GB2057625A

GB2057625A - Sound-proofing arrangement for gear wheels

Info

Publication number: GB2057625A
Application number: GB8023449A
Authority: GB
Original assignee: Societa Applicazioni Gomma Antivibranti SAGA SpA
Current assignee: Societa Applicazioni Gomma Antivibranti SAGA SpA
Priority date: 1979-08-24
Filing date: 1980-07-17
Publication date: 1981-04-01
Also published as: IT7925272A0; FR2469626B1; FR2469626A1; DE3023977A1; ES252174Y; ES252174U; JPS5635859A; IT1122813B; GB2057625B

Abstract

A sound-proofing arrangement is provided for absorbing acoustic vibrations in a gear wheel. The arrangement comprises an annular cavity (5) formed in the body (2, 4) of the gear wheel and housing an annulus (7) of elastomer material and a retainer ring (6). The annulus (7) of elastomer material is compressed between facing cylindrical surfaces of the ring (6) and body (2, 4). The ring (6) can be secured in position by the plastic deformation of an annular appendage (9) thereof into an undercut zone of the gear-wheel cavity (5). <IMAGE>

Description

SPECIFICATION Sound-proofing arrangement for gear wheels The present invention relates to arrangements for reducing the noise produced by the meshing of the teeth of gear wheels.

Previous attempts at reducing the noise produced by meshing gear wheels have concentrated on two approaches, the first concerning the proper design of the gear teeth (and, in particular their shape and the extent of their operative surfaces) and the second relating to the reduction of errors during machining and assembly.

Both these approaches to the problem of reducing noise, in addition to being costly, are also technically difficult to carry out and do not necessarily result in any appreciable decrease in noise levels.

The object of the present invention is to provide a sound-proofing arrangement for the absorption of acoustic vibration in a gear wheel, which is easy to use and economical to construct, and also ensures a significant reduction in noise.

In order to achieve this object the invention provides a sound-proofing arrangement for a gear wheel, which comprises an annular cavity formed in the body of the gear wheel, a retainer ring housed within the annular cavity, and a deformable annular element of elastomer material located within said cavity and radially compressed between facing cylindrical surfaces of the ring and body.

A gear-wheel soundproofing arrangement embodying the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing, in which: Figure 1 is a perspective view, in section, of a gear wheel incorporating the sound-proofing arrangement: and Figure 2 is a partially-exploded perspective view, in section, of a variant of the Figure 1 arrangement.

The gear wheel 1 shown in Figure 1 comprises an outer toothed rim 2 and an inner hub 4 of greater axial extent than the rim 2. The hub 4 and rim 2 are interconnected by an intermediate disc 3. The disc 3 has an axial extent less than the rim 2 so that in each radial face of the gear wheel 1 , the adjacent surfaces of the rim 2, of the disc 3 and of the hub 4 form a cavity 5. In each cavity 5 there is housed a retainer ring 6 of metallic material. The radial dimensions of the ring 6 are such that there is play in a radial direction between the ring and the facing cylindrical surfaces of the hub 4 and the rim 2.

An annular element 7 of elastomer material is located in the cavity 5 between the ring 6 and the rim 2. Prior to being positioned within the cavity 5, the ring 6 and annular element 7 are assembled together such that the element 7 extends around the periphery of the ring 6; at this stage the outer diameter of the annular element 7 is greater than the diameter D of the cylindrical surface of the toothed rim 2 which radially outwardly bounds the annular cavity 5. Consequently, in order to place the assembly of the ring 6 and element 7 within the cavity 5, it is necessary to radially compress the annular element 7. Thus, when the ring 6 and element 7 are in position in the cavity 5, the annular element 7 will be radially compressed between the ring 6 and the corresponding facing cylindrical surface of the toothed rim 2.

In the variant shown in Figure 2, each annular cavity 5 is radially inwardly defined by an inclined surface 8. This inclined surface 8 is constituted by a conical surface provided on the hub 4 and --divergent away from the centre of the gear wheel 1. In this manner the cavity 5 is provided with an undercut zone into which the ring 6 is arranged to project after assembly. As for the Figure 1 arrangement, in the assembled form of the Figure 2 variant, the annular element 7 is radially compressed between the ring 6 and the toothed rim 2.

The ring is made of aluminium and in its initial state prior to being fitted into the cavity 5, has a pair of annular appendages 9 which extend around the peripheral edges of the radially inner surface of the ring 6. These appendages project axially away from the ring 6 in a radially inwards direction. The axial spacing between the free ends of these appendages 9 is greater than the axial depth of the said cavity 5 and, in addition, the inner radius of these appendages 9 is equal to the inner radius of the entrance of the cavity 5.

In fitting the ring 6 into the cavity 5, one appendage 9 is first located within the cavity 5, and the ring 6 is subsequently subjected to axial pressure. The effect of the axial pressure is to plastically deform and compress the annular appendages 9 into the undercut zone of the cavity 5. As a result, the ring 6 is secured to the body of the toothed wheel 1, and there is no possibility of the ring 6 slipping out of its annular cavity 5.

1. A gear wheel provided with a sound-proofing arrangement for the absorption of acoustic vibrations in the gear wheel, said arrangement comprising an annular cavity formed in the body of the gear wheel, a retainer ring housed within the annular cavity, and a deformable annular element of elastomer material located within said cavity and compressed between facing cylindrical surfaces of the ring and body.

2. A gear wheel according to Claim 1, wherein the deformable annular element is formed as a circumferentially continuous annulus.

3. A gear wheel according to Claims 1 or 2, wherein said arrangement includes means for securing the retainer ring to the body of the gear wheel.

4. A gear wheel according to Claim 3, wherein said securing means comprise an appendage fixed to the retainer ring and plastically deformed into an undercut zone in one of the cylindrical surfaces of the body.

5. A gear wheel according to any one of the preceding claims, wherein the retainer ring is

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Sound-proofing arrangement for gear wheels The present invention relates to arrangements for reducing the noise produced by the meshing of the teeth of gear wheels. Previous attempts at reducing the noise produced by meshing gear wheels have concentrated on two approaches, the first concerning the proper design of the gear teeth (and, in particular their shape and the extent of their operative surfaces) and the second relating to the reduction of errors during machining and assembly. Both these approaches to the problem of reducing noise, in addition to being costly, are also technically difficult to carry out and do not necessarily result in any appreciable decrease in noise levels. The object of the present invention is to provide a sound-proofing arrangement for the absorption of acoustic vibration in a gear wheel, which is easy to use and economical to construct, and also ensures a significant reduction in noise. In order to achieve this object the invention provides a sound-proofing arrangement for a gear wheel, which comprises an annular cavity formed in the body of the gear wheel, a retainer ring housed within the annular cavity, and a deformable annular element of elastomer material located within said cavity and radially compressed between facing cylindrical surfaces of the ring and body. A gear-wheel soundproofing arrangement embodying the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing, in which: Figure 1 is a perspective view, in section, of a gear wheel incorporating the sound-proofing arrangement: and Figure 2 is a partially-exploded perspective view, in section, of a variant of the Figure 1 arrangement. The gear wheel 1 shown in Figure 1 comprises an outer toothed rim 2 and an inner hub 4 of greater axial extent than the rim 2. The hub 4 and rim 2 are interconnected by an intermediate disc 3. The disc 3 has an axial extent less than the rim 2 so that in each radial face of the gear wheel 1 , the adjacent surfaces of the rim 2, of the disc 3 and of the hub 4 form a cavity 5. In each cavity 5 there is housed a retainer ring 6 of metallic material. The radial dimensions of the ring 6 are such that there is play in a radial direction between the ring and the facing cylindrical surfaces of the hub 4 and the rim 2. An annular element 7 of elastomer material is located in the cavity 5 between the ring 6 and the rim 2. Prior to being positioned within the cavity 5, the ring 6 and annular element 7 are assembled together such that the element 7 extends around the periphery of the ring 6; at this stage the outer diameter of the annular element 7 is greater than the diameter D of the cylindrical surface of the toothed rim 2 which radially outwardly bounds the annular cavity 5. Consequently, in order to place the assembly of the ring 6 and element 7 within the cavity 5, it is necessary to radially compress the annular element 7. Thus, when the ring 6 and element 7 are in position in the cavity 5, the annular element 7 will be radially compressed between the ring 6 and the corresponding facing cylindrical surface of the toothed rim 2. In the variant shown in Figure 2, each annular cavity 5 is radially inwardly defined by an inclined surface 8. This inclined surface 8 is constituted by a conical surface provided on the hub 4 and --divergent away from the centre of the gear wheel 1. In this manner the cavity 5 is provided with an undercut zone into which the ring 6 is arranged to project after assembly. As for the Figure 1 arrangement, in the assembled form of the Figure 2 variant, the annular element 7 is radially compressed between the ring 6 and the toothed rim 2. The ring is made of aluminium and in its initial state prior to being fitted into the cavity 5, has a pair of annular appendages 9 which extend around the peripheral edges of the radially inner surface of the ring 6. These appendages project axially away from the ring 6 in a radially inwards direction. The axial spacing between the free ends of these appendages 9 is greater than the axial depth of the said cavity 5 and, in addition, the inner radius of these appendages 9 is equal to the inner radius of the entrance of the cavity 5. In fitting the ring 6 into the cavity 5, one appendage 9 is first located within the cavity 5, and the ring 6 is subsequently subjected to axial pressure. The effect of the axial pressure is to plastically deform and compress the annular appendages 9 into the undercut zone of the cavity 5. As a result, the ring 6 is secured to the body of the toothed wheel 1, and there is no possibility of the ring 6 slipping out of its annular cavity 5. CLAIMS

5. A gear wheel according to any one of the preceding claims, wherein the retainer ring is made of a metallic material.

6. A gear wheel according to Claim 5, wherein the retainer ring is made of aluminium.

7. A gear wheel according to claim 6, when dependant on claim 4, wherein the appendage comprises at least one annular projection integral with the body of the retainer ring.

8. A gear wheel according claim 1, substantially as described with reference to Figure 1 or Figure 2 of the accompanying drawings.