JPH0434248A - Crank pulley of internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce bending moment so as to suppress resonance with a power plant by enabling a belt receiving member to swivel relating to a pulley hub only in a region of generating bending vibration of a crankshaft and suppressing oscillating motion of a crank pulley. CONSTITUTION:When a rotational speed is increased, centrifugal force is increased, and the first stopper 9 is gradually retracted by overcoming centrifugal force acting on the second stopper 10 and energizing force of a return spring 17. In a rotational speed region where bending vibration of a crankshaft is generated, a small diameter part 9b is placed in a condition that it falls off from a cylindrical part 7a of a recessed part 7. Simultaneously, the second stopper 10 is a little advanced but not to reach fitting into a cylindrical part 8a. Accordingly, a belt receiving member 3 is placed in a condition that it can be swiveled with a turn shaft 5 of a pulley hub 2 serving as the center. Consequently, bending moment acting on the crankshaft from a crank pulley side is decreased by suppressing an oscillating motion of a crank pulley itself, and resonance with a power plant is suppressed by increasing a natural value of vibration of the crankshaft.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an improvement in a crank pulley attached to the end of a crankshaft of an internal combustion engine for driving auxiliary equipment.

BACKGROUND OF THE INVENTION A disc-shaped crank pulley is usually bolted to the front end of a crankshaft of an internal combustion engine to drive an auxiliary device such as an alternator with a belt.

FIG. 12 shows a conventional crank pulley 31. As shown in the figure, a pulley hub 32 at the center and a heald receiving section 33 at the outer circumferential side are integrally formed, and the pulley hub 32 is located at the end of the crankshaft 34. It is fixed to the part by a pulley bolt 35. In the illustrated example, the crankshaft 3
In order to damp the torsional vibration of 4, a torsional damper 38 consisting of a damper rubber 36 and a damper mass 37 is integrally provided (see, for example, Japanese Utility Model Application No. 62-49039).

Problems to be Solved by the Invention In the configuration in which the disk-shaped crank pulley 31 is fixed to the end of the crankshaft 34 as described above, as shown in FIG. As a result, the crank pulley 31 causes a swinging motion, and this swinging motion causes a problem such as vertical bending vibration of the power plant. Particularly in an in-line four-cylinder engine, forces act on the crankshaft from two directions differing by 180a in terms of crank angle, so the above-mentioned oscillating motion tends to become noticeable, causing muffled noise in the vehicle interior.

Means for Solving the Problems Therefore, in the present invention, the belt receiving member on the outer circumferential side of the crank pulley is made swingable only in the rotation speed range where bending vibration of the crankshaft occurs, thereby suppressing the swinging motion of the crankboo. This is what I did. That is, the crank pulley for an internal combustion engine according to the present invention includes a pulley hub fixed to the end of the crankshaft, and a pair of rotating shafts disposed on the outer periphery of the pulley hub and extending in the diametrical direction. a supported annular belt receiving member; a first stopper and a second stopper disposed on the belt receiving member so as to be movable in the radial direction; The second stopper is configured to include a link mechanism that links the second stopper to protrude when the first stopper retreats due to a force, and a return spring that biases the first stopper to protrude when the centrifugal force is small. There is.

In a region where the operating engine speed is low, the first stopper projects due to the biasing force of the return spring and fits into the recess of the pulley hub, so that the belt receiving member and the pulley hub are integrated.

When the engine speed rises to a predetermined speed range, the first stopper moves back due to centrifugal force and is removed from the recessed portion of the pulley hub. Therefore, the belt receiving member can swing relative to the pulley hub, and the swinging motion of the crank pulley caused by bending vibration of the crankshaft is suppressed.

When the rotational speed further increases, the second stopper protrudes as the first stopper retreats, fits into the recess of the pulley hub, and the belt receiving member and pulley hub are integrated again.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

1 to 4 show an embodiment of a crank pulley 1 according to the present invention.

In this crank pulley l, a central pulley hub 2 and an annular belt receiving member 3 located on the outer periphery of the pulley hub 2 are constructed as separate members, and are fitted into each other with an appropriate gap 4 in between. There is. The pulley hub 2 has a pair of rotation shafts 5 along the diameter direction at two locations 180° apart, and the belt support member 3 can be swung by the rotation shafts 5 via a ball bearing 6. (See Figures 1 and 4). Note that the rotation shaft 5 is
In the case of an in-line four-cylinder engine, it is provided in a direction perpendicular to the direction in which the crank arm extends. As shown in FIG. 3, this pulley hub 2 is firmly fixed to the end of the crankshaft 11 by a pulley bolt 12.

Further, a pair of recesses 7 are provided on the outer peripheral surface of the pulley hub 2 in a direction perpendicular to the rotation axis 5 .

This recessed portion 7 has a cylindrical portion 7a closer to the bottom and a tapered portion 7b closer to the opening surface. Further, a pair of recesses 8 are provided between the recess 7 and the rotation shaft 5, that is, in a direction approximately 45° to the axis of the rotation shaft 5. This recess 8
It also has a cylindrical portion 8a and a tapered portion 8b.

A pair of first stoppers 9 corresponding to the recess 7 and a pair of second stoppers 10 corresponding to the recess 8 are disposed on the inner peripheral side of the belt receiving member 3.

The first stopper 9 has a large diameter portion 9a on the base end side and a small diameter portion 9b on the distal end side, both of which are connected by a tapered portion 9c, and the small diameter portion 9b also has a tapered portion 9d at the distal end. are doing. The large diameter portion 9a is pivotally fitted into a guide hole 13 formed in the belt receiving member 3 in the radial direction. Further, a link pin 14 is provided on the proximal peripheral surface of the large diameter portion 9a.
is provided protrudingly, and the link pin 14 passes through a slit 15 in the belt receiving member 3 (see FIG. 3).

The second stopper 10 has a flange portion 10b at the base end of a cylindrical portion 10a, and is provided with a tapered tip portion 10C. It is slidably fitted into a guide hole 16 formed in the radial direction of the belt receiving member 3, and is always urged in the backward direction by a return spring 17 fitted into the outer periphery of the cylindrical portion 10a. (See Figure 1).

Further, a link pin 18 is provided protruding from the circumferential surface of the flange portion Job, and the link pin 18 passes through a slit 19 of the belt receiving member 3.

Note that the first stopper 9. The second stoppers 10 are both made of metal, but the first stopper 9 has a larger mass than the second stopper IO.

” Ju 1. Second stopper9. lO link bin 14.
1B, as shown in FIG. 2, are linked to each other by links 20 having elongated holes at both ends. Above link 20
is swingably supported by the belt receiving member 3 by a fulcrum pin 21 in the intermediate portion. Therefore, 11. Second stopper9. When one of the lO protrudes toward the pulley hub 2 side, the other one retreats.

Incidentally, on the outer peripheral side of the belt receiving member 3, a torsional damper 24 consisting of a damper rubber 22 and a damper mass 23 is installed, similar to a conventional crank boot.
(See Figures 3 and 4).

Next, the operation of the above embodiment will be explained.

First, when the rotation speed of the internal combustion engine is in a relatively low speed range, the centrifugal force acting on the first stopper 9 is not so large, so the biasing force of the return spring 17 causes the second stopper to stop.
The stopper 10 is in the retracted position, and the first stopper 9 linked by the link 20 is in the extended position. In other words, as shown in FIG. 5, the first stopper 9 fits relatively tightly into the recess 7 of the pulley hub 2, and thereby the pulley hub 2 and the belt receiving member 3 are substantially integrated. . Therefore, unnecessary rattling or the like is prevented.

As the rotational speed of the internal combustion engine increases, the centrifugal force acting on the first stopper 9 increases, overcoming the centrifugal force acting on the second stopper IO and the biasing force of the return spring 17, and the first stopper 9 increases. gradually retreat. In the rotation speed region where bending vibration of the crankshaft 11 occurs, the sixth
As shown in the figure, the small diameter portion 9b of the first stopper 9 is in a state of being pulled out from the cylindrical portion 7a of the recess 7. At the same time, although the second stopper IO moves forward somewhat, it does not fit into the cylindrical portion 8a of the recessed portion 8. Therefore, the belt receiving member 3 is in a state where it can swing around the rotation axis 5 of the pulley hub 2. Therefore, as is clear from FIG. 8, the swinging motion of the crank pulley l itself is suppressed, and the bending moment acting on the crankshaft 11 from the crank pulley l side is reduced, and the eigenvalue of the vibration of the crankshaft 11 is reduced. This increases the height and suppresses resonance with the power plant.

In the above-mentioned state in which the belt receiving member 3 can swing with respect to the pulley hub 2, the tapered end portion 9d of the first stopper 9 or the tapered end portion 10c of the second stopper 10 is connected to the tapered portion 7b of each recess 7.8. , 8b.

Therefore, as shown in FIG. 7, the swing angle of the belt receiving member 3 is always regulated within an appropriate range.

Further, when the engine speed further increases beyond the bending vibration generation range of the crankshaft 11, the second stopper IO protrudes instead of the first stopper 9 retreating, as shown in FIG.
Fits into the recess 8. Therefore, the belt receiving member 3 and the pulley hub 2 are integrated again, and unnecessary rattling does not occur.

In this way, in the above configuration, the belt receiving member 3 is allowed to swing only in the rotational speed region where the swinging motion of the crank pulley 1 is likely to occur, that is, in the region where the bending vibration of the crankshaft 11 occurs.
It is possible to suppress rust swinging motion and crankshaft l1 bending vibration.

FIG. 1O shows the characteristics of the moment change of the link 20 with respect to the change in rotation speed. The mass of each stopper 9, 10, the length of the arm of the link 20, etc. are set so that the moment (b) due to the resultant force is exceeded in the range of a predetermined rotation speed N or more.

Next, Figure 1 shows different embodiments of the present invention. In this embodiment, a cylindrical rubber sleeve 25 is press-fitted between the rotating shaft 5 of the pulley hub 2 and the bearing hole of the belt receiving member 3, and the elastic deformation of the rubber sleeve 25 causes the belt receiving member to can swing relative to the pulley hub 2.

According to this embodiment, the structure can be simplified compared to the one using the ball bearing 6 described above, and a vibration damping effect due to the torsion of the rubber sleeve 25 can be obtained, which is more advantageous in suppressing bending vibration.

Effects of the Invention As is clear from the above explanation, according to the crank pulley for an internal combustion engine according to the present invention, the belt receiving member can swing relative to the pulley hub only in the region where bending vibration of the crankshaft occurs, and the crank pulley Since the oscillating motion of the crankshaft is suppressed, the bending moment input from the crankshaft to the crankshaft is reduced, the natural value of the vibration of the crankshaft is increased, and resonance with the power plant is suppressed.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the essential parts showing one embodiment of a crank pulley according to the present invention, Fig. 2 is a front view showing its overall appearance, and Fig. 3 is a view taken along the line ■-■ in Fig. 1. 4 is a sectional view taken along line IV-IV in FIG. 1, FIG. 5 is an explanatory diagram showing the state in a low speed range, and FIG. 6 is an explanatory diagram showing the state in an intermediate speed range. , Fig. 7 is an enlarged explanatory diagram of the main parts in this intermediate speed range, Fig. 8 is an explanatory diagram showing the bending vibration of the entire crankshaft equipped with the crank pulley of this embodiment, and Fig. 9 is the state in the high speed range. FIG. 10 is a characteristic diagram showing the characteristics of the moment acting on the link, FIG. 11 is a sectional view of the main part showing different embodiments of the crank pulley according to the present invention, and FIG. 12 is a conventional crank pulley. FIG. 13, which is a sectional view showing a pulley, is an explanatory diagram showing bending vibration of the entire crankshaft equipped with a conventional crank pulley. 1... Crank pulley, 2... Pulley hub, 3...
- Belt receiving member, 5... Rotating shaft, 9... First stopper, 10... Second stopper, 17 Return spring, 20... Link. 3. Belt change 871 class 5: I] Power axis: 1st stroke 7 no 10: dormitory 2 stroke, lg 17: return spring. Figure Figure S Figure Figure n Figure Figure Figure '°] Figure 10 Figure

Claims (1)

[Claims] (1) a pulley hub fixed to the end of the crankshaft; an annular belt support member disposed around the outer periphery of the pulley hub and swingably supported by a pair of rotating shafts along the diameter direction; A first stopper and a second stopper are disposed on the belt receiving member so as to be movable in the radial direction, and the tip of the stopper can fit into the recess of the pulley hub. A crank pulley for an internal combustion engine, comprising a link mechanism that links the stopper so that the stopper projects, and a return spring that biases the first stopper so that the first stopper projects under a small centrifugal force.