JPH0532678Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a crankshaft damper pulley that reduces vibrations of a crankshaft in an engine, and in particular to a crankshaft damper pulley that reduces vibrations of the front end of the crankshaft. Regarding damper pulleys.

[Conventional technology]

BACKGROUND ART Damper pulleys have been known in which a torsional damper is formed on a pulley that is provided at the front shaft end of a crankshaft and drives auxiliary equipment to reduce torsional vibration of the crankshaft.

FIG. 3 shows the damper pulley described above.
In the figure, reference numeral 1 indicates a pulley hub attached to the tip of a crankshaft (not shown), and a damper mass 2 is disposed around the outer periphery of the pulley hub 1. A circumferentially extending rubber 3 is interposed between the damper mass 2 and the pulley hub 1, and the damper mass 2 is connected to the pulley hub 1 by the rubber 3. That is, a torsional damper 4 is formed on the outer periphery of the pulley hub 1 by a damper mass 2 and rubber 3. However, this damper pulley cannot reduce the bending vibration of the crankshaft.

In vehicles equipped with recent lightweight engines, the noise inside the car is particularly high due to the transmission of vibrations from the engine.
The noise is louder in the range of 200 to 600 Hz, and the cause of this noise is the vibration characteristics of the entire structure of the engine and transmission, especially the resonance system. FIG. 5 shows the vibration mode of the vertical vibration of the engine and transmission at the resonant frequency, and the vibrations at the rear ends of the crankshaft pulley 5 and transmission 6 shown in the figure are particularly large. Therefore, in order to reduce the noise caused by this vibration, it has been proposed that a damper pulley is provided at the front end of the crankshaft to suppress the bending vibration of the crankshaft (for example, the
(Publication No. 54-111252, Japanese Utility Model Application No. 59-85443, Japanese Utility Model Application No. 59-171243) [Problems to be solved by the invention] The vertical vibration level of the engine mentioned above is
In reality, it is determined by the magnitude of the excitation force and the position where the excitation force is applied, so the engine vibration level differs depending on the rotation angle direction of the crankshaft. For example, as shown in Figure 6, when the first cylinder explodes, an excitation force is applied to the crankshaft and at the same time the crankshaft is bent, causing the front end of the crankshaft to vibrate. Since the bending stiffness of
The oscillation vibration caused by the explosion in the second cylinder is larger than the oscillation vibration caused by the explosion in the other cylinders. Therefore, the swinging vibration of the crankshaft during the explosion of the first cylinder has the strongest influence on noise generation.

Note that a damper device in which an inertial mass is provided at one end of the crankshaft via an elastic body, and the elasticity of this elastic body is varied within a plane orthogonal to the center line of the rotating shaft is disclosed in Japanese Utility Model Application Publication No. 134441/1983. However, it does not particularly aim at reducing the vibration during explosion in the first cylinder, which has the greatest effect on noise generation.

As described above, bending vibration and torsional vibration act on the crankshaft, but if both of these vibrations can be reduced with one dynamic damper, the structure of the damper pulley can be simplified and costs can be reduced.

The present invention focuses on the above-mentioned points, and aims to provide a crankshaft damper pulley that can reduce torsional vibration and particularly reduce swing vibration of the crankshaft when the first cylinder explodes. shall be.

[Means for solving problems]

The crankshaft damper pulley of the present invention, which meets this purpose, has a damper mass arranged on the inner periphery of the pulley hub attached to the end of the crankshaft.
In a crankshaft damper pulley that constitutes a dynamic damper by connecting the damper mass and the pulley hub with an elastic body, a tuning hole is provided in the elastic body to change a spring constant in a radial direction of the elastic body, The tuning hole is arranged so that the elastic body is mainly used in the shearing direction with respect to the excitation force of the first cylinder closest to the pulley hub, and the tuning hole adjusts the resonance frequency of the dynamic damper. is tuned to near the vibration frequency of the crankshaft at the time of the first cylinder explosion.

[Effect]

In the crankshaft damper pulley configured in this manner, an excitation force is applied to the crank bearing due to the explosion of each cylinder, the crankshaft is bent, and the front end of the crankshaft vibrates.
Here, the elastic body connecting the crankshaft pulley hub and the damper mass is provided with a tuning hole that can change the spring constant in the radial direction, so the resonance frequency of the dynamic damper is adjusted to the first cylinder. It becomes possible to perform tuning near the vibration frequency of the crankshaft at the time of explosion.

Therefore, vibrations transmitted from the engine are suppressed to a small level, and noise inside the vehicle is reduced.

Since the tuning holes are arranged so that the elastic body is used in the shearing direction with respect to the maximum excitation force of the first cylinder, almost no tensile force acts on the elastic body at the time of maximum excitation. The elastic body is
Since the elastic body is stronger against shear loads than tensile loads, by arranging the tuning holes in this manner, it is possible to increase the durability of the elastic body.

〔Example〕

Hereinafter, preferred embodiments of the crankshaft damper pulley of the present invention will be described with reference to the drawings.

1 and 2 show a crankshaft damper pulley according to an embodiment of the present invention.
In the figure, 11 indicates a pulley hub attached to the front end of a crankshaft (not shown).
The pulley hub 11 includes a boss portion 11a, a hub 11b,
The connecting portion 11c is formed integrally with the connecting portion 11c. The boss portion 11a is the pulley hub 11
A hole 12 is formed in the center. An end of a crankshaft (not shown) is fitted into the hole 12, and a keyway 13 for fastening is provided on the inner periphery of the hole 12. A cylindrical hub 11b is located on the outer periphery of the boss portion 11a, and the hub portion 11b is concentric with the boss portion 11a. The boss portion 11a and the hub portion 11b are
They are connected by a coupling part 11c provided on the outer periphery of the boss part 11a and protruding outward in the radial direction.

The position of the boss portion 11a is shifted in the axial direction with respect to the hub portion 11b, as shown in the figure. That is,
One end surface of the boss portion 11a is located approximately in the axial center of the hub portion 11b, and the other end surface of the boss portion 11a projects beyond the end surface of the hub portion 11b on the crankshaft side. As a result, the pulley hub 11 has the inner circumference of the hub portion 11b, the boss portion 11
A concave portion 14 that opens in the axial direction is formed by one end surface of a and one side of the coupling portion 11c.

A damper mass 15 is disposed on the outer periphery of the hub portion 11b of the pulley hub 11.
A damper rubber 16 as an elastic body and a ring 17 are interposed between the hub portion 11b and the hub portion 11b. The damper mass 15 is connected to the pulley hub 11 by press-fitting a ring 17 into the hub portion 11b. Note that the hub portion 11b and the damper mass 15 are connected by using the damper rubber 16 without using the ring 17.
This may be done by vulcanization adhesion. The damper mass 15 and damper rubber 16 function as a torsional damper for a crankshaft (not shown).

A cylindrical damper mass 18 is disposed on the inner periphery of the pulley hub 11, that is, in the recess 14.
The hole 19 in the center of the damper mass 18 is a large diameter hole 19.
a and a small diameter hole 19b, and a large diameter hole 19b.
One end of the boss portion 11a of the pulley hub 11 is located within a. A ring 20 and a damper rubber 21 as an elastic body are interposed between the inner circumferential wall of the hub portion 11b and the outer circumferential surface of the damper mass 18.

The damper mass 18 is attached to the pulley hub 1 by press-fitting a ring 20 vulcanized and bonded to the damper rubber 21.
1. The damper mass 18 and damper rubber 21 function as a dynamic damper 22 against bending vibrations of a crankshaft (not shown).

The damper rubber 21 extends in the circumferential direction, and arc-shaped tuning holes 23, 2 are formed in the damper rubber 21.
4, 25, and 26 are formed. The tuning holes 23, 24, 25, and 26 have the function of changing the spring constant of the damper rubber 21 in the radial direction. The tuning holes 23, 24, 25, 26 are
This is a space where a part of the damper rubber 21 is removed, and this tuning hole allows the damper rubber 2
1 is partially penetrated in the same direction as the axial direction of the pulley hub 11. This tuning hole 23,2
4, the damper rubber 21 is used mainly in the shear direction with respect to the maximum excitation force of the first cylinder.

The tuning holes 23 and 24 are formed larger than the tuning holes 25 and 26, and the center of the tuning hole 23 is located at the top dead center position of the piston of the first cylinder (keyway 13), as shown in FIG.
The position is set at a position 20° in the direction of rotation from the center of the The center position of the tuning hole 24 is located a half turn away from the center position of the tuning hole 23. Tuning hole 25,
26 is a straight line A connecting the tuning holes 23 and 24
It is formed almost at right angles to the In this embodiment, the position of the tuning holes 24 is particularly important, and by appropriately setting the positions of the tuning holes 23 and 24, the resonance frequency of the dynamic damper 22 can be adjusted to the same level as that of the crankshaft when the first cylinder explodes. Tuned near the swing frequency.

In this embodiment, the center of the tuning hole 23 is set at a position 20 degrees advanced from the piston top dead center position of the first cylinder, but the setting angle θ of the tuning hole 23 is not limited to this. It may be set within 50° in the rotational direction from the dead position. The angle φ between the damper rubber 21 separated by the tuning holes 25 and 26, and the hollow portion 25,
The sizes of 26 are set appropriately.

Further, by tuning the dynamic damper 22 to the torsional vibration of the crankshaft, it becomes possible to further reduce the torsional vibration. In this way, the crankshaft damper pulley of this embodiment has the function of reducing both bending vibration and torsional vibration.

Next, the operation of the above-mentioned crankshaft damper pulley will be explained.

The explosion of each cylinder generates oscillating vibration at the front end of the crankshaft, and the pulley hub 11 vibrates accordingly. Since a dynamic damper 22 is formed on the pulley hub 11 by a damper mass 18 and a damper rubber 21, oscillation vibration of the front end of the crankshaft is suppressed. here,
Tuning holes 23 and 24 that can change the spring constant in the radial direction are formed in the damper rubber 21, and the tuning holes 23 are rotated from the top dead center of the piston where the explosion excitation force of the first cylinder is approximately the maximum. Set within 50° in the direction of the tuning hole 24
By deviating half a turn from the hollow portion 23, the displacement of the damper mass 18 at the time of explosion of the first cylinder can be increased. Therefore, it is possible to most effectively tune the resonance frequency of the dynamic damper 22 to near the vibration frequency of the crankshaft when the first cylinder of the engine explodes, especially when the first cylinder explodes. The vibration of the crankshaft is suppressed to a small level.

In addition, immediately after the piston of the first cylinder passes the top dead center, the damper rubber 21 is used in the shear direction with respect to the bending direction, so the bending position is lower than the rotational position where the damper rubber 21 is used in the compression direction. This makes it easier for the damper mass 18 to move in this direction, making it easier to adapt to the frequency range of 250 to 600 Hz, where noise inside the vehicle is a problem. At angles other than the above, the damper rubber 21 is located in the compression direction, so the damper rubber 21
1 spring constant is increased. This restricts the movement of the damper mass 18 and improves the durability of the damper rubber 21.

[Effect of idea]

According to the crankshaft damper pulley of the present invention, the following effects can be obtained.

(1) A tuning hole is provided in the elastic body that connects the crankshaft pulley hub and the damper mass to change the spring constant in the radial direction of the elastic body, and this tuning hole adjusts the resonance frequency of the dynamic damper to the first cylinder. It becomes possible to perform tuning near the vibration frequency of the crankshaft at the time of explosion. Therefore, it is possible to particularly suppress the vibration of the crankshaft during the explosion of the first cylinder, where the vibration of the crankshaft is the largest, and the effect is that noise in the vehicle interior can be reduced. is obtained.

(2) The tuning holes are arranged so that the elastic body is mainly used for shearing force against the excitation force of the first cylinder, which is closest to the damper pulley. Almost no tensile force acts on it. Since the elastic body is stronger against shear loads than tensile loads, by arranging the tuning holes in this manner, the durability of the elastic body can be increased.

(3) Since the damper mass can also be displaced in the circumferential direction, it is possible to reduce not only the bending vibration of the crankshaft but also the torsional vibration. As a result, there is no need to provide two dynamic dampers, one for bending vibration and one for torsional vibration, and the structure of the damper pulley can be simplified and costs can be reduced.

[Brief explanation of drawings]

Fig. 1 is a front view of the crankshaft damper pulley of the present invention, Fig. 2 is a sectional view taken along the - line in Fig. 1, Fig. 3 is a front view of a conventional damper pulley for torsional vibration, and Fig. 4 is a sectional view of the crankshaft damper pulley of the present invention. 5 is an explanatory diagram showing the vibration mode at the resonant frequency of the vertical vibration of a conventional engine and transmission. FIG. 6 is a sectional view taken along the - line in the figure. FIG. An explanatory diagram showing the state,
It is. 11...Pulley hub, 12...Damp mass, 2
1... Damper rubber as an elastic body, 22... Dynamic damper, 23, 24... Tuning holes.

Claims (1)

[Scope of utility model registration request] A crankshaft damper pulley in which a dynamic damper is constructed by disposing a damper mass on the inner periphery of a pulley hub attached to an end of the crankshaft, and connecting the damper mass and the pulley hub with an elastic body. A tuning hole is provided to change the spring constant in the radial direction of the elastic body, so that the elastic body is mainly used in the shearing direction in response to the excitation force of the first cylinder closest to the pulley hub. A crankshaft damper pulley, characterized in that the tuning hole is provided, and the tuning hole allows the resonance frequency of the dynamic damper to be tuned to near the oscillation frequency of the crankshaft at the time of the first cylinder explosion. .