FR2645937A1 - DEVICE FOR GUIDING AND SEALING A VALVE - Google Patents

Abstract

The invention relates to a device for guiding and sealing a valve, the stem 10 of which is slidably mounted in a tubular valve guide 14 mounted in the cylinder head 12 of a combustion engine and which projects axially from it. 'a bearing surface 20 of the cylinder head, perpendicular to the axis XX of the valve and on which rests one end of a return spring 26 of the valve with the interposition of a bearing cup 24 in the form of washer through which the projecting part 18 of the valve guide 14 passes. A sealing ring 32 is held axially against this projecting part 18 by a bush 30. According to the invention, the bush and the support cup are made of a single piece 22, the cylindrical part forming the sleeve 30 of which extends axially from the cup 24 beyond the free end 50 of the projecting part 18 of the valve guide 14 by an end portion 40 of which the internal surface completely envelops the sealing ring tee 32.

Description

The present invention relates to a device for guiding and

  the sealing of a valve whose stem is slidably mounted in a tubular valve guide mounted in the cylinder head of an engine, in particular an internal combustion engine. It has already been proposed devices of this type in which the valve guide protrudes axially from a bearing surface of the cylinder head perpendicular to the axis of the valve and on which bears an end of a spring of recall of the valve with the interposition of a washer-shaped bearing cup traversed by the projecting portion of the valve guide. The seal between the rod and the valve guide is ensured by means of a sealing ring whose lip cooperates with the rod and which is held axially by means of a socket

  fitted on the protruding part of the guide.

  In this type of device in which the valve guide, cast iron or brass, is force-fitted into a light alloy cylinder head, it is necessary to provide an elastic ring or a ring to hold the valve guide axially relative to the cylinder head, especially in the case where the clamping thereof in the cylinder head is very low in order to avoid mechanical stresses in these elements. Devices of this type are complex and the various functions of maintenance and sealing are obtained by multiple and independent components. The assembly of these elements requires a succession of delicate operations and difficult to automatize such as in particular the establishment of the elastic ring and the fitting of the seal to

lip with its socket.

  In order to overcome these drawbacks, the invention proposes a device of the type mentioned above, characterized in that the bushing and the support cup are made in one piece, the cylindrical portion forming a sleeve extends axially from the cup beyond the free end of the projecting portion of the guide by an end portion whose inner surface envelopes

  completely the sealing ring.

  According to other features of the invention: the sealing ring cooperates with the radial free end face of the projecting portion of the valve guide; - The cylindrical sleeve portion comprises a base portion which is fitted on the projecting portion of the valve guide and which comprises means for axial immobilization of the sleeve relative to the guide; - The immobilizing means comprise at least one tab cut in the base portion, which projects radially inwards from the inner surface of this base portion and whose end is received in a radial groove of the valve guide. ; the immobilization means are constituted by a plurality of cut tabs distributed angularly about the axis of the sleeve and which project radially in the same plane; the immobilization tabs extend in the radial plane in which the support cup is located;

  - the end of each leg of immobilisa-

  tion is bent axially towards the free end of the valve guide; - The free end edge of the sleeve portion has an axial radial retaining axial shoulder of the sealing ring; - The sealing ring is fixed by adhesion or bonding to the inner wall of the sleeve portion; and the sealing ring comprises a first lip extending radially inwards which cooperates with the valve stem and a second lip extending axially towards the end face of the valve guide with which it

cooperates.

  Other features and benefits of

  the invention will appear on reading the description of the

  Detailed description which will follow for the understanding of which reference will be made to the attached drawing whose single figure shows in axial section a device

  maintaining and sealing according to the invention.

  The figure shows the stem, or tail, of an internal combustion engine valve which is guided axially in a portion of the cylinder head 12 of this engine by a valve guide 14.

hollow cylindrical sleeve shape.

  The guide 1A is fitted into a bore 16 of the cylinder head and is positioned axially so that a portion 18 of this guide protrudes axially out of the cylinder head 12 from a perpendicular support surface 20 thereof. at the XX axis of

the valve.

  According to the invention, a single element 22 made of cut sheet metal and stamped acts as a support cup 24 for a spring 26 of the valve return and mounting sleeve 30 for

a sealing ring 32.

  The lower part 24, considering the figure, of the single element 22 is constituted by a radial blank folded 180 'in the form of washer which is traversed by the projecting portion 18 of the valve guide f4 and which is supported on the face 20 of the breech. The lower end 36 of the return spring 26 bears on the portion 24 which acts as a support cup for the return spring. Part 24 extends vertically towards

  the top by a cylindrical portion forming a sleeve 30.

  The cylindrical portion 30 has a base portion 38 which is force-fitted on the connecting portion 18 of the guide 14 and a cylindrical end portion 40 which receives the ring

32.

  The sealing ring 32 is fixed, for example by adhesion or gluing, against the inner surface 42 of the end portion 40 and is

  entirely enveloped by this last.-

  The axial retention of the sealing ring 32 is ensured by means of an internal radial shoulder 44 which extends from the free end edge of the

end portion 40.

  The sealing ring has a first inner radial lip 46 which cooperates with the valve stem 10 and a second axial lip 48 which cooperates with the radial end face 50 of the projecting portion 18 of the guide 14. The two-ring lip 32 thus ensures the seal between the valve stem 10

and the valve guide 14.

  The base portion 38 of the single element 22

  comprises a series of legs 52 distributed angular-

around the X-X axis.

  Each of the tabs 52 extends radially inwards in the direction of the X-X axis, its free end being bent axially upwards. Each of the tabs 52 is received in an internal radial groove 54 formed in the projecting portion 18 of the valve guide 14 to constitute axial immobilization means of the element 22 with respect to the guide 14 and the guide 14 relative to at the cylinder head 12 in the axial direction downwards in

considering the figure.

  The single element 22 thus makes it possible to ensure simultaneously the bearing function of the spring 26 on the face 20 of the cylinder head, the maintenance of the sealing ring 32 by the inside of the cylindrical part which completely protects it from shocks during handling, the centering of the sealing ring and the support cup relative to the valve guide, the centering of the spring 26 by the outside of the cylindrical portion which is also used for gripping the single element by an automatic mounting device and the axial retention of the guide

  valve 14 by the locking tabs 52.

  It should also be noted that the radial clearance "r" between the cylindrical portion 30 of the element 22 and the interior of the spring 26 may be small without the risk of causing interference and damage with the sealing ring 32, as in FIG. the case of known elements of the state of the art, the ring 32

being fully protected.

  The axial size of the element is also reduced compared to devices of the state of the art, in particular those in which the retaining sleeve must have a length of fitting particularly large to ensure a good behavior of the ring. sealing on the guide, the latter being pinched between the outer cylindrical surface of the guide and the cylindrical surface

internal socket.

Claims (10)

  1. Device for guiding and sealing   a valve whose stem '10) is slidably mounted in a tubular valve guide (14) mounted in the cylinder head (12) of a combustion engine and which protrudes axially from a bearing surface (20) of the cylinder head, perpendicular to the axis (XX) of the valve and on which bears an end (28) of a return spring (26) of the valve with the interposition of a support cup ( 24) in the form of a washer traversed by the projecting portion (18) of the valve guide (14), the seal between the rod (10) and the guide (14) being ensured by means of a sealing ring ( 32) which is held axially by means of a sleeve (30) fitted on the projection (18) of the valve guide (14), characterized in that the sleeve and the support cup are made in one piece (22) having a cylindrical sleeve portion (30) extending axially from the cup (24) beyond the free end (50) of the projecting portion (18) of the valve guide ('14) by an end portion (40) whose inner surface completely surrounds the ring sealing (32).   2. -Dispositif according to claim 1, characterized in that the sealing ring (32) cooperates with the radial end face free (50) of   the protruding portion (18) of the valve guide (14).   3. Device according to one of the claims   1 or 2, characterized in that the cylindrical sleeve portion (30) has a base portion (38) which is fitted to the projecting portion (18) of the valve guide (14) and which includes means (52). ) axial immobilization of the sleeve relative to the valve guide.   4. Device according to claim 3.   characterized in that the immobilizing means comprise at least one tab (52) cut in the base portion (38), which projects radially inwards from the inner surface of this base portion and whose end is received in a radial groove (54) of the projecting portion (18) of the valve guide (14).   5. Device according to claim 4, characterized in that the immobilizing means comprise a plurality of cut tabs (52) angularly distributed around the axis of the sleeve and which   protrude radially in the same plane.   6. Device according to one of the claims   4 or 5, characterized in that the immobilization tab or tabs extend in the radial plane in   which is located the support cup (24).   7. Device according to any one of   Claims 4 to 6, characterized in that each   locking tab (52) is bent axially towards the free end of the valve guide (14). 8. Device according to any one of   Claims 2 to 7, characterized in that the edge   free end of the socket portion has an internal radial retaining shoulder (44)   axial direction of the sealing ring (32).   9. Device according to any one of   Claims 2 to 8, characterized in that the ring   seal (32) is fixed by adhering or gluing to the inner wall of the forming portion socket (30).   10. Device according to any one of   Claims 2 to 9, characterized in that the ring   seal (32) has a first radially inwardly extending first lip (46) which cooperates with the valve stem (10) and a second lip (48) extending axially towards the radial face of end (50) of the valve guide (14) with which she cooperates.