JP2024053823A - Soundproof cap and torsional damper equipped with soundproof cap - Google Patents

Abstract

[Problem] To provide a torsional damper capable of effectively suppressing damage caused by contact with surrounding obstructions due to changes in the axial direction of the soundproof cap. [Solution] The torsional damper includes a hub 2 having a first cylindrical portion 25 fixed to a crankshaft and a second cylindrical portion 21 disposed concentrically with the first cylindrical portion 25 at a position radially outward of the first cylindrical portion 25, a damper body 8 having a vibration ring 7 and a rubber-like elastic body 6, and a disk-shaped soundproof cap 3 held on an inner peripheral surface 22 of the second cylindrical portion 21 of the hub 2, the hub 2 having an annular groove 31 disposed on the inner peripheral surface 22 of the second cylindrical portion 21, the soundproof cap 3 having an annular protrusion 23 disposed on an outer peripheral edge of the soundproof cap 3 and inserted into the annular groove 31, and the soundproof cap 3 has a shape symmetrical in the central axial direction X with respect to an axis of symmetry Y perpendicular to the central axis X in a cross section including the central axis X of the torsional damper 1. [Selected Figure] Figure 1

Description

The present invention relates to a soundproofing cap used in a torsional damper for reducing torsional vibrations generated in crankshafts (rotating drive shafts) in engines for automobiles and general industrial machinery, and to a torsional damper equipped with such a soundproofing cap.

Torsional dampers are attached to the crankshafts of engines for automobiles and general industrial machinery in order to reduce their torsional vibration. With such torsional dampers, the crankshaft vibrations generated by the combustion pressure inside the cylinder and the reciprocating motion of the pistons while the engine is running are transmitted to the torsional damper attached to the tip of the crankshaft, causing radiated noise from the torsional damper.

For this reason, technology has been proposed to attach a soundproofing cap to the torsional damper in order to block noise emitted from the torsional damper and the chain case of the engine behind it, as well as noise emitted from the hub of the torsional damper (for example, Patent Document 1).

Patent Document 1 discloses a torsional damper equipped with a soundproof cap 1003 as shown in FIG. 4. FIG. 4 is a cross-sectional view showing a typical conventional torsional damper. As shown in FIG. 4, the soundproof cap 1003 engages an annular protrusion 1023 provided on the inner peripheral surface 1022 of the cylindrical portion 1021 of the hub 1002 with an annular groove 1031 provided on the outer peripheral edge of the soundproof cap 1003, thereby fixing the soundproof cap 1003 in the axial direction. In addition, the soundproof cap 1003 is prevented from rotating freely by providing circumferential irregularities (i.e., the irregular engagement portion 1004) on the above-mentioned annular protrusion 1023 and annular groove 1031. Specifically, the irregular engagement portion 1004 is composed of engagement protrusions 1231 provided at multiple locations on the annular protrusion 1023 and an engagement groove 1311 provided in the annular groove 1031 corresponding to the engagement protrusions 1231.

JP 2008-267419 A

However, a torsional damper equipped with a soundproof cap 1003 as shown in FIG. 4 requires complex machining using precision casting, milling, etc., to mold the circumferential uneven shape of the annular protrusion 1023 of the hub 1002, making the torsional damper very expensive.

In addition, the soundproof cap disclosed in Patent Document 1 has a recess 1032 for receiving the head 1011 of the bolt 1001 at approximately the center of the soundproof cap 1003, as shown in Fig. 4. When the torsional damper rotates, the soundproof cap 1003 has a problem that the central structure of the soundproof cap 1003, which avoids the fastening bolt (bolt 1001) of the crankshaft, bulges outward due to centrifugal force, and the central part of the soundproof cap 1003 may be significantly deformed on the opposite side to the engine (for example, the left side of the paper in Fig. 4) due to the resultant vector of the forces acting on each part of the soundproof cap 1003. For example, if there is some kind of interference in the direction in which the central part of the soundproof cap 1003 shown in Fig. 4 is deformed, the soundproof cap 1003 may be damaged by contact with the interference. Here, in FIG. 4, reference numeral 1005 indicates a service hole, reference numeral 1006 indicates a rubber-like elastic body, and reference numeral 1007 indicates a mass member.

To address these issues, there was a strong need for the development of a soundproofing cap that would effectively prevent damage by minimizing axial deformation and limiting contact with obstructing objects in the engine compartment.

In view of the above problems, the present invention provides a soundproofing cap that suppresses axial deformation of the soundproofing cap and effectively prevents damage associated with the deformation, and a torsional damper equipped with such a soundproofing cap.

To solve the above problems, the present invention provides the following soundproof cap and torsional damper equipped with a soundproof cap.

[1] A disk-shaped soundproof cap that is held on the inner circumferential surface of a cylindrical portion of a hub that is fixed to a rotating shaft,
The cylindrical portion of the hub has an annular groove provided on the inner peripheral surface of the cylindrical portion, and the soundproof cap has an annular protrusion provided on an outer peripheral edge portion of the soundproof cap and inserted into the annular groove, and
A soundproof cap having a shape that is symmetrical in the direction of the central axis of the hub with respect to an axis of symmetry perpendicular to the central axis in a cross section including the central axis of the hub.

[2] The soundproof cap described in [1] above, which is made of a material containing at least one selected from the group consisting of urethane foam, glass wool, rock wool, felt, melamine foam, and polyethylene terephthalate fiber.

[3] A hub having a first cylindrical portion fixed to a crankshaft, and a second cylindrical portion that is shifted in an axial direction from the first cylindrical portion and is provided concentrically with the first cylindrical portion at a position radially outward from the first cylindrical portion;
a damper body having a vibration ring provided concentrically on the radially outer side of the second cylindrical portion of the hub, and a rubber-like elastic body provided between the second cylindrical portion and the vibration ring;
a disk-shaped soundproof cap held on an inner circumferential surface of the second cylindrical portion of the hub,
the hub has an annular groove provided on the inner circumferential surface of the second cylindrical portion, and the soundproof cap has an annular protrusion provided on an outer circumferential edge portion of the soundproof cap and inserted into the annular groove; and
A torsional damper, wherein the soundproof cap has a shape that is symmetrical in the direction of the central axis of the torsional damper with respect to an axis of symmetry perpendicular to the central axis in a cross section including the central axis of the torsional damper.

[4] The torsional damper described in [3], wherein the soundproof cap is made of a material containing at least one selected from the group consisting of urethane foam, glass wool, rock wool, felt, melamine foam, and polyethylene terephthalate fiber.

The above-mentioned soundproofing cap and the torsional damper equipped with the soundproofing cap are able to suppress deformation of the soundproofing cap in the axial direction (more specifically, in the direction of the central axis of the hub to which the soundproofing cap is attached), and can effectively suppress damage to the soundproofing cap that accompanies such deformation. In other words, damage caused by contact with surrounding obstructions that accompanies deformation of the soundproofing cap due to centrifugal force can be effectively suppressed.

In addition, although the soundproofing cap has a very simple attachment mechanism to the cylindrical portion (e.g., the second cylindrical portion of the hub), it can be securely attached to the cylindrical portion due to the large frictional force that utilizes the centrifugal force acting on the soundproofing cap. Therefore, unlike conventional torsional dampers, there is no need to provide the outer peripheral edge of the soundproofing cap with an uneven shape that is difficult to mold or process in order to prevent the soundproofing cap from spinning freely. Therefore, the soundproofing cap and torsional damper configured as described above also contribute greatly to reducing production costs.

1 is a cross-sectional view showing a schematic diagram of an embodiment of a torsional damper. 2 is a cross-sectional perspective view showing an assembled state of a soundproof cap in the torsional damper shown in FIG. 1 . 2 is a cross-sectional perspective view showing a state in which a soundproof cap is removed from the torsional damper shown in FIG. 1 . FIG. 1 is a cross-sectional view that illustrates a conventional torsional damper.

The following describes an embodiment of the present invention with reference to the drawings. It should be understood that the present invention is not limited to the following embodiment, and that appropriate design changes and improvements may be made based on the ordinary knowledge of a person skilled in the art without departing from the spirit of the present invention.

The soundproof cap of this embodiment and the torsional damper equipped with the soundproof cap will be described below using the torsional damper 1 shown in Figures 1 to 3 as an example. The torsional damper 1 of this embodiment is a torsional damper 1 equipped with a hub 2 fastened to a crankshaft, a damper body 8 having a vibration ring 7 and a rubber-like elastic body 6, and a soundproof cap 3, as shown in Figures 1 to 3. Here, Figure 1 is a cross-sectional view that shows a schematic diagram of an embodiment of a torsional damper. Figure 2 is a cross-sectional perspective view showing the assembled state of the soundproof cap in the torsional damper shown in Figure 1. Figure 3 is a cross-sectional perspective view showing the state in which the soundproof cap has been removed from the torsional damper shown in Figure 1. Note that Figure 1 shows a cross-section of the torsional damper 1 cut along a plane that includes the central axis X of the torsional damper 1.

The hub 2 has a first cylindrical portion 25 fixed to the crankshaft, and a second cylindrical portion 21 that is axially offset from the first cylindrical portion 25 and is provided concentrically with the first cylindrical portion 25 at a position radially outward from the first cylindrical portion 25. A boss or the like is provided on the inner peripheral surface of the first cylindrical portion 25, and is fixed to the crankshaft, for example, by a bolt (not shown). The first cylindrical portion 25 may be directly attached and fixed to the crankshaft, or the hub 2 may be indirectly attached to the crankshaft via a member such as a sleeve provided on the outer peripheral surface of the crankshaft. In Figures 1 to 3, the reference numeral 5 denotes a service hole 5 provided in the hub 2. In the torsional damper 1, the soundproof cap 3 is held by the inner peripheral surface 22 of the second cylindrical portion 21 of the hub 2.

The damper body 8 has a vibration ring 7 arranged concentrically with the second cylindrical portion 21 of the hub 2 on the radially outer side, and a rubber-like elastic body 6 arranged between the second cylindrical portion 21 and the vibration ring 7. The annular rubber-like elastic body 6 is press-fit between the outer peripheral surface of the second cylindrical portion 21 and the inner peripheral surface of the vibration ring 7. The vibration ring 7 forms the mass of the dynamic vibration absorber. The damper body 8 can suppress (in other words, absorb) the torsional resonance of the crankshaft by the vibration ring 7 resonating in the rotational direction.

The rubber-like elastic body 6 is not particularly limited, but may be, for example, one obtained by vulcanization molding. Ethylene propylene rubber (EPDM), which has excellent durability, heat resistance, and vibration reduction effects, can be suitably used as a material for the rubber-like elastic body 6.

The soundproofing cap 3 is a disk-shaped member held on the inner circumferential surface 22 of the second cylindrical portion 21 of the hub 2. The hub 2, which fastens the crankshaft, may have an opening for weight reduction, through which the radiated sound of the engine chain case may pass and be released outside the vehicle as noise. In addition, when the hub 2 itself resonates, the radiated sound may be radiated from the hub 2 itself and released outside the vehicle as noise. The torsional damper 1 of this embodiment is equipped with the soundproofing cap 3 held on the inner circumferential surface 22 of the second cylindrical portion 21 of the hub 2, and therefore can block the above-mentioned radiated sound extremely effectively.

In the torsional damper 1, the hub 2 has an annular groove 31 provided on the inner peripheral surface 22 of the second cylindrical portion 21, and the soundproof cap 3 has an annular protrusion 23 provided on the outer peripheral edge of the soundproof cap 3, which is inserted into the annular groove 31. That is, the annular groove 31 is a groove (recess) formed in an annular shape so as to go around the inner peripheral surface 22 of the second cylindrical portion 21. On the other hand, the annular protrusion 23 is an annular protrusion formed so as to extend radially outward from the outer peripheral edge of the soundproof cap 3. The annular groove 31 of the second cylindrical portion 21 configured in this manner is fitted with the annular protrusion 23 of the soundproof cap 3 to form the soundproof cap mounting portion 4 for mounting the soundproof cap 3 to the torsional damper 1. The annular groove 31 is not particularly limited, but can be provided by lathe machining on the inner peripheral surface 22 of the second cylindrical portion 21 of the hub 2.

The soundproof cap 3 has a particularly important configuration in its shape. That is, in the cross section of the torsional damper 1 as shown in FIG. 1, the soundproof cap 3 has a shape symmetrical in the direction of the central axis X with respect to the axis of symmetry Y perpendicular to the central axis X. Here, the central axis X of the torsional damper 1 means the central axis X of the rotation axis of the torsional damper 1, and the direction of the central axis X means a direction parallel to the central axis X, for example, the left-right direction of the paper in FIG. 1 (i.e., a direction perpendicular to the axis of symmetry Y). Hereinafter, the above-mentioned central axis X direction may be simply referred to as the "axial direction."

By making the soundproof cap 3 symmetrical with respect to the symmetry axis Y as described above, the soundproof cap 3 can be deformed in the outer circumferential direction by the centrifugal force acting on the soundproof cap 3. For example, near the center of the hub 2, the soundproof cap 3 deforms toward the outer periphery, and near the outer periphery of the hub 2, it deforms further toward the outer periphery. Then, in the part corresponding to the outermost periphery of the hub 2, all the chain deformations of the soundproof cap 3 described above are concentrated, and the soundproof cap 3 adheres to the inner circumferential surface 22 of the second cylindrical portion 21 with the greatest force at the outermost periphery of the hub 2. Due to the adhesion effect caused by such centrifugal force, a large frictional force is generated between the soundproof cap 3 and the inner circumferential surface 22 of the second cylindrical portion 21, and the soundproof cap 3 can be held on the inner circumferential surface 22 of the second cylindrical portion 21 without spinning freely. In addition, for example, as in the conventional soundproof cap 1003 shown in FIG. 4, there is no need to create a circumferentially uneven shape (i.e., the uneven engagement portion 1004) to suppress the soundproof cap 1003 from spinning freely. The concave-convex engagement portion 1004 of the soundproof cap 1003 as shown in FIG. 4 is difficult to mold or process, resulting in increased manufacturing costs. On the other hand, the torsional damper 1 as shown in FIGS. 1 to 3 has a very simple shape for the soundproof cap 3 and its attachment mechanism, which contributes greatly to reducing production costs.

In addition, the symmetry of the soundproof cap 3 as described above extremely effectively prevents deformation in the axial direction. This reduces contact between the soundproof cap 3 and surrounding objects (e.g., objects in the engine compartment) and effectively prevents damage caused by such contact.

The soundproofing cap 3 can be, for example, one molded from rubber or resin-like elastic material. By making the soundproofing cap 3 from the elastic material described above, it becomes easy to fit the annular protrusion 23 of the soundproofing cap 3 into the annular groove 31 on the inner circumferential surface 22 of the second cylindrical portion 21, and to remove the soundproofing cap 3 from the fitted state.

The soundproof cap 3 is preferably made of a material containing at least one selected from the group consisting of urethane foam, glass wool, rock wool, felt, melamine foam, and polyethylene terephthalate fiber, although there is no particular limitation to this material.

As explained above, the soundproof cap 3 has a shape that is symmetrical in the direction of the central axis X with respect to the axis of symmetry L in the cross section shown in FIG. 1, but this symmetry in the direction of the central axis X is allowed to have a geometric tolerance on the order of the drawing tolerance. The geometric tolerance allowed for the soundproof cap 3 can be expressed as a difference (tolerance) from a reference dimension, and if the reference dimension is taken as 100, a tolerance of about 100±0.2 to 0.3 is allowed.

This concludes the description of this embodiment. Note that, although this embodiment describes a torsional damper that is attached to the end of a shaft such as a crankshaft, the torsional damper of this embodiment is not limited to this. The torsional damper of this embodiment can be applied to torsional dampers for reducing torsional vibrations in various rotating shafts of engine camshafts and other devices, as well as crankshafts of automobiles, construction machinery, ships, etc. Furthermore, the soundproofing caps described so far can also be applied to crank pulleys that do not have a torsional damper mechanism.

The soundproofing cap and torsional damper of the present invention can be used to reduce torsional vibrations that occur in crankshafts (rotating drive shafts) in engines for automobiles and general industrial machinery.

1: Torsional damper 2: Hub 3: Soundproof cap 4: Soundproof cap mounting portion 5: Service hole 6: Rubber-like elastic body 7: Vibration ring 8: Damper body 21: Second cylindrical portion 22: Inner peripheral surface 23: Annular protrusion 25: First cylindrical portion 31: Annular groove 1001: Bolt 1002: Hub 1003: Soundproof cap 1004: Concave-convex engagement portion 1005: Service hole 1006: Rubber-like elastic body 1007: Mass member 1011: Head 1021: Cylindrical portion 1022: Inner peripheral surface 1023: Annular protrusion 1031: Annular groove 1032: Recess 1231: Engagement protrusion 1311: Engagement groove

Claims (4)

A disk-shaped soundproof cap is held on the inner circumferential surface of a cylindrical portion of a hub fixed to a rotating shaft,
The cylindrical portion of the hub has an annular groove provided on the inner peripheral surface of the cylindrical portion, and the soundproof cap has an annular protrusion provided on an outer peripheral edge portion of the soundproof cap and inserted into the annular groove, and
A soundproof cap having a shape that is symmetrical in the direction of the central axis of the hub with respect to an axis of symmetry perpendicular to the central axis in a cross section including the central axis of the hub. The soundproof cap according to claim 1, which is made of a material containing at least one selected from the group consisting of urethane foam, glass wool, rock wool, felt, melamine foam, and polyethylene terephthalate fiber. a hub having a first cylindrical portion fixed to a crankshaft, and a second cylindrical portion displaced in an axial direction from the first cylindrical portion and disposed concentrically with the first cylindrical portion at a position radially outward from the first cylindrical portion;
a damper body having a vibration ring provided concentrically on the radially outer side of the second cylindrical portion of the hub, and a rubber-like elastic body provided between the second cylindrical portion and the vibration ring;
a disk-shaped soundproof cap held on an inner circumferential surface of the second cylindrical portion of the hub,
the hub has an annular groove provided on the inner circumferential surface of the second cylindrical portion, and the soundproof cap has an annular protrusion provided on an outer circumferential edge portion of the soundproof cap and inserted into the annular groove; and
A torsional damper, wherein the soundproof cap has a shape that is symmetrical in a cross section including a central axis of the torsional damper with respect to an axis of symmetry perpendicular to the central axis. The torsional damper according to claim 3, wherein the soundproof cap is made of a material containing at least one selected from the group consisting of urethane foam, glass wool, rock wool, felt, melamine foam, and polyethylene terephthalate fiber.

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