JP2017155877A - Power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power transmission device capable of reducing irregular sound informing a trouble occurred at an auxiliary machine for a vehicle as time elapses.SOLUTION: A torque limiter mechanism 30 is arranged between a pulley 10 and a rotating shaft 21 of an auxiliary machine 20. The torque limiter mechanism 30 is formed by a cover 31 connected to an outer side surface of the pulley 10 and a hub 41 fixed to a shaft end part of the rotating shaft 21 and formed with saw teeth 42 at its outer periphery. A cylindrical part 35 formed at the cover 31 is provided with an engaging piece 36, the engaging piece 36 is engaged with the saw teeth 42 of the hub 41 and a rotation of the pulley 10 is transmitted to the rotating shaft 21 of the auxiliary machine 20 for an automobile. When the auxiliary machine 20 for an automobile is troubled to cause a rotating load of the rotating shaft 21 to be increased, the engaging piece 36 rides over the saw teeth 42, a transmission of rotation from the pulley 10 to the rotating shaft 21 is cut off. In addition, riding over of saw teeth 42 causes the engaging piece 36 to have plastic deformation, an irregular sound is generated when the engaging piece 36 strikes against the teeth crests of the saw teeth 42, and the engaging piece 36 is worn out through contact at the time of striking action to reduce the irregular sound.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power transmission device that transmits power from an engine to an automobile accessory.

  In general, when driving an automotive accessory such as an air conditioner compressor, the rotation of the crankshaft of the engine is transmitted to the rotating shaft of the automotive accessory by a belt transmission. At this time, if the rotational load of the rotating shaft of the automobile auxiliary machine increases, the belt tension increases and slippage occurs at the contact portion between the pulley and the belt attached to the rotating shaft, which may damage the belt.

  In order to eliminate such inconvenience, Patent Document 1 proposes a power transmission device having a torque limiter mechanism. In the power transmission device described in Patent Document 1, a pulley for transmitting engine power via a belt, a hub attached to a rotating shaft of a compressor, and a torque limiter mechanism provided between the hub and the pulley. And have.

  The torque limiter mechanism connects one end of an arc-shaped connecting member to a pulley, and the other end of the connecting member is provided with a slit having a wide portion that opens at the end of the connecting member. A columnar body formed by a rivet that penetrates the flange of the hub and a collar through which the rivet penetrates is provided, the columnar body is inserted into the wide portion of the slit, and a disc spring is incorporated between the hub and the connecting member. Thus, the other end of the connecting member and the head of the rivet are elastically contacted, and the rotation of the pulley is transmitted to the hub at the elastic contact portion. Further, when the rotational load of the rotating shaft increases, slipping occurs at the elastic contact portion, and torque transmission is interrupted by the withdrawal of the columnar body from the slit, so that the pulley is rotated freely.

International Publication No. 2014/148414

  By the way, in the power transmission device described in Patent Document 1, the load variation of the compressor and the variation of the rotational torque applied to the pulley are absorbed by the slip of the elastic contact portion of the other end of the connecting member and the rivet head. Although it has a damper effect, since the damper force depends on the elastic force of the disc spring, it is necessary to replace the disc spring when adjusting the damper force, and there is an inconvenience that it takes time to adjust the damper force.

  In addition, since the connecting member is in a deformed state in which the pulley and the hub are connected, the operation state of the torque limiter mechanism in which the columnar body is pulled out from the wide portion of the slit is plastically deformed when held in a connected state for a long period of time. Thus, the connecting member that rotates together with the pulley may interfere with the head of the rivet and continue to generate noise, which may cause discomfort.

  An object of the present invention is to easily adjust a damper force that absorbs a load fluctuation of an automobile auxiliary machine such as a compressor and a fluctuation of a rotational torque applied to a pulley, and an abnormal noise that informs a failure of the automobile auxiliary machine is time-sensitive. It is an object of the present invention to provide a power transmission device that can be reduced as time passes.

  In order to solve the above problems, in the present invention, a pulley supported rotatably around a pulley support shaft provided coaxially with a rotation shaft of an automobile accessory, and the pulley and the rotation shaft A torque limiter mechanism which is provided between the pulley and transmits the rotation of the pulley to the rotating shaft and cuts off the rotation transmission from the pulley to the rotating shaft when the rotational load of the rotating shaft exceeds a set value. In the power transmission device, the torque limiter mechanism includes an annular cover coupled to an outer surface of the pulley, and a hub attached to an end portion of the rotating shaft and having a sawtooth formed on an outer periphery thereof. A cylindrical portion that can accommodate the hub is formed on the inner periphery of the rim, and an engagement piece that engages with the saw blade in the rotation direction is provided on the cylindrical portion, and elastic deformation is performed until the engagement piece gets over the saw blade. And get over the saw blade It was adopted comprising a resilient deformability to the plastic deformation configuration.

  In the power transmission device configured as described above, when the pulley rotates, the cover rotates together with the pulley, the rotation is transmitted from the engagement piece and the engagement portion of the sawtooth to the hub, and the rotation shaft rotates. Operates.

  When a fluctuation in the load of the automobile auxiliary machine or a fluctuation in the rotational torque applied to the pulley from the engine occurs, the engagement piece elastically deforms, and a damper action due to the elastic deformation causes a load fluctuation of the automobile auxiliary machine or a torque fluctuation from the engine. Absorbed. The damper force due to the damper action can be adjusted by changing the number of engaging pieces and the contact angle with the sawtooth.

  When the rotational load of the rotary shaft increases due to troubles, etc. in the operating state of the automobile auxiliary equipment, a large load is applied to the engagement piece, and the engagement piece is deformed by the load and overcomes the saw blade, from the pulley to the rotary shaft The rotation transmission of is interrupted, and the pulley and the cover rotate freely. The free rotation of the pulley prevents the belt on the pulley from becoming over-tensioned.

  Further, when the engagement piece gets over the saw blade, the engagement piece reaches the plastic region and is permanently deformed, and the engagement piece collides with the tooth tip surface of the saw blade of the hub and noise is generated. The occurrence of the abnormal noise makes it possible to know that the automobile auxiliary equipment has failed.

  Here, every time the engagement piece gets over the saw blade of the hub, an abnormal noise is generated. However, the tip of the engagement piece is worn by the contact of the saw blade with the tooth tip surface, and the abnormal noise is gradually reduced by reducing the amount of interference. .

  The engaging piece that engages with the saw blade of the hub is preferably provided with an outwardly bent portion at the tip. If an outwardly bent portion is provided at the tip of the engagement piece, the bent portion can be brought into line contact during contact rotation with the tooth tip surface of the saw blade, so that the bent portion is easily worn and abnormal noise is generated. It is possible to mute the sound at an early stage and reduce the discomfort given to the driver.

  The hub material may be a sintered material or a resin. When the hub is made of a sintered material or resin, the hub can be easily formed by molding, and a low-cost hub can be obtained.

  In the present invention, as described above, when a load fluctuation of the automobile auxiliary machine or a fluctuation of the rotational torque from the engine occurs, the engagement piece elastically deforms, and a damper action caused by the deformation causes a load fluctuation of the automobile auxiliary machine or the engine. Torque fluctuations from the vehicle can be absorbed, so that the auxiliary vehicle can be smoothly rotated.

  Further, the damper force by the damper action can be adjusted by changing the number of engagement pieces and the contact angle of the hub with the saw blade, and the damper force can be easily adjusted.

  In addition, when the rotational load on the rotating shaft increases in the operating state of the automotive accessory, the engaging piece is deformed and gets over the saw blade, the engagement with the saw blade is released, and the rotation transmission from the pulley to the rotating shaft is interrupted. Since the pulley rotates freely, the belt can be prevented from being damaged due to excessive tension.

  Further, when the engagement piece gets over the saw blade, the engagement piece reaches the plastic region and is permanently deformed, and the engagement piece collides with the tooth tip surface of the saw blade of the hub and generates an abnormal noise. By this, it can be known that the automobile auxiliary equipment is out of order.

  Here, every time the engagement piece gets over the saw blade of the hub, an abnormal noise is generated. However, since the tip of the engagement piece is worn due to contact with the tooth tip surface of the saw blade, the abnormal noise is reduced with time. be able to.

A longitudinal sectional view showing an embodiment of a power transmission device according to the present invention Partial cutaway right side view of FIG. Partially cutaway side view showing enlarged torque limiter mechanism (A) is sectional drawing which shows the rotation transmission state of a torque limiter mechanism, (b) is sectional drawing which shows the interruption | blocking state of rotation transmission

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the power transmission device includes a pulley 10 to which power from an engine (not shown) is transmitted, a rotating shaft 21 of an automobile auxiliary machine 20, and a mutual connection between the pulley 10 and the rotating shaft 21. The torque limiter mechanism 30 is provided between the pulley 10 and the rotation of the pulley 10 so as to transmit the rotation to the rotation shaft 21 and cut off the rotation transmission from the pulley 10 to the rotation shaft 21 when the rotation load of the rotation shaft 21 increases.

  The pulley 10 includes a belt guide wheel 11, an annular plate 12 provided on the inner periphery of the belt guide wheel 11, and a cylindrical boss portion 13 provided on the inner periphery of the annular plate 12. A pair of flanges 14 are provided on both sides of the outer circumference of the belt guide wheel 11, and a plurality of V-shaped grooves 15 around which the V-belt is wound are provided between the pair of flanges 14.

  A bearing housing 16 is incorporated inside the boss portion 13. The bearing housing 16 is secured by an annular projecting portion 13 a provided on the inner periphery of one end of the boss portion 13. The bearing housing 16 is prevented from rotating by a serration 17 formed on the outer periphery of one end and the inner periphery of one end of the boss portion 13, and a rolling bearing 18 is incorporated in the bearing housing 16.

  Here, a double row ball bearing is employed as the rolling bearing 18. The rolling bearing 18 is press-fitted into a cylindrical pulley support shaft 23 provided in the housing 22 of the automobile auxiliary machine 20 and is prevented from being removed by a retaining ring 24 attached to the outer periphery of the end of the pulley support shaft 23.

  Here, a compressor for an air conditioner is employed as the automobile auxiliary machine 20. The pulley support shaft 23 provided on the housing 22 of the automobile auxiliary machine 20 is provided coaxially with the rotary shaft 21, and the pulley 10 is supported rotatably about the pulley support shaft 23.

  The torque limiter mechanism 30 includes an annular cover 31 provided on the outer surface of the pulley 10 and a hub 41 attached to the shaft end of the rotating shaft 21. The cover 31 is made of a metal sheet press-molded product provided with an annular bulging portion 33 projecting to one side on the inner peripheral portion of the annular plate portion 32, and the annular bulging portion 33 has a U-shaped cross section. As shown in FIG. 3, a plurality of engagement pieces 36 are formed at equal intervals in the circumferential direction inside the small-diameter side cylindrical portion 35. A bent portion 37 is provided outward at the tip of the combined piece 36.

  Here, the engagement piece 36 is formed by forming a U-shaped cut in the small diameter side cylindrical portion 35 and cutting and raising the inner portion of the cut to the inner diameter side.

  As shown in FIG. 1, the cover 31 is attached so that the annular plate portion 32 abuts the outer surface of the annular plate 12 in the pulley 10. With this attachment, the outer end of the rolling bearing 18 is covered with the annular bulge 33.

  When attaching the cover 31, here, a nut fitting hole 38 is provided in the annular plate 12 of the pulley 10, a nut 39 is fitted into the nut fitting hole 38, and a screw 40 screwed into the nut 39 is tightened to cover the cover 31. 31 is attached, but a screw hole may be directly formed in the annular plate 12 of the pulley 10 and the screw 40 may be screwed into the screw hole.

  The hub 41 has a configuration in which a small-diameter shaft portion 41b is provided on one side surface of the disc portion 41a, and a shaft hole 43 that opens at the end surface of the small-diameter shaft portion 41b is formed. The hub 41 is set on the small-diameter shaft portion 21 a so that the small-diameter shaft portion 21 a formed at the shaft end portion of the rotary shaft 21 is fitted in the shaft hole 43, and is formed on the shaft center of the hub 41. The bolt 46 is screwed into the screw hole 45 provided in the small-diameter shaft portion 21a from the inserted hole 44 and is attached to the rotary shaft 21. At this time, the shaft hole 43 and the small-diameter shaft portion 21a are fitted to the serration 47, and the hub 41 is prevented from rotating around the rotary shaft 21.

  By attaching the hub 41 to the rotating shaft 21, the disk part 41a is accommodated in the small diameter side cylindrical part 35 of the cover 31, and a plurality of saw teeth 42 are formed at equal pitches on the outer diameter surface of the disk part 41a.

  As shown in FIG. 4, of the tooth surfaces 42 a and 42 b provided on the front and rear in the circumferential direction of the saw tooth 42, the inclination angle of the succeeding tooth surface 42 b during forward rotation of the hub 41 is the leading tooth surface. The bent portion 37 of the engaging piece 36 provided on the cylindrical portion 35 of the cover 31 is engaged with the tooth surface 42b on the succeeding side which is smaller than the inclination angle 42a and has a small inclination angle.

  Here, the forward rotation of the hub 41 refers to the rotation direction of the hub 41 when the rotation of the pulley 10 driven by the engine is transmitted to the rotary shaft 21 via the torque limiter mechanism 30. The inclination angles of the tooth surfaces 42a and 42b are angles with respect to a tangent line passing through the intersection of each tooth surface and the tooth bottom.

  The hub 41 is a molded product made of a sintered material in order to reduce component costs, but may be a molded product made of resin.

  As shown in FIG. 4A, the engaging piece 36 that engages with the saw blade 42 of the hub 41 is elastically deformed until it gets over the saw blade 42, and when it gets over the saw blade 42 as shown in FIG. 4B. It has elastic deformability to plastically deform.

  The power transmission device shown in the embodiment has the above-described structure. When the rotation from the engine is transmitted and the pulley 10 rotates in the forward direction indicated by the arrow in FIG. Is transmitted to the hub 41 from the engaging portion of the engaging piece 36 and the saw blade 42 shown in FIG. 3 to rotate the rotating shaft 21 and the automobile auxiliary machine 20 operates.

  When fluctuations in the load of the automobile auxiliary machine 20 or fluctuations in the rotational torque applied to the pulley 10 from the engine occur, as shown in FIG. 4A, the engagement piece 36 is a tooth surface on the trailing side of the sawtooth 42 in the rotation direction. It is elastically deformed while shifting along the line 42b, and the load fluctuation of the automobile auxiliary machine and the torque fluctuation from the engine are absorbed by the damper action due to the elastic deformation. For this reason, even if rotation fluctuation occurs, the rotating shaft 21 rotates smoothly.

  The damper force due to the damper action can be easily adjusted by changing the number of the engagement pieces 36 and the contact angle of the engagement pieces 36 with respect to the saw teeth 42.

  When the automobile auxiliary machine 20 breaks down and the rotational load of the rotary shaft 21 increases in the operating state of the automobile auxiliary machine, a large load is applied to the engagement piece 36, and the engagement piece 36 is deformed by the load, and FIG. As shown in (b), the saw blade 42 is overcome and the engagement piece 36 is disengaged from the saw blade 42. Due to the disengagement, the rotation transmission from the pulley 10 to the rotating shaft 21 is cut off, and the pulley 10 and the cover 31 rotate freely. The free rotation of the pulley 10 prevents the belt (not shown) on the pulley 10 from becoming over-tensioned.

  Here, as shown in FIG. 4B, when the engagement piece 36 gets over the saw blade 42, the engagement piece 36 reaches the plastic deformation region and is permanently deformed, and rotates in the deformed state, so that the hub 41 An abnormal noise is generated by colliding with the tooth tip surface of the saw tooth 42.

  Thus, when the automobile auxiliary machine 20 breaks down, the engagement piece 36 collides with the tooth tip surface of the saw tooth 42 of the hub 41 and generates an abnormal noise. It is possible to know that the automobile auxiliary equipment has failed due to the generated abnormal noise.

  Here, every time the engaging piece 36 gets over the saw tooth 42 of the hub 41, an abnormal noise is generated. However, the tip of the engaging piece 36 is worn by the contact of the saw tooth 42 with the tooth tip surface, and the noise is reduced by reducing the amount of interference. The sound is gradually reduced.

  As described above, since the noise generated by the collision of the engagement piece 36 against the tooth tip surface of the saw tooth 42 of the hub 41 is reduced with the passage of time, the discomfort given to the driver is gradually reduced, and safe driving is enabled. .

DESCRIPTION OF SYMBOLS 10 Pulley 20 Car auxiliary machine 21 Rotating shaft 23 Pulley support shaft 30 Torque limiter mechanism 31 Cover 35 Cylindrical part 36 Engagement piece 37 Bending part 41 Hub 42 Sawtooth

Claims (4)

A pulley supported rotatably about a pulley support shaft provided coaxially with a rotation shaft of an automobile accessory, and a pulley provided between the pulley and the rotation shaft to rotate the pulley to the rotation shaft In a power transmission device having a torque limiter mechanism that transmits and interrupts rotation transmission from the pulley to the rotating shaft when the rotational load of the rotating shaft exceeds a set value,
The torque limiter mechanism includes an annular cover connected to the outer surface of the pulley, and a hub attached to the shaft end of the rotating shaft and formed with a sawtooth on the outer periphery, and on the inner periphery of the cover A cylindrical portion that can accommodate the hub is formed, and an engagement piece that engages with the saw blade in the rotation direction is provided on the cylindrical portion, and the engagement piece is elastically deformed and climbs over the saw blade until it gets over the saw blade. A power transmission device characterized by having an elastic deformability capable of plastic deformation.   The power transmission device according to claim 1, wherein the engagement piece has an outwardly bent portion at a distal end portion.   The power transmission device according to claim 1, wherein the hub is made of a sintered material.   The power transmission device according to claim 1, wherein the hub is made of resin.

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