JP2015124825A - Sheet metal pulley for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a structure which can rigidly fasten a sheet metal bottomed-cylindrical pulley in a state that a rotating plate is not loosened even if there occurs spring-back.SOLUTION: A plurality of bolt penetration holes 23 are formed at a bottom plate 17 of a pulley 11. A center hole 22 is formed at the bottom plate 17. In the manufacturing of the pulley 11 by drawing processing, the bottom plate 17 is manufactured in a slightly-inwardly protrusive state. A through-hole 27 is formed outside the bolt penetration holes 23 of the bottom plate 17, and cutout holes 28 opened toward the center hole 22 are arranged between the adjacent bolt penetration holes 23. Since the bottom plate 17 is fastened to a rotating plate 20 while being deformed in a direction of spring-back, resistance against a head 25 of a bolt 21 is small compared with the case that the bottom plate is manufactured outwardly protrusive. By the through-hole 27 and the cutout hole 28, resistance against the head 25 of the bolt 21 becomes further smaller.

Description

  The present invention relates to a sheet metal (metal plate) pulley used for power transmission by a belt in an internal combustion engine.

  In an internal combustion engine, a belt is used as power transmission means, and the belt is wound around a pulley fixed to a rotating shaft. A representative example of the belt is an accessory driving belt wound around a crank pulley, and an alternator, a water pump, an air conditioner compressor, and the like are driven by the accessory driving belt (for example, Patent Document 1).

  Cast pulleys and die cast products are also used for the pulleys, but sheet metal is also widely used from the standpoint of ease of processing, weight reduction, and strength enhancement. In this case, the pulley has a cylindrical portion around which the belt is wound and a bottom plate continuous to one end thereof, and the bottom plate is fastened with a bolt (or a bolt and a nut) to a rotary plate provided on the rotary shaft. . The bottom plate often has a central hole.

JP 2009-221874 A

  The pulley made of sheet metal is manufactured in a form having a cylindrical portion and a bottom plate by drawing a flat material plate using a press machine. In this case, since the metal plate has elasticity, it is unavoidable that the spring back is generated when processing the metal plate, so the design is made in anticipation of the spring back, but it is unavoidable that the variation occurs. Is designed so that the bottom plate protrudes to the outside of the cylinder by the spring back, and is brought into close contact with the rotating plate by fastening with bolts.

  However, if the bottom plate is convex toward the outside, the elastic force of the bottom plate acts as a strong resistance against the fastening of the bolt, so even if the bolt is tightened with the set torque, the actual fastening torque Is smaller than the required value, and there is a problem that the bolt is easily loosened.

  The present invention has been made to improve the current situation.

  The pulley made of sheet metal of the present invention has a cylindrical portion around which a belt is wound, and a disc-shaped bottom plate continuous to one end of the cylindrical portion. In a configuration in which a bolt insertion hole for fastening with a bolt to a rotating plate arranged in the cylinder part is provided, the bottom plate protrudes toward the inside of the cylinder part from a reference posture orthogonal to the axis of the cylinder part. The bottom plate is provided with a deformation facilitating means for improving the adhesion to the rotating plate when fastened by the bolt.

  As a means for facilitating deformation, a through hole slit or notch is formed in a portion radially outward from the bolt insertion hole, or a through hole, slit or incision is formed between bolt insertion holes adjacent in the circumferential direction. Alternatively, it is possible to employ a thin-walled portion formed at a portion radially outward from the bolt insertion hole. This may take only one form or a plurality of forms.

  In the present invention, since the bottom plate is bent in a convex state toward the inner side of the cylindrical portion, when the bottom plate is fastened to the rotating plate with a bolt, the bottom plate returns and deforms in the springback direction. For this reason, the bottom plate can be deformed with a lighter force than before.

  Further, in the present invention, since the deformation facilitating means is provided, the resistance of the bottom plate to the bolt tightening is remarkably lowered. In combination with this and the above-described ease of return deformation, in the present invention, the pulley can be strongly fastened in a state in which it is difficult to loosen with respect to the rotating plate. In other words, the adhesion between the bolt head and the bottom plate and the adhesion between the bottom plate and the rotating plate can be remarkably improved, and the fastening strength can be improved.

  A fastening structure in which a stud bolt is fixed to the rotating plate and a nut is screwed into the rotating plate from the outside of the bottom plate can also be adopted. In this case, the above-mentioned “bolt head” may be read as “nut”. Therefore, the bolt of the present invention includes a stud bolt.

It is a rough front view of an internal combustion engine. (A) is an enlarged front view of a water pump pulley, (B) is a BB sectional view of (A). (A) is a sectional view taken along line IIIA-IIIA in FIG. 2 (A) in a state where the internal structure is displayed, (B) is an enlarged front view of the main part, (C) is a sectional view in a state immediately before fastening, D) is a sectional view of a conventional example. It is a figure which shows other embodiment.

(1). Outline of Internal Combustion Engine Next, an embodiment of the present invention will be described based on the drawings. First, the outline of the internal combustion engine will be described with reference to FIG. FIG. 1 is a schematic front view of an internal combustion engine. The internal combustion engine has a cylinder block 1 which is a main part of the engine body and a cylinder head 2 fixed to the upper surface thereof. A cylinder head cover 3 is fixed, and an oil pan 4 is fixed to the lower surface of the cylinder block 1. Although one side of the cylinder block 1 and the cylinder head 2 is covered with a chain cover, it is omitted in the figure.

  One end portion of the crankshaft 5 protrudes from one end surface of the cylinder block 1, and a crank pulley 6 is fixed to the protruding end portion, and an alternator 8 and a water pump are driven by an auxiliary machine drive belt 7 wound around the crank pulley 6. 9 and the air conditioner compressor 10 are driven. Accordingly, the alternator 8 includes an alternator pulley 11, the water pump 9 includes a water pump pulley 12, and the air conditioner compressor 10 includes air conditioner pulleys 11, 12, and 13.

  In this case, the alternator 8, the water pump 9, and the air conditioner compressor 10 are disposed close to one side of the engine body, and the water pump 9 is disposed between the alternator 8 and the air conditioner compressor 10. . Therefore, the alternator pulley 11 and the air conditioner pulley 13 are wound around the inner peripheral surface of the accessory drive belt 7, but the water pump pulley 11 is wound around the outer peripheral surface of the accessory drive belt 7. That is, the auxiliary pump driving belt 7 is hung on the water pump pulley 12.

  And the inner peripheral surface of the auxiliary machine drive belt 7 is uneven in cross section, and along with this, the outer peripheral surfaces of the alternator pulley 11 and the air conditioner pulley 13 are also uneven in cross section. The outer peripheral surface of the pulley 12 is a smooth surface. Therefore, the water pump 12 is manufactured by simply drawing a metal plate.

(2) Details of Water Pump Pulley 11 Next, details of the water pump pulley 11 will be described with reference to FIG. The water pump pulley 11 includes a cylindrical portion 15 around which the accessory drive belt 7 is wound, and a bottom plate 17 integrally connected to an outer end of the cylindrical portion 15 via a step portion 16.

  As shown in FIG. 3 (A), the water pump 9 has a housing 18, a rotating plate 20 is fixed to a rotor 19 that is rotatably fitted in the housing 18, and the water pump pulley 11 is fixed to the rotating plate 20. The bottom plate 17 is overlapped and fastened with three bolts 21. The bottom plate 17 of the water pump pulley 11 has a center hole 22 from which the rotor 19 protrudes. The three bolts 21 are arranged at equal intervals in the circumferential direction, the bolt insertion hole 23 is vacant in the bottom plate 17, and the female screw hole 24 is vacant in the rotating plate 20.

  The bolt 21 has a hexagonal head 25, and the head 25 is provided with a circular flange 25a. A washer 26 (a plain washer or a spring washer) is also used. Of course, it is possible not to use the washer 26 or to use a bolt without the flange 25a. It is also possible to use hexagon socket head bolts.

  And, as an example of the deformation facilitating means described in the claims, the bottom plate 17 is directed toward the center hole 24 between the punched hole 27 located on the radially outer side of the bolt insertion hole 23 and the adjacent bolt insertion hole 23. An open slit 28 is formed.

  The punch hole 27 extends along an arc line having the center of the bottom plate 17 as the center of the radius of curvature, and the circumferential length is set to be slightly larger than the outer diameter of the flange 25a of the head 25 of the bolt 21. However, it may be smaller than the outer diameter of the flange 25a. In the present embodiment, the edge of the flange 25a (and the washer 26) of the head 25 in the bolt 21 is set to wrap with the punch hole 27, and the outer peripheral edge of the rotating plate 20 is also wrapped with the punch hole 27. Yes.

  On the other hand, the slit hole 28 has a substantially trapezoidal shape with a narrow center side, and as can be understood from FIG. 3 (B), a portion sandwiched between adjacent slit holes 28 (parallel dotted lines in FIG. 3 (B)). The width of the inner end portion of the inner end portion 29) shown in FIG. 6 is approximately the same as the outer diameter of the flange 26 a of the head 25 of the bolt 21.

  As described above, the water pump pulley 11 is manufactured by drawing a metal plate. At the time of drawing, as shown in an exaggerated manner in FIG. The drawing is excessively drawn so as to be convex inward from the reference plane 30 orthogonal to the center line O (in the drawing, it is exaggerated for easy understanding, but in actuality The dimensions of the inward convex are slight.)

  Conventionally, as shown in FIG. 3D, the bottom plate 17 is directed outward by the spring back, and is in close contact with the rotating plate 20 by fastening the bolt 21, but the bottom plate 17 is opposite to the spring back direction. Since it is bent to the side, the elastic force of the bottom plate 17 acts as a strong resistance on the head of the bolt 21 after fastening. For this reason, the fastening strength becomes insufficient and loosening is likely to occur.

  On the other hand, in the present embodiment, as shown in FIG. 3C, the bottom plate 17 is bent in the spring back direction so as to be in close contact with the rotating plate 20, so that the bottom plate 17 with respect to the head 25 of the bolt 21 after fastening. The reaction force is smaller than before, and as a result, the fastening strength is high.

  When the bottom plate 17 is deformed so as to be in close contact with the rotating plate 20, the inner diameter of the center hole 22 tends to be reduced. For this reason, the inner peripheral portion of the bottom plate 17 acts as a resistance, but the head 25 of the bolt 21 has an end portion close to the center hole 22 strongly hitting the bottom plate 17, and the head 25 of the bolt 21 contacts the center hole 22. Since there is only a small span L1 to the portion, a strong moment cannot be applied to the inner peripheral portion of the bottom plate 17. Also in this respect, it can be said that conventionally, the elastic force of the bottom plate 17 acts on the head 25 of the bolt 21 as a strong resistance, and the fastening force is insufficient.

  On the other hand, if the bottom plate 17 is formed inwardly convex as in the present embodiment, the head 25 of the bolt 21 has an end on the outer peripheral side of the bottom plate 17 as can be understood from FIG. Since the span L2 from the inner periphery of the center hole 22 to the portion where the head 25 of the bolt 21 hits strongly is large, a strong moment can be applied to the bottom plate 17, and the bottom plate 17 is light. By deforming with force, the adhesion to the rotating plate 20 can be improved (that is, the fastening strength can be improved).

  For the deformation of the bottom plate 17, the base portion where the bottom plate 17 is connected to the step portion 16 acts as a large resistance. However, as in the present embodiment, the bolt insertion hole 23 is used as a deformation facilitating means. Since the portion of the bottom plate 17 where the washer 26 overlaps is easily deformed when the punched hole 27 is provided on the outside, most of the torque applied to the bolt 21 can be used as the adhesion to the rotating plate 20. . Thereby, high fastening strength is securable.

  Further, when the cut-off hole 28 is provided in the bottom plate 17, there is no tension action due to the central hole 22 being narrowed at the time of fastening, so that the resistance inside the bolt insertion hole 23 in the bottom plate 17 is significantly reduced. Thereby, the resistance of the bottom plate 17 with respect to the head 25 of the bolt 21 can be remarkably reduced and the fastening strength can be improved. In this case, when the lateral width of the inner end portion 29 of the bottom plate 17 is set to be approximately the same as the outer diameter of the head 25 of the bolt 21 as in the embodiment, the positioning function due to the center hole 22 fitting into the rotor 19 is secured. This is an advantage that the bending deformation of the inner end portion 29 can be facilitated.

(3). Other Embodiments FIG. 4 shows another embodiment. Among these, in the embodiment shown in (A), the cylindrical portion 15 and the bottom plate 17 are directly connected to form a simple bottomed cylindrical shape. On the contrary, it is also possible to provide a plurality of step portions (different diameters in a plurality of steps) or to connect the cylindrical portion 15 and the bottom plate 17 with a tapered portion.

  In the embodiment shown in (B), as means for facilitating the deformation of the bottom plate 17, an outer peripheral cut 33 is formed outside the bolt insertion hole 23, and a central hole is formed at a location between adjacent bolt insertion holes 23. An inner circumferential cut 34 is formed that is open toward 22.

  As shown by a one-dot chain line in (B), an arc-shaped slit 35 (or an arc-shaped cut) is provided at a portion on the outer peripheral side of the bolt insertion hole 23 and between the adjacent bolt insertion holes 23. Is possible. Although not shown in the drawing, slits or notches that are long in the radial direction can be formed from the vicinity of the inner periphery of the bottom plate 17 to the vicinity of the outer periphery.

  In the embodiment shown in (C), a slit 36 concentric with the bolt insertion hole 23 is formed outside the bolt insertion hole 23. In the embodiment shown in (D), an outwardly convex curled portion 37 is formed on the outer periphery of the bottom plate 17 as a deformation facilitating means. In the case of (D), if a plurality of cuts or slits crossing the curled portion 37 are formed in the circumferential direction in the curled portion 37, the resistance of the curled portion 37 can be further reduced.

  The present invention can be embodied in various ways other than the above-described embodiment. For example, it is also possible to provide a T-shaped slit or notch in which a slit or notch extending in the outer peripheral direction of the bottom plate and a slit or notch extending in the radial direction are connected to each other between adjacent bolt insertion holes.

  The present invention can be applied not only to the water pump pulley but also to other pulleys. Furthermore, the present invention can be applied to a forward pulley around which the inner circumference of the belt is wound. When applied to a forward pulley, if the belt has a concavo-convex shape, an uneven portion may be provided on the outer periphery of the pulley.

  The present invention can be embodied in a pulley such as a water pump pulley. Therefore, it can be used industrially.

6 Crank pulley 7 Auxiliary machine drive belt 9 Water pump 12 Water pump pulley 15 Tube portion 16 Step portion 17 Bottom plate 19 Rotor 20 Rotating plate 21 Bolt 22 Center hole 23 Bolt insertion hole 27 Deformation hole as an example of deformation facilitating means 28 Deformation Cut hole as an example of facilitating means

Claims (1)

A rotating plate having a cylindrical portion around which a belt is wound and a disc-shaped bottom plate continuous to one end of the cylindrical portion, and the bottom plate being disposed in the cylindrical portion at a plurality of locations of the bottom plate A bolt insertion hole for fastening with a bolt,
The bottom plate is bent in a convex state toward the inside of the cylindrical portion from a reference posture orthogonal to the axis of the cylindrical portion, and the bottom plate is attached to the rotating plate when fastened by the bolt. Provided with a means for facilitating deformation to improve adhesion,
Sheet metal pulley for internal combustion engines.

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