JP2012225447A - Auto tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auto tensioner of low cost excellent in mounting workability onto an engine.SOLUTION: The auto tensioner 6 has: a cylinder 9 whose lower part is closed; a rod 10 inserted into the cylinder 9 in a manner movable in the axial direction; a hydraulic damper mechanism 11 that buffers a pushing force imparted to the rod 10; a spring seat 12 fixed on the end of the rod 10 projecting out from the cylinder 9; and a return spring 13 that biases the rod 10 via the spring seat 12 in a direction in which the rod 10 is projected out from the cylinder 9. An annular metal band 31 is wound around the spring seat 12 and the cylinder 9 so as to regulate the shifting move of the rod 10 in the direction in which the rod 10 is projected out from the cylinder 9.

Description

  The present invention relates to an auto tensioner used for maintaining tension of an accessory belt that drives an automobile accessory such as an alternator.

  An auxiliary machine of an automobile, for example, an alternator, a car air conditioner, a water pump, and the like, is driven through an auxiliary machine belt whose rotating shaft is connected to an engine crankshaft by an auxiliary machine belt. In order to keep the tension of the auxiliary belt within an appropriate range, generally, a pulley arm provided so as to be swingable about a fulcrum shaft, a tension pulley rotatably attached to the pulley arm, and the tension pulley as an auxiliary belt. A tension adjusting device including an auto tensioner that urges the pulley arm in the pressing direction is used.

  As an auto tensioner incorporated in this tension adjusting device, for example, the one described in Patent Document 1 is known. The auto tensioner of Patent Document 1 includes a cylinder closed at the bottom, a rod inserted in the cylinder so as to be movable in the axial direction, a hydraulic damper mechanism for buffering a pushing force applied to the rod, and the rod And a return spring that urges the rod in a direction to protrude from the cylinder via the spring seat.

  This auto tensioner is used by connecting an upper connecting piece provided on a spring seat to a pulley arm and a lower connecting piece provided on a closed end of a cylinder to an engine block. When the tension of the accessory belt fluctuates, the rod moves to a position where the tension of the accessory belt and the urging force of the return spring balance, absorbs the tension fluctuation of the accessory belt, and is applied from the accessory belt to the rod. The pushing force is buffered by a hydraulic damper mechanism to stabilize the auxiliary belt tension.

  By the way, when assembling the engine, an auxiliary machine or an auto tensioner is attached to the engine in advance, and then an auxiliary machine belt is wound around a pulley, a crank pulley, or a tension pulley that drives each auxiliary machine. Here, when the auxiliary belt is wound, if the auto tensioner is in the extended state by the urging force of the return spring, the auxiliary belt is stretched and the auxiliary belt cannot be attached.

  Therefore, when wrapping the auxiliary belt, it is necessary to squeeze the auto tensioner against the return spring and wrap the auxiliary belt while maintaining the contracted state of the auto tensioner. However, the contracted state of the auto tensioner is maintained. However, the operation of winding the auxiliary belt is complicated.

  Therefore, in order to improve the workability of winding the auxiliary machine belt, an auto tensioner described in Patent Document 2 has been proposed. The auto tensioner of Patent Document 2 is made of a metal having a U-shaped cross section including a pair of opposing side walls facing the left and right with a spring seat and a cylinder in between, and a front wall connecting the front edges of the pair of side walls. The cover has a cover, and protrusions bent inward are provided at the upper and lower ends of each side wall of the cover, and the flanges of the spring seat and the closed end of the cylinder are vertically sandwiched between the protrusions. Thus, the rod is restricted from moving in the direction protruding from the cylinder.

Japanese translation of PCT publication 2-500210 Japanese Patent Laid-Open No. 10-306859

  However, the auto tensioner disclosed in Patent Document 2 needs to distinguish between the front and rear of the auto tensioner when connecting to the pulley arm, and the workability of connecting to the pulley arm is poor. That is, when removing the cover with a U-shaped cross section, it can only be removed from the open side of the U-shaped cross section, so if you accidentally connect the auto tensioner to the pulley arm with its front and back reversed, connect the auto tensioner and pulley arm to the engine. Even if it is attempted to remove the cover after being attached to the cover, the cover may interfere with the engine block or the like, and the cover may not be removed. For this reason, when connecting the auto tensioner to the pulley arm, it is necessary to distinguish between the front and rear of the auto tensioner.

  Further, in the auto tensioner of Patent Document 2, it is necessary to remove the cover and extend the auto tensioner in order to apply tension to the accessory belt after the operation of winding the accessory belt is completed. For this purpose, it is necessary to further contract the contracted auto tensioner against the urging force of the return spring in order to release the contact with the protruding piece of the cover, which is complicated.

  In addition, the auto tensioner of Patent Document 2 has a complicated cover shape, and the cover manufacturing cost is high.

  The problem to be solved by the present invention is to provide an auto tensioner that is excellent in assembling workability to an engine and is low in cost.

  In order to solve the above problems, a cylinder closed at the bottom, a rod inserted in the cylinder so as to be movable in the axial direction, a hydraulic damper mechanism for buffering the pushing force applied to the rod, A spring seat fixed to a projecting end from the cylinder; and a return spring for biasing the rod in a direction projecting from the cylinder through the spring seat, the spring seat supporting an upper end of the return spring In an auto tensioner having an end plate and an upper connecting piece protruding upward from the end plate, and the lower connecting piece is provided at the closed end of the cylinder, the rod moves in a direction protruding from the cylinder. An annular fixture that is wound around the spring seat and the cylinder is provided so as to regulate the above.

  In this way, the annular fixture can be cut and removed from either the front side or the rear side of the auto tensioner, so that it is not necessary to distinguish the front and rear of the auto tensioner when connecting the auto tensioner to the pulley arm. Therefore, it is excellent in assembling workability to the engine. Further, when the annular fixture is cut and removed, there is no need to further shrink the contracted autotensioner in order to remove the fixture. Moreover, since the shape of the fixture is simple, the production cost of the fixture is low.

  It is preferable that the annular fixing tool is wound around the upper connecting piece and the lower connecting piece so as to form a cutting tool insertion space between the annular fixing tool and the upper connecting piece. If it does in this way, the operation | work which cut | disconnects a cyclic | annular fixing tool will become very easy.

  A metal band is preferably used as the annular fixture. The metal band has high strength without causing creep elongation unlike the resin band when the urging force of the return spring is applied.

  It is preferable that the metal band is curved in advance according to the shape of the spring seat and the cylinder. If it does in this way, the operation | work which mounts | wears with an annular fixing tool will become very easy. In this case, if the shape of the metal band is vertically symmetrical, it is not necessary to distinguish between the upper and lower sides of the metal band when the metal band is wound around the spring seat and the cylinder, and the workability of the assembly of the auto tensioner can be improved. Become.

  The metal band may be a seamless one having no connection part, but if a band consisting of a strip part having an elongated cross-sectional flat shape and a connection part connecting both ends of the band part is adopted, Band production costs can be reduced. If both ends of the band portion are connected by spot welding and the connecting portion is the connection portion, the manufacturing cost of the metal band can be particularly reduced. Further, when a connecting portion comprising a worm screw attached to one end of the band portion and a screw groove provided at the other end of the band portion is adopted, the worm is extended in a direction in which the circumferential length of the metal band is increased. By rotating the screw, the metal band can be removed without cutting, and the removed metal band can be reused as an annular fixture.

  Further, as the annular fixture, for example, a resin band formed of a resin containing fibers, a woven belt made of synthetic fiber yarn, or a rubber belt in which a synthetic resin core wire is covered with a rubber material is used. can do.

  The auto tensioner of the present invention can be cut and removed from the front side or the rear side of the auto tensioner, so that it can be connected to the pulley arm without distinguishing the front and rear of the auto tensioner. Excellent assembling workability. Moreover, since the annular fixture can be cut and removed, it is not necessary to further contract the contracted autotensioner in order to remove the fixture. Moreover, since the shape of the fixture is simple, the production cost of the fixture is low.

The front view which shows the tension adjustment apparatus incorporating the auto tensioner of embodiment of this invention 1 is an enlarged sectional view of the auto tensioner shown in FIG. Side view of the auto tensioner shown in FIG. Enlarged view of the vicinity of the upper connecting piece of the auto tensioner shown in FIG. The figure which shows the other example of the connection part shown in FIG. The figure which shows the further another example of the connection part shown in FIG. Enlarged sectional view of the connecting portion shown in FIG. The figure which shows the other example of the annular fixing tool shown in FIG. The figure which shows the further another example of the annular fixture shown in FIG. The figure which shows the further another example of the annular fixture shown in FIG. FIG. 10 is an enlarged cross-sectional view along the line XI-XI.

  FIG. 1 shows a tension adjusting device for an accessory belt 1 that drives an automobile accessory. This tension adjusting device has a pulley arm 4 supported so as to be swingable around a fulcrum shaft 3 fixed to an engine block 2 (see FIG. 3), and a tension pulley 5 attached to the pulley arm 4 so as to be rotatable. One end of an auto tensioner 6 according to an embodiment of the present invention is rotatably connected to the pulley arm 4 via a connecting shaft 7, and the other end of the auto tensioner 6 is supported by a fulcrum shaft 8 fixed to the engine block 2. Has been.

  As shown in FIG. 2, the auto tensioner 6 includes a cylinder 9, a rod 10 that is movably inserted in the cylinder 9 in the axial direction, a hydraulic damper mechanism 11 that buffers a pushing force applied to the rod 10, A spring seat 12 fixed to a projecting end of the rod 10 from the cylinder 9, and a return spring 13 that biases the rod 10 in a direction of projecting from the cylinder 9 via the spring seat 12.

  The cylinder 9 is formed in a cylindrical shape in which the lower part is closed and the upper end is opened. The closed end of the cylinder 9 is integrally provided with a lower connecting piece 15 having a front-rear direction through-hole 14 through which the fulcrum shaft 8 is inserted. Such a cylinder 9 can be formed by cold forging of aluminum. In the cylinder 9, air and hydraulic oil are accommodated in two upper and lower layers.

  The hydraulic damper mechanism 11 is formed between a sleeve 16 fixed in the cylinder 9 so as to be in sliding contact with the outer periphery of the rod 10, a pressure chamber 17 formed inside the sleeve 16, and the sleeve 16 and the cylinder 9. A reservoir chamber 18, an oil passage 19 communicating with the lower portion of the pressure chamber 17 and the lower portion of the reservoir chamber 18, and a check valve that allows only the flow of hydraulic oil from the reservoir chamber 18 side to the pressure chamber 17 side of the oil passage 19 20 and a leak gap 21 formed between the sliding surface of the sleeve 16 and the cylinder 9.

  The sleeve 16 is coaxially inserted into the cylinder 9, and the lower outer periphery of the sleeve 16 is fitted into a sleeve fitting recess 22 formed on the inner surface of the closed end of the cylinder 9. The oil passage 19 is formed between the fitting surface of the sleeve fitting recess 22 and the sleeve 16. The check valve 20 is provided at the end of the oil passage 19 on the pressure chamber 17 side.

  The spring seat 12 is made of synthetic resin. The protruding end of the rod 10 from the cylinder 9 is fixed to the spring seat 12 by molding the spring seat 12 (insert molding) in a state where it is set in the molding die of the spring seat 12.

  The spring seat 12 includes an end plate 23 that supports the upper end of the return spring 13, an upper connecting piece 24 that protrudes upward from the end plate 23, and a cylindrical inner skirt 25 and outer skirt 26 that extend downward from the end plate 23. Consists of. The upper connecting piece 24 has a through hole 27 in the front-rear direction through which the connecting shaft 7 is inserted. The inner skirt 25 is disposed so as to face the upper inner periphery of the cylinder 9 and is in sliding contact with an annular oil seal 28 attached to the upper inner periphery of the cylinder 9. The oil seal 28 seals the hydraulic oil in the cylinder 9. The outer skirt 26 is disposed to face the outer periphery of the upper portion of the cylinder 9 and prevents the oil seal 28 from being exposed to the outside.

  The return spring 13 is a coil spring made of a wire extending in a spiral shape, and is incorporated between the inner periphery of the cylinder 9 and the outer periphery of the sleeve 16. The lower end of the return spring 13 is supported by the closed end of the cylinder 9 via a washer 29, and the upper end of the return spring 13 presses the end plate 23 of the spring seat 12 upward, and the rod 10 causes the cylinder to be pressed. It is urged in a direction protruding from 9. A washer 29 that receives the lower end of the return spring 13 is locked in a locking groove 30 formed on the outer periphery of the sleeve 16, and a downward force acting on the locking groove 30 from the return spring 13 through the washer 29. The upward movement of the sleeve 16 is restricted.

  As shown in FIGS. 2 and 3, an annular metal band 31 is wound around the spring seat 12 and the cylinder 9 so as to circumscribe the upper connecting piece 24 and the lower connecting piece 15. Here, the metal band 31 is wound in a state in which the auto tensioner 6 in a natural state where no external force is applied is compressed against the return spring 13, and the rod 10 projects in a direction in which the rod 10 protrudes from the cylinder 9. The movement is restricted.

  In addition, the width | variety of the metal band 31 is about 8-12 mm, and the urging | biasing force of the return spring 13 in the state which pushed and shrunk the auto tensioner 6 is about 1000-2000N. The breaking load of the metal band 31 is set to 1.5 times or more the urging force of the spring 13.

  As shown in FIG. 2, the metal band 31 linearly extends between the left and right edges of the end plate 23 formed so as to protrude from the base of the upper connecting piece 24 to the left and right and the top of the upper connecting piece 24. Thus, a cutting tool insertion space 32 into which a cutting tool N such as a nipper can be inserted is formed between the metal band 31 and the upper connecting piece 24.

  The metal band 31 includes an elongated band portion 33 having a flat cross section and a connection portion 34 that connects both ends of the band portion 33. The connecting portion 34 is a portion where both ends of the band portion 33 are connected by spot welding. As a material of the metal band 31, for example, steel or aluminum can be used, but using steel is inexpensive. The metal band 31 is curved in advance according to the shape of the spring seat 12 and the cylinder 9. Here, the metal band 31 may be formed so as to completely match the contour shape of the spring seat 12 and the cylinder 9, but circumscribes the contour shape of the spring seat 12 and the cylinder 9 as shown in FIG. 2. If it forms in a polygonal shape, the number of the bending process parts 35 can be restrained and it is low-cost.

  For example, the auto tensioner 6 is assembled to the engine block 2 as follows.

  First, as shown in FIG. 1, an auto tensioner 6 held in a contracted state by winding a metal band 31 and a pulley arm 4 to which a tension pulley 5 is attached are prepared. Next, the upper connecting piece 24 of the auto tensioner 6 is connected to the pulley arm 4 via the connecting shaft 7. Subsequently, the lower connection piece 15 and the pulley arm 4 of the auto tensioner 6 are attached to the engine block 2 via the fulcrum shafts 3 and 8, respectively. Thereafter, the accessory belt 1 is wound around a pulley (not shown) for driving each accessory and a tension pulley 5. At this stage, since the auto tensioner 6 is held in the contracted state, no tension is applied to the auxiliary belt 1. Thereafter, as shown in FIG. 4, a cutting tool N such as a nipper is inserted into the cutting tool insertion space 32, and the metal band 31 is cut and removed. As a result, the rod 10 moves in a direction protruding from the cylinder 9 and the auto tensioner 6 extends, so that tension is applied to the auxiliary belt 1.

  Next, an operation example of the auto tensioner 6 will be described.

  When the tension of the auxiliary belt 1 is reduced during the operation of the engine, the rod 10 protrudes from the cylinder 9 to a position where the tension of the auxiliary belt 1 and the biasing force of the return spring 13 are balanced, and the slack of the auxiliary belt 1 is absorbed. At this time, the pressure in the pressure chamber 17 decreases, the check valve 20 opens, and the hydraulic oil flows from the reservoir chamber 18 to the pressure chamber 17 through the oil passage 19, so that the rod 10 moves quickly.

  On the other hand, when the tension of the auxiliary belt 1 increases during engine operation, the rod 10 is pushed into the cylinder 9 to a position where the tension of the auxiliary belt 1 and the biasing force of the return spring 13 are balanced, and the tension of the auxiliary belt 1 is increased. Absorbs. At this time, the pressure in the pressure chamber 17 rises and the check valve 20 is closed, and the hydraulic oil in the pressure chamber 17 flows into the reservoir chamber 18 through the leak gap 21, and the damper force is increased by the viscous resistance of the hydraulic oil. As it occurs, the rod 10 moves slowly.

  Since the auto tensioner 6 can be removed by cutting the metal band 31 from the front side or the rear side of the auto tensioner 6, it is necessary to distinguish the front and rear of the auto tensioner 6 when connecting the auto tensioner 6 to the pulley arm 4. There is no. Therefore, it is excellent in assembling workability to the engine.

  Further, since the auto tensioner 6 can be removed by cutting the metal band 31, it is not necessary to further contract the contracted auto tensioner 6 in order to remove the fixture as in the prior art. Excellent assembling workability. Further, since the shape of the metal band 31 is simple, the manufacturing cost can be kept low. Further, since the metal band 31 as the annular fixture has a flat cross section, the contact area of the annular fixture to the spring seat 12 and the cylinder 9 is wider than when a wire having a round cross section is adopted as the annular fixture, The metal band 31 is unlikely to drop off due to vibration during the conveyance of the auto tensioner 6.

  In addition, since the auto tensioner 6 is formed by bending the metal band 31 in advance according to the shapes of the spring seat 12 and the cylinder 9, the work of attaching the metal band 31 is extremely easy. In FIG. 2, the shape of the metal band 31 is asymmetric in the vertical direction, but the shape of the metal band 31 may be a vertically symmetrical polygonal shape that circumscribes the contour shape of the spring seat 12 and the cylinder 9. In this way, it is not necessary to distinguish between the upper and lower sides of the metal band 31 when the metal band 31 is wound around the spring seat 12 and the cylinder 9, and the workability of assembling the auto tensioner 6 can be improved.

  The metal band 31 may be a seamless one that does not have the connection portion 34, but as shown in the above embodiment, the metal band 31 includes the band portion 33 and the connection portion 34 that connects both ends of the band portion 33. If a thing is employ | adopted, the manufacturing cost of the metal band 31 can be held down.

  In the above embodiment, in order to particularly reduce the manufacturing cost of the metal band 31, the portion where both ends of the band portion 33 are connected by spot welding is used as the connection portion 34. However, as shown in FIG. It is also possible to make the connecting portion 34 a portion that is folded by overlapping.

  As shown in FIGS. 6 and 7, a worm screw 36 attached to one end of the band portion 33 and a screw provided at the other end of the band portion 33 as a connecting portion 34 for connecting both ends of the band portion 33. It is also possible to employ one comprising a groove 37. In this case, the metal band 31 can be removed without cutting by rotating the worm screw 36 in the direction in which the circumferential length of the metal band 31 becomes longer, and the removed metal band 31 can be used as an annular fixture. Can be reused. In FIG. 7, the worm screw 36 is accommodated in a case 38 fixed to one end of the band portion 33, and is supported so as to be rotatable and non-movable in the axial direction of the worm screw 36.

  In the above-described embodiment, the metal band 31 is described as an example of the annular fixture that is wound around the spring seat 12 and the cylinder 9. However, as illustrated in FIG. 9, the resin band 40 is used instead of the metal band 31. Also good. When the resin band 40 is used, creeping elongation may occur in the resin band 40 when the urging force of the return spring 13 is applied. Therefore, in order to prevent this creep elongation, a resin containing fibers is used. The resin band 40 is preferably molded. Examples of the fiber to be blended in the resin include glass fiber and aramid fiber.

  Further, as shown in FIG. 8, a woven belt 39 made of synthetic fiber yarn can be used as an annular fixture, and as shown in FIG. 10, a rubber belt 41 can also be used as an annular fixture. is there. In order to prevent the rubber belt 41 from elastically extending due to the urging force of the return spring 13, the rubber belt 41 covers the outer side of the synthetic resin core wire 42 with a rubber material 43 as shown in FIGS. It is preferred to use

6 Auto tensioner 9 Cylinder 10 Rod 11 Hydraulic damper mechanism 12 Spring seat 13 Return spring 15 Lower connection piece 23 End plate 24 Upper connection piece 31 Metal band 32 Cutting tool insertion space 33 Band part 34 Connection part 36 Warm screw 37 Screw groove 39 Textile belt 40 Resin band 41 Rubber belt 42 Core wire 43 Rubber material

Claims (11)

A cylinder (9) whose lower part is closed, a rod (10) inserted in the cylinder (9) so as to be movable in the axial direction, and a hydraulic damper mechanism (for damping the pushing force applied to the rod (10)) 11), a spring seat (12) fixed to the projecting end of the rod (10) from the cylinder (9), and the rod (10) projecting from the cylinder (9) via the spring seat (12). A return spring (13) biased in the direction, and the spring seat (12) includes an end plate (23) that supports the upper end of the return spring (13), and an upper side from the end plate (23). An auto-tensioner having a protruding upper connecting piece (24) and having a lower connecting piece (15) provided at the closed end of the cylinder (9);
An annular fixture (31) wound around the spring seat (12) and the cylinder (9) is provided so as to restrict the rod (10) from moving in a direction protruding from the cylinder (9). Auto tensioner.   The annular fixture (31) is wound around the upper connecting piece (24) and the lower connecting piece (15) so as to be circumscribed, and is cut between the annular fixture (31) and the upper connecting piece (24). The auto tensioner according to claim 1, wherein a tool insertion space (32) is formed.   The auto tensioner according to claim 1 or 2, wherein a metal band (31) is used as the annular fixture.   The auto-tensioner according to claim 3, wherein the metal band (31) is curved in advance according to the shape of the spring seat (12) and the cylinder (9).   The auto tensioner according to claim 4, wherein the shape of the metal band (31) is vertically symmetrical.   6. The metal band (31) according to any one of claims 3 to 5, wherein the metal band (31) includes an elongated band portion (33) having a flat cross section and a connection portion (34) connecting both ends of the band portion (33). Auto tensioner.   The auto tensioner according to claim 6, wherein the connecting portion (34) is a portion in which both ends of the belt portion (33) are connected by spot welding.   The said connection part (34) consists of a worm screw (36) attached to one end of the said band part (33), and a screw groove (37) provided in the other end of the said band part (33). 6. The auto tensioner according to 6.   The auto tensioner according to claim 1 or 2, wherein a resin band (40) formed of a resin containing fibers is used as the annular fixture.   The auto tensioner according to claim 1 or 2, wherein a woven belt (39) made of synthetic fiber yarn is used as the annular fixture.   The auto tensioner according to claim 1 or 2, wherein a rubber belt (41) in which an outer side of a core wire (42) made of a synthetic resin is covered with a rubber material (43) is used as the annular fixture.

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