JP2011140972A - Tension adjusting device of wrapping transmission member in wrapping transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tension adjusting device of a wrapping transmission member in a wrapping transmission device, capable of restraining excessive tension and a power loss. <P>SOLUTION: A rockably supported chain guide 6 is contacted with the outside of a loose side chain 5a of a chain 5, and a rolling bearing 10 is arranged in a rocking side end part of its chain guide 6. A rotatable tension adjusting cam 11 is arranged inside the chain 5, and the rolling bearing 10 is guided to its tension adjusting cam 11, and a cam surface 14 is arranged for energizing the chain guide 6 in the direction for tensioning the chain 5 by drawing the rolling bearing 10 near to the rotational center side of the tension adjusting cam 11 by rotation in one direction of the tension adjusting cam 11. The tension adjusting cam 11 is energized in the direction for rotating in one direction by adding elastic force of a spiral spring 15 of becoming gradually weak in the elastic force by shape restoration to a natural state to the tension adjusting cam 11, and tension of the chain 5 is held constant by rotation of its tension adjusting cam 11 and elastic deformation of the spiral spring 15. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tension adjusting device for a winding transmission member in a winding transmission device that maintains a constant tension of a winding transmission member such as a chain of a chain transmission device or a belt of a belt transmission device.

  Generally, in a chain transmission that transmits the rotation of the crankshaft of an engine to a camshaft, in order to absorb the chain elongation due to secular change and the shrinkage during cooling, an adjustment force in the tensioning direction is applied to the chain. The tension is kept constant.

  Also in belt transmission devices that drive engine accessories such as alternators, compressors for air conditioners, water pumps, etc., for the purpose of preventing slippage due to belt extension and cutting of the belt due to increased tension during contraction. The belt is loaded with adjustment force to keep the tension constant.

  Here, as a chain tension adjusting device that keeps the chain tension constant, a chain guide supported in a swingable manner on the slack side chain of the chain is brought into contact with the chain tensioner described in Patent Document 1. Conventionally, a chain guide is pressed against the chain while applying an adjusting force, and the chain tensioner absorbs a change in chain tension.

  Further, as a belt tension adjusting device that keeps the belt tension constant, a hydraulic auto tensioner described in Patent Document 2 is connected to a swingable pulley arm that supports a tension pulley, and the hydraulic auto tensioner is connected to the pulley arm. It has been conventionally known that the tension pulley urges the pulley arm in the direction in which the tension pulley presses the belt with the applied adjustment force, and the belt tension change is absorbed by the hydraulic auto tensioner to keep the belt tension constant. It has been.

  In the above chain tensioner and hydraulic auto tensioner (hereinafter simply referred to as a tensioner), the coil spring is energized in the direction of extension by the coil spring incorporated therein, and when the pushing force is applied, the coil spring The pushing force is buffered by the elastic deformation and hydraulic damper action.

JP 2002-286103 A JP 2001-141007 A

  By the way, in the tension adjusting device that adjusts the tension of the chain or belt (hereinafter simply referred to as a winding transmission member) using the tensioner, the tension change of the winding transmission member is absorbed by expansion and contraction of the tensioner. The extension (extension) of the tensioner changes the spring height (length) of the coil spring, and the spring load also changes.

  For example, if the tension is reduced due to elongation in the winding transmission member, the tensioner is extended, the length of the coil spring is increased and the spring load is reduced, and the tension of the winding transmission member is reduced, A predetermined tension state cannot be secured.

  Therefore, conventionally, a coil spring having a large spring constant is used so as to ensure a predetermined tension state in which a winding transmission member such as a chain is in an extended state.

  For this reason, at the initial assembly of the tensioner, there is a disadvantage that the winding transmission member becomes excessively tensioned to promote elongation and power loss increases.

  An object of the present invention is to provide a tension adjusting device for a winding transmission member in a winding transmission device that is capable of suppressing excess tension and power loss.

  In order to solve the above-described problems, in the present invention, a guide member supported so as to be able to swing is brought into contact with the outer side of the slack side winding transmission member of the endless winding transmission member, and the swing side end of the guide member A contactor is provided at a portion, a rotatable tension adjusting cam is provided inside the winding transmission member, and the contactor is slidably guided to the tension adjusting cam. A contact surface is drawn toward the rotation center side of the tension adjustment cam, the cam member is wound around, and a cam surface is provided to urge the transmission member in a tensioning direction. A configuration in which the tension adjusting cam is urged in the direction of rotation in one direction by applying the elastic force of the elastic member that gradually becomes weak is adopted.

  Here, the winding transmission member means a chain or a belt.

  In the tension adjusting device configured as described above, when the winding transmission member is stretched and the tension is weakened, the tension adjusting cam rotates in one direction due to the elasticity of the elastic member, and the contact portion of the cam surface with respect to the contact adjusts the tension. The cam is displaced in the direction of decreasing the radius to the rotation center of the cam. For this reason, the guide member is pulled toward the tension adjusting cam, the elongation of the winding transmission member is absorbed, and the tension of the winding transmission member is kept constant.

  Contrary to the above, when the tension of the winding transmission member increases as in the initial driving of the engine, a pressing force is applied from the winding transmission member to the cam surface of the tension adjusting cam via the guide member, and the pressing force causes The tension adjustment cam rotates in the other direction against the elasticity of the elastic member, and the contact portion of the contact with the cam surface is displaced in a direction in which the radius to the rotation center of the tension adjustment cam increases, so that the guide member is elastic. The member swings outward to a position where the elastic force and tension of the member are balanced, and the change in tension of the winding transmission member is absorbed by the swing.

  Here, the load that prevents the slack of the transmission member by pulling the guide member toward the tension adjustment cam is F, and T is the rotational torque that causes the elastic member to rotate the tension adjustment cam. A load F that prevents the winding transmission member from slackening can be expressed by F = T / r, where r is an action radius to the rotation center of the tension adjusting cam in the region.

  Therefore, in the tension adjusting device having the above-described configuration, the elastic deformation amount of the elastic member increases and the restoring elastic force increases as the action radius r increases, and the elastic deformation amount decreases as the action radius r decreases. Since the restoring elastic force is also reduced, the rotational torque T by which the elastic member rotates the tension adjusting cam becomes large when the action radius r is large, and becomes small when the action radius r is small. For this reason, the load F for preventing the winding transmission member from slackening is always substantially constant, and the tension of the winding transmission member can be kept substantially constant.

  In the tension adjusting device for the winding transmission member according to the present invention, when the cross-sectional shape of the cam surface is a concave arc shape, and the outer periphery of the contact is a convex arc shape adapted to the concave arc-shaped cam surface, The surface pressure of the contact portion between the cam surface and the contact can be lowered, wear of the contact portion can be prevented, and durability can be improved.

  In addition, a low friction material layer is provided on the cam surface to reduce the contact resistance to the contactor, or by adopting a rolling bearing as the contactor, the rotation resistance of the tension adjustment cam is reduced, and the tension adjustment cam is made smoother. Can be rotated.

  Here, the tension adjusting cam may be provided with a guide wall extending in the circumferential direction on the outer peripheral portion of one surface, and provided with a cam surface made of an involute curve or the like on the inner periphery of the guide wall. A slot extending in the circumferential direction may be formed in the part, and the outer surface of the slot may be a cam surface.

  In adopting a tension adjustment cam with the inner circumference of the guide wall as the cam surface, an inward stopper is provided at the large-diameter end of the guide wall, and an inward flange is provided at the outer edge of the guide wall. It is preferable to prevent the contact from falling off.

  In the tension adjusting device for a winding transmission member according to the present invention, a spiral spring, a torsion coil spring, or a compression coil spring can be employed as the elastic member. When a spiral spring or a torsion coil spring is employed, one end thereof is connected to a tension adjusting cam and the other end is connected to a stationary member such as an engine block.

  On the other hand, when a compression coil spring is used as the elastic member, a gear is provided on the circumference of the tension adjustment cam centering on the rotation axis, the rack is engaged with the gear, and the compression coil is fitted to the rack. The elastic force of the spring is applied to urge the rack in a direction in which the tension adjusting cam rotates in one direction.

  In the tension adjusting device for the winding transmission member according to the present invention, the tension of the winding transmission member is connected to the guide member by connecting a damper that cushions an impact force applied to the guide member from the winding transmission member. Since the impact force applied to the guide member can be absorbed by the damper at the time of increase, the impact force is less applied to the elastic member, and an effect can be obtained in preventing damage to the elastic member.

  As described above, in the present invention, the tension adjusting cam rotates due to the tension change of the winding transmission member, and when the tension of the winding transmission member increases, the elastic member is greatly elastically deformed to increase the restoring elastic force, And the contact radius to the center of rotation of the tension adjusting cam of the contact portion with respect to the contact increases, and when the tension of the winding transmission member is reduced, the elastic member is elastically deformed small and the restoring elastic force is reduced, and Since the contact radius to the center of rotation of the tension adjustment cam of the contact portion with respect to the contact becomes small, the load for preventing the slack of the winding transmission member can be kept constant at all times, and the tension of the winding transmission member is always substantially constant. Can be held constant. As a result, excessive tension and power loss of the winding transmission member can be suppressed.

Schematic diagram of a chain transmission device employing a tension adjusting device for a winding transmission member according to the present invention The front view which expands and shows the tension adjustment part of FIG. Right side view of FIG. Sectional view along line IV-IV in FIG. Front view showing chain tension adjustment The front view which shows the other example of the tension adjustment cam shown in FIG. Sectional drawing along the VII-VII line of FIG. Front view showing still another example of tension adjusting cam Sectional view along line IX-IX in FIG. Sectional view showing still another example of tension adjusting cam The front view which shows the other example of the guide member shown in FIG. Sectional drawing along the XII-XII line of FIG. Front view showing still another example of tension adjusting cam Sectional view along line XIV-XIV in FIG. Front view showing another example of installation of tension adjustment cam Sectional view along line XVI-XVI in FIG. Front view showing another example of a tension adjusting device according to the present invention Front view showing still another example of the tension adjusting device according to the present invention. Sectional view along line XIX-XIX in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a chain transmission as a winding transmission. In this chain transmission device, a chain 5 is wound around a sprocket 2 attached to each of the sprocket 2 attached to the crankshaft 1 and the two camshafts 3 as a transmission member, and the crankshaft 1 is rotated. Transmission is made to the camshaft 3.

  A chain guide 6 as a guide member is provided outside the slack side chain 5 a of the chain 5. As shown in FIG. 3, the lower end of the chain guide 6 is supported by a shaft 8 projecting from the engine block 7, and is swingable about the shaft 8.

  As shown in FIGS. 2 to 4, the chain guide 6 has a chain guide surface 6 a on a surface facing the chain 5, and the length of the chain guide 6 on one side of the chain guide surface 6 a on the engine block 7 side. A guide protrusion 6b extending in the vertical direction is provided.

  A support piece 9 projecting toward the chain 5 is provided at the swinging side end of the guide protrusion 6b, and a rolling bearing 10 as a contact is rotatably supported by the support piece 9.

  A tension adjusting cam 11 is provided inside the chain 5 on one side of the swing side end of the chain guide 6. The tension adjustment cam 11 is supported rotatably about a fulcrum shaft 12 screwed into the engine book 7.

  The tension adjusting cam 11 is formed with a guide wall 13 extending in the circumferential direction on the outer peripheral portion of the back surface facing the engine block 7, and the inner periphery of the guide wall 13 guides the rolling bearing 10 supported by the chain guide 6. The cam surface 14 is made.

  The cam surface 14 is formed of an involute curve, and the radius with respect to the center of the fulcrum shaft 12 that becomes the rotation center of the tension adjusting cam 11 gradually increases from one end to the other end in the circumferential direction.

  For this reason, when the tension adjusting cam 11 rotates in the direction indicated by the arrow in FIG. 2, the chain guide 6 is drawn toward the tension adjusting cam 11 side, and the slack side chain 5a is pressed by the chain guide 6 and the slack side chain. 5a is getting nervous.

  A spiral spring 15 as an elastic member is provided between the opposed portions of the engine block 7 and the tension adjusting cam 11 so as to surround the fulcrum shaft 12. The inner end of the spiral spring 15 is connected to a pin 16 provided on the tension adjusting cam 11, and the outer end is connected to a pin 17 projecting from the engine block 7. The spiral spring 15 urges the tension adjusting cam 11 in the direction indicated by the arrow in FIG. 2 to apply a constant tension to the chain 5.

  The chain tension adjusting device in the chain transmission shown in the embodiment has the above-described structure. When the chain 5 is stretched and the tension is weakened, the tension adjusting cam 11 is indicated by an arrow in FIG. Rotate in the direction.

  At this time, the contact portion of the cam surface 14 with the rolling bearing 10 is displaced in a direction in which the radius to the rotation center of the tension adjusting cam 11 decreases, so that the chain guide 6 is attracted to the tension adjusting cam 11 side and the slack side chain. Press 5a. By the pressing, the elongation of the chain 5 is absorbed, and the tension of the chain 5 is kept constant.

  Contrary to the above, when the tension of the chain 5 increases as in the initial driving of the engine, a pressing force is applied from the chain 5 to the cam surface 14 of the tension adjusting cam 11 through the chain guide 6, and the tension is generated by the pressing force. The adjustment cam 11 rotates in the direction opposite to the direction indicated by the arrow in FIG. 2 against the elasticity of the spiral spring 15.

  Due to the rotation of the tension adjusting cam 11, as shown in FIG. 5, the contact portion of the rolling bearing 10 with respect to the cam surface 14 is displaced in a direction in which the radius to the center of rotation of the tension adjusting cam 11 increases, and from the chain 5. As a result of the pressing, the chain guide 6 swings outward to a position where the elastic force of the spiral spring 15 and the tension of the slack side chain 5a are balanced. A constant tension is maintained.

  Here, as shown in FIG. 2, the load that pulls the chain guide 6 toward the tension adjusting cam 11 to prevent the chain 5 from slackening is F, and the rotational torque that causes the spiral spring 15 to rotate the tension adjusting cam 11 is F. The load F for preventing the slack of the chain 5 is represented by F = T / r, where T is R and the working radius of the contact portion between the cam surface 14 and the rolling bearing 10 to the rotation center of the tension adjusting cam 11 is r. Can do.

  Therefore, in the chain tension adjusting device having the above-described configuration, the amount of elastic deformation of the spiral spring 15 increases and the restoring elastic force increases as the operating radius r increases, and the amount of elastic deformation increases as the operating radius r decreases. Since the restoring elastic force is also reduced, the rotational torque T that causes the spiral spring 15 to rotate the tension adjusting cam 11 becomes large when the acting radius r is large and becomes small when the acting radius r is small. For this reason, the load F that prevents the chain 5 from slacking is always substantially constant, and the tension of the chain 5 can always be kept substantially constant.

  In the embodiment shown in FIGS. 1 to 5, the chain 5 is shown as the winding transmission member, but the winding transmission member is not limited to the chain. For example, a belt may be used. In the belt tension adjusting device, a tension pulley is brought into contact with a slack side belt of the belt and a swingable pulley arm that supports the tension pulley is subjected to a rotational force in one direction by a spiral spring 15. To pull it toward the belt side.

  Further, in the embodiment, the rolling bearing 10 is used as the contact, but a pin-shaped one may be adopted. At this time, since the contact resistance of the pin-shaped contact 10 with respect to the rolling bearing 10 increases with respect to the cam surface 14, as shown in FIGS. 6 and 7, a low friction material layer 18 is provided on the cam surface 14, It is preferable to reduce the contact resistance.

  As shown in FIGS. 6 and 7, if an inward stopper 19 is provided at the large-diameter end of the guide wall 13, the rolling bearing 10 can be prevented from falling off in the circumferential direction.

  8 and 9 show another example of the tension adjusting cam 11. In this example, a flange 20 facing inward over the entire length is provided on the outer edge of the guide wall 13. Thus, by providing the flange 20, it is possible to prevent the rolling bearing 10 as a contactor from dropping from the cam surface 14 in the axial direction.

  FIG. 10 shows still another example of the tension adjusting cam 11. In this example, the cross-sectional shape of the cam surface 14 on the inner periphery of the guide wall 13 is a concave arc shape, and the outer periphery of the rolling bearing 10 is a convex arc shape that fits the concave arc cam surface 14. Since the cam surface 14 has a concave arc shape and the outer periphery of the rolling bearing 10 has a convex arc shape as described above, the surface pressure at the contact portion between the cam surface 14 and the rolling bearing 10 can be reduced. Further, wear of the contact portion can be prevented and durability can be improved.

  In the embodiment shown in FIG. 2, the support piece 9 is provided at the swing side end of the chain guide 6 and the rolling bearing 10 is supported by the support piece 9, but as shown in FIGS. 11 and 12, the chain guide The rolling bearing 10 as a contact may be supported directly and freely at the end of the swinging side 6.

  By supporting the rolling bearing 10 as a contactor rotatably at the swinging side end of the chain guide 6, the length of the tension adjusting device in the left-right direction can be reduced.

  In the embodiment shown in FIG. 2, the guide wall 13 is formed on one surface of the tension adjusting cam 11, and the inner surface of the guide wall 13 is the cam surface 14. However, as shown in FIGS. A slot 21 extending in the circumferential direction may be formed on the outer periphery of the adjustment cam 11, and the outer surface of the slot 21 may be used as the cam surface 14.

  As described above, the slot 21 is formed in the tension adjusting cam 11, and the outer surface of the slot 21 is used as the cam surface 14, so that the guide wall 13 shown in FIG. 7 can be made compact in height.

  Further, in the embodiment shown in FIG. 2, the guide wall 13 is provided on the back side of the surface of the tension adjusting cam 11 facing the engine block 7, but as shown in FIGS. 15 and 16, the engine of the tension adjusting cam 11 is provided. You may make it provide the guide wall 13 in the outer peripheral part of the opposing surface with respect to the block 7. FIG.

  17 to 19 show still another embodiment of the tension adjusting device according to the present invention. The tension adjusting device shown in FIG. 17 is different from the tension adjusting device shown in FIG. 2 in that a damper 30 is connected to the swing side end of the chain guide 6.

  For this reason, the same components as those in the tension adjusting device shown in FIG.

  Here, the damper 30 shown in FIG. 17 includes a piston 33 slidably incorporated in the end of the piston rod 32 in the cylinder 31 to provide a damper chamber 34 inside the cylinder 31. The rod chamber 35 communicated with the outside air is communicated by a passage 36, and an air damper having a check valve 37 incorporated in the passage 36 is formed.

  The damper 30 is assembled with the cylinder 31 supported by the engine block 7 and the piston rod 32 connected to the swing side end of the chain guide 6, and the tension of the slack side chain 5 a increases, and the slack side chain The pushing force applied to the chain guide 6 from 5a is buffered by the damper action of the air sealed in the damper chamber 34.

  As described above, by connecting the damper 30 to the chain guide 6, when the tension of the chain 5 is increased, the tension change can be absorbed by the spiral spring 15 and the damper 30. For this reason, an impact force is not applied to the spiral spring 15, and an effect can be obtained in preventing the spiral spring 15 from being damaged.

  In place of the air damper 30, a hydraulic damper may be employed.

  2, 11, 13, 15, and 17, the spiral spring 15 is used as an elastic member, and the elastic force of the spiral spring 15 is directly applied to the tension adjusting cam 11. Instead, a torsion coil spring or a compression coil spring may be used.

  In adopting the torsion coil spring, the torsion coil spring is provided outside the fulcrum shaft 12, one end thereof is connected to the tension adjusting cam 11, and the other end is connected to the engine block 7.

  On the other hand, when the compression coil spring is employed, as shown in FIGS. 18 and 19, the tension adjusting cam 11 is provided with a gear 40 on the circumferential surface around the fulcrum shaft 12, and a rack 41 is provided on the gear 40. The rack 41 is movably supported by a guide rod 43 provided on the gear case 42, the elastic force of the coil spring 44 is loaded on the rack 41, and the tension adjusting cam 11 is in the direction indicated by the arrow in FIG. The rack 41 is urged so as to rotate to the right.

  In the example shown in FIGS. 18 and 19, when the chain 5 is slack, the rack 41 is moved upward in FIG. 18 by the pressing of the compression coil spring 44, and the tension adjusting cam 11 is in the direction indicated by the arrow in FIG. The chain guide 6 is drawn toward the slack side chain 5a, and the slackness of the chain 5 is absorbed by the drawing.

  On the other hand, when the chain 5 is tensioned, the tension adjusting cam 11 is rotated in the opposite direction as indicated by the arrow in FIG. 18 by the pressing force applied to the chain guide 6 from the slack side chain 5a, and the rack 41 is rotated by the rotation. The compression coil spring 44 is compressed and deformed by moving downward in the figure, and the change in tension of the chain 5 is absorbed by the elastic deformation of the compression coil spring 44.

5 Chain (wound transmission member)
6 Chain guide (guide member)
10 Rolling bearing (contact)
11 Tension adjusting cam 13 Guide wall 14 Cam surface 15 Spiral spring (elastic member)
18 Low friction material layer 19 Stopper 20 Flange 21 Slot 30 Damper 40 Gear 41 Rack 44 Compression coil spring (elastic member)

Claims (12)

  A guide member supported so as to be able to swing is brought into contact with the outer side of the slack-side winding transmission member of the endless winding transmission member, and a contact is provided at the swing-side end of the guide member. A tension adjusting cam that can be rotated inside is provided. The tension adjusting cam slides and guides the contact, and the tension adjusting cam is rotated in one direction to draw the contact toward the center of rotation of the tension adjusting cam. The guide member is wound around to provide a cam surface that urges the transmission member in a tensioning direction, and the tension adjusting cam is added with the elastic force of an elastic member that gradually weakens due to the shape restoration to the natural state. The tension adjusting device of the winding transmission member in the winding transmission device in which the tension adjustment cam is urged in the rotating direction.   The tension adjusting device for a winding transmission member in the winding transmission device according to claim 1, wherein the contact comprises a rolling bearing.   The tension adjustment of the winding transmission member in the winding transmission device of Claim 1 or 2 which provided the guide wall extended in the circumferential direction in the outer peripheral part of the single side | surface of the said tension adjustment cam, and made the inner periphery of the guide wall a cam surface. apparatus.   The tension adjusting device for the winding transmission member in the winding transmission device according to any one of claims 1 to 3, wherein the cam surface comprises an involute curve.   The tension adjusting device for a winding transmission member in the winding transmission device according to claim 3 or 4, wherein a stopper for preventing the contact from falling off is provided at an end portion on the large diameter side of the guide wall.   The tension adjusting device for a winding transmission member in the winding transmission device according to any one of claims 3 to 5, wherein a flange facing inward is provided on an outer edge of the guide wall.   The winding according to any one of claims 1 to 6, wherein a cross-sectional shape of the cam surface is a concave arc shape, and an outer periphery of the contact is a convex arc shape adapted to the concave arc cam surface. A tension adjusting device for a winding transmission member in a hanging transmission.   The tension adjusting device for a winding transmission member in the winding transmission device according to claim 1 or 2, wherein a slot extending in the circumferential direction is formed in an outer peripheral portion of the tension adjusting cam, and an outer surface of the slot is a cam surface.   The tension adjusting device for a winding transmission member in a winding transmission device according to any one of claims 1 to 8, wherein a low friction material layer is provided on the cam surface.   The winding transmission member in the winding transmission device according to any one of claims 1 to 9, wherein a damper that cushions an impact force applied to the guide member from the winding transmission member is connected to the guide member. Tension adjustment device.   The tension adjustment cam is provided with a gear on a circumferential surface centered on the rotation axis thereof, the rack is engaged with the gear, and the rack is urged by an elastic member in a direction in which the tension adjustment cam rotates in one direction. The tension adjusting device of the winding transmission member in the winding transmission device according to any one of claims 1 to 10.   The tension adjusting device for a winding transmission member in the winding transmission device according to any one of claims 1 to 11, wherein the elastic member is a kind of a spiral spring, a torsion coil spring, or a compression coil spring.

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