Cam follower roller device

Abstract

The cam follower roller device provides a tappet body, a pin and a roller mounted on the pin. The tappet body provides holes for mounting pin ends of the pin on the tappet body. The device further provides one deformable ring disposed between each pin end of the pin and an inner wall of the associated hole of the tappet body.

Claims

1. A cam follower roller device comprising: a tappet body, a pin having two pin ends, an outer pin surface located between the two pin ends and having a cylindrical shape, the pin having an initial central axis, a roller mounted on the pin, the tappet body having holes for mounting the two pin ends of the pin on the tappet body, and each of the two pin ends having one deformable ring disposed between the outer pin surface adjacent the associated pin end and an inner wall of the associated hole of the tappet body such that the one deformable ring only radially contacts the outer pin surface and such that the pin may tilt angularly relative to the intial central axis.

2. The device according to claim 1, wherein each deformable ring is secured to the tappet body.

3. The device according to claim 1, wherein an outer surface of each deformable ring is in radial contact with the inner wall of the associated hole of the tappet body.

4. The device according to claim 1, wherein a bore of each deformable ring is in radial contact with the associated pin end of the pin.

5. The device according to claim 1, wherein each deformable ring is made from deformable material.

6. The device according to claim 5, wherein each deformable ring is made from elastically deformable material.

7. The device according to claim 1, wherein the tappet body is made in one part.

8. A cam follower roller device comprising: a tappet body, a pin, a roller mounted on the pin, the tappet body having holes for mounting pin ends of the pin on the tappet body, one deformable ring disposed between each pin end of the pin and an inner wall of the associated hole of the tappet body, and one sleeve interposed between each pin end of the pin and the associated deformable ring.

9. The device according to claim 8, wherein each pin end of the pin is press-fitted into the associated sleeve.

10. The device according to claim 8, wherein each sleeve comprises at least one tubular portion interposed between each pin end of the pin and the associated deformable ring.

11. The device according to claim 10, wherein each sleeve further comprises a radial flange connected to the tubular portion and extending radially outwards, the radial flange being axially located on the side opposite to the roller with respect to the tappet body.

12. The device according to claim 11, wherein the radial flange of each sleeve extends one end of the tubular portion.

13. The device according to claim 11, wherein the radial flange of each sleeve axially comes into contact with at least one of the associated deformable ring and the tappet body.

14. The device according to claim 8, wherein each sleeve is made from metal.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(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 on which:

(2) FIG. 1 is a cross-section of a cam follower roller device according to a first example of the invention, and

(3) FIG. 2 is a cross-section of a cam follower roller device according to a second example of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(4) As shown on FIG. 1, a cam follower roller device 10 provides a tappet housing or body 12 extending along an axis 12a, a shaft or pin 14 extending along an axis 14a perpendicular to the axis 12a, and a roller 16, with an axis 16a coaxial with the axis 14a, mounted on the pin and movable in rotation relative to the pin. In the disclosed embodiment, the roller 16 is directly mounted on the pin 14. Alternatively, a rolling bearing or a plain bearing may be radially interposed. The roller 16 provides an axial cylindrical outer surface (not referenced) which forms a contact surface intended to bear against the associated cam of the internal combustion engine, and two opposite radial frontal end faces (not referenced) axially delimiting the outer surface.

(5) The pin 14 is mounted on the tappet body 12. The tappet body 12 supports the pin 14. The pin 14 provides two opposite pin ends 14b, 14c and a central portion (not referenced) extending between the pin ends. The central portion of the pin delimits a cylindrical outer bearing seat for the roller 16. The portion of the pin 14 left free by the tappet body 12 delimits the central portion. The pin ends 14b, 14c extend axially on either side of the roller 16. The tappet body 12 provides through-holes 12b, 12c for mounting the pin ends 14b, 14c. The through-holes face one another.

(6) As will be described later, the device 10 further provides two annular deformable rings 18, 20 each radially interposed between one of the pin ends 14b, 14c and an inner wall of the associated through-hole 12b, 12c of the tappet body.

(7) In the disclosed example, the tappet body 12 is made in one part. The tappet body 12 delimits a first open cavity 22 inside which is located the roller 16. The roller 16 is mounted inside the cavity 22. The roller 16 axially protrudes outwards with respect to an upper face (not referenced) of the tappet body. The tappet body 12 also delimits a second open cavity 24 oriented axially on the side opposite to the cavity 22. A movable element (not shown), such as a piston of a fuel injection pump, is intended to extend into the cavity 24 and to axially bear against a rear abutment surface 26 of the tappet body. The rear abutment surface 26 is oriented axially on the side opposite to the roller 16. The rear abutment surface 26 is planar and extends radially.

(8) The tappet body 12 provides an outer axial sleeve portion 12d and an inner radial portion 12e extending radially an inner bore of the sleeve portion. The radial portion 12e delimits the rear abutment surface 26. The sleeve portion 12d has a tubular form. The through-holes 12b, 12c are formed on the axial sleeve portion 12d. The through-holes 12b, 12c are made into the thickness of the sleeve portion 12d and open into the cavity 22. Each through-hole 12b, 12c is delimited in the radial direction by its inner wall or bore. The cavity 22 is delimited axially by the radial portion 12e. The cavity 22 is delimited radially by the bore of the sleeve portion 12d. Similarly to the cavity 22, the cavity 24 is delimited axially by the radial portion 12d and radially by the bore of the sleeve portion 12e. The cavities 22, 24 are disposed on either side of the radial portion 12e.

(9) Each pin end 14b, 14c is mounted into the deformable ring 18, 20 itself inserted into the associated through-hole 12b, 12c of the tappet body. Each deformable ring 18, 20 is radially located between the pin end 14b, 14c and the inner wall of the associated through-hole 12b, 12c. In the illustrated example, each deformable ring 18, 20 is in radial contact with the pin end 14b, 14c on one side and in radial contact with the tappet body 12 on the other side. Each deformable ring 18, 20 comes radially into contact with the inner wall of the associated through-hole 12b, 12c. Each deformable ring 18, 20 comes radially into contact with the outer surface of the associated pin end 14b, 14c. Accordingly, as previously mentioned, each deformable ring 18, 20 is radially interposed between one of the pin ends 14b, 14c and the tappet body 12.

(10) Each deformable ring 18, 20 provides an axial cylindrical outer surface 18a, 20a in radial contact with the bore of the associated through-hole 12b, 12c, and a cylindrical bore 18b, 20b radially opposed to the outer surface and in radial contact with the outer surface of the associated pin end 14b, 14c.

(11) Each deformable ring 18, 20 also provides two opposite inner and outer lateral surfaces (not referenced) which axially delimit the outer surface 18a, 20a and the bore 18b, 20b. In the illustrated example, the inner lateral surface of each ring 18, 20 is axially offset outwards with respect to an inner wall of the tappet body. Alternatively, the inner lateral surface may be coplanar with the inner wall or may axially slightly protrude towards the roller 16. An axial gap 28, 30 is provided between each frontal surface of the roller and the tappet body 12.

(12) Each deformable ring 18, 20 is secured to the tappet body 12. Each deformable ring 18, 20 is secured into the associated through-hole 12b, 12c, by any appropriate means, for example by gluing or overmoulding. Each deformable ring 18, 20 is made from deformable flexible material, for example elastically deformable material. Each deformable ring 18, 20 may be made from synthetic material such as plastic material or elastomer or nitrile rubber or polyurethane.

(13) With the disposition of the deformable rings 18, 20 between the pin ends 14b, 14c of the pin and the through-holes 12b, 12c of the tappet body 12, a flexible connection is provided between the pin and the tappet body. Accordingly, an angular tilting of the pin 14 supporting the roller 16 with respect to the tappet body 12 may be obtained. The axis 14a of the pin may tilt angularly relative to the abutment surface 26 of the tappet body. Such a tilting may be obtained since the axial gaps 28, 30 are provided between the roller 16 and the tappet body 12. The deformable rings 18, 20 are locally compressed in this case.

(14) When the device 10 is mounted into the associated housing, such as a pump housing, the pin 14 is able to move angularly relative to the tappet body 12 to accommodate angular misalignment between the axis of the housing and the axis 12a of the tappet body. With a contact between the roller 16 of the device and the cam of the internal combustion engine, the roller supported by the pin 14 may tilt angularly relative to the tappet housing 12. This has the effect of reducing the edge stresses that may occur at the ends of the roller 16. Accordingly, in operation, the pressure contact between the roller 16 and the cam may be reduced.

(15) The example illustrated on FIG. 2, in which identical parts are given identical references, differs from the previous example in that the device 10 further provides a sleeve 32, 34 radially interposed between each deformable ring 18, 20 and the associated pin end 14b, 14c of the pin. Here, contrary to the first example, each deformable ring 18, 20 secured to the tappet body is not in direct contact with the associated pin end 14b, 14c.

(16) Each deformable ring 18, 20 is in radial contact with the associated sleeve 32, 34 on one side and in radial contact with the tappet body 12 on the other side. Each deformable ring 18, 20 comes radially into contact with the outer surface of the associated sleeve 32, 34. The bore 18a, 20a of each deformable ring is mounted in radial contact with the associated sleeve 32, 34. Each pin end 14b, 14c of the pin is inserted into an axial bore or hole delimited by the associated sleeve 32, 34. Each pin end 14b, 14c is fixed into the hole of the associated sleeve 32, 34 for example by push-fitting. Preferably, each sleeve 32, 34 is made from metal. Alternatively, each sleeve may be made from other rigid material, for example from a synthetic material such as PA.

(17) Each sleeve 32, 34 provides an axial tubular portion 32a, 34a delimiting the outer surface in contact with the associated deformable ring 18, 20 and the hole into which is inserted the associated pin end 14b, 14c. The tubular portion is radially interposed between each pin end 14b, 14c and the associated deformable ring 18, 20.

(18) Each sleeve 32, 34 further provides a radial flange 32b, 34b extending radially outwards from one end of the tubular portion 32a, 34a. Each flange 32b, 34b is axially located on the side opposite to the roller 16 with respect to the tappet body 12. In the illustrated example, each flange 32b, 34b comes axially into contact with the outer lateral surface of the associated deformable ring 18, 20 and with the tappet body 12. Alternatively, a slight axial gap may be provided therebetween. The flange 32b, 34b of each sleeve prevents an axial flow or creep of the associated deformable ring 18, 20 when a tilting of the pin 14 occurs. However, in another embodiment, it could be possible to design the sleeves 32, 34 without the flanges.

(19) In the illustrated examples, each deformable ring of the device is made from an elastically deformable material. Alternatively, each deformable ring may be made from a plastically deformable material.