JP2013241963A - Guide plate for timing belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a guide plate for a timing belt capable of suppressing the sliding of a timing belt driving pulley and an auxiliary belt driving pulley relative to each other.SOLUTION: A guide plate 36 includes a circular base 51 pressed into contact with the front end surface of a timing pulley 35 and the rear end surface of a stepped cylindrical part 45a in a crank pulley 15, and a circular guide 52 extending to the outer diameter side of the outer peripheral edge 51a of the base 51. The base 51 includes a circular shaft hole 53 in which the pulley mounting shaft 32 of the crank shaft 31 fits, and a key groove 54 in which a parallel key 38 fits which are formed in a continuous manner. Four circular arc openings 61 are projected inside from the outer peripheral edge 51a at the angular interval of 90° and coaxially to the shaft hole 53, and the inner edge of the shaft hole 53, three circular arc notches 62 are arrayed with the key groove 53 in a peripheral direction avoiding the key groove 54 in parallel with the key groove 54.

Description

  The present invention relates to a timing belt guide plate interposed between an engine timing belt driving pulley and an accessory belt driving pulley, and more particularly to a technique for suppressing relative slippage between both pulleys.

  In reciprocating engines installed in automobiles, etc., the camshaft must be operated reliably during operation, so the crankshaft and camshaft are connected via a power transmission member (timing belt, silent chain, etc.) that does not cause slippage. Has been. Further, in an automobile engine, in order to drive various auxiliary machines (alternator, water pump, cooler compressor, etc.), the crankshaft and these auxiliary machines are connected by an auxiliary machine belt. In an engine employing a timing belt, a timing belt guide plate that prevents a lateral shift of the timing belt between a timing belt driving pulley (timing pulley) and an auxiliary belt driving pulley (crank pulley). It is known that these are fastened to the pulley mounting shaft portion of the crankshaft by means of a crankshaft bolt (see Patent Document 1).

Japanese Utility Model Publication No. 63-6267

  In the case of a reciprocating engine, it is accelerated in the expansion stroke of each cylinder and decelerated in the other strokes, causing minute rotational fluctuations in the crankshaft, and the crankshaft bolt may be loosened as described below. there were. When rotation of the crankshaft occurs, the crank pulley loosely fitted to the pulley mounting shaft is alternating with respect to the crankshaft (pulley mounting shaft) so that it can be easily removed during maintenance (such as when replacing the timing belt). May cause relative slippage. Particularly in winter when the outside air temperature decreases, the elasticity of the damper bar (an annular rubber member interposed between the hub fitted on the pulley mounting shaft and the pulley ring around which the auxiliary belt is wound) (Ie, it becomes difficult to absorb rotation fluctuations), so that the relative slip between the pulley mounting shaft portion and the crank pulley is more likely to occur. When the crank pulley causes an alternating relative slip with the pulley mounting shaft, forces in both directions (friction force with the crank pulley) are alternately applied to the seat surface of the crankshaft bolt that fastens the crank pulley. If the engine is operated for a long period of time, the crankshaft bolt may loosen gradually.

  As a method of preventing the loosening of the crankshaft bolt, in order to improve the resistance against relative slip (so-called slip toughness), the friction area between the timing belt guide plate and both pulleys is increased, It is conceivable to increase the fastening axial force (that is, fastening torque). However, it is difficult to increase the friction area because the maximum outer diameter of the timing pulley or the like is restricted by the layout (or causes an increase in the size or weight of the engine). In addition, increasing the tightening torque of the crankshaft bolts makes it difficult to attach and detach the crankshaft bolts during assembly and maintenance, and also causes problems such as buckling deformation of the fastening seat surface. It was.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a timing belt guide plate that suppresses relative slip between a timing belt driving pulley and an accessory belt driving pulley.

  In the first aspect of the present invention, the pulley is fastened to the pulley mounting shaft portion (32) of the crankshaft (31) together with both pulleys while being interposed between the timing pulley (35) and the crank pulley (15). A disc-shaped guide plate (36) extending to the outer diameter side of the shaft hole (53) and the shaft hole, and being in pressure contact with the end face of the timing pulley and the end face of the crank pulley at the time of fastening. A base portion (51); and a guide portion (52) that extends to an outer diameter side of the base portion and guides the timing belt, and the base portion has an inner side from an outer peripheral edge (51a). Meat removal parts (61, 62, 65, 66) were provided.

  In the second aspect of the present invention, the thinned portion is a plurality of arc-shaped openings (61) formed concentrically with the shaft hole.

  In the third aspect of the present invention, the thinned portion is an annular thin portion (65) or a plurality of arcuate thin portions (66) formed concentrically with the shaft hole.

  In the fourth aspect of the present invention, a plurality of arc-shaped notches (62) are formed at the inner edge of the shaft hole.

  In the fifth aspect of the present invention, a key groove (54) into which a key (38) provided on the pulley mounting shaft portion is fitted is formed so as to be continuous with the shaft hole, and the diameter of the arcuate notch The direction dimension (α) was set smaller than the radial direction dimension (β) of the keyway.

  According to the first aspect of the present invention, the thinned portion is provided on the inner side of the outer peripheral edge of the base portion, whereby the equivalent friction radius between the pulleys and the timing belt guide plate is increased, and the crankshaft bolt The loosening of the crankshaft bolt caused by the relative slip between the crankshaft and the crank pulley can be suppressed without increasing the fastening torque. In addition, in the case where the thinned portion is a plurality of arc-shaped openings formed concentrically with the shaft hole, a timing belt guide plate can be manufactured using a relatively simple press die. When the thinned portion is an annular thin portion formed concentrically with the shaft hole or a plurality of arcuate thin portions, the mechanical strength of the timing belt guide plate alone can be improved. In addition, in the case where a plurality of arc-shaped notches are formed around the shaft hole, the equivalent friction radius between both pulleys and the timing belt guide plate becomes larger, which causes relative slip between the crankshaft and the crank pulley. The resulting loosening of the crankshaft bolt can be more effectively suppressed. In addition, the key groove into which the key provided on the pulley mounting shaft portion is inserted is formed so as to be continuous with the shaft hole, and the radial dimension of the arc-shaped notch is set smaller than the radial dimension of the key groove. Since the timing pulley and the timing belt guide plate can be reliably positioned in the rotational direction, it is easy to place the drain hole on the timing belt guide plate side at a position corresponding to the tooth bottom of the timing pulley.

It is a front view of the engine concerning a 1st embodiment. It is II-II expanded sectional drawing in FIG. It is a disassembled perspective view of the pulley attachment site | part which concerns on 1st Embodiment. It is a front view of the guide plate which concerns on 1st Embodiment. It is VV sectional drawing in FIG. It is VI-VI expanded sectional drawing in FIG. It is a front view of the guide plate which concerns on 2nd Embodiment. It is a VIII-VIII expanded sectional view in FIG. It is a front view of the guide plate which concerns on 3rd Embodiment. It is XX expanded sectional drawing in FIG.

  Hereinafter, with reference to FIGS. 1-8, two embodiment of the guide plate for timing belts of the engine for motor vehicles to which this invention is applied is described in detail. In the description of each member, up, down, left and right, front and back are indicated by arrows in FIG. 1 or FIG. 2, and positions and directions are indicated along these.

[First Embodiment]
<< Configuration of First Embodiment >>
<Overall configuration>
An engine 1 shown in FIG. 1 is a four-cycle in-line four-cylinder gasoline engine mounted on an automobile, and an outer shell is constituted by a cylinder block 2, a cylinder head 3, an oil pan 4, a head cover 5, a timing belt cover 6, and the like. ing. The timing belt cover 6 is an injection-molded product made of resin, and is fastened to the front surfaces of the cylinder block 2 and the cylinder head 3 so as to cover a timing pulley 35 and a timing belt 41 described later.

  In the engine 1, an alternator 11 is disposed on the intake side (left side in FIG. 1), and a power steering pump 12 and a cooler compressor 13 are disposed on the exhaust side (right side in FIG. 1). These auxiliary machines 11 to 13 are rotationally driven by a crankshaft 31 to be described later via a survivorine type auxiliary machine belt 17 wound around a crank pulley 15 and driven pulleys (auxiliary machine pulleys) 11a to 13a. . The timing belt cover 6 is provided with two idler pulleys 19 in order to ensure the wrapping angle of the auxiliary belt 17 with respect to the crank pulley 15 and the auxiliary pulleys 11a to 13a.

  As shown in FIG. 2, a crankshaft 31 is rotatably supported at the lower portion of the cylinder block 2 via upper and lower main bearings 21 and 22. A pulley mounting shaft portion 32 is formed at the front end of the crankshaft 31, and a timing pulley 35, a guide plate 36, and the above-described crank pulley 15 are fitted on the pulley mounting shaft portion 32 in this order. A screw hole 33 is provided in the shaft center of the pulley mounting shaft portion 32, and a screw portion 37 a of a crankshaft bolt 37 that fastens the pulleys 35, 15 and the guide plate 36 is screwed into the screw hole 33. A key groove 34 is formed in the pulley mounting shaft portion 32, and both pulleys 35, 15 and the guide plate 36 are positioned in the rotation direction by a parallel key 38 fitted and inserted in the key groove 34. A thick washer 39 is interposed between the crankshaft bolt 37 and the crank pulley 15 in order to transmit the fastening axial force of the crankshaft bolt 37 to the crank pulley 15.

  An oil pump cover 48 having a foreign matter discharge hole 48 a formed at the lower end is fastened to the front surface of the cylinder head 2, and a timing belt cover 6 is further fastened to the front surface of the oil pump cover 48. A timing belt chamber 40 is defined between the oil pump cover 48 and the timing belt cover 6, and a timing pulley 35, a timing belt 41, and a camshaft pulley (not shown) are accommodated in the timing belt chamber 40. As shown in FIG. 3, the timing pulley 35 includes a belt driving unit 43 having teeth 43 a meshing with teeth 41 a (see FIG. 2) of the timing belt 41 on the outer periphery, and a guide for preventing the rearward displacement of the timing belt 41. It has a flange 44 and is loosely fitted to the pulley mounting shaft portion 32. On the other hand, the crank pulley 15 elastically connects the hub 45 fitted around the pulley mounting shaft portion 32, the pulley ring 46 around which the accessory belt 17 is wound, the inner peripheral surface of the pulley ring 46, and the outer peripheral surface of the hub 45. A damper bar 47 coupled to the pulley mounting shaft portion 32 is loosely fitted to the pulley mounting shaft portion 32. A stepped cylindrical portion 45 a having a small diameter on the rear side is formed on the axial center side of the hub 45, and the rear end surface of the stepped cylindrical portion 45 a is in pressure contact with the guide plate 36. Note that a labyrinth 49 is formed between the rear surface of the hub 45 and the front surface of the timing belt cover 6 in order to prevent dust and the like from entering the timing belt cover 6.

<Guide plate>
The guide plate 36 is a disk-shaped press-molded product made of a steel plate, and as shown in FIGS. 4 and 5, when the crankshaft bolt 37 is tightened, the front end face of the timing pulley 35 and the step on the crank pulley 15 are provided. An annular base portion 51 (indicated by cross-hatching in FIG. 4) that is in pressure contact with the rear end surface of the attached cylindrical portion 45a, an annular guide portion 52 that extends to the outer diameter side of the outer peripheral edge 51a of the base portion 51, It is made up of. Here, the outer peripheral edge 51a is a circle indicating the boundary between the base part 51 and the guide part 52, and the guide plate 36 does not have a step corresponding to the outer peripheral edge 51a. In this embodiment, as shown in FIG. 2, the outer diameter of the rear end surface of the crank pulley 15 is smaller than the outer diameter (tooth diameter) of the front end surface of the timing pulley 35. The area to be in pressure contact is the base portion 51.

  The base portion 51 is provided with a circular shaft hole 53 into which the pulley mounting shaft portion 32 of the crankshaft 31 is fitted, and a key groove 54 into which the parallel key 38 is fitted is formed so as to be continuous with the shaft hole 53. . In addition, the guide portion 52 includes a flare portion 55 having an outer peripheral edge inclined forward, and a plurality (23 in the illustrated example) corresponding to each tooth bottom (between adjacent teeth 43a) of the timing pulley 35. The water drain hole 56 is formed. The drain holes 56 are all circular holes having the same diameter, and are arranged at equiangular intervals on a circle concentric with the shaft hole 53 (that is, concentric with the axis of the pulley mounting shaft portion 32). . The drain hole 56 is configured such that the outer peripheral edge of the rear end surface of the crank pulley 15 (that is, the outer peripheral edge 51a of the base portion 51) is all the drain hole in a state where the rear end surface of the crank pulley 15 is in pressure contact with the guide plate 36. 56 is positioned so as to contact the guide plate 36 radially inside.

  As shown in FIGS. 4 to 6, in the base portion 51 of the present embodiment, four arc-shaped openings 61 are formed at an angular interval of 90 ° concentrically with the shaft hole 53 on the inner side of the outer peripheral edge 51 a. In addition, three arc-shaped notches 62 are provided on the inner edge of the shaft hole 53 so as to avoid the key groove 54 so as to be aligned with the key groove 54 in the circumferential direction. Since the key groove 54 is formed deep in the radial direction, the key groove 54 is disposed at a position shifted in the circumferential direction so as not to overlap the arc-shaped notch 62, and the radial dimension α of the arc-shaped notch 62 is determined by the guide The parallel key 38 is set to be significantly smaller than the radial dimension β of the key groove 54 so that the parallel key 38 does not enter the arcuate notch 62 when the plate 36 is assembled to the pulley mounting shaft portion 32. Stiffness is also improved.

<< Operation of First Embodiment >>
In an assembly line or a maintenance shop of the engine 1, an assembly worker or a maintenance worker wraps the timing belt 41 around the timing pulley 35 and the cam pulley and externally fits the guide plate 36 to the pulley mounting shaft portion 32. The belt cover 6 is fastened to the cylinder block 2 and the cylinder head 3. Next, the assembly operator externally fits the crank pulley 15 and the washer 39 to the pulley mounting shaft portion 32 and fastens them with the crankshaft bolt 37, and then attaches the auxiliary machine belt 17 to the crank pulley 15 and the auxiliary machines 11 to 13. It is wound around (driven pulleys 11a to 13a).

  In the guide plate 36 of the present embodiment, the base portion 51 is provided with the arc-shaped opening 61 and the arc-shaped notch 62, so that the base portion 51 and the pulleys 35, 15 are compared with those in which these are not provided. The equivalent friction radius of the pressure contact surface is significantly increased. As a result, even when the axial force of the crankshaft bolt 37 is set to be relatively small (that is, even when the tightening torque is set to be relatively low), both pulleys 35, when the engine 1 is operated in winter, 15 and the guide plate 36 hardly slide relative to each other. As a result, the alternating relative slip between the crank pulley 15 and the pulley mounting shaft portion 32 is less likely to occur (the slip toughness of the crank pulley 15 is improved), and the crankshaft bolt 37 that has been a problem in the conventional apparatus is loosened. It can be effectively prevented. The radial dimension γ (see FIG. 4) between the arc-shaped opening 61 and the outer peripheral edge 51a of the base portion 51 is the radial dimension δ between the arc-shaped opening 61 and the inner edge of the base portion 51 (see FIG. 4). ), The equivalent friction radius becomes larger, and the loosening of the crankshaft bolt 37 due to relative slip can be more effectively prevented.

  In the present embodiment, the radial dimension α of the arcuate notch 62 is set to be significantly smaller than the radial dimension β of the key groove 54, so that the guide plate 36 is parallel when assembled to the pulley mounting shaft portion 32. The key 38 does not enter the arcuate notch 62 (that is, the timing pulley 35 and the guide plate 36 are reliably positioned in the rotational direction). As a result, even when water adheres to the timing belt 41, the water flows from the tooth bottom of the timing pulley 35 into the timing belt chamber 40 via the drain hole 56 and is then discharged from the oil pump cover 48. It is discharged to the outside through the hole 48a.

  Thus, in this embodiment, without increasing the outer diameters of the pulleys 35 and 15 and the tightening torque of the crankshaft bolt 37 (that is, without enlarging the engine 1 and reducing workability). The loosening of the crankshaft bolt 37 can be effectively prevented.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The second embodiment also has substantially the same configuration as the first embodiment described above, but the shape of the base portion 51 in the guide plate 36 is different. That is, as shown in FIGS. 7 and 8, the base portion 51 of this embodiment is not provided with an arc-shaped opening or an arc-shaped notch as in the first embodiment, and a circle around the shaft hole 53. An annular thin portion 65 is provided. The annular thin portion 65 is fitted on the pulley mounting shaft portion 32, but is not pressed against the end surfaces of the pulleys 35 and 15 even when the crankshaft bolt 37 is tightened. In the present embodiment, by adopting such a configuration, the equivalent friction radius of the pressure contact surface between the base portion 51 and the pulleys 35 and 15 is also increased, and the same effects as those of the first embodiment are achieved.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. The third embodiment also has a configuration substantially similar to that of the first embodiment described above, but the shape of the base portion 51 in the guide plate 36 is still different. That is, as shown in FIGS. 9 and 10, the base portion 51 of the present embodiment is also not provided with the arc-shaped opening or the arc-shaped notch as in the first embodiment, and 4 around the shaft hole 53. Two arcuate thin portions 66 are provided at an angular interval of 90 °. The arcuate thin portion 66 is fitted on the pulley mounting shaft portion 32, but is not pressed against the end surfaces of the pulleys 35 and 15 even when the crankshaft bolt 37 is tightened. In the present embodiment, by adopting such a configuration, the equivalent friction radius of the pressure contact surface between the base portion 51 and the pulleys 35 and 15 is also increased, and the same effect as in the first and second embodiments is obtained. Play.

  This is the end of the description of specific embodiments. However, aspects of the present invention are not limited to these embodiments. For example, in both the above-described embodiments, the number of arc-shaped openings and the number of arc-shaped thin portions is four, but the number may be five or more, or may be three or less. Further, the number of arc-shaped notches in the first embodiment may be other than three, and is not necessarily provided. In addition, the shape of the opening, the thin portion, and the notch may be other than the arc shape. In addition, as long as it does not deviate from the gist of the present invention, the shape of the pulley mounting shaft portion and both pulleys can be changed as appropriate.

DESCRIPTION OF SYMBOLS 1 Engine 15 Crank pulley 31 Crankshaft 32 Pulley attachment shaft part 35 Timing pulley 36 Guide plate 37 Crankshaft bolt 38 Parallel key 41 Timing belt 51 Base part 52 Guide part 53 Shaft hole 54 Key groove 61 Arc-shaped opening (thickening part)
62 Arc notch (thickened part)
65 Annular thin part (thickening part)
66 Arc-shaped thin part (thickening part)

Claims (5)

A disc-shaped guide plate fastened to the pulley mounting shaft portion of the crankshaft together with both pulleys in a state of being interposed between the timing pulley and the crank pulley,
A shaft hole,
A base portion that extends to an outer diameter side of the shaft hole and press-contacts with an end face of the timing pulley and an end face of the crank pulley at the time of the fastening;
A guide portion that extends to the outer diameter side of the base portion and guides the timing belt;
A guide plate for a timing belt, wherein the base portion is provided with a thinned portion inside the outer peripheral edge thereof.   The timing belt guide plate according to claim 1, wherein the lightening portion is a plurality of arc-shaped openings formed concentrically with the shaft hole.   2. The timing belt guide plate according to claim 1, wherein the thinned portion is an annular thin portion or a plurality of arc-shaped thin portions formed concentrically with the shaft hole.   4. The timing belt guide plate according to claim 1, wherein a plurality of arc-shaped notches are formed at an inner edge of the shaft hole. 5.   A key groove into which a key provided on the pulley mounting shaft portion is fitted is formed to be continuous with the shaft hole, and the radial dimension of the arc-shaped notch is set smaller than the radial dimension of the key groove. The guide plate for a timing belt according to claim 4, characterized in that:

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