FR2474249A1 - STOP RING TO LIMIT THE AXIAL MOBILITY OF THE ROTOR OF A SMALL ENGINE - Google Patents

Abstract

THIS RING IS SHAPED OF A HOLLOW CYLINDER 2 IN RUBBER OR ANOTHER ELASTOMER AND OF A RING 1 IN HARDENED STEEL WHICH IS RECESSED IN THE FRONT FACE OF THIS CYLINDER AND HAS A RADIAL STOP FACE 5. THE CYLINDER 2 AND THE RING 1 ARE ASSEMBLED BY VULCANIZATION AND THE CYLINDER HAS AN ADVANCE 4 LOCATED RADIALLY INSIDE THE RING AND EXTENDING TO THE STOP FACE 5.

Description

The invention relates to a stop ring for limiting the axial mobility of the

  rotor of an engine, in particular a small engine, formed of a hollow rubber cylinder and a steel ring

  hardened which is embedded in the front face of this cylinder and pre-

  feels a radial abutment face. Refer to the Ringsdorff-MK-Sintermetall-Lager brochure, 1977, from Ringsdorff-Werke GmbH, 5300 Bonn-Bad Godesberg, for abutment rings of this type. The rings referred to in this brochure are made of a hollow rubber cylinder provided

  a circumferential recess opening angularly inward

laughing and in which is glued the clean ring or thrust washer-

  said hardened steel. The inside diameter of this ring is slightly larger than the outside diameter of the shaft and the inside diameter of the hollow cylinder is slightly smaller than the diameter of the shaft. The fixing of the ring relative to the shaft

  results from the elastic widening of the cylinder during assembly. This widening

elastic sliding, however, may have a detrimental effect on the bonded assembly of the two parts of the ring and of compromising

  the subsequent reliability thereof.

The invention aims to improve a stop ring of this type so that, on the one hand, it can be manufactured in a simple and economical manner, on the other hand, it fulfills its function.

with great safety.

  According to an essential characteristic of the invention,

the cylinder and the ring are assembled by vulcanization and the cylin-

  dre has a projection located radially inside the ring

  and extending to the abutment face thereof.

The strength of the connection between the two parts of the ring can be further improved by a layer of adhesive between the contact surfaces. It is best to use an epoxy resin for this and apply the adhesive layer before the process.

vulcanization, at least on the rear side and on the radiating edge

inside the ring.

To manufacture a ring according to the invention, the ring is placed in a vulcanization mold, where the concentric position of the ring is ensured by projections provided in the mold and associated with the external lateral wall of the molding impression. , there is introduced into this cavity, around the ring, by injection or pressing, an elastomer intended to form the hollow cylinder and the vulcanization of this elastomer is produced, its fixing on the ring and its precise shaping. A recovery is therefore not necessary after cooling, the ring leaving the mold can be mounted

as is.

  As in the prior art, the determining factor for fixing the ring is the adaptation of the inside diameter of the cylinder to the diameter of the shaft on which the ring is to be mounted. There is however an essential difference because the actual bearing area of the ring on the shaft is moved on the projection in the case of a ring according to the invention. After mounting the ring, the projection is pressed radially inward on the shaft and radially outward on the inner edge of the ring. Therefore, relaxation phenomena of the elastomer can not have harmful effects, even after a long service life, and a particularly good fixing of the ring is ensured. The contact surface between the ring and the cylinder is largely free of mechanical preloads, and detachment is therefore no longer to be feared in this area, even after prolonged service. The overall safety of the ring in service has thus

could be increased considerably.

- It is advantageous, especially when the ring is relatively

  vement petite, to achieve the advance of the hollow cylinder as a circumferential bead, for which a rectangular profile in axial section is generally preferred. Semicircular profiles on the radially inner side are also possible, however, and prove to be advantageous if the cylinder part located axially behind the ring has a profile other than rectangular in order to improve the elasticity in the axial direction. The fixing of the ring is then ensured only by the part of cylinder located radially inside the ring,

that is to say by the advance, the rest of the cylinder possibly being able to-

  have an inner diameter larger than the diameter of the sealed shaft. In this area, the cylinder may have a profile similar to that of a membrane, forming a bulge directed radially outward and surrounding an interior cavity resembling

  a sphere. It is also possible, according to other embodiments.

  tion of the invention, to give this cylinder part outside the projection the shape of a bellows and to reinforce it if necessary by additional elastic reinforcements in metal, such as coil coil springs or spring washers. These reinforcements can be installed separately or be incorporated into the

vulcanization ring.

  Advantageous development provides that the advance

is shared by uniformly distributed circumferential notches

  tially in segments oriented parallel to the axis of rotation.

  Such an execution is advantageous especially when it is a question of stop rings for trees of relatively large diameter, of more than 15 mm

  for example. Assembly is thus easier.

  The segments can, in principle, have any desired width but it is preferable that it does not exceed three times the radial thickness. The segments can be rounded on the side

inside, facing the tree.

  The number of segments evenly distributed in the

  circumferential direction can be freely chosen but it is preferred-

  rable that it is divisible by three because the ring is so

  always mounted in symmetry of revolution with respect to the shaft.

To obtain the desired secure attachment of the ring relative to the shaft, it is important that the ratio between the axial length and the radial thickness of the projection is between 1: 0.9 and 1: 1.5. The radial thickness of the projection must be between 0.03 and 0.05 times the inside diameter of the cylinder, with a minimum value of 0.2 mm. As regards the determination of this thickness, it can be considered that the inside diameter of the cylinder is equal to the diameter of the shaft. The stability of the attachment is excellent for all existing shaft diameters if the ranges

  indicated above are respected.

Other characteristics and advantages of the invention

will emerge more clearly from the description which will follow from two

  nonlimiting exemplary embodiments, as well as the attached drawing, in which:

2474249.

  Figure 1 is an axial half-section of a ring

stop according to the invention, having a rectangular profile and

taking a stop ring embedded in the vulcanization in one of the faces of the ring; and FIG. 2 is a similar view of a stop ring according to the invention comprising two stop rings, each embedded during vulcanization in the two end faces of the ring, the hollow elastomer cylinder forming the body of the stop ring having circumferential recesses radially on the outside

  and inside to improve elasticity in the axial direction.

  The stop ring shown in Figure 1 has a body formed of a hollow cylinder 2 of elastomer, preferably rubber. This body is fixed directly by vulcanization to the ring

  stopper 1, which has a radial stopper surface 5. The fixing

  tion on the shaft not shown is ensured especially in the region of the advance 4, o, after assembly, the elastomer is compressed between

  the inner edge of the ring 1 and the outer surface of the shaft.

  If the projection 4 extends continuously around the entire periphery, it is sufficient that the internal diameter 3 of the cylinder 2 is slightly more

  smaller than the corresponding shaft diameter. However, if the

  cée 4 is divided into a number of segments by axial cuts, the difference between the inside diameter of the cylinder and the diameter of the shaft in the direction indicated must be greater. * Figure 2 shows a stop ring in each of the opposite faces of which is embedded in the vulcanization a stop ring 1. The elastomer body 2 in the form of a hollow cylinder has a profile which is weakened in the area between the two rings by two circumferential grooves, one in the outer side wall and the other in the inner side wall,

which gives this profile an X shape. The remarks made relati-

  vement to the example of Figure 1 are also valid in this case as regards the fixing on the shaft. The narrowed shape of the longitudinal section profile provides much better elasticity

to the ring in the axial direction.

2,474,249;

Claims (6)

R E V E N D I C A T I 0 N S 1. Stop ring to limit the axial mobility of the rotor of an engine, in particular of a small engine, formed by a hollow rubber cylinder and a hardened steel ring which is embedded in the front face of this cylinder and has a radial abutment face, characterized in that the cylinder (2) and the ring (1) are assembled by vulcanization and in that the cylinder has a projection (4) located radially inside the ring and extending   up to the abutment face (5) thereof. 2. Ring according to claim 1, characterized in that the projection (4) is produced as a circumferential bead.   3. Ring according to claim 1 or 2, characterized in that   that the projection (4) is shared by uniformly distributed notches circumferentially in segments parallel to the axis of rotation.   4. Ring according to claim 3, characterized in that the   number of segments is divisible by three.   5. Ring according to any one of claims 1 to 4,   characterized in that the radial thickness of the projection (4) is com-   taken between 0.03 and 0.05 times the inside diameter of the cylinder, with a minimum value of 0.2 mm.   6. Ring according to any one of claims 1 to 5,   characterized in that the ratio between the axial length and the thickness   the radial advance (4) is between 1: 0.9 and 1: 1.5.