JP2017155804A - Pulley unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulley unit having high vibration control performance.SOLUTION: A pulley unit 1 has a hollow hub 10 having a first tooth 10a on an outer peripheral face, a hollow pulley 13 having a first groove 13b on an inner peripheral face and relatively rotatably supported at an outer side of the hub 10 through bearings 21, 24, a nut 16 having a second groove 16a engaged with the first tooth 10a on an inner peripheral face, having a second tooth 16b engaged with the first groove 13b on an outer peripheral face, and axially displaced by relative rotation of the hub 10 and the pulley 13, a first elastic body 14 disposed at an axial one side of the nut 16, and elastically deformed in accompany with the axial displacement of the nut 16, and a second elastic body 15 disposed at the axial other side of the nut 16 and elastically deformed in accompany with the axial displacement of the nut 16. An elastic coefficient of the first elastic body 14 and an elastic coefficient of the second elastic body 15 are different from each other.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 unit of Patent Document 1, the nut is sandwiched between the pulley and the hub, and the elastic body is installed on both sides in the axial direction of the nut, thereby improving the vibration damping performance of the pulley. 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 2004-257535 A

  The adoption of ISG (Integrated Starter Generator) has been promoted by microhybridization. The pulley unit for ISG transmits torque during both motor assist (driving) and power generation (following). Although the magnitude of torque differs between driving and driven, this point is not fully considered in the conventional pulley unit. For this reason, high vibration control performance cannot be exhibited both during driving and during driving.

  An object of the present invention is to provide a pulley unit having high vibration damping performance.

  A pulley unit according to an aspect of the present invention has a hollow hub having first teeth on an outer peripheral surface and a first groove on an inner peripheral surface, and can be relatively rotated outside the hub via a bearing. A hollow pulley supported on the inner surface, a second groove meshing with the first tooth on the inner peripheral surface, and a second tooth meshing with the first groove on the outer peripheral surface, A nut that is displaced in the axial direction by relative rotation of the pulley; a first elastic body that is disposed on the one axial side of the nut and elastically deforms in accordance with the axial displacement of the nut; A second elastic body disposed on the other axial side of the nut and elastically deforming in accordance with the axial displacement of the nut, and the elastic coefficient of the first elastic body and the second The elastic coefficients of these are different from each other.

  According to this configuration, since the elastic coefficient of the first elastic body and the elastic coefficient of the second elastic body are different from each other, the movable range of the first elastic body and the second elastic body both at the time of driving and at the time of following Can be used effectively. Therefore, high vibration damping performance is exhibited both during driving and following.

  According to the present invention, a pulley unit having high vibration damping performance can be provided.

FIG. 1 is a cross-sectional view of a pulley unit according to the first embodiment. FIG. 2 is an exploded view of the pulley unit. FIG. 3 is a schematic diagram of the torque transmission unit. FIG. 4 is a diagram illustrating the operation of the torque transmission unit. FIG. 5 is a diagram illustrating the operation of the torque transmission unit. FIG. 6 is a schematic diagram of the power transmission mechanism. FIG. 7 is a cross-sectional view of the pulley unit according to the second embodiment. FIG. 8 is a diagram illustrating a relationship between an axial load for displacing the nut and deformation amounts of the first elastic body and the second elastic body.

  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 according to the first embodiment]
FIG. 1 is a cross-sectional view of a pulley unit 1 according to the first 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 plain bearing (bearing) 24 is installed on the flange portion 12 via a bush guide 23. The plain bearing 24 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 spacer 19 is fitted on the other end side of the body portion 11 in the axial direction. The spacer 19 is fixed to the outer peripheral surface of the hub 10 by a retaining ring 20 and rotates integrally with the hub 10. A radial bearing (bearing) 21 is installed on the spacer 19. The radial bearing 21 is sandwiched between the spacer 19 and the pulley 13 and supports the pulley 13 so as to be rotatable relative to the hub 10.

  Both ends of the pulley 13 are supported by a slide bearing 24 and a radial bearing 21. Therefore, the pulley 13 is unlikely to be inclined. Since the slide bearing 24 is installed on the outer peripheral surface of the flange portion 12, the length of the pulley unit 1 in the axial direction is not increased. Therefore, the axial length of the pulley unit 1 is short.

  A nut 16 is provided between the flange portion 12 and the spacer 19. The hub 10 has first teeth 10a on the outer peripheral surface. The pulley 13 has a first groove 13b on the inner peripheral surface. The nut 16 has a second groove 16a that meshes with the first tooth 10a on the inner peripheral surface, and a second tooth 16b that meshes with the first groove 13b on the outer peripheral surface.

  The first tooth 10a and the second groove 16a extend in the axial direction, for example. The first groove 13b and the second tooth 16b extend, for example, in a direction intersecting the axis AX. The first groove 13b is a groove having a twist angle. The nut 16, the hub 10, and the pulley 13 are relatively moved in the axial direction in a state where the first teeth 10 a and the second grooves 16 a are engaged and the first grooves 13 b and the second teeth 16 b are engaged. To do.

  The inner diameter of the bottom of the first groove 13b is smaller than the inner diameter of the inner peripheral surface of the pulley 13 positioned on one axial end side (radial bearing 21 side) than the position where the first groove 13b is formed. There is no structure protruding on the inner diameter side of the bottom 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 formation position of the first groove 13b. 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 of the bottom of the first groove 13b is the inner peripheral surface of the pulley 13 located on the other end side (flange portion 12 side) with respect to the formation position of the first groove 13b. It is preferably smaller than the inner diameter.

  The width W2 of the outer peripheral surface of the nut 16 is smaller than the width W1 of the inner peripheral surface of the nut 16. For example, the nut 16 has an inner diameter portion 17 that faces the hub 10 and an outer diameter portion 18 that faces the pulley 13. The axial width W2 of the outer diameter portion 18 is smaller than the axial width W1 of the inner diameter portion 17. The outer diameter portion 18 and the inner diameter portion 17 intersect in a T shape. When the outer diameter portion 18 becomes thinner, the axial length of the second teeth 16b provided on the outer peripheral surface of the outer diameter portion 18 becomes shorter. Shorter teeth reduce processing and lower costs.

  The surface pressure at the connection portion between the nut 16 and the pulley 13 is inversely proportional to the area of the contact portion. Therefore, the surface pressure of the outer peripheral surface of the nut 16 having a large diameter is less likely to be larger than the surface pressure of the inner peripheral surface of the nut 16. Further, the number of teeth on the outer peripheral surface of the nut 16 is larger than the number of teeth on the inner peripheral surface of the nut 16. Therefore, the area of the connection portion between the nut 16 and the pulley 13 is larger than the area of the connection portion between the nut 16 and the hub 10, and the surface pressure is further reduced. Therefore, the width W2 of the outer peripheral surface of the nut 16 is set to the width W1 of the inner peripheral surface while reducing the surface pressure of the contact portion between the nut 16 and the pulley 13 to the same level as the surface pressure of the contact portion between the nut 16 and the hub 10. Can be made smaller.

  A first elastic body 14 is disposed on one side of the nut 16 in the axial direction. A second elastic body 15 is disposed on the other axial side of the nut 16. For example, the first elastic body 14 is sandwiched between the outer diameter portion 18 and the flange portion 12 and elastically deforms with the axial displacement of the nut 16. For example, the second elastic body 15 is sandwiched between the outer diameter portion 18 and the spacer 19, and is elastically deformed along with the axial displacement of the nut 16. Since the outer diameter portion 18 has a small width, an elastic member having a large movable range is installed on the side of the outer diameter portion 18 as the first elastic body 14 and the second elastic body 15. A shim 22 is sandwiched between the first elastic body 14 and the flange portion 12.

  The first elastic body 14 and the second elastic body 15 are, for example, disc springs. However, the first elastic body 14 and the second elastic body 15 are not limited to this. For example, a coil spring or rubber may be used as the first elastic body 14 and the second elastic body 15.

  A torque transmission portion TC is formed by the nut 16, the first elastic body 14, and the second elastic body 15. The torque transmission unit TC converts the torque input to the pulley 13 or the hub 10 into an axial displacement of the nut 16. Of the first elastic body 14 and the second elastic body 15, the elastic body positioned in the displacement direction of the nut 16 is elastically deformed as the nut 16 is displaced. Due to the elastic deformation of the elastic body, a part of the driving torque input to the pulley 13 or the hub 10 is absorbed by the elastic body. Torque absorbed by the elastic body 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, 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. Further, in the pulley unit 1, when the nut 16 is displaced, power transmission is performed between the hub 10 and the pulley 13 while the hub 10 and the pulley 13 are relatively rotated.

  A space S between the pulley 13 and the hub 10 is filled with a lubricant (not shown) such as grease. For example, the end of the space S on the flange portion 12 side is liquid-tightly sealed with an oil seal 25 so that the lubricant does not leak outside.

  FIG. 3 is a schematic diagram of the torque transmission unit TC. 4 and 5 are diagrams illustrating the operation of the torque transmission unit TC.

  As shown in FIG. 3, the outer diameter portion 18 of the nut 16 is sandwiched between the first elastic body 14 and the second elastic body 15 from the axial direction. For example, the first elastic body 14 is elastically deformed when the pulley 13 rotates at a rotational phase larger than that of the hub 10. For example, the second elastic body 15 is elastically deformed when the hub 10 rotates at a rotational phase larger than that of the pulley 13. The elastic coefficient k1 of the first elastic body 14 and the elastic coefficient k2 of the second elastic body 15 are different from each other. In the present embodiment in which disc springs are used as the first elastic body 14 and the second elastic body 15, the elastic coefficient means a spring constant.

  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 pulley 13 rotates with a larger rotation phase than the hub 10. 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 hub 10 rotates with a larger rotational phase than the pulley 13.

  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. For this reason, the elastic coefficient of an elastic body that is elastically deformed by a relatively large driving torque is larger than the elastic coefficient of an elastic body that is elastically deformed by a relatively small driving torque. For example, in this embodiment, the driving torque F1 at the time of following is larger than the driving torque F2 at the time of driving. Therefore, the elastic coefficient k1 of the first elastic body 14 is larger than the elastic coefficient k2 of the second elastic body 15. Thereby, the movable range of the 1st elastic body 14 and the 2nd elastic body 15 can be used effectively both at the time of a drive and a driven. It becomes difficult for the deformation amount of the first elastic body 14 and the second elastic body 15 to be biased during driving and following. Therefore, high vibration damping performance is exhibited both during driving and following.

[Power transmission mechanism]
FIG. 6 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 electric 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 electric power from the battery when starting.

  In the pulley unit 1 of the present embodiment described above, the elastic coefficient of the first elastic body 14 and the elastic coefficient of the second elastic body 15 are different from each other. Therefore, the movable range of the first elastic body 14 and the second elastic body 15 can be effectively used both during driving and following. Therefore, high vibration damping performance is exhibited both during driving and following.

  Moreover, in the pulley unit 1 of this embodiment, the width of the nut 16 changes in the radial direction. Therefore, a large installation space for installing the first elastic body 14 and the second elastic body 15 is formed in a portion where the width of the nut 16 is small. Therefore, the first elastic body 14 and the second elastic body 15 having a large size can be used, and the pulley unit 1 having excellent vibration damping performance is provided.

  In this embodiment, the width of the outer peripheral surface of the nut 16 is smaller than the width of the inner peripheral surface. Therefore, an elastic body having a large movable range can be installed in the vicinity of the outer peripheral surface of the nut 16. Since the outer peripheral surface of the nut 16 is larger in diameter than the inner peripheral surface, the surface pressure at the contact portion between the nut 16 and the pulley 13 tends to be smaller than the surface pressure at the contact portion between the nut 16 and the hub 10. Therefore, the width of the outer peripheral surface of the nut 16 can be reduced while reducing the surface pressure of the contact portion between the nut 16 and the pulley 13 to the same level as the surface pressure of the contact portion between the nut 16 and the hub 10. By reducing the width of the outer peripheral surface, the processing cost of the outer peripheral surface is also reduced.

[Pulley unit according to the second embodiment]
FIG. 7 is a cross-sectional view of the pulley unit 2 according to the second embodiment. FIG. 8 is a diagram showing the relationship between the axial load L for displacing the nut 16 and the deformation amount D of the first elastic body 30 and the second elastic body 31. In FIG. 8, the load L when the pulley 13 rotates with a larger rotational phase than the hub 10 is positive, and the load L when the hub 10 rotates with a larger rotational phase than the pulley 13 is negative. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  This embodiment is different from the first embodiment in that the first elastic body 30 and the second elastic body 31 are each composed of a plurality of elastic members having different elastic coefficients. For example, the first elastic body 30 includes a first elastic member 26 and a second elastic member 28. The second elastic body 31 includes a third elastic member 27 and a fourth elastic member 29.

  The second elastic member 28 is disposed closer to the inner diameter side (hub 10 side) than the first elastic member 26. The fourth elastic member 29 is disposed on the inner diameter side with respect to the third elastic member 27. The outer diameter portion 18 of the nut 16 is sandwiched between the first elastic member 26 and the third elastic member 27 from the axial direction, for example. For example, the inner diameter portion 17 of the nut 16 is sandwiched between the second elastic member 28 and the fourth elastic member 29 from the axial direction.

  The elastic coefficient k11 of the first elastic member 26 is, for example, larger than the elastic coefficient k12 of the second elastic member 28. The elastic coefficient k21 of the third elastic member 27 is larger than, for example, the elastic coefficient k22 of the fourth elastic member 29. The first elastic member 26 and the third elastic member 27 are, for example, disc springs, and the second elastic member 28 and the fourth elastic member 29 are, for example, coil springs. The elastic coefficient k11 and the elastic coefficient k21 may be the same or different. The elastic coefficient k12 and the elastic coefficient k22 may be the same or different.

  The first elastic body 30 and the second elastic body 31 are subjected to a surface treatment for increasing the friction between the elastic members, for example. As a result, the amount of torque converted into heat increases, and the vibration damping performance increases. As an example of the surface treatment, there is a treatment of coating a surface of an elastic member with a resin-based wear material.

  In the pulley unit 2 of the present embodiment, as the load L increases, the deformation amount (flexibility) of the first elastic body 30 and the second elastic body 31 per unit load decreases. Therefore, even if the load L increases, the first elastic body 30 and the second elastic body 31 are not easily crushed. Therefore, even when the load L is large, the vibration damping performance is maintained. When the load L is small, the first elastic body 30 and the second elastic body 31 are flexibly deformed. Therefore, high vibration damping performance is demonstrated.

  In the present embodiment, the first elastic body 30 and the second elastic body 31 are each composed of two elastic members. However, the number of elastic members constituting the first elastic body 30 and the second elastic body 31 is not limited to this. The number of elastic members constituting the first elastic body 30 and the second elastic body 31 may be three or more. Moreover, the kind of elastic member is not limited to a disc spring or a coil spring.

1, 2 Pulley unit 10 Hub 10a First tooth 12 Flange portion 13 Pulley 13b First groove 14, 30 First elastic body 15, 31 Second elastic body 16 Nut 16a Second groove 16b Second tooth 21, 24 Bearing

Claims (1)

A hollow hub having first teeth on the outer peripheral surface;
A hollow pulley having a first groove on the inner peripheral surface and supported on the outside of the hub via a bearing so as to be relatively rotatable;
An inner peripheral surface has a second groove that meshes with the first tooth, an outer peripheral surface has a second tooth that meshes with the first groove, and the hub and the pulley rotate relative to each other to rotate the shaft. A nut that is displaced in the direction;
A first elastic body disposed on the one axial side of the nut and elastically deforming in accordance with the axial displacement of the nut;
A second elastic body disposed on the other axial side of the nut and elastically deforming in accordance with the axial displacement of the nut;
Have
The elastic unit of the first elastic body and the elastic coefficient of the second elastic body are different from each other.

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