supporting the power piston 40 so as to be slidable on an axis parallel to the reciprocating movement axis. Thus, with a simple configuration having the first and second connecting rods 62 and 72, the smooth operation of the displacer piston 20 and the power piston 40 can be ensured, and the size and weight can be reduced. As well as improved reliability and durability. Therefore, even when industrial exhaust heat at around 500 ° C. is used as a heat source, heat energy can be efficiently converted into electric energy, so that it can be put to practical use as an exhaust heat recovery device. For example, even with a medium temperature exhaust heat of around 500 ° C., even when the working fluid is at a pressure of 1 Mpa or less, the annular flow path (CP in FIG. 3) with a constant gap is reliably maintained and the displacer piston 20 can be smoothly reciprocated. It can be carried out.

  FIG. 5 shows an example of a mounting state of the Stirling engine generator SE including the Stirling engine and the motor generator shown in FIG. 1 and FIG. 2 and an example of a control circuit used for power generation control. The cylinder head 11 is exposed to high-temperature exhaust gas that is mounted so as to extend into the cylinder EX and passes through the exhaust heat cylinder EX, and is heated. The motor generator 2 is connected to a DC power source 202 by a main circuit 201 via a relay RC1 that intermittently connects the motor generator 2, and three circuits are connected in parallel to the main circuit 201.

  First, the first circuit is a rotation speed substitute circuit, in which a relatively small resistor 203 and a relatively large resistor 204 are connected in series, and the voltage Vs across the relatively large resistor 204 varies in the range of 0 to 10V. Is set as follows. Since this voltage Vs is proportional to the engine speed, it is used as a value representing the rotational speed. Next, the second circuit is a dummy resistor circuit, and includes a dummy resistor 205 having a capacity capable of absorbing the power generation capacity, and a relay RC2 that intermittently connects the circuit leading to the dummy resistor 205. The third circuit is a battery charging circuit, and a charge controller 206 is interposed between the relay RC3 and the battery 207 for intermittently connecting the third circuit. The voltage of 0 to 30V on the power generation side is regulated to about 14V by the charge controller 206, and supplied to the 12V battery 207 for charging. In addition, power is supplied to the cooling fan 208 attached to the outside via the charge controller 206.

  In FIG. 5, as an example of power use of the battery 207, the DC-AC converter 209 converts the voltage from DC 12 V to AC 100 V and uses the external device 210 such as lighting. It is desirable that the power generated by the external device 210 on the power use side and the Stirling engine generator SE be substantially equal to reduce the power consumed by the dummy resistor 205. When the battery 207 is in the vicinity of full charge or the like, the load on the generator side becomes light, the engine speed enters an overspeed state, and the voltage Vs becomes equal to or higher than the reference voltage Vh, the charging circuit for the battery 207 Is cut off, the power generation side is connected to the dummy resistor 205, the engine rotation is returned to normal, and the dummy resistor 205 absorbs part of the generated power. On the other hand, when the power of the battery 207 is consumed and charging is started from a state close to empty discharge, initially, the charging current is large, so the load increases and the engine speed tends to decrease. As a result, when the voltage Vs becomes equal to or lower than the reference voltage Vl, the circuit of the dummy resistor 205 on the generator side is cut off, recovery of the engine speed is promoted, and the voltage on the generator side is Is controlled to be 14V to 30V, and the battery 207 is appropriately charged.

  Thus, the battery 207 can be charged by the Stirling engine generator SE in a stable state without being affected by the change in the temperature condition of the external heat source or the change in the load state due to the intermittent circuit of the dummy resistor 205. it can. If the generated voltage Vs is zero (0) even though the heat source temperature is sufficiently high, this indicates that the Stirling engine is in a stopped state, so that the motor is started quickly and the Stirling engine is always in operation. It is good to control so that it may be maintained.

DESCRIPTION OF SYMBOLS 1 Housing 2 Motor generator 10 Cylinder 11 Cylinder head 12 Cylinder main body 13 Support cylinder 20 Displacer piston 30 Regenerator 40 Power piston 50 Slider rod 60 First slider crank mechanism 62 First connecting rod 70 Second slider crank mechanism 72 Second connecting rod 80 Flywheel 90 Guide rod HS High temperature space LS Low temperature space B1-B4 Bearing

Claims (3)

A displacer piston is accommodated in the cylinder to form a high temperature space and a low temperature space, and the displacer piston reciprocates in the axial direction of the cylinder while the working fluid in both spaces periodically moves through the regenerator, In a Stirling engine configured such that a power piston arranged coaxially with the displacer piston reciprocates in the axial direction of the cylinder, a flywheel that rotatably supports a housing that fixes the cylinder, and the flywheel A first crank having a first rotation center at a first offset position with respect to the rotation axis of the power piston, and one end portion rotatably supported by the first crank and the other end portion at the radial center of the power piston A first connecting rod for swingably supporting the power piston. And a first slider crank mechanism that is fixed to one end of the displacer piston, the other end extending through the power piston, and an axis parallel to the reciprocating axis of the power piston A slider rod which is slidably supported by the power piston, a second crank having a second center of rotation at a second offset position with respect to the rotational axis of the flywheel, and the second crank A second slider crank mechanism having a second connecting rod that rotatably supports one end of the slider rod and rotatably supports the other end of the slider rod on the other end of the slider rod. And arranged on an axis parallel to the reciprocating movement axis of the power piston, and one end is fixed to one side of the power piston and the displacer piston. Both the Stirling engine, characterized in that a guide rod for supporting the other end portion slidably on the other side of said power piston the displacer piston. Claim 1, wherein the fixing position of the guide rod, set on the slider rod the power piston distance from a position through equal radial distance to the radial center of the power piston and spaced on the axis The described Stirling engine. The slider rod and the guide rod are arranged so that the plane including the slider rod and the guide rod includes the rotation axis of the flywheel, and on a plane orthogonal to the plane including the slider rod and the guide rod. Stirling engine according to claim 2, characterized in that said first and second connecting rod is arranged so as to swing.

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