JP2017150525A - Pulley unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive pulley unit of high durability.SOLUTION: A pulley unit 1 has a hub 10, a pulley 13 having a first groove 13b, a first cam plate 14 fixed to an outer peripheral face of the hub 10, a second cam plate 15 having a first tooth 15a engaged with the first groove 13b, and axially opposed to the first cam plate 14 through a rolling element 16, a thrust bearing 18 fixed to the second cam plate 15, an elastic body 23 held between the thrust bearing 18 and a flange portion 12 of the hub 10, and a radial bearing 28 held between the flange portion 12 and the pulley 13. An inner diameter D1 of a bottom GB of the first groove 13b is smaller than an inner diameter D2 of an inner peripheral face of the pulley 13 positioned at an axial one end side with respect to a formation position of the first groove 13b.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pulley unit.

  The rotational power of the engine is transmitted from the engine crankshaft to the auxiliary machine via a belt. Engines undergo rotational fluctuations associated with explosions. As a result, the belt also undergoes rotational fluctuations through the crankshaft. When the belt tension is insufficient, an abnormal slip occurs between the belt and the pulley. Therefore, in the pulley units of Patent Documents 1 to 4, a torque cam and an elastic body are built in the pulley to enhance the vibration damping performance of the pulley unit. By using a pulley unit having high vibration damping performance, fluctuations in the rotation of the pulley are suppressed, and the belt tension can be set low. Thereby, mechanical loss is reduced and fuel consumption is improved.

JP 2006-009899 A US2009 / 0194380 JP 2009-281436 A Japanese Patent Laid-Open No. 10-227351

  Various structures are installed inside the pulley. For this reason, the durability tends to decrease due to friction between structures. In addition, although complicated processing is performed inside the pulley, the conventional pulley unit does not fully consider these processability. Therefore, an inexpensive and highly durable pulley unit cannot be provided.

  An object of the present invention is to provide an inexpensive and highly durable pulley unit.

  A pulley unit according to an aspect of the present invention includes a hollow hub having a flange portion, a hollow pulley disposed coaxially with the hub and having a first groove on an inner peripheral surface, and an outer periphery of the hub. A first cam plate fixed to the surface, and a first tooth meshing with the first groove, and disposed opposite to the first cam plate in the axial direction with a rolling element interposed therebetween, A second cam plate that is displaced in the axial direction by rotating relative to the cam plate, a thrust bearing fixed to the second cam plate, and sandwiched between the thrust bearing and the flange portion An elastic body that is elastically deformed in accordance with the axial displacement of the second cam plate, and a radial bearing that is sandwiched between the flange portion and the pulley. The inner diameter of the bottom is located on the one end side in the axial direction from the formation position of the first groove Smaller than the inner diameter of the inner peripheral surface of the over Li.

  According to this configuration, since the elastic body is disposed at a position where relative rotation does not occur with other members, the elastic body is not easily worn even if the hub and the pulley rotate. Further, since the radial bearing does not receive an axial force due to expansion and contraction of the elastic body, durability of the radial bearing is enhanced. In addition, the inner diameter of the bottom of the first groove is smaller than the inner diameter of the inner peripheral surface of the pulley located on the one end side in the axial direction than the position where the first groove is formed. On the inner peripheral surface of the pulley located on one end side in the axial direction from the position where the first groove is formed, there is no structure projecting toward the inner diameter side from the bottom of the first groove. Therefore, the first groove can be easily processed by broaching or the like. Therefore, an inexpensive and highly durable pulley unit is provided.

  According to the present invention, an inexpensive and highly durable pulley unit can be provided.

FIG. 1 is a cross-sectional view of a pulley unit according to an embodiment. FIG. 2 is an exploded view of the pulley unit. FIG. 3 is an enlarged view of the second cam plate. FIG. 4 is a cross-sectional view of cam grooves provided in the first cam plate and the second cam plate. FIG. 5 is a diagram for explaining the operation of the torque cam. FIG. 6 is a diagram for explaining the operation of the torque cam. FIG. 7 is a schematic diagram of the power transmission mechanism.

  EMBODIMENT OF THE INVENTION About the form (embodiment) for inventing, it demonstrates in detail, referring drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.

[Pulley unit]
FIG. 1 is a cross-sectional view of a pulley unit 1 according to an embodiment. FIG. 2 is an exploded view of the pulley unit 1.

  The pulley unit 1 transmits the rotational power of the engine to the auxiliary machine. The pulley unit 1 transmits the rotational power of the auxiliary machine to the engine. The pulley unit 1 includes a hollow hub 10 into which a shaft of an auxiliary machine is inserted, and a hollow pulley 13 arranged coaxially with the hub 10. On the outer peripheral surface of the pulley 13, a plurality of pulley grooves 13 a for passing the belt are provided. The pulley 13 is driven by a belt and rotates around the axis AX. Hereinafter, a direction parallel to the axis AX is referred to as an “axial direction”.

  The hub 10 includes a hollow body portion 11 and a flange portion 12 provided on one end side in the axial direction of the body portion 11. The flange portion 12 protrudes from the body portion 11 toward the pulley 13 side. A radial bearing 28 is installed on the flange portion 12. The radial bearing 28 is sandwiched between the flange portion 12 and the pulley 13 and supports the pulley 13 so as to be rotatable relative to the hub 10.

  A first cam plate 14 is provided on the other axial end side of the body portion 11. A second cam plate 15 is provided on the flange portion 12 side of the first cam plate 14. The second cam plate 15 is disposed opposite to the first cam plate 14 in the axial direction with the rolling element 16 interposed therebetween. The first cam plate 14 and the second cam plate 15 are plate-like members whose axial thickness periodically changes along the circumferential direction.

  The pulley 13 has a first groove 13b on the inner peripheral surface. The 2nd cam board 15 has the 1st tooth | gear 15a which meshes with the 1st groove | channel 13b on an outer peripheral surface. The hub 10 has second teeth 10a on the outer peripheral surface. The first cam plate 14 has a second groove 14a that meshes with the second teeth 10a on the inner peripheral surface.

  For example, the first groove 13b, the first tooth 15a, the second tooth 10a, and the second groove 14a extend in the axial direction. The first cam plate 14 is fixed to the outer peripheral surface of the hub 10 by a retaining ring 26. The first cam plate 14 rotates integrally with the hub 10 with its axial position fixed. The pulley 13 and the second cam plate 15 move relative to each other in the axial direction in a state where the first groove 13b and the first teeth 15a are engaged with each other. The second cam plate 15 is displaced in the axial direction by rotating relative to the first cam plate 14.

  The inner diameter D1 of the bottom GB of the first groove 13b is smaller than the inner diameter D2 of the inner peripheral surface of the pulley 13 located on one axial end side (radial bearing 28 side) than the position where the first groove 13b is formed. There is no structure protruding on the inner diameter side of the bottom GB of the first groove 13b on the inner peripheral surface of the pulley 13 positioned on one end side in the axial direction from the position where the first groove 13b is formed. The first groove 13b is formed by, for example, performing broaching on the inner peripheral surface of the pulley 13 with a tool inserted from one axial end side of the pulley 13. In order to improve the workability of broaching, the inner diameter D1 may be smaller than the inner diameter D3 of the inner peripheral surface of the pulley 13 located on the other end side (slide bearing 25 side) from the position where the first groove 13b is formed. preferable.

  The rolling element 16 is, for example, a roller. However, the rolling element 16 is not limited to this. For example, a ball may be used as the rolling element 16. Between the first cam plate 14 and the second cam plate 15, a plurality of rolling elements 16 are arranged around the axis AX at regular intervals. The plurality of rolling elements 16 are held by a holder 17.

  A thrust bearing 18 is provided on the surface of the second cam plate 15 on the flange portion 12 side. The thrust bearing 18 is fixed to the second cam plate 15 and rotatably supports the second cam plate 15. The thrust bearing 18 includes, for example, a bearing body 19 and a bearing race 22 (washer). The bearing body 19 includes a plurality of rolling elements 21 and a cage 20. The rolling element 21 may be a ball or a roller. In the present embodiment, a needle-like roller is used as the rolling element 21. The plurality of rolling elements 21 are arranged at regular intervals around the axis AX and are held by the cage 20.

  An elastic body 23 and a shim 24 are provided between the thrust bearing 18 and the flange portion 12. The elastic body 23 is sandwiched between the thrust bearing 18 and the flange portion 12 and is elastically deformed as the second cam plate 15 is displaced in the axial direction. The elastic body 23 is, for example, a disc spring. However, the elastic body 23 is not limited to this. For example, a coil spring or rubber may be used as the elastic body 23. In the present embodiment, for example, a combination of a plurality of disc springs in parallel is used as the elastic body 23 so as to increase the hysteresis.

  The elastic body 23 is sandwiched between the bearing race 22 of the thrust bearing 18 and the flange portion 12. The bearing ring 22 and the flange portion 12 do not rotate relative to each other. Therefore, even if the pulley 13 rotates, the elastic body 23 is not easily worn.

  A torque cam TC is formed by the first cam plate 14, the second cam plate 15, and the plurality of rolling elements 16. The torque cam TC converts the torque input to the pulley 13 or the hub 10 into an axial displacement of the second cam plate 15. The elastic body 23 is elastically deformed as the second cam plate 15 is displaced in the axial direction. Due to the elastic deformation of the elastic body 23, part of the driving torque input to the pulley 13 or the hub 10 is absorbed by the elastic body 23. Torque absorbed by the elastic body 23 is converted into heat or the like. Further, a rotational phase difference is generated between the pulley 13 and the hub 10 according to the deformation amount of the elastic body 23, and the angular velocity of the driven hub 10 or the pulley 13 is reduced. Thereby, damping performance is imparted to the pulley unit 1.

  A slide bearing 25 is attached to the outer peripheral surface of the first cam plate 14. The slide bearing 25 is sandwiched between the first cam plate 14 and the pulley 13 and supports the pulley 13 so as to be rotatable relative to the first cam plate 14. The first cam plate 14 rotates together with the second cam plate 15. As a result, power is transmitted between the pulley 13 and the hub 10. Both ends of the pulley 13 are supported by a slide bearing 25 and a radial bearing 28. Therefore, the pulley 13 is unlikely to be inclined. Since the slide bearing 25 is installed on the outer peripheral surface of the first cam plate 14, the axial length of the pulley unit 1 is not increased. Therefore, the axial length of the pulley unit 1 is short.

  A space S between the pulley 13 and the hub 10 is filled with a lubricant (not shown) such as grease. Thereby, friction generated in the torque cam TC, friction generated between the sliding bearing 25 and the first cam 14 and the pulley 13, friction generated between the second cam 15 and the hub 10 and the pulley 13, thrust The friction generated in the bearing 18 and the friction generated in the elastic body 23 are reduced. For example, the filling rate of the lubricant is determined so that at least a region outside the inner diameter of the rolling element 16 in the volume of the space S is filled with the lubricant. For example, the end of the space S on the first cam plate 14 side is liquid-tightly sealed with an oil seal 27 so that the lubricant does not leak outside.

  FIG. 3 is an enlarged view of the second cam plate 15. FIG. 4 is a cross-sectional view of cam grooves provided in the first cam plate 14 and the second cam plate 15. 5 and 6 are diagrams for explaining the operation of the torque cam TC.

  As shown in FIGS. 3 and 4, a plurality of cam grooves 15 </ b> G extending in the radial direction are provided on a surface 15 </ b> S of the second cam plate 15 that faces the first cam plate 14. The plurality of cam grooves 15G are arranged at regular intervals around the axis AX. The cam groove 15G has a pair of cam surfaces 30 inclined in opposite directions. In the present embodiment, for example, as the pair of cam surfaces 30, a first cam surface 31 and a second cam surface 32 having a constant inclination angle with respect to a plane orthogonal to the axis AX are provided.

  As shown in FIGS. 4 to 6, the cam leads of the pair of cam surfaces 30 are different from each other. The cam lead is a parameter representing the magnitude of the inclination of the cam surface 30. The cam lead is defined as a height at which the cam surface 30 reaches the axial direction when the cam surface 30 is extended by one turn along the rotation direction of the second cam plate 15. When the inclination angle of the cam surface 30 with respect to the surface orthogonal to the axis AX is θ, the size of the cam lead is approximately proportional to tan θ. Therefore, in the following description, the inclination angle of the cam surface 30 is described as the size of the cam lead for convenience.

  The first cam surface 31 is an inclined surface of the cam groove 15G against which the rolling element 16 is pressed when the second cam plate 15 rotates at a rotational phase larger than that of the first cam plate 14. The second cam surface 32 is an inclined surface of the cam groove 15 </ b> G against which the rolling element 16 is pressed when the first cam plate 14 rotates with a larger rotational phase than the second cam plate 15.

  For example, when power is generated by transmitting the rotational power of the engine to the ISG (when driven), the hub 10 rotates following the rotation of the pulley 13. Therefore, the second cam plate 15 driven by the pulley 13 rotates with a larger rotational phase than the first cam plate 14. When assisting the traveling of the vehicle by the rotational power of ISG (during driving), the pulley 13 rotates following the rotation of the hub 10. Therefore, the first cam plate 14 driven by the hub 10 rotates with a larger rotational phase than the second cam plate 15.

  The magnitude of the driving torque F1 for driving the hub 10 by the ISG is different from the magnitude of the driving torque F2 for driving the pulley 13 by the engine. Therefore, the cam lead of the cam surface 30 to which the rolling element 16 is pressed by a relatively large driving torque is larger than the cam lead of the cam surface 30 to which the rolling element 16 is pressed by a relatively small driving torque. For example, in the present embodiment, the driving torque F2 at the time of follow is larger than the driving torque F1 at the time of driving. Therefore, the cam lead θ1 of the first cam surface 31 is larger than the cam lead θ2 of the second cam surface 32.

  A plurality of cam grooves 14G having the same structure as the cam groove 15G are also provided on the surface 14S of the first cam plate 14 facing the second cam plate 15. The cam groove 14G has a pair of cam surfaces 35 inclined in opposite directions. In the present embodiment, for example, as the pair of cam surfaces 35, a first cam surface 33 and a second cam surface 34 having a constant inclination angle with respect to a plane orthogonal to the axis AX are provided.

  The first cam surface 33 is an inclined surface of the cam groove 14 </ b> G against which the rolling element 16 is pressed when the second cam plate 15 rotates at a rotation phase larger than that of the first cam plate 14. The second cam surface 34 is an inclined surface of the cam groove 14G to which the rolling element 16 is pressed when the first cam plate 14 rotates at a rotational phase larger than that of the second cam plate 15.

  The cam lead of the cam surface 35 to which the rolling element 16 is pressed by a relatively large driving torque is larger than the cam lead of the cam surface 35 to which the rolling element 16 is pressed by a relatively small driving torque. For example, in the present embodiment, the driving torque F2 at the time of follow is larger than the driving torque F1 at the time of driving. Therefore, the cam lead θ3 of the first cam surface 33 is larger than the cam lead θ4 of the second cam surface 34. Thereby, the movable range of the elastic body 23 can be used effectively both at the time of driving and at the time of following. It is difficult for the deformation amount of the elastic body 23 to be biased during driving and following. Therefore, high vibration damping performance is exhibited both during driving and following.

[Power transmission mechanism]
FIG. 7 is a schematic diagram of a power transmission mechanism 100 to which the pulley unit 1 is applied.

  The power transmission mechanism 100 includes a plurality of pulleys P, an idler ID, a tensioner TE, and a belt B. In the present embodiment, a crank pulley 101, an ISG pulley 102, a water pump pulley 103, and a compressor pulley 104 are provided as the plurality of pulleys P. The crank pulley 101 is connected to the engine crank. The ISG pulley 102 is connected to the ISG. The water pump pulley 103 is connected to the water pump. The compressor pulley 104 is connected to the compressor.

  An endless belt B is stretched around the plurality of pulleys P, the idler ID, and the tensioner TE. The rotational power of the engine is supplied to the ISG, water pump and compressor via the belt B. The tension of the belt B is adjusted by a tensioner TE. The configuration of the pulley unit 1 shown in FIGS. 1 and 2 is applied to the ISG pulley 102. The ISG generates power using the engine rotational power transmitted to the ISG pulley 102, and assists the running of the vehicle by rotating the ISG pulley 102 with the electric power from the battery when starting and accelerating.

  In the pulley unit 1 of the present embodiment described above, the elastic body 23 is disposed at a position where relative rotation does not occur with other members. Therefore, even if the hub 10 and the pulley 13 rotate, the elastic body 23 does not rotate. Hard to wear. Further, since the radial bearing 28 does not receive the axial force due to the expansion and contraction of the elastic body 23, the durability of the radial bearing 28 is enhanced. Further, the inner diameter D1 of the bottom GB of the first groove 13b is smaller than the inner diameter D2 of the inner peripheral surface of the pulley 13 positioned on one end side in the axial direction from the position where the first groove 13b is formed. There is no structure protruding on the inner diameter side of the bottom GB of the first groove 13b on the inner peripheral surface of the pulley 13 positioned on one end side in the axial direction from the position where the first groove 13b is formed. Therefore, the first groove 13b can be easily processed by broaching or the like. Thus, the inexpensive and highly durable pulley unit 1 is provided.

  In the pulley unit 1 of the present embodiment, the cam leads of the pair of cam surfaces 30 provided in the cam groove 15G are different depending on the magnitude of torque during driving and following. Further, the cam leads of the pair of cam surfaces 35 provided in the cam groove 14G differ depending on the magnitude of torque during driving and following. Therefore, the movable range of the elastic body 23 can be used effectively both during driving and following. Therefore, high vibration damping performance is exhibited both during driving and following.

DESCRIPTION OF SYMBOLS 1 Pulley unit 10 Hub 12 Flange part 13 Pulley 13b 1st groove 14 1st cam board 15 2nd cam board 15a 1st tooth | gear 16 Rolling element 18 Thrust bearing 23 Elastic body 28 Radial bearing

Claims (1)

A hollow hub having a flange portion;
A hollow pulley disposed coaxially with the hub and having a first groove on an inner peripheral surface;
A first cam plate fixed to the outer peripheral surface of the hub;
The shaft has a first tooth meshing with the first groove, is opposed to the first cam plate in the axial direction with a rolling element interposed therebetween, and rotates relative to the first cam plate to thereby rotate the shaft. A second cam plate that is displaced in the direction;
A thrust bearing fixed to the second cam plate;
An elastic body sandwiched between the thrust bearing and the flange portion and elastically deforming in accordance with the axial displacement of the second cam plate;
A radial bearing sandwiched between the flange portion and the pulley;
Have
A pulley unit, wherein an inner diameter of a bottom of the first groove is smaller than an inner diameter of an inner peripheral surface of the pulley located on one end side in the axial direction than a position where the first groove is formed.

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