FR2633027A1 - SEALING FOR SLIDING ROD, ESPECIALLY FOR VALVE RODS - Google Patents

Abstract

The seal for a sliding rod in particular for the rod 2 of a valve of an internal combustion engine is characterized in that it comprises a first part 3 integral with an element 5 supporting said rod 2 and a second part 7 within which are formed an upper annular lip and a lower annular lip 13, 14 cooperating and in contact with said rod 2 and defining together and with said rod 2 an annular fluid-tight chamber 18 designed to permanently trap lubricating oil when rod 2 is idling.

Description

The present invention relates to a seal for a rod

  sliding, in particular for the stem of an intake or exhaust valve of a

internal combustion.

  The seals of the aforementioned type are used to prevent the lubricating oil of the cams from seeping along the valve stem in the engine and comprise a first cylindrical part adapted to a cylindrical part of a sleeve supporting the rod and lodged

  inside the cylinder head; and a second cylin-

  dric inside which is formed an annular lip

  the surface cooperating with the valve stem. Cam lubrication oil also lubricates the contact surface between the valve stem and the sealing lip

  to reduce friction between these elements.

  When the engine is idling for a while, the lubricating oil oozes out of the cylinder head resulting in drying of the sealing lip and sticking to the valve stem when the engine is

  put back into operation and this results in inconvenience

obvious things.

  The object of the present invention is to provide a seal - made to eliminate the aforementioned drawback, that is to say to prevent the seal lip from sticking to the valve stem when the engine is left at slowed down for an extended period of time. The present invention therefore provides a seal for a sliding rod, in particular for the rod.

  a valve of an internal combustion engine which is

  characterized in that it includes a first solid part

  of an element supporting said rod and a second

  part inside which an an-

  upper ring and a lower annular lip in

  contact with and cooperating with said rod and defi-

  connecting with said rod a fluid-tight annular chamber made to permanently trap the oil

  lubrication when the rod is idling.

  The present invention will be better understood by referring by way of nonlimiting example to the appended drawing. In the accompanying drawing, 1 designates a lining

  seal for a sliding rod 2, in the example shown

  shown, the stem is a stem of an intake valve

  or exhaust from an internal combustion engine (not re-

presented).

  - The seal 1 is essentially made of an elastomeric material and comprises a lower part 3 in the form of a cylindrical sleeve arranged to fit on the cylindrical part 4 of a sheath 5 supporting the rod 2, a part central 6 essentially

  in the form of a frustoconical sleeve and an upper part

  7 in the form of a cylindrical sleeve having an outer diameter smaller than that of part 3. The

  part 3 presents a solid external reinforcement sleeve

  8 preferably made of metal having an upper edge 11

  in the form of an annular flange covered by an appen-

  peripheral annular dice 12 projecting radially from the central part 6. The sleeve 8 is connected

  advantageously to parts 3 and 6 during the hardening stage

  cissement and the sheath 5 which is of a known and represented type

  only partially felt is housed in the cylinder head of the engine.

  Inside the upper part 7 of the gar-

  seal 1, two annular lips are provided

  13 and 14 upper and lower projecting radially-

  arranged to cooperate slidingly with the

  ge 2 which extends through said lips and slides axially inside the seal 1 in

  due to a known oil wedge effect (not shown).

  We planned between lips 13 and 14 and closer

  of the lip 13, an outer lateral surface 9 of a part

  tie 7, an annular spring 10 whose function is to exert a predetermined radial pressure on the lips

  13 and 14 and press them onto the outer side surface

  re of a rod 2. The lips 13 and 14 have a triangular radial section, the rounded most inward free vertex

  not radially cooperating with the rod 2. More particular-

  ment =, the upper lip 13 has an inner edge 15 defining a more rounded top than that defined by the corresponding inner edge 16 of the lower lip 14, which ensures greater contact with the rod 2. Furthermore,

  the lips 13 and 14 are designed to cooperate in different ways

  ferent with stem 2 due to the fact that the upper lip

  13 is more important than the lower lip 14 and

therefore cooperates more with the rod -2.

  In service, the lips 13 and 14 together define

  ble and with the outer surface of the rod 2 an annular chamber 18 fluid-tight arranged when the rod 2 is idling to permanently trap part of the oil usually present in the cylinder head of the engine

  to lubricate the cam control rod 2.

  When the engine is running, i.e. when the rod 2 slides axially inside the seal 1, the lubricating oil outside the seal 1 can flow out. inside the chamber 18 due to the slightly rounded shape of the edge on the lip 13 and despite the fact that the lip 13 cooperates with the rod 2. Due to the sharper edge 16 of the lip 14, the oil penetrating into the chamber 18 cannot flow outside and: therefore gradually fills the chamber 18. When the rod 2 is at idle, the aforementioned design of the lips 13 and 14 ensures total tightness

  thanks to the provision of the upper lip 13 and of the lip

  vre lower 14 on the rod 2, which prevents a leak both up and down. When the rod 2 is therefore at idle, the oil inside the chamber 18 is

  imprisoned for. ensure adequate lubrication of the

  vres 13 and 14 when the rod 2 is again in operation-

  The advantages of the present invention are apparent

  clearly from the previous description. In particular,

  when the engine is idling, sufficient oil

  is trapped between the lips 13 and 14 to prevent them from adhering to the rod 2 and to ensure that they are properly lubricated even for a period of time

  prolonged, which ensures a uniform start and without

suitable for the engine.

  The invention is not limited to the embodiment

  tion represents and describes in detail and various modifications

  tions can be made to the packing 1

  without departing from the scope of the present invention.

Claims (6)

RESELL I CATIONS   1.Seal for sliding rod no-   especially for the stem (2) of a valve of a combustion engine   internal tion, characterized in that it comprises a first part (3) integral with an element (5) supporting said rod (2) and a second part (7) inside which an upper annular lip is formed and a lower annular lip (13, 14) cooperating and in contact with said rod (2) and defining together and with said rod (2) a fluid-tight annular chamber (18) designed   to permanently trap the lubricating oil   tion when the rod (2) is idling.   2. A seal according to claim 1, characterized in that the lips (13,14) have a triangular radial section and cooperate with said rod (2) by means of respective rounded edges (15, 16) defining respective free vertices, said edge (15) of said upper lip (13) being more rounded than   that of the edge (16) of the lower lip (14).   3.Seal packing according to claim 2, characterized in that said lips (13,14) are designed   to cooperate differently with said rod (2), la-   said upper lip (13) being greater than the lower lip superior (14).   4.Seal packing according to any one   claims 1 to 3, characterized in that on the   outer surface of the second part (7), springs (10) are provided for pushing said lips (13,14) on said rod (2), said springs (10) being adapted between said lips (13,14) and more near the upper lip (13) 5.Seal packing according to any one   claims 1 to 4, characterized in that the first   re part (3) is in the form of a cylindrical sleeve and designed to fit on a cylindrical part (4) of a   element (5) supporting said rod (2) and in that the pre-   first part (3) has an external metal sleeve   integral (8) having an edge in the form of an annular flange   area (11) and covered by a peripheral annular appendage   risk (12), of a part (6) connecting said first (3) and second (7) parts of the seal. 6.Seal packing according to any one   claims 1 to 5, characterized in that the first   part (3) and the second part (7) are made of material re elastomer.