WO2010119312A1

WO2010119312A1 - Pulley

Info

Publication number: WO2010119312A1
Application number: PCT/IB2010/000559
Authority: WO
Inventors: Toshiaki Miyake; Takeshi Hasegawa; Mitsuhiro Nakamura
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2009-04-17
Filing date: 2010-03-18
Publication date: 2010-10-21
Also published as: JP2010249265A

Abstract

A pulley (1) is fastened to an end of a rotary shaft (200) with a bolt (210). The pulley (1) includes an axial force transmission portion (10). When the bolt with which the pulley is fastened to the rotary shaft is loosened, the axial force transmission portion (10) transmits an axial force of the bolt in a pull-out direction to the pulley.

Description

PULLEY

BACKGROUND OF THE INVENTION

1. Field of the Invention [0001] The present invention relates to a pulley that is installed on a crankshaft or other rotary shaft of an engine (internal combustion engine) that is mounted in a vehicle or the like.

2. Description of the Related Art

[0002] Generally, engines mounted in vehicles or the like have pistons. The pistons are reciprocally accommodated in a cylinder block that defines cylinders. Each piston is connected to a crankshaft or an output shaft through a connecting rod. A cylinder head is provided on an upper end of the cylinder block. The cylinder head and each piston define a combustion chamber therebetween. An air-fuel mixture is combusted in the combustion chamber of each cylinder. This causes the piston to reciprocate. The reciprocating motion of the piston is converted into rotations of the crankshaft through the connecting rod.

[0003] The rotational force generated as a result of the force of combustion in each cylinder and an inertial force of each piston in the cylinder is periodically applied to the crankshaft of the engine. This generates torsional vibrations on the crankshaft. The torsional vibrations generated on the crankshaft cause wear of the crankshaft system and noise. Japanese Patent Application Publication No. 2007-211947 (JP-A-2007-211947) describes a damper pulley that reduce such torsional vibrations. The damper pulley has a damper function compared to a crank pulley that transmits rotary power to vehicle-mounted auxiliary equipment (e.g. a water pump, an alternator, a power steering pump, and an air conditioner compressor).

[0004] FIG. 9A and FIG 9B show an example of the damper pulley. A damper pulley 501 includes a boss 502, a cylindrical rim 503, an annular damping mass 504, and an annular damper rubber 505. The boss 502 is attached to the crankshaft. The rim 503 is integrally provided with the boss 502 through a flange 521. The damping mass 504 is disposed along an outer periphery of the rim 503. The damper rubber 505 is interposed between the rim 503 and the damping mass 504. The damper pulley 501 has a structure to cause a resonance between the rim 503 and the damping mass 504 with the damper rubber 505 interposed therebetween as the crankshaft rotates, thereby to reduce the torsional vibrations of the crankshaft. In the damper pulley 501 shown in FIG 9A and FIG 9B, the damping mass 504 has a plurality of outer peripheral V-shaped grooves 504a. A power transmission belt is wound around the V-shaped grooves 504a in order to transmit power to the auxiliary equipment.

[0005] Japanese Patent Application Publications No. 2007-278417 and No. 2001-159448 (JP-A-2007-278417 and JP-A-2001-159448) both describe an isolation damper pulley that is installed on the crankshaft. In addition to the damping the torsional vibrations of the crankshaft, the isolation damper pulley reduces rotational speed variations of the crankshaft. The rotational speed variations are a result of torque variations of the engine at low engine speed, mainly during idling. [0006] FIG. 10 shows an example of the isolation damper pulley. An isolation damper pulley 601 includes a first hub 602, a second hub 603, a pulley section 604 a torsional damper rubber 605, a torsional damping mass 606, and an isolation rubber 607. A plurality of V-shaped grooves 641a is formed in the pulley section 604. The torsional damping mass 606 is provided around an outer periphery of the first hub 602 through the torsional damper rubber 605. The isolation rubber 607 connects a connecting portion 642 of the pulley section 604 to the second hub 603. The isolation damper pulley 601 has a structure to reduce the torsional vibrations of the crankshaft by use of a damper section and to absorb rotational variations (torque variations) of the crankshaft by use of the isolation rubber 607. The damper section includes the torsional damper rubber 605 and the torsional damping mass 606.

[0007] The crank pulley is removed from the crankshaft by first removing a set bolt, with which the crank pulley is fastened to the crankshaft, and then pulling the crank pulley out of the crankshaft.

[0008] Generally, the damper pulley of FIG. 9A and FIG 9B has a service hole 522. The service hole 522 is provided between the boss 502 and the rim 503 and passes through the flange 521. Thus, the damper pulley 501 is removed from the crankshaft by first loosening and removing the set bolt through the service hole 522, while holding the damper pulley 501 still, and then by fitting a jig or other tool in the service hole 522 and pulling the damper pulley off of the crankshaft.

[0009] However, unlike the damper pulley of FIG 9A and FIG 9B, the isolation damper pulley has no service hole to be bored therethrough. The isolation damper pulley 601 of FIG 10 has a sliding bearing 608 that is disposed between the pulley section 604 and the torsional damper mass 606. Because a hole is bored through the pulley section 604 (the connecting portion 642), sand, dust and other materials enter into the sliding bearing 608 through the hole. This causes wear of the sliding bearing 608. If the isolation rubber 607 has a through hole, the isolation rubber 607 significantly loses its durability due to the through hole.

[0010] Due to these structural reasons, a service hole is generally not bored through the isolation damper pulley. Therefore, the isolation damper pulley is removed from the crankshaft by loosening the set bolt, while holding the crank pulley still by, for example, locking a ring gear on a flywheel, and then manually pulling the isolation damper pulley out of the crankshaft. However, manually pulling-out the isolation damper pulley in a straight line is difficult. For instance, when an oblique force is applied to the crankshaft, the boss is stuck on the crankshaft. Thus, it may be difficult to pull the isolation damper pulley off from the crankshaft.

SUMMARY OF THE INVENTION

[0011] The present invention provides a pulley that is easily removable from a rotary shaft such as a crankshaft.

[0012] A first aspect of the present invention is directed to a pulley that is fastened to an end of a rotary shaft by a bolt. The pulley includes an axial force transmission portion in which when the bolt that fastens the pulley to the rotary shaft is loosened, the axial force transmission portion transmits an axial force of the bolt in a pull-out direction to the pulley.

[0013] In the pulley according to the first aspect of the present invention, when the bolt that fastens the pulley to the rotary shaft (crankshaft) is loosened, the axial force of the bolt disengages the pulley from the rotary shaft. Therefore, when the bolt is loosened, the pulley is pulled out of the rotary shaft at the same time. Accordingly, the pulley may be easily and efficiently removed from the rotary shaft.

[0014] The axial force transmission portion may be a ring member that is detachably mounted on the pulley and engages the bolt when the bolt is being loosened.

With this configuration, the pulley is first bolted to the rotary shaft, and then the ring member is mounted on the pulley. This prevents interference between the bolt and the ring member when the pulley is installed on the rotary shaft.

[0015] An alternative configuration may be employed. In this configuration, a groove is formed on an inner surface of the boss and extends in a circumferential direction of the boss. Thus, the pulley is bolted to the rotary shaft, and then the ring member is fitted into the groove, whereby the ring member is mounted to the pulley. [0016] The ring member may be a C-shaped snap ring.

[0017] The axial force transmission portion may be provided on an inner surface of a boss of the pulley and on an opposite side to the rotary shaft with respect to a flange of the bolt, and at least one of the axial force transmission portion may extend to a position further inward than an outer peripheral end of the flange in a radial direction of the rotary shaft.

[0018] The ring member may have inner circumference end which is located at a position further inward than an outer peripheral end of the flange in a radial direction of the rotary shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The foregoing and further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein:

FIG 1 is a vertical cross-sectional view of an example of a crank pulley;

FIG 2 is a front view of the crank pulley shown in FIG 1;

FIG 3 is a vertical cross-sectional view of the crank pulley of FIG 1 when installed on a crankshaft;

FIG 4 is a vertical cross-sectional view of the crank pulley of FIG 1 when installed on the crankshaft;

FIG 5 is a view of removing the crank pulley;

FIG 6 is a view of removing the crank pulley; FIG 7 is a vertical cross-sectional view of another example of the crank pulley;

FIG 8 is a vertical cross-sectional view of the crank pulley of FIG 7 when installed on the crankshaft;

FIG 9A and FIG 9B are a front view and a vertical cross-sectional view, respectively, of an example of a damper pulley of a related art; and FIG 10 is a vertical cross-sectional view of an example of an isolation damper pulley of a related art.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] With reference to FIG. 1 and FIG 2, an example of a crank pulley according to a first embodiment of the invention will be described below.

[0021] A crank pulley 1 is an isolation damper pulley that is connected to a crankshaft 200 (see FIG. 3 and FIG. 4) of an engine mounted in a vehicle. The crank pulley 1 transmits the rotational force of the crankshaft 200 to auxiliary equipment (e.g. a water pump, an alternator, a power steering pump, and an air conditioner compressor) through a belt that is wound around the outer peripheral surface of the crank pulley 1. The crank pulley 1 includes an isolation rubber 7 that is placed in a radial direction of the crank pulley 1.

[0022] The crank pulley 1 includes a first hub 2, a second hub 3, a pulley section 4, a torsional damper rubber 5, a torsional damping mass 6, the isolation rubber 7, and a sliding bearing 8.

[0023] The first hub 2 includes a cylindrical boss 21 and a rim 22 that has a diameter larger than a diameter of the boss 21. The boss 21 is formed integrally with the rim 22 through a disc-shaped flange 23. The torsional damper rubber 5 is an annular member that is disposed along an outer periphery of the rim 22 of the first hub 2. The torsional damping mass 6 is an annular member that is disposed along an outer periphery of the torsional damper rubber 5.

[0024] The second hub 3 is a cylindrical member. The second hub 3 is formed integrally with an inner flange (a circular flange) 31. The second hub 3 includes a cylindrical part 3a that is positioned rearward (on the first hub 2 side) relative to the inner flange 31. The cylindrical part 3a is machined with its inner diameter sized smaller than an outer diameter of the boss 21 of the first hub 2 by a predetermined amount. The boss

21 of the first hub 2 is assembled into the cylindrical part 3a of the second hub 3 by press fit

(spigot joint). This allows the first hub 2 and the second hub 3 to be formed as one-piece structure.

[0025] The pulley section 4 includes a cylindrical belt winding portion 41 and a connecting portion 42 that is formed integrally with the belt winding portion 41.

[0026] The belt winding portion 41 has a plurality of outer peripheral V-shaped grooves 41a that extend over the circumference of the belt winding portion 41. A power transmission belt (not shown) is wound along the V-shaped grooves 41a. The connecting portion 42 includes an annular portion 42a and a cylindrical part 42b. The annular portion

42a extends from one axial end of the belt winding portion 41 (parallel to a rotary axis of the crank pulley 1), which is opposed to the other axial end on the first hub 2 side, toward the rotary axis of the crank pulley 1. The cylindrical part 42b extends in an axial direction from an inner peripheral edge of the annular portion 42a toward the first hub 2.

[0027] The rim 22, the torsional damper rubber 5, and the torsional damping mass 6 of the first hub 2 are inserted and placed between the belt winding portion 41 and the cylindrical part 42b of the pulley section 4 with a predetermined clearance. The sliding bearing 8 is disposed between the torsional damping mass 6 and the pulley section 4. The pulley section 4 (the cylindrical part 42b of the connecting portion 42) is connected to the second hub 3 through the isolation rubber 7.

[0028] The torsional damper rubber 5 and the torsional damping mass 6 form a dynamic damper. The crank pulley 1 uses the dynamic damper to reduce torsional vibrations of the crankshaft 200. The isolation rubber 7 connects the second hub 3 to the pulley section 4. The isolation rubber 7 absorbs rotational variations (torque variations) of the crankshaft 200.

[0029] In the crank pulley 1, the second hub 3 is provided with a rectangular cross-section groove 32 on an inner peripheral surface 3b of the second hub 3. A C-shaped snap ring 10 that is shown in FIG 3 is fitted into the groove 32. The groove 32 is positioned forward (opposite to the first hub 2 side) relative to the inner flange 31 of the second hub 3. As shown in FIG 3 and FIG 4, the groove 32 is positioned in front of a flange 210a (the side opposite from the first hub 2 side) of a set bolt (a hexagonal flanged bolt) 210 that has been tightened. [0030] As shown in FIG 4, the C-shaped snap ring 10 in the first embodiment of the invention has an inner diameter that is smaller than an outer diameter of the flange 210a of the set bolt 210 and smaller than an inner diameter of the inner peripheral surface 3b of the second hub 3. Therefore, when the C-shaped snap ring 10 is fitted into the groove 32, the inner periphery of the C-shaped snap ring 10 protrudes from the inner peripheral surface 3b of the second hub 3. Also, when the tightened set bolt 201 is loosened, the flange 210a of the set bolt 210 contacts the C-shaped snap ring 10 (see FIG 5 and FIG. 6).

[0031] Now, with reference to FIG. 3 to FIG 6, the procedure for installing and removing the crank pulley 1 onto and from the crankshaft 200 will be described, as well as on the functions and effects of the first embodiment of the invention. [0032] The crank pulley 1 is installed onto the crankshaft 200 as follows. First, the boss 21 of the crank pulley 1 is fitted onto an end of the crankshaft 200. Then, an end face (the engine-side end face) of the boss 21 is brought into contact with a positioning member (e.g. bearing) 201 that is provided on, for example, an engine chain cover (not shown). Under this contact condition, the set bolt 210 is screwed into a female screw hole 200a of the crankshaft 200, using a socket wrench or other appropriate tool. Thus, the crank pulley 1 is fastened to the end of the crankshaft 200. Once the crank pulley is fastened, the end face (the engine-side end face) of the boss 21 of the first hub 2 is brought into contact with the positioning member 201, while the flange 210a of the set bolt 210 is brought into contact with the inner flange 31 of the second hub 3. This allows the crank pulley 1 to be securely positioned on the end of the crankshaft 200.

[0033] As shown in FIG 3, after the fastening process is completed, the C-shaped snap ring 10 is fitted into the groove 32 on the inner peripheral surface 3b of the second hub 3 of the crank pulley 1. The crank pulley 1 is thereby installed onto the crankshaft 200 completely. As described above, the set bolt 210 is first tightened, and then the C-shaped snap ring 10 is fitted into the crank pulley 1. This prevents interference between the C-shaped snap ring 10 and the set bolt 210 during the tightening of the set bolt 210.

[0034] Next, the crank pulley 1 is removed from the crankshaft 200 as follows. First, the set bolt 210 is loosened using the socket wrench or other appropriate tool. In the process of loosening the set bolt 210, when the flange 210a of the set bolt 210 contacts the C-shaped snap ring 10 (see FIG 5), an axial force of the set bolt 210 (indicated by a thick arrow in FIG 5) is transmitted to the crank pulley 1. Accordingly, as the set bolt 210 moves in a pull-out direction, the crank pulley 1 also moves (see FIG 6). Then, as the set bolt 210 further loosened, the crank pulley 1 is detached from the crankshaft 200.

[0035] As described above, in the first embodiment of the invention, the crank pulley 1 is easily pulled off from the crankshaft 200 solely by loosening the set bolt 210. Moreover, the two steps of removing the set bolt 210 and pulling out the crank pulley 1 may be performed simultaneously. This increases the efficiency of the removal of the crank pulley 1.

[0036] The crank pulley 1 is installed back onto the crankshaft 200 as follows. First, while the C-shaped snap ring 10 remains removed from the groove 32 of the second hub 3, the crank pulley 1 is fastened to the crankshaft 200 with the set bolt 210. Then, the C-shaped snap ring 10 is fitted into the groove 32 of the second hub 3. [0037] With reference to FIG 7, an example of the crank pulley according to a second embodiment of the invention will be described below.

[0038] The crank pulley 101 differs from the crank pulley of the first embodiment in a point that an isolation rubber 107 is placed in an axial direction of the crank pulley 101.

[0039] The crank pulley 101 includes a first hub 102, a second hub 103, a pulley section 104, a torsional damper rubber 105, a torsional damping mass 106, the isolation rubber 107, and sliding bearings 108, 110.

[0040] The first hub 102 includes a cylindrical boss 121 and a rim 122 that has a diameter larger than a diameter of the boss 121. The boss 121 is formed integrally with the rim 122 through a disc-shaped flange 123. The torsional damper rubber 105 is an annular member that is disposed along an outer periphery of the rim 122 of the first hub 102. The torsional damping mass 106 is an annular member that is disposed along an outer periphery of the torsional damper rubber 105. [0041] The second hub 103 is a cylindrical member. The second hub 103 is formed integrally with an inner flange (a circular flange) 131. The second hub 103 includes a cylindrical part 103a that is positioned rearward (on the first hub 102 side) relative to the inner flange 131. The cylindrical part 103a is machined with its inner diameter sized smaller than an outer diameter of the boss 121 of the first hub 102 by a predetermined amount. The boss 121 of the first hub 102 is assembled into the cylindrical part 103a of the second hub 103 by press fit (spigot joint). This allows the first hub 102 and the second hub 103 to be formed as a unitary structure.

[0042] One end of the second hub 103 (then end distal to the first hub 102 side) is formed integrally with an annular retaining member 133. An annular connecting member 109 is attached to an outer periphery of the second hub 103.

[0043] The pulley section 104 includes a cylindrical belt winding portion 141. The belt winding portion 141 has a plurality of outer peripheral V-shaped grooves 141a that extend in a circumferential direction of the belt winding portion 141. A power transmission belt (not shown) is wound around the V-shaped grooves 141a. One end of the belt winding portion 141 (the end distal to the first hub 102 side) is formed integrally with a disc-shaped connecting portion 142. The connecting portion 142 extends toward the rotary axis of the crank pulley 101. The belt winding portion 141 and the connecting portion 142 form the pulley section 104. The pulley section 104 (the connecting portion 142) is connected to the second hub 103 through the isolation rubber 107 and the connecting member 109.

[0044] The rim 122, the torsional damper rubber 105, and the torsional damping mass 106 of the first hub 102 are inserted and placed on an inner peripheral side of the belt winding portion 141 of the pulley section 104 with a predetermined clearance. The sliding bearing 108 is disposed between the torsional damping mass 106 and the pulley section 104. The sliding bearing 110 is disposed between the connecting portion 142 of the pulley section 104 and the retaining member 133 of the second hub 103.

[0045] The torsional damper rubber 105 and the torsional damping mass 106 form a dynamic damper. The crank pulley 101 uses the dynamic damper to reduce torsional vibrations of the crankshaft 200 (see FIG 8). The isolation rubber 107 connects the second hub 103 and the pulley section 104 to each other. The isolation rubber 7 absorbs rotational variations (torque variations) of the crankshaft 200.

[0046] As with the first embodiment, in the crank pulley 101, the second hub 103 is provided with a rectangular groove 132 formed on the inner peripheral surface 103b of the second hub 103. The C-shaped snap ring 10 that is shown in FIG 3 is fitted into the groove 132. Therefore, with the second embodiment shown in FIG 8, first the crank pulley 101 is fastened to the crankshaft 200 with the set bolt 210, and then the C-shaped snap ring 10 is fitted into the groove 132 of the second hub 103. Thus, as with the first embodiment, in the process of loosening the set bolt 210 to remove the crank pulley 101, an axial force of the set bolt 210 in a pull-out direction is transmitted to the crank pulley 101 through the flange 210a and the C-shaped snap ring 10. This helps easily pull the crank pulley 101 off from the crankshaft 200.

[0047] The above embodiments employ the C-shaped snap ring 10. However, the present invention is not restricted to the C-shaped snap ring 10. Any other type of ring member that is capable of transmitting the axial force of the set bolt 210 to the crank pulley 1 (the crank pulley 101) may be employed. In addition, the present invention is not restricted to the ring member. An axial force transmission member in any other form may also be employed as long as the axial force transmission member engages (contacts) the set bolt 210 in the process of pulling out the set bolt 210.

[0048] For example, the axial force transmission member may be provided on the inner peripheral side of the second hub as protrusion with its distal end extending further toward the axis of the second hub than the outer diameter of the flange 210a of the set bolt 210. As in the case of the above-described embodiments, the axial force transmission member is positioned on the opposite side of the flange 210a from the crankshaft. More specifically, the axial force transmission member is positioned in front of the flange 210a of the set bolt 210 after the set bolt 210 has been tightened.

[0049] The present invention is also applicable to pulleys other than the crank pulley. [0050] The present invention is available for a pulley that is installed on the crankshaft or other rotary shafts of the engine (internal combustion engine) that is mounted in a vehicle or the like.

[0051] While the invention has been described with reference to example embodiments thereof, it is to be understood that the invention is not limited to the described embodiments or constructions. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the disclosed invention are shown in various example combinations and configurations, other combinations and configurations, including more, less or only a single element, are also within the scope of the appended claims.

Claims

CLAIMS:

1. A pulley fastened to an end of a rotary shaft by a bolt, the pulley comprising: an axial force transmission portion, wherein when the bolt that fastens the pulley to the rotary shaft is loosened, the axial force transmission portion transmits an axial force of the bolt in a pull-out direction to the pulley.

2. The pulley according to claim 1, wherein the axial force transmission portion is provided on an inner surface of a boss of the pulley and on an opposite side to the rotary shaft with respect to a flange of the bolt, and at least one of the axial force transmission portion extends to a position further inward than an outer peripheral end of the flange in a radial direction of the rotary shaft.

3. The pulley according to claim 1 or 2, wherein the axial force transmission portion is a ring member that is detachably mounted in the pulley and engages the bolt when the bolt is being loosened.

4. The pulley according to claim 2, wherein the axial force transmission portion is a ring member that is detachably mounted in the pulley and engages the bolt when the bolt is being loosened, and the ring member has an inner circumference end which is located at a position further inward than an outer peripheral end of the flange in a radial direction of the rotary shaft.

5. The pulley according to claim 3 or 4, wherein a groove is formed on the inner surface of the boss and extends along the circumference direction of the boss, and the ring member is fitted into the groove.

6. The pulley according to any one of claims 3 to 5, wherein the ring member is a C-shaped snap ring.