EP0084267A1 - Moteur à combustion interne à quatre temps avec des arbres à came en tête et poussoirs y afférents - Google Patents

Moteur à combustion interne à quatre temps avec des arbres à came en tête et poussoirs y afférents Download PDF

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Publication number
EP0084267A1
EP0084267A1 EP82307003A EP82307003A EP0084267A1 EP 0084267 A1 EP0084267 A1 EP 0084267A1 EP 82307003 A EP82307003 A EP 82307003A EP 82307003 A EP82307003 A EP 82307003A EP 0084267 A1 EP0084267 A1 EP 0084267A1
Authority
EP
European Patent Office
Prior art keywords
tubular body
abutment
disc spring
shim
tappet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP82307003A
Other languages
German (de)
English (en)
Inventor
Sanzio Pio Vincenzo Piatti
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
VINCENT PATENTS Ltd
Original Assignee
VINCENT PATENTS Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by VINCENT PATENTS Ltd filed Critical VINCENT PATENTS Ltd
Publication of EP0084267A1 publication Critical patent/EP0084267A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/12—Transmitting gear between valve drive and valve
    • F01L1/14—Tappets; Push rods
    • F01L1/143—Tappets; Push rods for use with overhead camshafts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/12—Transmitting gear between valve drive and valve
    • F01L1/14—Tappets; Push rods
    • F01L1/16—Silencing impact; Reducing wear
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/20—Adjusting or compensating clearance
    • F01L1/205—Adjusting or compensating clearance by means of shims or the like
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/02—Engines characterised by their cycles, e.g. six-stroke
    • F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
    • F02B2075/027—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle four

Definitions

  • This invention relates to tappets through the intermediary of which the poppet valves of a four-stroke internal combustion engine are actuated by the cams of an overhead camshaft.
  • Such tappets are generally in the form of inverted cup-shaped cylindrical bodies which slide in guide apertures in a part of the cylinder head assembly, the upturned flat face of the base of a tappet being engaged by the associated cam of the camshaft, and the central region of the inside of the base of the tappet engaging the end of the stem of the associated spring-loaded valve of the engine.
  • the camshaft rotates, the cam moves across the flat face of the tappet base and moves the tappet axially to move the valve stem and the valve against the loading of the spring.
  • the relatively large diameter tappet ensures that, as it slides axially in its guide aperture, the flat face of its base is always presented normal to the cam, and the sideways thrust produced by the cam moving across that face is absorbed by the sliding surface of the tappet in its guide aperture and is not transmitted to the valve stem.
  • a shim is inserted either between the inside of the base of the tappet and the end of the valve stem or between the upturned base of the tappet and the cam.
  • a tappet with this latter arrangement of the shim (hereinafter called “a tappet of the kind referred to”) has the advantage that the shim can be changed to adjust the clearance gap without dismantling the camshaft.
  • the shim must be sufficiently large to be in contact with the cam in all its positions.
  • the outside of the base of the tappet is recessed to provide a base wall surrounded by a peripheral rim within which the shim is located and kept in position against the cam.
  • the cam transmits its thrust to the shim at locations which change continuously from near the periphery to the centre of the shim according to the different phases of cam rotation. It is therefore necessary for the smooth underside of the shim to rest firmly and without rocking on the base wall, to which end a peripheral zone of the shim rests on a ground annular land on the.outer face of the base wall. From the underside of the shim the thrust is transmitted to this peripheral annular land and the efforts travel in the base wall from the periphery toward the * axis of the tappet.
  • the central region of the inside of the base wall applies the thrust against the end of the valve stem. Said central region is also usually ground flat.
  • Tappets of the kind referred to are thus expensive to fabricate and must be sufficiently sturdy to withstand the radial forces consequent upon the thrust forces having to travel radially through the integral base wall.
  • the present invention has for an object to simplify the fabrication of such tappets, to which end the tappet basically comprises a tubular body formed or provided around its internal surface with at least one abutment against which is supported the periphery of a disc spring (comprising a single spring disc or an assembly of several spring discs) facing one end of the tubular body, said at least one abutment or one of the abutments serving to support the periphery of a shim inserted into the other end of the tubular body.
  • a disc spring comprising a single spring disc or an assembly of several spring discs
  • a transfer member having a convex, e.g. part-spherical, surface is located between the disc spring and the end of the valve stem when the tappet is operatively installed in an engine, whereby the disc spring progressively wraps itself around the convex surface, from its centre outwardly, as the tappet moves to open the valve.
  • the transfer member is conveniently assembled as a piston slidable in the bore of the tappet so that it automatically locates against the end of the valve stem when the tappet is positioned in its guide aperture in the engine cylinder head.
  • the disc spring and the convex surface of the transfer member, and the relative setting and initial pressure exerted by the disc spring preferably conform with the teaching of European Patent Application No.79302975.2 (Publication No.0013135) in order to obtain the advantages of that invention and thereby also reduce the number of shims of different grade thicknesses by increasing the gradation step required to effect efficient valve setting.
  • Fig.1 shows a known tappet-actuated valve system in which a cam l'of an overhead camshaft actuates an inverted cup-shaped tappet 2 slidable in a guide aperture 3 in the cylinder head 4.
  • the tappet 2 has a cylindrical recess in its upper end, defined by the base wall 5 and the surrounding rim 6, in which is located a shim 7 against which the cam 1 exerts its thrust.
  • the central region 8 of the underside of the base wall 5 engages the end of the stem 9 of a poppet valve 10 which is normally urged against its seat 11 in the cylinder head 4 by a strong helical spring 12 compressed between a spring retainer 13, secured to the valve stem 9 by split cotters 14, and the cylinder head.
  • a peripheral zone of the underside of the shim rests on the ground annular land 15 on the upper surface of the base wall 5.
  • the central region 8 of the underside of the base wall also comprises a raised land with a ground surface.
  • the external cylindrical surface of the tappet and at least the internal surface of the rim 6 are also ground.
  • the desired clearance gap is adjusted by inserting the appropriate selected one of a range of shims of graded thicknesses in the recess in the top of the tappet.
  • Fig. 2 shows one embodiment of the improved tappet and actuating system according to this invention, parts which are the same as those in Fig. 1 being indicated by the same references.
  • the tappet comprises a tubular body 20 formed with an internal peripheral groove 21, normal to the tube axis, which receives a circlip 22 which serves to support the shim 7.
  • Abutting the underside of the circlip 22 is an annular member 23 having an abutment surface 24 against' which rests the periphery of a disc spring 25.
  • Slidable in the bore of the tubular body 20 is a transfer member 26 having a convex, preferably part-spherical, upper surface 27 which abuts the underside of the disc spring 25.
  • the underside of the member 26 abuts the end of the valve stem 9.
  • the member 26 conveniently has a skirt portion to slidably guide the member 26 like a piston in the bore of the tubular body, although it is not necessary to prevent air leakage between the piston and the bore.
  • the disc spring 25, annular abutment member 23 and the convex surface of the member 26 are designed according to the disclosure and teaching in E.P.O. Publication No. 0013135 which is incorporated herein by reference.
  • the shim 7 is selected so that the disc spring is partially deflected at initial adjustment as described in the aforesaid publication.
  • the tubular body 30 has a ridge or rib 31 machined on its inside surface.
  • the upper surface 32 of the ridge is square to the tube axis and serves to support a shim.
  • the lower surface 33 of the ridge is shaped to form the annular abutment surface for the disc spring.
  • tubular body 40 is machined internally to form a step 41 against which a ring 42 is pressed in from below to form an annular abutment of which the upper surface supports the shim and the lower surface form an abutment surface for the disc spring.
  • Fig. 5 is similar to Fig. 4 except that the step 51 in the tubular body 50 faces in the opposite direction and the abutment ring 52 is inserted from above.
  • Fig. 6 comprises a plain tubular body 60 into which an abutment ring 61 is pressed with considerable interference.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)
EP82307003A 1982-01-04 1982-12-30 Moteur à combustion interne à quatre temps avec des arbres à came en tête et poussoirs y afférents Withdrawn EP0084267A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8200092 1982-01-04
GB8200092 1982-01-04

Publications (1)

Publication Number Publication Date
EP0084267A1 true EP0084267A1 (fr) 1983-07-27

Family

ID=10527421

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82307003A Withdrawn EP0084267A1 (fr) 1982-01-04 1982-12-30 Moteur à combustion interne à quatre temps avec des arbres à came en tête et poussoirs y afférents

Country Status (1)

Country Link
EP (1) EP0084267A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1613117A (en) * 1923-04-23 1927-01-04 Jacob C Miller Cushioned valve tappet
US3183901A (en) * 1965-01-29 1965-05-18 Niel C Thuesen Compression-compensating means for poppet valves
US3431896A (en) * 1967-02-23 1969-03-11 Riv Officine Di Villar Perosa Valve tappets and method of making same
GB1165446A (en) * 1966-09-19 1969-10-01 Fiat Spa Valve Tappet
FR2129420A5 (fr) * 1971-03-08 1972-10-27 Cigala & Bertinetti Sas
EP0013135A1 (fr) * 1978-12-27 1980-07-09 Sanzio Pio Vincenzo Piatti Commande des soupapes d'une machine à combustion interne et un nécessaire de transformation pour adapter une machine à combustion interne à une telle commande des soupapes

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1613117A (en) * 1923-04-23 1927-01-04 Jacob C Miller Cushioned valve tappet
US3183901A (en) * 1965-01-29 1965-05-18 Niel C Thuesen Compression-compensating means for poppet valves
GB1165446A (en) * 1966-09-19 1969-10-01 Fiat Spa Valve Tappet
US3431896A (en) * 1967-02-23 1969-03-11 Riv Officine Di Villar Perosa Valve tappets and method of making same
FR2129420A5 (fr) * 1971-03-08 1972-10-27 Cigala & Bertinetti Sas
EP0013135A1 (fr) * 1978-12-27 1980-07-09 Sanzio Pio Vincenzo Piatti Commande des soupapes d'une machine à combustion interne et un nécessaire de transformation pour adapter une machine à combustion interne à une telle commande des soupapes

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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AK Designated contracting states

Designated state(s): DE FR GB IT

17P Request for examination filed

Effective date: 19840126

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19860723

RIN1 Information on inventor provided before grant (corrected)

Inventor name: PIATTI, SANZIO PIO VINCENZO