JPH0788890B2 - Damper pulley - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is mounted on the crankshaft shaft end of an internal combustion engine, transmits rotational power of the engine, and combines an elastic body and an inertial body. The present invention relates to a damper pulley including a dynamic damper that absorbs vibrations from the crankshaft when combined.

(Prior Art) As is well known, in an internal combustion engine, a crankshaft that generates rotational power generates various vibrations together with rotational force.

A means for removing or reducing the above-mentioned vibration transmitted from the crankshaft is to mount an inertial body (damper mass) on a pulley through an elastic body so as to have a two-degree-of-freedom vibration system having a crankshaft and a pulley. As a vibration system, one resonance point that appears as a one-degree-of-freedom vibration system is divided into two resonance points to be excluded from the constant velocity region or the normal (rotational speed) region. This is the so-called dynamic damper method.

In the past, however, among the various vibrations described above, mainly in the circumferential direction, there is a measure to prevent breakage of the crankshaft and countermeasures against the so-called "nothing" phenomenon of fine slip of the belt suspended on the pulley. That is, countermeasures against torsional vibration have become the mainstay.

FIG. 7 shows a first conventional example in which the method of the dynamic damper is applied to the vibration in the circumferential direction.

An inertia body 5 having a belt groove formed therein is fitted to the outer periphery of the rim 3 of the pulley body 1 fixed to the shaft via an elastic body 4 such as rubber.

As is apparent from the figure, in the above-mentioned conventional example, no consideration is given to longitudinal vibration in the rotation axis direction or whirling vibration of the pulley due to bending of the shaft.

Next, in addition to the above-mentioned torsional vibration, FIG. 8 shows a second conventional example devised in consideration of the axial direction or whirling vibration of the pulley caused by the bending of the crankshaft.

As shown in the figure, the structure for torsional vibration is exactly the same as that of the first conventional example, but in the rear cavity of the rim 3 of the pulley body 1, axial and whirling vibrations (hereinafter abbreviated as bending vibrations). An independent inertial body 5a is fixed to the mounting member 8 via an elastic body 4a as a dynamic damper against vibrations (including vibration due to bending of the crankshaft). The mounting member 8 is provided on the back surface of the rim 3.

In this example, the vibrations appearing at the shaft end of the crankshaft are detected according to the form, and each is equipped with a separate independent damper. By properly selecting the specifications, the purpose of installing a damper can be achieved. Is.

(Problems to be Solved by the Invention) However, in the second conventional example, it is necessary to divide the vibrations appearing at the shaft end of the crankshaft by form and attach individual dynamic dampers to each other, which complicates the structure and increases the number of parts used. However, it is obvious that the cost will be high.

The present invention has been made in order to solve the conventional problems, and attenuates various forms of vibration appearing at the crankshaft shaft end of an internal combustion engine to transmit smooth rotational power, and to provide specifications as a damper. It is an object of the present invention to provide a low cost damper pulley that can be freely selected and has a simple structure.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, the damper pulley of the present invention is mounted on the crankshaft shaft end of an internal combustion engine and transmits rotational power of the engine. In a damper pulley provided with a dynamic damper that absorbs vibrations from the crankshaft by a combination of an elastic body and an inertial body, torsional vibration is applied to a thin plate steel material having elasticity in the axial direction of the damper pulley. Equipped with a dynamic damper composed of an elastic body and an inertial body that damp, the torsional vibration is damped by the dynamic damper, and the dynamic damper and the mounting portion of the dynamic damper are used as one inertial body, and the inertial body and the elastic body are combined. Bending vibrations are damped by combination with thin plate steel with To.

(Operation) As described above, the damper pulley of the present invention is equipped with a dynamic damper composed of an elastic body and an inertial body for damping torsional vibration on a thin plate-shaped steel material having elasticity in the axial direction of the damper pulley, The dynamic damper damps torsional vibrations, and the dynamic damper and the mounting portion of the dynamic damper are used as one inertial body, and the bending vibration is damped by a combination of the inertial body and the elastic thin plate-shaped steel material. With this configuration, not only the torsional vibration of the crankshaft but also the bending vibration can be reduced, and it is possible to cope with a plurality of different forms of vibration with one dynamic damper. The original can be independently selected.

(Examples) Hereinafter, various examples of the present invention will be described with reference to the drawings.

1 and 2 show a first embodiment of the present invention. FIG. 1 is a partially cutaway front view, and FIG.
FIG. 2 is a sectional view taken along line II.

As shown in the figure, the damper pulley P has a hub portion in which a key groove 12 is provided in a shaft hole 11 that fits into a shaft end of a crankshaft.
10 and a rim portion 2 in which a plurality of belt grooves 21 and 22 are engraved on the outer periphery.
0, a web portion 30 which is an intermediate body between the two, and a dynamic damper 40 attached to the back tubular surface of the rim portion 20 in a cavity provided in the back portion of the rim portion 20.

The belt groove provided in the rim portion 20 includes a group of belt grooves 21 and a group of belt grooves 22 in the present embodiment, and the rotational power transmitted from the crankshaft is branched to two different driven objects. It is what is done.

A large cavity exists in the rim portion 20 at the back of the group of belt grooves 21, and the dynamic damper 40 is accommodated in the cavity portion.

Dynamic damper 40 is this dynamic damper
An inertia body 43 is attached to the inner peripheral surface of the rim portion 20 as an attachment portion of the 40 through a press-fitting ring 41 and a rubber-like elastic body 42.

The web portion 30 and the rim portion 20 are integrally formed of a tough steel material, and the inner peripheral edge of the web portion 30 is provided with a protruding portion 31 outwardly and is attached to the end portion of the hub portion 10. There is.

The web portion 30 is formed into a thin plate shape as shown in the drawing, and has elasticity in the axial direction. That is, the web portion 30 is used as a spring, and the rim portion 20 that is the attachment portion of the dynamic damper 40 is used.
And the dynamic damper 40 constitute a second vibration system having one inertial body as a total mass.

As shown in the figure, the web part 30 has a plurality of punched holes 32.
And the spokes 32a remaining between the holes 32 form the actual web portion 30. And the spoke 32
The width of a, in other words, the size of the punched hole 32 determines the constant of the portion as the damper spring, that is, the spring constant.

The operation of the first embodiment having the above structure will be described below.

When the damper pulley P is mounted on the shaft end of the crankshaft and driven, the torsional vibration is first damped by the dynamic damper 40.

On the other hand, vibrations in the axial direction and whirling caused by the bending of the crankshaft are caused by the second vibrating system composed of the springiness of the web portion 30 and the inertial body composed of the dynamic damper 40 and the rim portion 20. Will be reduced. In this case, the spring constant of the web portion 30 can be brought close to a desired value by the punching hole 32, and the rim portion 20 as the inertial body and the dynamic damper as described above.
It is clear that the combined mass with 40 is relatively large, and is sufficiently large, for example, as compared with the second conventional example cited as the conventional example, and as a result, it appears in the amplitude-frequency curve. The first resonance point qualitatively appears in the low frequency region.

FIG. 3 shows a diagram for explaining the above pattern.

The figure shows bending vibration, where the horizontal axis represents the frequency ratio λ and the vertical axis represents the amplitude ratio μ.

A region between λ _{1 and} λ ₂ indicates a noise problem region of the internal combustion engine, and the resonance point is preferably outside the range.

A curve C shows a resonance curve in the case where the damper against bending vibration is not taken into consideration as in the first conventional example, which is large because it has one degree of freedom and has one peak.

The curve B shows the case of the second conventional example, and shows the possibility that the action as a damper is insufficient and that a part of the danger zone is reached.

Curve A, there is according to the present invention, the division of the curve C is made sufficiently, the first resonance point in a low frequency region, the second resonance point is separated into a high frequency range, both lambda ₁ ~ Λ
It is outside the _two areas.

Next, a second embodiment of the present invention will be described with reference to FIG.

This embodiment also has almost the same structure as the above-mentioned first embodiment, but in the case of this embodiment, as shown in FIG.
Is constituted by another web portion constituting member 30a.

Therefore, in the case of the present embodiment, it is not necessary to integrally configure the rim portion 20 and the web portion 30 with the tough steel material as in the above-described first embodiment, and the web portion configuration that constitutes the web portion 30 is provided. Only the member 30a may be made of a tough steel material.

As a result, the degree of freedom in design can be improved and the cost can be reduced as compared with the first embodiment.

Next, a third embodiment of the present invention will be described with reference to FIGS.

In this embodiment, the dynamic damper 40 is attached to the damper attaching member 50 which is a separate member.

The damper mounting member 50 is formed by forming a thin steel plate having a spring property into a cylindrical portion 51 and a flat portion 52, and a protrusion portion 53 is provided on the inner peripheral edge of the flat portion 52 and is fixed to the hub portion 10. is there.

A plurality of punched holes 54 are provided in the flat portion 52 to adjust the spring constant.

In the third embodiment, since the damper mounting member 50 is provided independently of the web portion 30 of the damper pulley P, the load bearing capacity of the belt is increased and the strength of the web portion can be freely increased.

Dynamic damper 40 is this dynamic damper
It is fitted to the cylindrical portion 51 of the damper mounting member 50 made of a thin steel plate which is the mounting portion of 40, and the punching hole 54 allows the spring constant to be freely selected.

[Effects of the Invention] As described above, the damper pulley of the present invention is provided on a thin plate-shaped steel material having elasticity in the axial direction of the damper pulley.
A dynamic damper composed of an elastic body and an inertial body for damping torsional vibration is provided. The dynamic damper is used for damping the torsional vibration, and the dynamic damper and the mounting portion of the dynamic damper are used as one inertial body. Since it is configured to damp the bending vibration by the combination of the elastic thin plate-shaped steel material and not only the torsional vibration of the crankshaft, but also the axial and torsional vibrations can be damped. With the damper pulley, it is possible to deal with a plurality of different forms of vibration, and the specifications can be independently selected.

Further, since the dynamic damper and the mounting portion of the dynamic damper are one inertial body, the mass of the inertial body can be made sufficiently large, whereby the first resonance point is in the low frequency region and the second resonance point. The points can be separated into high frequency regions and can be easily selected outside the noise problem region of the internal combustion engine.

Moreover, it is possible to provide a low-cost damper pulley that has a simple structure and uses a small number of parts.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of the first embodiment, FIG. 2 is a sectional view taken along line II-II of the same as above, and FIG. 3 is a frequency ratio to amplitude ratio diagram for explaining the performance of the damper pulley. FIG. 4 is a sectional view showing the second embodiment, FIG. 5 is a partially cutaway front view of the third embodiment, and FIG. 6 is a sectional view taken along line VI-VI of the same as above, FIG. 7 and FIG. FIG. 6 is an explanatory diagram of a conventional damper pulley. P …… Damper pulley 10 …… Hub part, 20 …… Rim part 30 …… Web part, 32 …… Punching hole 32a …… Spoke 40 …… Dynamic damper 42 …… Elastic body, 43 …… Inertia body50 …… Damper mounting member 54 …… Punching hole, 54a …… Spoke

Claims (1)

[Claims] 1. A dynamic damper mounted on an end of a crankshaft of an internal combustion engine for transmitting rotational power of the engine and absorbing vibration from the crankshaft by a combination of an elastic body and an inertial body. In the damper pulley, a thin plate-shaped steel material having elasticity in the axial direction of the damper pulley is equipped with a dynamic damper composed of an elastic body and an inertial body for damping the torsional vibration, and the dynamic damper is used for damping the torsional vibration. The dynamic damper and the mounting portion of the dynamic damper are used as one inertial body, and the combination of the inertial body and the elastic thin plate-shaped steel material is configured to damp bending vibration. Pulley.