Cam follower with anti-rotation device

Abstract

A cam follower including a plunger intended to execute a reciprocating movement in an exterior body. The plunger includes a plunger body having a cylindrical exterior surface, an anti-rotation device extending radially beyond the cylindrical exterior surface of the pusher body and engaging via a matching structure in the exterior body, a roller providing the contact with a cam, and a sleeve rotatably supporting the roller in the plunger body. The plunger body includes at least one lateral bore and the sleeve is inserted in the bore. In order to avoid additional components and assembly steps to constitute the anti-rotation device, the present invention proposes to use one end of the sleeve as the anti-rotation device.

Claims

1. A cam follower including a plunger configured to execute a reciprocating movement in an exterior body, the plunger including: a plunger body having a cylindrical exterior surface; an anti-rotation device extending radially beyond the cylindrical exterior surface of the plunger body and configured to engage a matching structure in the exterior body; a roller providing the contact with a cam; a sleeve rotatably supporting the roller in the plunger body; and at least one lateral bore included in the plunger body, wherein the sleeve is inserted in the bore, wherein the anti-rotation device is one end of the sleeve extending radially beyond the cylindrical exterior surface of the plunger body, and wherein the sleeve is free-floating in the plunger body.

2. The cam follower as claimed in claim 1, wherein at least one of the axial ends of the sleeve is rounded.

3. The cam follower as claimed in claim 2, wherein at least one of the axial ends of the sleeve has an anti-friction coating.

4. The cam follower as claimed in claim 1, wherein the end of the sleeve has a non-circular profile.

5. The cam follower as claimed in claim 1, the sleeve further includes a bolt head constituting the anti-rotation device.

6. The cam follower as claimed in claim 1, the plunger body further includes two facing lateral bores, the sleeve being inserted in the bores.

7. A cam follower including a plunger configured to execute a reciprocating movement in an exterior body, the plunger including: a plunger body having a cylindrical exterior surface; an anti-rotation device extending radially beyond the cylindrical exterior surface of the plunger body and configured to engage a matching structure in the exterior body; a roller providing the contact with a cam; a sleeve rotatably supporting the roller in the plunger body; and at least one lateral bore included in the plunger body, wherein the sleeve is inserted in the bore, wherein the anti-rotation device is one end of the sleeve extending radially beyond the cylindrical exterior surface of the plunger body, and wherein the sleeve is not axially fixed relative to the plunger body.

8. A cam follower including a plunger configured to execute a reciprocating movement in an exterior body, the plunger comprising: a cylindrical plunger body having an exterior surface lying on a cylinder and at least one lateral bore; a sleeve free-floatingly mounted in the at least one lateral bore; and a roller rotatably mounted on the sleeve in the plunger body, the roller being configured to contact a cam, wherein an end of the sleeve projects radially outside the cylinder, the end of the sleeve being configured to engage a matching structure in the exterior body to function as an anti-rotation device.

9. The cam follower as claimed in claim 8, wherein the end of the sleeve has a non-circular profile.

10. The cam follower as claimed in claim 8, wherein the at least one lateral bore comprises a first lateral bore and a second lateral bore spaced from the first lateral bore, the sleeve extending from the first lateral bore to the second lateral bore and the end of the sleeve being located on a side of the second lateral bore opposite the first lateral bore.

11. The cam follower as claimed in claim 8, wherein the end of the sleeve is rounded.

12. The cam follower as claimed in claim 8, wherein the end of the sleeve has an anti-friction coating.

13. The cam follower as claimed in claim 8, the sleeve further includes a bolt head constituting the anti-rotation device.

14. The cam follower as claimed in claim 8, the plunger body further includes two facing lateral bores, the sleeve being inserted in the bores.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention and its advantages will be better understood by studying the detailed description of specific embodiments given by way of non-limiting examples and illustrated by the appended drawings in which:

(2) FIG. 1 is a sectional view of a cam follower in accordance with a first embodiment of the invention characterized in that the sleeve is free floating;

(3) FIG. 2 shows the cam follower shown in FIG. 1;

(4) FIG. 3 is a perspective view of the cam follower shown in FIGS. 1 and 2;

(5) FIG. 4 is a sectional view of a cam follower in accordance with a second embodiment of the invention characterized in that the sleeve is fixed by a circlip on the interior wall of a plunger body;

(6) FIG. 5 is a sectional view of a cam follower in accordance with a third embodiment of the invention characterized in that the sleeve is fixed by a circlip outside a plunger body;

(7) FIG. 6 is a sectional view of a cam follower in accordance with a fourth embodiment of the invention characterized in that the sleeve is fixed by plastic deformation;

(8) FIG. 7 is a sectional view of a cam follower in accordance with a fifth embodiment of the invention characterized in that the end of the sleeve has a rectangular profile; and

(9) FIG. 8 is a sectional view of a cam follower in accordance with a sixth embodiment of the invention characterized in that the sleeve includes a bolt head.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

(10) FIGS. 1 to 3 are diagrammatic representations of a cam follower in accordance with the invention including a plunger 10 adapted to execute a reciprocating movement in an exterior body (not shown). The plunger 10 includes a plunger body 12 having a cylindrical exterior surface 12a. A roller 14 projects axially from the plunger body 12; it is designed to provide the contact with a cam, for example in an internal combustion engine, and to be driven by the cam in order to execute a reciprocating movement. In accordance with a preferred embodiment, the cam follower is used to drive the piston of a fuel injection pump in an internal combustion engine. An opening at the rear of the plunger, at the end opposite the axial end where the roller 14 is mounted, is adapted to receive a piston rod spring-loaded by a coil spring.

(11) The roller 14 is mounted in a recess in the plunger body 12 corresponding to the shape of the roller 14. A bottom of the recess is open toward the rear opening to enable a lubricant to flow toward the roller 14 and the cam.

(12) A sleeve 16 is fitted, its longitudinal direction being oriented orthogonally to the direction of the reciprocating movement, which is parallel to the central axis of the exterior surface 12a of the plunger body. The sleeve 16 is inserted in a central bore of the roller 14 to support the roller 14 rotatably in the plunger body 12 so that the rotation axis of the roller 14 is parallel to the rotation axis of the cam with a high level of precision. The roller 14 may be supported on the sleeve 16 by a smooth bearing, a roller bearing or a needle bearing, according to the technical requirements.

(13) The sleeve 16 is oriented perpendicularly to the direction of the reciprocating movement. The plunger body 12 includes two facing lateral bores 18a, 18b, the sleeve 16 being inserted in the bores 18a, 18b. An anti-rotation device is provided that is designed to project from the cylindrical exterior surface 12a of the plunger body 12. An axial rib on the anti-rotation device extending all the length of the guide bore engages in the exterior body.

(14) The end 16a of the sleeve 16 projects beyond the cylindrical exterior surface 12a or a continuation thereof and the invention proposes to use this end 16a as an anti-rotation device. Using the end 16a of the sleeve 16 as an anti-rotation device avoids recourse to the additional components and assembly steps generally required for this purpose and it is possible to manufacture a cam follower at lower cost.

(15) In accordance with the embodiment of FIGS. 1 to 3, both axial ends of the sleeve 16 are rounded and the sleeve is free floating, i.e. is not fixed axially. Moreover, the axial ends of the sleeve 16 have an anti-friction coating.

(16) FIGS. 4 to 8 show other possible embodiments of the invention. To avoid repetition, the following description concentrates on the differences with respect to the embodiment of FIGS. 1 to 3, and the reader should refer to the description of FIG. 1 for similar or identical features. In order to highlight the common functioning or concept, identical or similar reference numbers are used for features having identical or very similar functions.

(17) FIG. 5 shows a second embodiment of the invention characterized in that the sleeve 16 is fixed inside the plunger body 12 by a circlip 20. The position of the sleeve 16 is fixed so that the axial ends do not come into contact with the walls or the bottom of the matching structure or the groove, which makes it possible to avoid machining the ends to round them or coating them.

(18) The circlip 20 is fixed to the end 16a of the sleeve 16 positioned on the exterior wall of said plunger body 12 directly adjoining the wall of the plunger body 12. The circlip 20 engages in a circumferential groove (not shown) in the exterior surface of the sleeve 16. The sleeve 16 features a central bore that reduces its weight and simplifies handling it when the axial ends are machined or coated.

(19) FIG. 4 shows a third embodiment of the invention characterized in that a circlip 20 is fixed to the sleeve 16 positioned on the interior wall of said plunger body 12 and in particular between the roller 14 and the interior wall of the plunger body 12, the axial end of the roller 14 including a groove adapted to receive the circlip 20. The circlip 20 engages in a circumferential groove 22 on the exterior surface of the sleeve 16.

(20) Another economical way to fix the axial position of the sleeve 16 inside the plunger body 12 is by a plastic deformation 22 of the sleeve 16 of rod shape, for example by bossing up. FIG. 6 is a diagrammatic representation of this. The plastic deformation 22 of the sleeve is on an axially intermediate portion of the exterior surface 22a of the sleeve so that the sleeve has a shaft end portion 22b constituting all or part of the anti-rotation device. The plastic deformation advantageously extends all around the circumference of the exterior surface 22a of the sleeve. In another embodiment of the invention, this plastic deformation 22 extends around only a circumferential portion of the exterior surface 22a of the sleeve, at one or more locations. The plastic deformation 22 of the sleeve bears against an exterior surface of the plunger body in order to position the sleeve axially in the bore or bores 18a, 18b of the plunger body 12.

(21) Another possible configuration of the end 16a of the sleeve 16 is shown in FIG. 7. The end has a profile different from the circular profile of the main portion of the sleeve 16. The end 16a of the sleeve 16 has a non-circular profile, which is rectangular in the instance shown.

(22) A further possible configuration of the end 16a of the sleeve 16 is shown in FIG. 8. The sleeve 16 includes a bolt head 24 constituting the end 16a and the anti-rotation device, also preventing any contact of the other end of the sleeve 16 with the wall of the exterior body including the bore.