JP4314245B2 - Bicycle front derailleur - Google Patents

Description

  The present invention relates to a derailleur, and more particularly to a bicycle front derailleur that can be fixed to a bicycle frame.

An exterior transmission is adopted for a bicycle, particularly a sports type bicycle. The exterior transmission includes a front transmission configured by a front chainwheel having two or three sprockets and a front derailleur, a multi-stage gear having 7-10 sprockets, and a rear derailleur. It is often composed of. A front derailleur of this type of transmission includes a base member that can be fixed to a bicycle frame, a chain guide that is movable with respect to the base member, and a moving mechanism that moves the chain guide (for example, , See Patent Document 1). The chain guide includes an inner member and an outer member that is disposed at a distance from the inner member and can guide the chain between the inner member and the inner member. In the front derailleur, a chain is passed between the inner member and the outer member, and the chain guide is moved in a direction in which the chain guide is in contact with or separated from the frame, thereby guiding one of the plurality of sprockets of the chain.
U.S. Pat. No. 4,551,121

  In such a front derailleur, when the chain is downshifted to guide the chain from the large-diameter side sprocket to the small-diameter side sprocket, the chain will drop further inward without engaging the small-diameter side sprocket. There is. Even if the chain is dropped, if the shifting operation to the large diameter side is performed, the chain may come into contact with the large-diameter side sprocket and be caught by the large-diameter side sprocket, thereby eliminating the chain dropping. However, this probability is very low, and it is usually necessary to stop the bicycle and return the chain to the sprocket by hand once the chain has dropped. For this reason, if a chain drop occurs during a bicycle race, a fatal time loss may occur.

  An object of the present invention is to make it easy to return a chain to a sprocket by a shift-up operation when the chain is dropped in a bicycle front derailleur.

  The bicycle front derailleur according to the first aspect includes a base member that can be fixed to the bicycle, a chain guide, and a moving mechanism. The chain guide includes an inner member and an outer member that is arranged at a distance from the inner member and can guide the chain between the inner member and is movable with respect to the base member. The inner member has a first protrusion that is provided on the rear end side on which the chain enters and protrudes toward the outer member. The moving mechanism is a mechanism for moving the chain guide. The inner member is integrally formed with the outer member, and is connected by a bolt member on the rear end side, and the first projecting portion is a spacer member fixed by the bolt member.

  In this front derailleur, when the chain is passed between the inner member and the outer member of the chain guide, the chain can be guided to one of a plurality of sprockets by performing a speed change operation and moving the chain guide by the moving mechanism. it can. In addition, when a chain drop occurs in the speed change operation from the large-diameter side sprocket to the small-diameter side sprocket, the chain moves to the rear end side of the chain guide. Since the rear end side is provided with a first protrusion that protrudes toward the outer member, the gap between the chain and the sprocket becomes narrower when the chain moves to the rear end side. In this state, if a shift-up gear shifting operation is performed toward the large-diameter sprocket while pedaling, the dropped chain is pressed by the first protrusion toward the large-diameter sprocket. When the chain is pressed, the chain is sandwiched between the first protrusion and the side of the large-diameter sprocket and comes into contact with the large-diameter sprocket. The rotating sprocket pulls the chain in the rotational direction and returns to the sprocket. It becomes easy. Here, the first projecting part that projects toward the outer member is provided on the rear end side of the inner member on the chain entry side where the chain is often placed when the chain is dropped. When the operation is performed, the chain comes into contact with the sprocket by the first projecting portion and is moved between the sprocket and easily moved back to the sprocket.

  In addition, the structure of the front derailleur is simplified, and the rear end side is connected by a bolt member, so that rigidity can be maintained high even when the chain is guided.

  Furthermore, since the first protrusion is provided separately from the inner member, the first protrusion can be retrofitted to a conventional derailleur, and the first protrusion can be worn even if the first protrusion is worn by contact with the chain. Part can be exchanged.

  A bicycle front derailleur according to a second aspect of the present invention is the derailleur according to the first aspect, wherein the spacer member further includes a first tapered portion that gradually protrudes from the front end side. In this case, when the chain moves to the rear end side, the chain is smoothly guided to the first protrusion.

The bicycle front derailleur according to the invention 3 is the derailleur according to the invention 2,
The inner member extends from the rear end to the front end so as to intersect the chain, and has a chain passage through which the chain can pass between the rear end and the front end. In this case, the chain that is normally disposed between the rear end and the front end and disposed in the chain passage is guided to one of the plurality of sprockets by the chain guide.

  A bicycle front derailleur according to a fourth aspect is the derailleur according to the second or third aspect, wherein the inner member includes a first edge on the chain entry side and a second edge on the chain withdrawal side from the rear end toward the front end. The first protrusion is partially provided on the second edge side of the rear end. In this case, since the first protrusion is disposed only on the side close to the large-diameter sprocket, the chain is surely brought into contact with the sprocket even if the first protrusion is provided on a part of the rear end side of the inner member. be able to.

A bicycle front derailleur according to a fifth aspect of the present invention is the derailleur according to any one of the first to fourth aspects, wherein the first projecting portion projects to the outer member side within a range of 1 to 2 mm from the adjacent portion. In this case, since the clearance between the first protrusion and the small-diameter side sprocket is set within an appropriate range, the chain contacts the small-diameter side sprocket and the chain is sandwiched between the first protrusion and the sprocket. Even if this happens, the chain will be difficult to lock in the gap.
.

  According to the present invention, since the first projecting portion projecting toward the outer member is provided at the rear end of the chain entry side in which the chain is often disposed when the chain is dropped, the upshifting operation is performed when the chain is dropped. If it carries out, it will become easy to return a chain to a sprocket using the rotation of a sprocket because the chain is pinched between the 1st projection part and a sprocket.

  In addition, the structure of the front derailleur is simplified, and the rear end side is connected by a bolt member, so that rigidity can be maintained high even when the chain is guided.

  Furthermore, since the first protrusion is provided separately from the inner member, the first protrusion can be retrofitted to a conventional derailleur, and the first protrusion can be worn even if the first protrusion is worn by contact with the chain. Part can be exchanged.

<Overall configuration>
In FIG. 1, a bicycle 101 employing a reference example for explaining an embodiment of the present invention is a road racer, and includes a diamond-shaped frame 102 having a front fork 98 and a handle portion 104 fixed to the front fork 98. And a drive unit 105 including a crank 96 to which a chain 95 and a pedal PD are mounted, front and rear derailleurs 97f and 97r, front and rear sprocket groups 99f and 99r, etc., a front fork 98 and a front wheel and a rear wheel mounted to the rear part of the frame 102 Wheels 106f and 106r, front and rear brake devices 107f and 107r, and shift operation units 110f and 110r for shifting the front and rear derailleurs 97f and 97r are provided.

  The handle portion 104 includes a handle stem 111 and a handle bar 112 fitted and fixed at the upper end of the handle stem 111. The handle stem 111 is fitted and fixed to the upper portion of the front fork 98. The handle bar 112 is of a drop handle type and includes a pair of left and right brake levers 113f and 113r. The brake levers 113f and 113r are provided with speed change operation portions 110f and 110r. The speed change operation units 110f and 110r are connected to the front and rear derailleurs 97f and 97r via speed change cables 115f and 115r.

  As described above, the drive unit 105 includes the chain 95, front and rear derailleurs (an example of a transmission) 97f and 97r that replace the chain 95, and front and rear sprocket groups 99f and 99r. The front derailleur 97f is provided on the seat tube 102a of the frame 102 and is positioned at two shift positions by the shift operation unit 110f to guide the chain 95. The rear derailleur 97r is provided in the rear claw portion 102b of the rear portion of the frame 102, and is positioned at ten shift positions by the shift operation portion 110r to guide the chain 95.

  The front sprocket group 99f has two sprockets F1 and F2 with different numbers of teeth arranged side by side in the axial direction of the crankshaft. The rear sprocket group 99r has ten sprockets with different numbers of teeth arranged side by side in the axial direction along the hub axle 106a of the rear wheel. Here, in the front sprocket group 99f, the inner sprocket F1 has fewer teeth than the outer sprocket F2. In the rear sprocket group 99r, the number of teeth decreases in order from the innermost sprocket, and the top sprocket on the outermost side has the smallest number of teeth. The front and rear derailleur 97f, 97r moves the chain 95 to one of a plurality of sprockets to perform a speed change operation. This speed change operation is performed by the speed change operation portions 110f and 110r using the brake levers 113f and 113r.

<Configuration of front derailleur>
The front derailleur 97f is of a downswing type, and as shown in FIG. 2, a base member 40 that can be fixed to the seat tube 102a, and a chain guide 41 that is movable in a shifting direction that is in contact with and away from the base member 40. And a movement mechanism 45 for pivotally connecting the base member 40 and the chain guide 41 to move the chain guide. The moving mechanism 45 includes an inner link 42 and an outer link 43 that are arranged in parallel to each other.

  The base member 40 includes a first base bracket 50 and a second base bracket 51 that is attached to the first base bracket 50 so as to be freely opened and closed, and that embraces the seat tube 102a with the first base bracket 50. The first base bracket 50 is provided with a pair of inner link support portions 50a on which the inner link 42 is swingably mounted via a link shaft 42a. Further, an outer link support portion 50b is provided obliquely above the inner link support portion 50a. The outer link support portion 50b is mounted so that the outer link 43 can swing through the link shaft 43a.

  The chain guide 41 moves to two shift positions: a low position facing the small-diameter sprocket F1 arranged on the inner side, and a top position facing the large-diameter sprocket F2 arranged on the outer side. , F2 is guided to the chain 95. The chain guide 41 is swingably connected to the lower ends of the inner link 42 and the outer link 43. The chain guide 41 includes an inner plate (an example of an inner member) 55 and an outer plate (an example of an outer member) 56 that is disposed outside the inner plate 55 and spaced from the inner plate 55. The chain 95 can be guided between the inner plate 55 and the outer plate 56.

In this reference example , the inner plate 55 and the outer plate 56 are formed by cutting a metal thin plate into a predetermined shape with a press and then bending it. Therefore, in this reference example , both plates 55 and 56 are integrally formed, and are connected by a connecting bolt 57 at one place on the rear end side. Further, the upper front connecting portion 58 and the rear connecting portion 59 are integrally connected in a state of being bent in a C shape. The rear connecting portion 59 is formed with a pair of outer link connecting portions 59a bent upward. A lower portion of the outer link 43 is connected to the outer link connecting portion 59a via a link shaft 43b.

  The inner plate 55 is provided with a pair of inner link connecting portions 55f that are bent back. The lower end of the inner link 42 is swingably connected to the inner link connecting portion 55f via the link shaft 42b. A torsion coil spring 46 as a biasing member that biases the chain guide 41 to the low position is disposed on the outer peripheral side of the link shaft 42b. The torsion coil spring 46 has one end locked to the inner plate 55 of the chain guide 41 and the other end locked to the inner link 42, and is covered with a spring cover 46a made of synthetic resin.

  As shown in FIGS. 2 to 5, the inner plate 55 is formed in an arc shape extending along the sprockets F <b> 1 and F <b> 2 and crossing the chain 95 from the rear end toward the front end. The inner plate 55 has, from the rear end toward the front end, an upper side (an example of a first edge) 55d1 and a lower side (an example of a second edge) 55d2 on the chain entry side. The inner plate 55 is formed with higher strength than the outer plate 56 by forming irregularities and edges by press working. This is because the inner plate 55 is used when the chain 95 is derailed from the sprocket F1 at the time of shift-up that requires a strong force from the low position to the top position. When the inner plate 55 is disposed at the outer top position, as shown in FIGS. 6 and 7, the lower side 55d2 is disposed radially inward from the tooth tip of the sprocket F2.

  A first protrusion 55 a is formed on the rear end side of the inner plate 55. The first protrusion 55a is formed to protrude toward the outer plate 56 slightly downward from the direction in which the chain 95 is arranged. The protrusion amount of the first protrusion 55a is preferably in the range of 1 to 2 mm. The first projecting portion 55a is arranged at the rear end portion where the chain 95 is often arranged by being connected by the connecting bolt 57 when the chain is dropped, and it is easy to return the chain 95 to the sprocket F2 when the chain is dropped. Is provided to do. As shown in FIG. 7, the first projecting portion 55a is disposed at a position facing the sprocket F2, and the gap with the sprocket F2 is narrower than the other portions.

  A taper portion 55b that gradually protrudes from a portion adjacent to the first protrusion 55a toward the first protrusion 55a is formed at the front upper portion of the first protrusion 55a. The tapered portion 55b is formed so that the chain 95 moves smoothly toward the first protruding portion 55a when the chain drops. The protrusions including the first protrusion 55a and the taper part 55b are formed at the same time during press working. Further, the inner plate 55 has a chain passage 55c through which the chain 95 can pass between the front end portion and the rear end portion. Further, a second projecting portion 55e is formed at the front end portion (chain withdrawal side) of the inner plate 55 slightly projecting compared to the adjacent portion. The second projecting portion 55e is formed to reliably push the chain 95 into the sprocket F2 when shifting up to the sprocket F2.

  The outer plate 56 is formed in an arc shape that is disposed radially outward from the inner plate 55. When the outer plate 56 is disposed at the outer top position shown in FIGS. 6 and 7, a gap of about 1 to 3 mm is formed between the lower side 56a and the tooth tip of the sprocket F2. Accordingly, the front derailleur 97f is set on the seat tube 102a so that the above-described gap is formed. At the rear portion of the outer plate 56, a screwing portion 56 b is formed that is bent in a C shape and disposed on the outer surface of the rear portion of the inner plate 55. The screwing portion 56 b is connected and fixed to the inner plate 55 by a connecting bolt 57.

  As shown in FIG. 2, the inner link 42 is disposed below the base member 40 in a state where the base member 40 is mounted on the seat tube 102a, and both ends of the inner link 42 are rotatable with respect to the first base bracket 50 and the chain guide 41. It is connected to. One end of the inner link 42 is swingably connected between the pair of inner link support portions 50a. A chain guide 41 is swingably connected to the other end of the inner link 42.

  The outer link 43 is pivotally connected to the outer link support portion 50b of the base member 40 and the chain guide 41 at a position farther from the base member 40 than the inner link 42, and is arranged in parallel with the inner link 42. It is. The outer link 43 is swingably connected to the outer link support portion 50b, and a cable locking arm 44 that is bent away from the base member 40 and extends toward the seat tube 102a is integrally formed at the link support portion. Yes. At the extended end of the cable locking arm 44, a cable locking portion 44a for bolting the inner cable of the transmission cable is provided.

<Front derailleur shifting operation>
In the front derailleur 97f configured as described above, when the downshift from the top position to the low position is performed, the chain 95 contacts the outer plate 56 of the chain guide 41 and derails from the sprocket F2, and is guided to the sprocket F1. Is done. The replacement operation of the chain 95 at this time is shown by a solid line in FIG. At the time of downshifting, when the chain 95 is guided to the sprocket F1 side, the chain 95 starts derailing at the derailment point DR arranged at a specific rotational phase of the sprocket F2, and the chain 95 moves toward the sprocket F1. Go down. At the time of this downshifting, the chain 95 may fall off, causing the chain 95 to drop inward from the sprocket F1.

  When the chain is dropped, as shown by a two-dot chain line in FIG. 7, the chain 95 hangs down on the hanger portion 102 c of the frame 102 while being hooked on the rear portion of the chain guide 41. In this state, when a shift-up operation (shift from the sprocket F1 toward F2) is performed by the shift operation unit 110f, the chain guide 41 swings outward. When the chain guide 41 swings outward, as shown in FIG. 5, the chain 95 hooked on the rear part of the chain guide 41 is pressed toward the sprocket F2 by the first protrusion 55a. When the chain 95 is pressed, as shown in FIG. 7, the chain 95 comes into contact with the sprocket F2 and is caught by the tooth T1 near the first projecting portion 55a, or the sprocket F2 that rotates while in contact with the side surface. It is dragged and caught on the tooth T2 above the first protrusion 55a. As a result, the chain 95 can be easily returned to the sprocket F2 as indicated by a solid line in FIG.

  Here, the first projecting portion 55a that projects toward the outer plate 56 is provided on the rear end side of the inner plate 55 on the chain entry side in which the chain 95 is often disposed when the chain is dropped. Therefore, if the upshifting operation is performed when the chain is dropped, the chain 95 comes into contact with the sprocket F2 by the first projecting portion 55a and is moved between the sprocket F2 and easily returned to the sprocket F2. Become.

<Other reference examples >
(A) In the above-described reference example , the present invention has been described by taking the front derailleur having two sprockets for two-speed shifting for loading as an example, but the present invention is also applied to a front derailleur having three sprockets for three-speed shifting. it can.

(B) In the reference example, although integrally forming the inner plate and the outer plate, or separately from the inner side plate and the outer plate.

(C) In the reference example , the first projecting portion is formed by press molding with substantially the same thickness as the other portion, but may be formed with a thickness different from that of the other portion. Moreover, you may form separately from another part.

(D) In the reference example , the first protrusion 55a is provided on the entire rear surface of the inner plate 55 on the chain entry side. However, the present invention is not limited to this, and the first protrusion 55a only needs to be provided on at least a part of the rear end side of the inner plate 55. For example, in FIG. 8, the 1st protrusion part 155a is provided in a part of rear end side of the inner side plate 155. In FIG. In this case, since the lower side 55d2 on the inner peripheral side of the inner plate 55 is close to the sprocket F2, it is preferable to dispose the first projecting portion 155a on the lower side 55d2 side. In addition, a tapered portion 155b that gradually protrudes from a portion adjacent to the first projecting portion 155a toward the first projecting portion 155a is formed in the upper front portion of the first projecting portion 155a. The protrusion amount of the first protrusion 155a is preferably in the range of 1 to 2 mm.

In this case, when the chain is dropped, the chain 95 is pressed to the sprocket F2 side by the upshift operation, and the chain 95 is easily returned to the sprocket F2 as in the above-described reference example . In addition, since the first protrusion 155a is disposed only on the side close to the large-diameter sprocket F2, the chain 95 can be securely attached to the sprocket F2 even if the first protrusion 155a is provided on a part of the rear end side of the inner plate 55. Can be contacted.

  (E) As shown in FIGS. 9 to 11, the washer member 160 may be fixed to a connecting portion between the inner plate 155 and the outer plate 156 by a connecting bolt (an example of a bolt member) 157.

  In FIG. 9, a front derailleur 197f is an electric derailleur driven by a motor, and includes an electric drive unit 139, a base member 140, a chain guide 141, and a moving mechanism 145 having an inner link 142 and an outer link 143. is doing.

  The base member 140 is fixed to a dedicated fixing bracket (not shown) fixed to the seat tube 102a by welding. The electric drive unit 139 includes a drive motor and its control circuit. A battery box 138 for storing batteries as these power sources is connected to the base member 140.

The chain guide 141 is the same as that in the above-described reference example, and is swingably connected to the lower ends of the inner link 142 and the outer link 143. The chain guide 141 includes an inner plate (an example of an inner member) 155 and an outer plate (an example of an outer member) 156 disposed on the outer side of the inner plate 155 and spaced from the inner plate 155. The chain 95 can be guided between the inner plate 155 and the outer plate 156.

The inner plate 155 and the outer plate 156 are formed by cutting a metal thin plate into a predetermined shape with a press and then bending the same as in the reference example . Therefore, both plates 155 and 156 are integrally formed, and are connected by the connecting bolt 157 at one place on the rear end side. Further, the upper front connecting portion 158 and the rear connecting portion 159 are integrally connected in a state of being bent in a C shape. Thereafter, a pair of outer link connecting portions 159a are formed in the connecting portion 159 so as to be bent upward. The lower part of the outer link 143 is connected to the outer link connecting part 159a via the link shaft 143b.

The inner plate 155 is provided with a pair of inner link connecting portions 155f that are bent toward the back side. The lower end of the inner link 142 is swingably connected to the inner link connecting portion 155f via the link shaft 142b. On the rear end side of the inner plate 155, a first protrusion 255a is formed as shown in FIGS. The first protruding portion 255a is formed to protrude toward the outer plate 156 slightly downward from the direction in which the chain 95 is arranged. The protrusion amount of the first protrusion 255a is preferably in the range of 1 to 2 mm. A step 155g is formed at the rear end portion of the inner plate 155 in the same manner as in the reference example so as to be disposed on the inner surface of the bent screwing portion 156b of the outer plate 156. The step 155g is formed regardless of the presence or absence of the first protrusion 255a. However, since the first protrusion 255a is present, the step 155g is further increased as compared to the case without the first protrusion 255a. Therefore, the washer member 160 is fixed to the inner plate 155 with a connecting bolt (an example of a bolt member) 157 in order to fill the step 155g.

  The washer member 160 is a plate-like member, has a fixed portion 160a fixed by a connecting bolt 157 at the center, has an embedded portion 160b for filling the step 155g on the front side, and prevents rotation on the rear side. It has a locking portion 160c for prevention. The thickness of the washer member 160 is set so that the surface thereof has a height close to the protruding amount of the first protruding portion 255a, but some unevenness may occur with respect to the first protruding portion 255a.

  By providing the washer member 160 in this manner, the chain 95 is less likely to be caught by the step portion even if a step is generated between the first protrusion 255a. In particular, when shifting with an electric derailleur, it is difficult to adjust the force acting on the derailleur during shifting compared to when shifting manually. Therefore, even when the dropped chain 95 is returned, the chain 95 is pressed against the sprocket F2 with a constant force by the first projecting portion 255a. Therefore, when the chain 95 is caught by the step 155g, the chain 95 smoothly moves to the sprocket F2. There is a risk that it will not return to. However, since the washer member 160 is provided to make it difficult for the chain 95 to be caught by the step 155g, the chain 95 can easily return to the sprocket F2 even if the chain 95 is pressed with a constant force.

<Example>
In Reference Example, the first protrusion 55a, 155a, has been formed integrally 255a inside plates 55, 155, in this embodiment, a separate.

In FIG. 12, the outer plate 156 has the same shape as that of the reference example , but the first protrusion is not formed on the inner plate 255. Instead, the spacer member 260 having the first protrusion 260 a is fixed to the connecting portion between the inner plate 255 and the outer plate 256 by a connecting bolt (an example of a bolt member) 257.

The spacer member 260 has a first protrusion 260a on the front end side, and the rear end side is fixed to the inner plate 255 together with the screwing portion 256b of the outer plate 256 by a connecting bolt 257. The amount of protrusion of the first protrusion 260a is the same as in the reference example .

  If the first protrusion 260a is provided separately from the inner plate 255 in this manner, the first protrusion can be retrofitted to the derailleur having the conventional structure, and the first protrusion 260 is worn even if the first protrusion is worn by contact with the chain. The protrusion can be replaced.

The side view of the bicycle by which the reference example for describing one Example of this invention was employ | adopted. The perspective view of the front derailleur. The rear perspective view of a chain guide. The side perspective view of a chain guide. The front view of a chain guide. The figure which shows the chain replacement | exchange operation | movement at the time of downshift. The figure which shows the state of chain dropping, and chain return operation | movement. The figure equivalent to FIG. 2 of another reference example . Furthermore, the figure equivalent to FIG. 4 of another reference example . The rear perspective view of the chain guide. The rear top view of the chain guide. The figure equivalent to FIG. 11 of a present Example .

40 Base member 41 Chain guide 45 Movement mechanism 55 Inner plate (an example of inner member)
56 Outer plate (example of outer member)
55a, 155a, 255a, 260a First protrusion 55b, 155b Taper 55c Chain passage 55d1 Upper side (an example of the first edge)
Lower side of 55d2 (example of second edge)
97f, 197f Front derailleur 101 Bicycle 155g Step 160 Washer member 260 Spacer member F1, F2 Sprocket

Claims (5)

A bicycle front derailleur,
A base member that can be fixed to the bicycle;
A chain guide having an inner member and an outer member arranged at a distance from the inner member and capable of guiding a chain between the inner member and movable relative to the base member;
A moving mechanism for moving the chain guide,
The inner member may have a first projecting portion projecting provided on the end side after the a chain entry side the outer member,
The inner member is integrally formed with the outer member, and is connected by a bolt member on the rear end side,
The first projecting portion is a bicycle front derailleur , which is a spacer member fixed by the bolt member . It said spacer member further has a first tapered portion that protrudes from the front side gradually, front derailleur for a bicycle according to claim 1. The inner member extends to be crossing the chain toward the rear end from the front end, having a chain can pass through a chain path between said rear end and said front end, according to claim 2 Bicycle front derailleur as described in. The inner member toward the rear end from the rear end, and a second edge of the chain exit side to the first edge of the chain entering side,
The first projecting portion is partially provided on the second edge side of the rear end, a front derailleur for a bicycle according to claim 2 or 3.   4. The bicycle front derailleur according to claim 1, wherein the first protrusion protrudes toward the outer member within a range of 1 to 2 mm from an adjacent portion. 5.

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