JP2008240847A - Auto tensioner - Google Patents

Abstract

To provide an auto tensioner capable of visually determining that the timing chain has reached the replacement time without directly measuring the length of the timing chain.
An auto tensioner 28 for maintaining the tension of a timing chain 23 of an engine 1 at an appropriate value, a shoe 29 slidably contacting an outer peripheral portion of the timing chain 23, a tensioner body 31 fixedly attached to the engine 1, and a A tensioner rod 32 supported so as to be able to protrude and enter from the tensioner body 31 and having a distal end abutting the shoe 29 and a base end portion of the tensioner rod 32, and the tensioner rod 32 protrudes from the tensioner body 31. When the shoe 29 is pressed, a propulsive force applying mechanism (rotating shaft member 33 and mainspring spring 35) that applies a propulsive force to press the shoe 29 against the timing chain 23 and a predetermined distance from the tip of the side surface of the tensioner rod 32 are provided. Limit mark 57 provided at the position having L; It consists of.
[Selection] Figure 7

Description

  The present invention relates to an auto tensioner that can visually recognize how a timing chain extends.

Most OHC (overhead camshaft) engines having a camshaft provided in the upper part of the combustion chamber have a timing chain (also called a cam chain) for driving the overhead camshaft. Since this timing chain elongates over time, an auto tensioner is provided to maintain an appropriate tension (tension) at all times, and is maintenance-free with respect to the elongating timing chain (see, for example, Patent Document 1). As described above, the timing chain is elongated due to long-term use and needs to be replaced when it exceeds a predetermined amount of slack. However, the timing chain is maintenance-free and cannot be visually recognized from the outside because it is sealed inside the engine.
Japanese Patent Laid-Open No. 11-230281

  However, the auto tensioner that maintains the tension of the timing chain also wears according to the operating condition of the engine because of the structure that uses the friction of the internal screw. The function of the tensioner may be deteriorated, so that the tension of the timing chain cannot be maintained at an appropriate value (that is, the timing chain is slackened) and noise may be generated.

  In this way, if the timing chain is extended too much or if the auto tensioner's function deteriorates, abnormal noise is generated from the timing chain, so it is possible to determine which of these abnormal noises has reached the end of its life. First, the engine must be disassembled and the timing chain removed, and the length of the timing chain must be measured to determine the replacement time.

  The present invention has been made in view of such problems, and it is possible to visually determine that the timing chain has reached the replacement time without directly measuring the length of the timing chain. The purpose is to provide.

  In order to solve the above-described problem, an auto tensioner according to a first aspect of the present invention for maintaining the tension of a timing chain of an internal combustion engine (for example, the engine 1 in the embodiment) at an appropriate value is a shoe that is in sliding contact with the outer peripheral portion of the timing chain. A tensioner body fixedly attached to the internal combustion engine, a tensioner rod supported so as to be able to project and enter from the tensioner body, and having a distal end abutting the shoe, and a tensioner body provided at a base end portion of the tensioner rod. A thrust applying mechanism that applies a thrust to push the shoe against the timing chain by projecting the tensioner rod against the timing chain, and a position at a predetermined distance from the tip of the side of the tensioner rod Display indicators (for example, limit markers in the embodiment) And 57), it consists of.

  In the auto tensioner according to the first aspect of the present invention, the internal thread is formed inside the tensioner rod, and the propulsion force applying mechanism is rotatably attached to the tensioner body, and is a male thread portion that engages with the internal thread. And a mainspring spring that provides a propulsive force that rotates the rotary shaft member by a spring force and causes the tensioner rod to protrude from the tensioner body, and engages with the tensioner body and the rotary shaft member. It is preferable to be configured to be removed from the internal combustion engine with a regulating member (for example, the stopper 55 in the embodiment) regulating the rotation of the rotating shaft member with respect to the body.

  The autotensioner according to the second aspect of the present invention is fixed to the internal combustion engine so that the shoe slidingly contacts the outer periphery of the timing chain and an opening is formed on one surface, and the one surface faces outward. The tensioner body to be mounted and the other side of the tensioner body are supported so as to be able to protrude and enter, and a through-hole penetrating in the protruding and entering direction is formed, the tip part abuts the shoe and the tip of the through-hole A side opening is opposed to the shoe, and a proximal end opening of the through-hole is provided at a tensioner rod facing the opening of the tensioner body, and a base end of the tensioner rod, and the tensioner rod is attached to the tensioner body. A propulsive force imparting mechanism that provides a propulsive force that pushes the shoe against the timing chain by pressing it and pushing the shoe An inspection member (for example, the inspection rod 60 in the embodiment) provided with a display indicator at a position having a predetermined distance from the tip is inserted into the opening and the through hole from the tip side. Thus, the shoe is configured to come into contact with a shoe that comes into contact with the tip of the tensioner rod.

  When the auto tensioner according to the first aspect of the present invention is configured as described above, when the timing chain extends due to changes over time and exceeds a predetermined amount of slack, a display indicator provided on the tensioner rod comes out of the tensioner body. Therefore, it can be judged by visually observing the display indicator whether or not the cause of the abnormal noise due to the operation of the timing chain is due to the extension of the timing chain.

  In the case where the auto tensioner according to the first aspect of the present invention is a screw type (a system constituted by a rotating shaft member screwed to the tensioner rod and a spring spring), the auto tensioner is removed from the internal combustion engine with the regulating member attached. With this configuration, even if the auto tensioner is removed from the internal combustion engine, the amount of protrusion of the tensioner rod does not change. Therefore, the display indicator can be confirmed by removing the auto tensioner by a simple disassembly operation. Maintainability is improved. Of course, assembly can also be performed easily.

  Further, when the autotensioner according to the second aspect of the present invention is configured as described above, when the timing chain extends over time and exceeds a predetermined amount of slack, it is inserted into the opening and the through hole and brought into contact with the shoe. Since the display indicator of the inspection member is inserted into the tensioner body and disappears, it is possible to determine whether the cause of the noise due to the operation of the timing chain is due to the extension of the timing chain without removing the auto tensioner from the internal combustion engine. be able to.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, an engine 1 to which an auto tensioner according to the present invention is attached will be described with reference to FIGS. 1 and 2. In the present embodiment, the direction of arrow F shown in FIG. The engine 1 includes a cylinder head cover 2, a cylinder head 3, a cylinder block 4, and a crankcase 5 in order from the top. The cylinder block 4 is formed with a cylindrical cylinder penetrating vertically, and a cylinder chamber 6a is formed surrounded by a cylinder sleeve 6 fitted in the inner peripheral surface of the cylinder. A piston 7 is disposed in the cylinder chamber 6a so as to be slidable in the vertical direction. The piston 7 is connected via a connecting rod 8 to a crankshaft 9 rotatably held by the crankcase 5. ing. On the other hand, a combustion chamber 10 is formed in the cylinder head 3 attached to the upper end portion of the cylinder block 4 so as to open to the lower surface and align with the upper opening of the cylinder chamber 6a.

  An intake port 11 and an exhaust port 12 are formed in the combustion chamber 10 of the cylinder head 3, and an intake port 13 and an exhaust port 14 communicate with the combustion chamber 10 through the intake port 11 and the exhaust port 12, respectively. ing. The cylinder head 3 has a saddle-shaped intake valve 15 and an exhaust valve 16, one end of which is attached to the valve shaft and supported by the retainer, and the other end is supported by the cylinder head 3. Thus, the intake port 11 and the exhaust port 12 are attached in a direction to be always closed.

  A cam chain chamber 19 penetrating in the vertical direction is formed on the left side of the cylinder head 3 and the cylinder block 4. A camshaft 20 for opening and closing the intake valve 15 and the exhaust valve 16 is rotatably supported and attached above the combustion chamber 10 of the cylinder head 3. The left end portion of the camshaft 20 protrudes into the cam chain chamber 19, and a cam driven sprocket 22 is attached to the left end portion. A cam drive sprocket 21 is mounted on the opposite crankshaft 9 across the cam chain chamber 19 of the cam driven sprocket 22, and the cam chain chamber is interposed between the cam drive sprocket 21 and the cam driven sprocket 22. A timing chain 23 is wound around the interior 19.

  The gear ratio between the cam drive sprocket 21 and the cam driven sprocket 22 is configured such that the camshaft 20 rotates once when the crankshaft 9 rotates twice. Therefore, the camshaft 20 rotates in accordance with the rotation of the crankshaft 9, and the cams 24a and 24b formed on the camshaft 20 push down the intake valve 15 and the exhaust valve 16 through the rocker arms 25 and 26. The intake port 11 and the exhaust port 12 are opened and closed. Thus, the engine 1 has a so-called overhead cam mechanism.

  In the timing chain 23 having such a configuration, when the crankshaft 9 rotates at a high speed, a portion not engaged with the sprockets 21 and 22 vibrates. Therefore, the timing chain 23 is disposed in the cam chain chamber 19 between the sprockets 21 and 22 and is guided by a guide member 27 slidably contacting the front outer portion of the timing chain 23, and the cam chain chamber 19 It is guided by an auto tensioner 28 comprising a shoe 29 slidably in contact with the rear outer portion of the timing chain 23 and a tensioner body 30 that pushes the shoe 29 forward, and its tension is adjusted to an appropriate magnitude. Has been. The guide member 27 has an attachment portion 27 a formed at the top thereof fixed to the cylinder block 4 with a bolt or the like, and a lower end portion 27 b inserted into a holding portion 62 formed within the crankcase 5 and fixed. Further, the upper end 29a of the shoe 29 is attached to the cylinder head 3 by a bolt 63 so as to be swingable in the front-rear direction, and a substantially central part in the vertical direction is pushed forward by the tensioner body 30. .

  Next, the configuration of the tensioner main body 30 constituting the auto tensioner 28 will be described with reference to FIGS. As shown in FIG. 1, the tensioner body 30 includes a tensioner body 31 fixedly attached to the rear surface of the cylinder block 4, and the tensioner body that is prevented from rotating around the axis but can move in the axial direction. A tensioner rod 32 supported by 31, a rotary shaft member 33 arranged coaxially with the tensioner rod 32 and screwed into the tensioner rod 32, and fixed to the tensioner body 31 to thrust support the rotary shaft member 33. A tension member rod 32 is provided on a shoe 29 that includes a bearing member 34 and a spring spring 35 that is provided between the rotary shaft member 33 and the tensioner body 31 and that urges the rotary shaft member 33 to rotate. The tip of is abutted.

  The tensioner body 31 is formed in a cylindrical shape having a flange portion 31a projecting in a direction orthogonal to the above-described axis on the rear end side, and the tensioner body 31 is housed in order from the front end side. A hole 36, a mounting hole 37 having a diameter smaller than that of the storage hole 36, and a screw hole 38 having a diameter smaller than that of the mounting hole 37 are provided coaxially so as to penetrate the tensioner body 31 in the front-rear direction. A plug member 39 is screwed into the screw hole 38 and is sealed by a sealing washer 40 sandwiched between the plug member 39 and the rear end surface of the tensioner body 31. In addition, a pair of engaging recesses 54 that extend radially outwardly about the cylindrical axis of the screw hole 38 in the rear view is formed at the opening edge of the rear end opening of the screw hole 38 ( FIG. 5 shows a case where four sets of locking recesses 54a to 54d are provided.

  The tensioner rod 32 is coaxially disposed in the housing hole 36 and has a cylindrical cylindrical body 41 with a distal end protruding from the distal end of the tensioner body 31 and a spring pin 43 fixed to the distal end of the cylindrical body 41. The cap 42 is in contact with the shoe 11. A female screw 44 is formed at least on the rear end side of the tensioner rod 32, that is, on the inner periphery of at least the rear end side of the cylindrical body 41.

  The cylindrical body 41 is inserted through an insertion hole 46 provided at the center of a regulating member 45 formed in a dish shape. A pair of flat surfaces 41 a and 41 a extending in parallel along the axis are provided on the outer surface of the cylindrical body 41, and the insertion hole 46 is formed in a shape corresponding to the outer surface shape of the cylindrical body 41. Therefore, the cylindrical body 41 and the regulating member 45 enable relative movement in the direction along the axis of the cylindrical body 41, but relative rotation around the axis is prevented.

  A pair of first engaging claws 47a and 47a spaced apart by 180 degrees in the circumferential direction and the first engaging claws 47a and 47a in the circumferential direction of the regulating member 45 are 90 in the circumferential direction. A pair of second engaging claws 47b and 47b formed narrower than the first engaging claws 47a and 47a are provided so as to protrude radially outward. . On the other hand, the first engagement claw 47a, 47a, 47b, 47b are inserted into the distal end portion of the tensioner body 31 and engaged therewith (first engagement claw 47a, First engagement recesses 48a and 48a corresponding to 47a and second engagement recesses 48b and 48b) corresponding to second engagement claws 47b and 47b are formed. The first and second engaging claws 47a, 47a, 47b, 47b engaged with the first and second engaging recesses 48a, 48a, 48b, 48b are arranged on the outer periphery of the tip end portion of the tensioner body 31. The fitted fixing ring 49 is engaged in common, whereby the restricting member 45 is fixed to the tensioner body 31. That is, the tensioner rod 32 that cannot be rotated relative to the regulating member 45 around the axis is prevented from rotating around the axis, but is supported by the tensioner body 31 so as to be movable in the axial direction. .

  The rotary shaft member 33 includes a male screw portion 33a that meshes with the female screw 44 of the tensioner body 31, a neck portion 33b that has a smaller diameter than the male screw portion 33a, and a spring that has a larger diameter than the neck portion 33b. The engaging portion 33c and the support portion 33d having a larger diameter than the spring engaging portion 33c are coaxially connected and formed integrally. On the other hand, the bearing member 34 is press-fitted and fixed in the mounting hole 37 in the tensioner body 31, and the base end of the rotating shaft member 33, that is, the end surface of the support portion 33 d is thrust supported by the bearing member 34. Here, the bearing member 34 is press-fitted into the mounting hole 37 and a base end portion of the rotating shaft member 33, that is, a cylindrical portion 34a into which the support portion 33d is rotatably inserted, and a radially inward from one end of the cylindrical portion 34a. And an end surface of the support portion 33d is slidably supported by the flange portion 34b.

  The support portion 33d and the spring engagement portion 33c of the rotary shaft member 33 are provided with a shaft-side locking slit 50 that opens to the end surface of the support portion 33d, and is wound so as to surround the outer peripheral surface of the spring engagement portion 33c. The inner end of the spring spring 35 is engaged with the shaft side locking slit 50. Further, the tensioner body 31 is provided with a body-side locking slit 51 at a position corresponding to the spring engaging portion 33c, and the outer end of the mainspring spring 35 is engaged with the body-side locking slit 51. The rotary shaft member 33 is urged to rotate by the spring force of the mainspring spring 35. The rotation urging direction of the rotary shaft member 33 is advanced by moving the tensioner rod 32 forward by the engagement of the male screw portion 33a of the rotary shaft member 33 with the female screw 44. The direction is set.

  A ring-shaped washer 52 is engaged with the spring engaging portion 33 c of the rotating shaft member 33, and a cylindrical spacer 53 is interposed between the washer 52 and the regulating member 45 so as to surround the tensioner rod 32. It is attached. The washer 52 and the spacer 53 function to prevent the rotary shaft member 33 and the tensioner rod 32 from moving forward when the shoe 29 is not in contact with the tip of the tensioner rod 32.

  The tensioner body 30 configured in this way is attached to the engine 1, that is, in a state where the shoe 29 is not in contact with the tensioner rod 32, the above-described plug member 39 is removed, and instead of the tensioner body 31. A stopper 55 shown in FIG. 6 is inserted and attached to the screw hole 38 from the rear. The stopper 55 is formed by, for example, a metal material having rigidity in a plate shape, and is formed with a body engaging portion 55a having a wide width in the short-side direction and a width narrower than the body engaging portion 55a. It is comprised from the shaft engaging part 55b. The stopper 55 is inserted into the screw hole 38 from the side of the shaft engaging portion 55b, and this shaft engaging portion 55b is inserted into the shaft side locking slit 50 formed in the support portion 33d of the rotating shaft member 33 from the rear end side opening. The body engaging portion 55a is inserted into and engaged with any one of the locking recesses 54a to 54d formed in the rear end opening edge of the screw hole 38, whereby the urging force of the mainspring spring 35 is engaged. Thus, the rotation of the rotary shaft member 33 is restricted. Therefore, the tensioner rod 32 is configured not to advance with respect to the tensioner body 31 in a state where the stopper 55 is attached.

  1, the tensioner body 30 is attached so that the tip of the tensioner rod 32 comes into contact with the shoe 29 from the rear of the cylinder block 4 of the engine 1, and an attachment formed on the flange 31a of the tensioner body 31. After the bolts 56, 56 are inserted and fixed in the holes 31b, 31b and then the stopper 55 is removed, the rotary shaft member 33 is rotationally driven by the spring force of the mainspring spring 35, and the tensioner rod 32 shoe the cap 42 accordingly. The propulsion force of the tensioner main body 30 acts on the shoe 29 until it abuts against the shoe 29. In such a tensioner body 30, when the reaction force from the shoe 29 is received, the rotary shaft member 33 mainly has a frictional force at the threaded portion of the male screw portion 33 a and the female screw 44, and the rotary shaft member 33 and the bearing member. It strides without rotating due to the frictional force between 34 and suppresses vibration (flapping) of the cam chain 23.

  By the way, as shown in FIG. 7, a limit mark is placed on the side surface of the tensioner rod 32 constituting the tensioner body 30, that is, the flat surface 41a of the cylindrical body 41 at a predetermined distance L from the tip of the tensioner rod 32. 57 is provided. As described above, when the timing chain 23 extends due to changes over time, the tensioner rod 32 moves forward with respect to the tensioner body 31 according to the amount of extension (sag). That is, the protruding amount of the tensioner rod 32 protruding from the tip of the tensioner body 31 is increased. For this reason, the limit mark 57 is provided at a position L that comes out from the tip of the tensioner body 31 when reaching the extension amount when the timing chain 23 needs to be replaced. By removing the main body 30, it can be determined whether or not the timing chain 23 has been replaced by whether or not the limit mark 57 is visible.

  At this time, as described above, when the tensioner body 30 is removed from the cylinder block 4 without the stopper 55 attached, the rotary shaft member 33 is rotated by the spring force of the mainspring spring 35 so that the tensioner rod 32 moves relative to the tensioner body 31. When the timing chain 23 is to be visually checked for replacement, the stopper 55 is first engaged with one of the locking recesses 54a to 54d and the shaft side locking slit 50 as described above. After the attachment, it is necessary to perform an operation of removing the tensioner body 30 from the cylinder block 4. In addition, as shown in FIG. 5, the position which attaches the stopper 55 according to the position of the axis | shaft side latching slit 50 which changes according to rotation of the rotating shaft member 33 by providing two or more latching recessed parts 54 (54a-54d). Can be selected.

  In the above embodiment, the tensioner rod 32 is fixed to the tensioner body 31 using the stopper 55. Instead of the stopper 55, a plug member 39 screwed into the screw hole 38 is used. Thus, the rotation of the rotary shaft member 33 can be restricted and the tensioner rod 32 can be fixed. That is, the length of the shaft portion on which the male screw of the plug member 39 is formed is the same as the support portion 33d of the rotary shaft member 33 when the plug member 39 is screwed into the screw hole 38 and attached. It is formed to have a length that abuts against the rear end surface of the sheet. Then, when the plug member 39 is screwed into the screw hole 38 and tightened, the support portion 33d is pressed forward, the frictional force between the front end surface of the plug member 39 and the rear end surface of the support portion 33d, and When the shaft member 33 is pushed forward, the rotation of the rotary shaft member 33 by the mainspring spring 35 can be prevented by the frictional force of the threaded portion of the male screw portion 33a and the female screw 44.

  In the above embodiment, the case where the tension chain body 30 is removed from the cylinder block 4 and checked in order to determine whether or not the timing chain 23 has reached the replacement time is shown. With the configuration of the tensioner main body 30 ′ shown in FIG. 8A, it is possible to determine the replacement timing of the timing chain 23 with the tensioner main body 30 ′ still attached to the engine 1. In FIG. 8A, only the parts different from the tensioner main body 30 described above are replaced by the same reference numerals, and the same components are denoted by the same reference numerals and detailed description thereof is omitted.

  A through-hole 58 is formed in the rotary shaft member 33 'of the tensioner body 30' so as to penetrate along the cylindrical axis of the rotary shaft member 33 '. A through hole 59 that is aligned with the through hole 58 of the rotary shaft member 33 ′ is also formed in the cap 42 ′ constituting the tensioner rod 32 ′. That is, as shown in FIG. 8A, in the tensioner body 30 ′, the screw hole 38 formed in the rear portion of the tensioner body 31 and the through holes 58 and 59 are aligned and communicated. When inspecting the replacement timing of the timing chain 23, the plug member 39 is removed from the screw hole 38 with the tensioner body 30 'attached to the engine 1, and the inspection shown in FIG. Insert the rod 60. Then, the tip of the inspection rod 60 is brought into contact with the shoe 29 through the screw hole 38 and the through holes 58 and 59. The inspection bar 60 is provided with a limit mark 61 at a predetermined distance L ′ from the tip. Therefore, when the timing chain 23 reaches the extension amount when it needs to be replaced and the tensioner rod 32 'protrudes from the tensioner body 31 accordingly, the limit mark 60 is positioned at the position L' in the screw hole 38. Therefore, it is possible to determine whether or not it is time to replace the timing chain 23 based on whether or not the limit mark 60 is visible without removing the tensioner body 30 from the cylinder block 4.

1 is a left side view showing an engine to which an auto tensioner according to the present invention is attached. It is a right view of the said engine. It is side sectional drawing of the tensioner main body which comprises the said auto tensioner. It is IV-IV sectional drawing of FIG. It is a front view of the said tensioner main body. It is a figure which shows the stopper used for the said tensioner main body, Comprising: (a) is a top view, (b) is a side view. It is the perspective view which looked at the said tensioner main body from the front side. It is a figure which shows another embodiment of the auto tensioner which concerns on this invention, (a) is a sectional side view of a tensioner main body, (b) is a side view of a test | inspection rod.

Explanation of symbols

1 engine (internal combustion engine)
23 Timing Chain 28 Auto Tensioner 29 Shoe 31 Tensioner Body 32, 32 'Tensioner Rod 33 Rotating Shaft Member 33a Male Screw Part 35 Spring Spring 44 Female Screw 55 Stopper (Regulator Member)
57 Limit mark (display indicator)
58,59 Through hole 60 Inspection rod (inspection member)
61 Limit mark (display indicator)

Claims (3)

An auto tensioner that maintains the tension of the timing chain of the internal combustion engine at an appropriate value,
A shoe in sliding contact with the outer periphery of the timing chain;
A tensioner body fixedly attached to the internal combustion engine;
A tensioner rod that is supported so as to protrude and enter from the tensioner body, and a tip part of which abuts against the shoe;
A propulsive force imparting mechanism provided at a base end portion of the tensioner rod, which pushes the shoe against the timing chain by projecting the tensioner rod against the tensioner body and pressing the shoe; In the provided auto tensioner,
An auto tensioner comprising: a display indicator provided at a position on a side surface of the tensioner rod at a predetermined distance from the tip. An internal thread is formed inside the tensioner rod,
The propulsion force applying mechanism is
A rotary shaft member rotatably attached to the tensioner body and having a male screw portion screwed into the female screw;
A mainspring spring that rotates the rotating shaft member by a spring force to give a propulsive force that causes the tensioner rod to protrude from the tensioner body;
2. The structure according to claim 1, wherein a restriction member that engages with the tensioner body and the rotation shaft member and restricts rotation of the rotation shaft member with respect to the tensioner body is attached to the tensioner body and is removed from the internal combustion engine. Auto tensioner. An auto tensioner that maintains the tension of the timing chain of the internal combustion engine at an appropriate value,
A shoe in sliding contact with the outer periphery of the timing chain;
A tensioner body that is fixedly attached to the internal combustion engine so that an opening is formed on one surface and the one surface faces outward,
A through hole that is supported so as to protrude and enter from the other surface of the tensioner body and that penetrates in the projecting and entering direction is formed, and a front end portion abuts on the shoe and a front end opening of the through hole corresponds to the shoe. A tensioner rod facing the base end opening of the through-hole facing the opening of the tensioner body;
A propulsive force applying mechanism that is provided at a base end portion of the tensioner rod, and applies a propulsive force that presses the shoe against the timing chain by pressing the shoe by projecting the tensioner rod with respect to the tensioner body; Consisting of
An inspection member, which is a rod-shaped member and is provided with a display indicator at a position having a predetermined distance from the tip, is inserted into the opening and the through-hole from the tip side to the tip of the tensioner rod. An auto tensioner configured to abut on the abutting shoe.

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