JP2018165533A - Auto Tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auto tensioner not restricted in a mounting direction at low costs.SOLUTION: An auto tensioner includes a damper portion 10, an eccentric wheel 20 rotatable about an eccentric shaft, a pulley portion 30 disposed relatively rotatably to the eccentric wheel 20, and a tension adjustment spring 40 for energizing the eccentric wheel 20. The damper portion 10 has a damper cylinder 13 having a bottomed cylindrical rod insertion hole 13a, a rod 14 having a male screw 14a on an outer peripheral face and disposed in the rod insertion hole 13a, a nut 15 having a female screw 15a on an inner peripheral face and screwed to the rod 14, a buffer spring 16 disposed on a bottom portion of the rod insertion hole 13a and energizing the nut 15 toward an opening portion side of the rod insertion hole 13a, and a torsion coil spring 17 engaged with the rod 14 at noe end, engaged with the nut 15 at the other end, and energizing the rod 14 and the nut 15 to be relatively rotated, and these are housed in an inner diameter of the pulley portion 10.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an auto tensioner used for adjusting the tension of a timing belt of an automobile.

  In a belt drive device for driving a camshaft incorporated in an internal combustion engine of an automobile, its tension changes due to a change in the distance between the shafts due to thermal expansion of the engine body during engine operation and the extension of the timing belt due to aging. For this reason, in the belt transmission device as described above, the adjustment force of the auto tensioner is applied to the timing belt and the tension is kept constant, thereby preventing the generation of noise and tooth skipping due to the timing belt flapping. ing. Since the timing belt transmission as described above is arranged outside the engine front cover, it is considered that stones and mud are flying from the road surface while the vehicle is running. On the other hand, the intrusion of engine oil and the like is not considered like the parts inside the engine.

  As an example of the above-described auto tensioner, for example, an auto tensioner disclosed in Patent Document 1 can be employed. The auto tensioner mainly includes an eccentric wheel that supports a tension pulley and a hydraulic damper.

  The eccentric ring is rotatable around the eccentric axis. The eccentric wheel is provided with a tension adjusting spring, and the eccentric wheel rotates around the eccentric shaft by the urging force, and the tension pulley contacts the belt to apply tension to the belt. The hydraulic damper accommodates a plunger movably in the axial direction in a liquid chamber in an obliquely vertical direction provided in the damper cylinder. In this plunger, the lower end of a reservoir chamber provided inside along the axial center communicates with a pressure chamber formed at the lower end of the liquid chamber via a passage, a check valve is provided at the lower end of the passage, The return coil spring of the plunger is contracted. The damper cylinder is provided with a sub reservoir chamber arranged at a right angle to the reservoir chamber. The plunger of the hydraulic damper is in contact with a pin provided on the eccentric ring, and the rotation of the eccentric ring accompanying the fluctuation of the belt tension is transmitted to the plunger, and the damper action is exhibited. In this configuration, since the reservoir chamber and the auxiliary reservoir chamber are arranged at right angles, the hydraulic cylinder can be downsized.

JP-A-8-338488

  The auto tensioner described in Patent Document 1 is filled with an amount of hydraulic oil (oil) that fills the entire reservoir chamber and pressure chamber and a part of the sub reservoir chamber, and the upper space of the sub reservoir chamber becomes an air chamber. Arranged so that. If the air in the sub-reservoir chamber is mixed into the pressure chamber due to the inclination of the auto tensioner, the mixed air is compressed in the pressure chamber when the plunger is pushed in the axial direction as the belt tension increases. The damper characteristics may be lost. For this reason, the mounting direction of the auto tensioner is limited. Moreover, since a sealing means for sealing the oil in the cylinder is necessary, the number of parts increases. In addition, in order to keep the oil flow rate between the liquid chamber of the damper cylinder and the plunger at a predetermined amount, it is necessary to process each component with high accuracy, so that the cost tends to increase.

  Further, the current mainstream of automobile timing systems is timing chain systems, but in recent years, timing belt systems have been reviewed from the viewpoint of improving fuel efficiency and quietness. However, the timing chain system is used in an oil environment inside the engine front cover (chain cover), whereas the conventional timing belt system is used outside the front cover. Therefore, a change to the timing belt system requires a significant change in the engine body. On the other hand, if a conventional timing belt system that is not intended for use in an oil environment is used inside the engine front cover, engine oil may enter the tensioner section and bearing section, resulting in reduced functionality and life. is there.

  Therefore, an object of the present invention is to provide an auto tensioner that can be used in an oil environment and whose mounting direction is not limited at a low cost.

  In order to solve this problem, in the present invention, a damper portion fixed to the engine block, an eccentric wheel that is rotatable around an eccentric shaft inserted into the engine block, and an outer peripheral edge of the eccentric wheel. A pulley portion provided rotatably relative to the eccentric ring, and a tension adjusting spring that urges the eccentric ring in a direction in which a tension is applied to the timing belt spanned over the pulley portion. Is a damper cylinder formed with a bottomed cylindrical rod insertion hole, a male screw is formed on the outer peripheral surface, a rod provided in the rod insertion hole, a female screw is formed on the inner peripheral surface, and is screwed into the rod A nut, a buffer spring provided at the bottom of the rod insertion hole, and biasing the nut toward the opening side of the rod insertion hole; one end engaged with the rod; the other end connected to the nut A torsion coil spring that relatively rotates the rod and the nut and biases the rod in a direction protruding from the rod insertion hole, and the damper portion, the eccentric ring, and the tension adjustment An auto tensioner was constructed in which the spring for use was housed within the inner diameter of the pulley section.

  In this auto tensioner, the damper action is exhibited by the frictional force between the external thread formed on the rod and the internal thread formed on the nut and the buffer spring. In this configuration, since no oil is used to exert a damper action, the mounting direction of the auto tensioner is not limited. In addition, since the number of parts can be reduced as compared with the hydraulic type, the manufacturing cost can be reduced.

  In each configuration, the male screw and the female screw have a flank angle of a pushing-side flank that receives pressure when a load is applied in a direction of pushing the rod into the rod insertion hole, and the rod protrudes from the rod insertion hole. It is preferable to have a sawtooth shape that is larger than the flank angle of the protruding flank that receives pressure when a load in the direction to be applied is applied.

  Thus, by making the male screw and the female screw serrated, when a pushing force into the rod insertion hole is applied to the rod, a large friction force between the pushing side flank of both screws and a buffer spring, a high damper is achieved. The effect can be exerted. On the other hand, when the pushing force is eliminated, the urging force of the torsion coil spring can smoothly project the rod from the rod insertion hole.

  In each of the above configurations, a bottomed cylindrical spring accommodating hole that extends in the axial direction and opens toward the bottom of the rod insertion hole is formed inside the rod, and the tension adjusting spring is the spring. It can also be set as the structure accommodated in the accommodation hole. In this way, the installation space for the tension adjusting spring can be saved, and further downsizing can be achieved.

  In each said structure, the said buffer spring can be either a compression coil, a disc spring, or a wave spring, and the tension adjustment spring can be a compression coil spring. Since these members are both readily available and inexpensive, the cost of parts can be reduced.

  In this invention, the damper portion of the auto tensioner includes a damper cylinder in which a bottomed cylindrical rod insertion hole is formed, a male screw is formed on the outer peripheral surface, a rod provided in the rod insertion hole, and an inner peripheral surface. A female screw is formed, the nut is screwed into the rod, a buffer spring is provided at the bottom of the rod insertion hole and urges the nut toward the opening of the rod insertion hole, and one end is engaged with the rod. The other end is engaged with the nut, the rod and the nut are rotated relative to each other, and a torsion coil spring that biases the rod in a direction protruding from the rod insertion hole is used, and oil is used. Since it is set as the structure which does not carry out, an auto tensioner can be installed without the limitation of an attachment direction. In addition, since the number of parts can be reduced as compared with the hydraulic type, the manufacturing cost can be reduced.

1 is a longitudinal sectional view showing a first embodiment of an auto tensioner according to the present invention. Sectional view along the II-II line in FIG. Sectional view of the auto tensioner shown in FIG. Sectional drawing which shows the principal part of FIG. Sectional drawing which notched part which shows the state in which the rod of the auto tensioner shown in FIG. 1 was pushed further It is a longitudinal cross-sectional view which shows the modification of the buffer spring of the auto tensioner shown in FIG. 1, Comprising: (a) is the structure which employ | adopted the disc spring, (b) is the structure which employ | adopted the wave spring. 1 is a longitudinal sectional view showing a modification of the tension adjustment spring of the auto tensioner shown in FIG. A longitudinal sectional view showing a second embodiment of the auto tensioner according to the present invention Sectional drawing along the IX-IX line in FIG. Sectional view of the auto tensioner shown in FIG.

  A first embodiment of an auto tensioner according to the present invention will be described with reference to FIGS. This auto tensioner has a function of keeping the tension of the timing belt B for automobile (see FIG. 2) constant, and includes a damper portion 10, an eccentric wheel 20, a pulley portion 30, and a tension adjusting spring 40 as main components. As a component.

  The damper unit 10 is a mechanical damper that does not use oil, and is fixed to the engine block 12 of the vehicle by a fixing bolt 11. The damper portion 10 includes a damper cylinder 13, a rod 14, a nut 15, a buffer spring 16, and a torsion coil spring 17.

  The damper cylinder 13 is formed with a bottomed cylindrical rod insertion hole 13a into which the rod 14 is inserted. Further, the damper cylinder 13 is formed with a bolt insertion hole 13b and a pin insertion hole 13c. As shown in FIG. 1, a fixing bolt 11 is inserted into the bolt insertion hole 13 b, and the damper portion 10 is fixed to the engine block 12 by screwing the fixing bolt 11 into a bolt hole formed on the engine block 12 side. Is done. The fixing pin 18 is inserted into the pin insertion hole 13c. The fixing pin 18 is provided so as to penetrate the damper cylinder 13, and one end side thereof protrudes from the damper cylinder 13, and the other end side opposite to the one end side is a pin hole formed in the engine block 12. It is inserted.

  As shown in FIG. 3, the rod 14 is provided in a rod insertion hole 13 a formed in the damper cylinder 13. The rod 14 is formed with a male screw 14a on the outer peripheral surface thereof. A flange 14 b is formed at the opening side end of the rod insertion hole 13 a of the rod 14. The flange 14b is formed with a fixing groove 14c to which one end side of the torsion coil spring 17 is fixed.

  A female screw 15 a is formed on the inner peripheral surface of the nut 15, and the nut 15 is screwed into the rod 14. As shown in FIG. 4, the male screw 14 a of the rod 14 and the female screw 15 a of the nut 15 are pushed to receive pressure when a load in a direction of pushing the rod 14 into the rod insertion hole 13 a formed in the damper cylinder 13 is applied. A side flank and a protruding flank that receives pressure when a load in a direction in which the rod 14 protrudes from the rod insertion hole 13a is applied. The flank angle θ1 of the push-in flank is larger than the flank angle θ2 of the protrusion-side flank, and both flanks are formed in a sawtooth shape. An engagement groove 15b is formed at the opening side end of the rod insertion hole 13a of the nut 15 so that the other end of the torsion coil spring 17 opposite to the one end is engaged.

  The buffer spring 16 is provided at the bottom of the rod insertion hole 13a and urges the nut 15 toward the opening side of the rod insertion hole 13a. By providing the buffer spring 16, the nut 15 can be maintained at a predetermined position in the axial direction in the rod insertion hole 13a. Further, when a large pushing force is applied to the rod 14, the pushing force is buffered, and the male screw 14a of the rod 14 and the female screw 15a of the nut 15 can be prevented from coming into strong contact with each other to prevent the damper action from being exerted. . In this embodiment, a compression coil spring 16a is used as the buffer spring 16, but a disc spring 16b or a wave spring 16c may be employed as shown in FIGS.

  One end of the torsion coil spring 17 is engaged with an engagement groove 14 c formed on the rod 14, and the other end is engaged with an engagement groove 15 b formed on the nut 15, thereby rotating the rod 14 and the nut 15 relative to each other. As shown in FIG. The torsion coil spring 17 has a configuration in which engagement pieces are formed at both ends of the coil, and the engagement piece on one end side is an engagement formed on the rod 14 that is prevented from rotating to the damper cylinder 13. The engaging piece on the other end side is fixed to the engaging groove 15b formed in the nut 15 in the groove 14c.

  A pressing pin 21 inserted into a pin insertion hole 20a of an eccentric ring 20 described later is in contact with the flange 14b. By this contact, the rod 14 is prevented from coming out of the rod insertion hole 13a by the biasing force of the torsion coil spring 17, and the rotation around the eccentric shaft (fixing bolt 11) of the eccentric ring 20 is controlled by the rod 14 (damper portion). 10). When a pressing force acts on the rod 14 via the pressing pin 21, the torsion coil spring 17 urges the nut 15 to rotate relative to the rod 14, and the nut 15 is screwed into the rod 14.

  The eccentric ring 20 is rotatable around the eccentric axis. The eccentric shaft also serves as a fixing bolt 11 for fixing the damper portion 10 (damper cylinder 13) to the engine block 12. Inside the eccentric ring 20, a horizontal hole 20 b extending in a direction perpendicular to the eccentric shaft and having an opening on the side surface in the eccentric axis direction of the eccentric ring 20 is formed.

  The pulley portion 30 is provided on the outer peripheral edge of the eccentric ring 20 so as to be rotatable relative to the eccentric ring 20 via a rolling bearing 31. The timing belt B is bridged over the pulley portion 30 (see FIG. 2). In this embodiment, the pulley portion 30 and the outer ring of the rolling bearing 31 are integrally configured, but each may be a separate member.

  The tension adjusting spring 40 is provided in a bottomed lateral hole 20 b formed in the eccentric ring 20. One end side of the tension adjusting spring 40 is seated on the bottom surface of the horizontal hole 20b, and a spring seat 41 is provided on the other end side opposite to the one end. The spring seat 41 is in contact with the fixing pin 18 inserted from the opening of the lateral hole 20b. The eccentric ring 20 is urged by the urging force of the tension adjusting spring 40 in a direction in which tension is applied to the timing belt B stretched over the pulley portion 30. In this embodiment, the single compression coil spring 40a is used as the tension adjusting spring 40. However, as shown in FIG. 7, the type of spring is appropriately changed, such as using a double compression coil spring 40b. be able to.

  In this configuration, the members such as the damper portion 10, the eccentric wheel 20, and the tension adjustment spring 40 are all provided within the inner diameter of the pulley portion 30, thereby reducing the size. Thereby, this auto tensioner can be smoothly installed in a narrow engine room. Further, by reducing the size, the engine can be installed in a narrow space in the front cover of the engine. Furthermore, since the oil that has entered the tensioner can be used as a lubricant, it is not necessary to strictly prevent the oil from entering the tensioner.

  When a large tension acts on the timing belt B, the eccentric wheel 20 rotates counterclockwise of the eccentric shaft (fixing bolt 11) against the urging force of the tension adjusting spring 40 due to this tension (in FIG. 3). The direction of r1 of the white arrow). Then, the pressing pin 21 provided on the eccentric wheel 20 pushes the rod 14 into the rod insertion hole 13a (see FIG. 5) and absorbs the tension of the timing belt B. At this time, the pushing side flank of the male screw 14a of the rod 14 and the pushing side flank of the female screw 15a of the nut 15 slide relative to each other, so that the rod 14 and the nut 15 rotate relative to each other. The damper action is exhibited by the frictional resistance between the flank.

  On the other hand, when the tension of the timing belt B is weakened, the eccentric ring 20 is rotated clockwise by the biasing force of the tension adjusting spring 40 (as indicated by the white arrow in FIG. 3). r2 direction). Then, the pushing force acting on the rod 14 from the pressing pin 21 is reduced, and the rod 14 protrudes from the rod insertion hole 13a and absorbs the looseness of the timing belt B. At this time, due to the biasing force of the torsion coil spring 17, the projecting flank of the male thread 14a of the rod 14 and the projecting flank of the female thread 15a of the nut 15 come into contact with each other. Are relatively rotated, and the rod 14 protrudes from the rod insertion hole 13a.

  Further, when the engine is stopped, the tension of the timing belt B may increase depending on the stop position of the camshaft (not shown). Since the timing belt B does not vibrate when the engine is stopped, no slip occurs between the pushing side flank of the male screw 14a of the rod 14 and the pushing side flank of the female screw 15a of the nut 15, and the position of the rod 14 is fixed. The For this reason, when the engine is restarted, the timing belt B is hardly loosened, and the engine can be started smoothly.

  A second embodiment of the auto tensioner according to the present invention will be described with reference to FIGS. The auto tensioner has the same basic configuration as the auto tensioner according to the first embodiment, but the tension adjusting spring 40 (40a) is placed in the bottomed spring accommodating hole 14e formed in the rod 14. It differs in the point provided.

  Thus, by arranging the tension adjusting spring 40 inside the rod 14, the installation space for the tension adjusting spring 40 can be saved, and further downsizing can be achieved. In addition, since it is not necessary to provide the fixing pin 18 (see FIG. 1 and the like), it is possible to reduce processing costs and component costs.

  The auto tensioner according to each of the above embodiments is merely an example, and each member can be used as long as it can solve the problem of the present invention that the auto tensioner that can be used in an oil environment and the mounting direction is not limited is provided at low cost. It is permissible to change the shape and arrangement as appropriate.

DESCRIPTION OF SYMBOLS 10 Damper part 12 Engine block 13 Damper cylinder 13a Rod insertion hole 14 Rod 14a Male thread 14e Spring accommodation hole 15 Nut 15a Female thread 16 Buffer spring 16a Compression coil spring 16b Disc spring 16c Wave spring 17 Torsion coil spring 20 Eccentric ring 30 Pulley part 40 Tension Adjustment spring 40a Single compression coil spring (compression coil spring)
40b Double compression coil spring (compression coil spring)
B Timing belt θ1, θ2 Frank angle

Claims (5)

A damper portion (10) fixed to the engine block (12);
An eccentric wheel (20) that is inserted into the engine block (12) and is rotatable about an eccentric shaft;
A pulley portion (30) provided on the outer peripheral edge of the eccentric ring (20) so as to be rotatable relative to the eccentric ring (20);
A tension adjusting spring (40) that urges the eccentric ring (20) in a direction in which tension is applied to the timing belt (B) spanned over the pulley portion (30);
With
The damper part (10)
A damper cylinder (13) formed with a bottomed cylindrical rod insertion hole (13a);
A rod (14) having a male screw (14a) formed on the outer peripheral surface and provided in the rod insertion hole (13a);
A female screw (15a) is formed on the inner peripheral surface, and a nut (15) screwed into the rod (14);
A buffer spring (16) provided at the bottom of the rod insertion hole (13a) and biasing the nut (15) toward the opening side of the rod insertion hole (13a);
One end is engaged with the rod (14), the other end is engaged with the nut (15), the rod (14) and the nut (15) are relatively rotated, and the rod is inserted into the rod insertion hole (13a). A torsion coil spring (17) biased in a direction protruding from
Have
The damper portion (10), the eccentric ring (20), and the tension adjusting spring (40) are accommodated within the inner diameter of the pulley portion (30).
Auto tensioner.   The male screw (14a) and the female screw (15a) have a flank angle (θ1) of a pushing-side flank that receives pressure when a load in a direction of pushing the rod (14) into the rod insertion hole (13a) is applied, The auto of claim 1, wherein the rod (14) has a sawtooth shape larger than a flank angle (θ2) of a projecting flank that receives pressure when a load in a direction in which the rod (14) projects from the rod insertion hole (13a) is applied. Tensioner.   Inside the rod (14), a bottomed cylindrical spring accommodating hole (14e) extending in the axial direction thereof and opening toward the bottom of the rod insertion hole (13a) is formed, and the tension adjusting spring ( The auto tensioner according to claim 1 or 2, wherein 40) is housed in the spring housing hole (14e).   The auto tensioner according to any one of claims 1 to 3, wherein the buffer spring (16) is one of a compression coil (16a), a disc spring (16b), and a wave spring (16c).   The auto tensioner according to any one of claims 1 to 4, wherein the tension adjusting spring (40) is a compression coil spring (40a, 40b).

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