EP0870904A1 - Ensemble poussoir hydraulique - Google Patents
Ensemble poussoir hydraulique Download PDFInfo
- Publication number
- EP0870904A1 EP0870904A1 EP98106592A EP98106592A EP0870904A1 EP 0870904 A1 EP0870904 A1 EP 0870904A1 EP 98106592 A EP98106592 A EP 98106592A EP 98106592 A EP98106592 A EP 98106592A EP 0870904 A1 EP0870904 A1 EP 0870904A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- mounting member
- piston
- hydraulic tappet
- tappet assembly
- assembly
- 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- Withdrawn
Links
Images
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
- F01L1/20—Adjusting or compensating clearance
- F01L1/22—Adjusting or compensating clearance automatically, e.g. mechanically
- F01L1/24—Adjusting or compensating clearance automatically, e.g. mechanically by fluid means, e.g. hydraulically
- F01L1/245—Hydraulic tappets
- F01L1/25—Hydraulic tappets between cam and valve stem
Definitions
- This invention relates to a hydraulic tappet assembly of the kind comprising a tappet body providing a bearing surface, a mounting member within the tappet body, and a piston mounted in the body by the mounting member.
- the bodies of such hydraulic tappet assemblies are made from steel and the bearing surface is hardened by a suitable hardening process to withstand and give sufficient durability to bear on a cam lobe of a cam shaft of an internal combustion engine.
- the mounting members too are conventionally made of steel and are fixed within a hollow of the body by welding or blazing or a similar technique.
- the steel does not give optimum wear properties and an inherently harder material for the tappet bodies would be preferred, such as for example, cast iron.
- steel is an ideal material for the mounting members, but the steel cannot be fixed to an iron body by conventional fixing techniques.
- a hydraulic tappet assembly comprising a tappet body providing a bearing surface, a mounting member within the tappet body, and a piston mounted in the body by the mounting member characterised in that an inside wall of the body is provided with an interference formation and the mounting member is retained in the body at least primarily as an interference fit with the interference formation.
- the bearing surface of even an iron tappet body may need some surface treatment but the material is inherently harder and gives improved wear characteristics.
- the body is generally cylindrical providing a generally cylindrical hollow therein in which the mounting member is retained, and the interference formation of the inside wall of the body may comprises a groove e.g. extending around the cylindrical inside wall of the body in which a peripheral portion of the mounting member is received.
- the peripheral portion may comprise all or substantially all of the entire circular periphery of the mounting member in which case the groove may extend around the entire inside wall, or a part only of the circular periphery.
- peripheral portion of the mounting member may be of curved configuration in cross section and the corresponding surface part of the groove may be shaped to correspond closely to the curved configuration of the peripheral portion so that there is a minimal gap or space between the mounting member and the inside wall of the body.
- this may be closed with a filling material, such as an anaerobic adhesive.
- the periphery of the mounting member may comprises a plurality of separated segments, any gaps or spaces which could otherwise permit oil to leak therethrough, may be sealed with such adhesive.
- the invention has been developed particularly to enable a hydraulic tappet assembly to be produced in which the tappet body is made of cast iron and the mounting member is made of steel, the invention may be utilised where one or both of these components are made of other materials or are both made of one of these materials.
- the mounting member may comprise a generally central opening in which the piston is mounted, usually received in a cylinder which is retained by the mounting member such that the piston may move relative to the cylinder and the mounting member in use.
- a spring means is provided between the piston and the cylinder to bias the piston outwardly of the cylinder.
- a method of retaining a mounting member for a piston in a body of a hydraulic tappet assembly comprising the steps of providing in an inside wall of the body, a retaining formation and inserting the mounting member into the tappet body so that the mounting member is an interference fit with the retaining formation.
- a hydraulic tappet assembly 10 comprising a generally hollow tappet body 11 which in this example is generally cylindrical shape, having at one end thereof, an end wall 12 providing a bearing surface 13 which in use typically would bear on a lobe of a camshaft or the like of an internal combustion engine.
- mounting member 15 for mounting a piston assembly 16 which comprises a hollow piston 17 received in a cylinder 18.
- a spring 19 Between the piston 17 and the cylinder 18 there is provided a spring 19, the piston 17 being able to move within the cylinder 18 against the biasing force of spring 19 away from the end wall 12 of the body 11, as hydraulic fluid, typically oil enters a working space 20 of the tappet body 11 through an opening 21 in the cylindrical wall 22 of the body 11.
- the oil is transmitted via a passageway 23 into the hollow of the piston 17 and acts against the piston to urge it inwardly of the cylinder 18 against the force of the spring. Oil is supplied to the opening 21 from an oil way of the internal combustion engine in which the tappet assembly 10 is provided.
- the working space 20 of the body 11 is defined by the mounting member 15 which comprises a peripheral portion 25 of generally circular configuration, which conventionally is welded or braised to all inside surface 26 of the tappet body 11 both to fix the mounting member 15 in the hollow of the body 11, and the provide an oil seal around the mounting member 15 between the mounting member 15 and the inside wall 26 of the body 11.
- the mounting member 15 is made from steel, usually as a pressing, and the piston assembly 16 is retained by the mounting member 15, by a circlip 30 received in a circumferential groove of the cylinder 18, which a circlip prevents the cylinder 18 from being withdrawn from the mounting member 18 in a direction away from the end wall 12. Nevertheless, it will be appreciated that the cylinder 18 can be moved towards the end wall 12 by deforming the spring 19, and that the pressure of oil in the working space 20 of the body 11 and in the hollow of the piston, will move the cylinder 18 away from the end wall 12 to the maximum extent permitted by the circlip 30 and by a value stem or connecting rod bearing on an end surface 27 of the piston 18.
- the mounting member 15 is retained in the hollow of the body 11 and an interference fit, the peripheral portion 25 of the mounting member 15 engaging in a retaining formation 40 provided in the inside wall 26 of the body 11.
- the retaining formation 40 comprises a very shallow groove to receive the peripheral portion 25 of the mounting member 15 and prevent the mounting member 15 from moving outwardly of the hollow of the body 11.
- any gap may be sealed by using an adhesive such as an anaerobic adhesive to prevent oil escaping from the working space 20 between the end wall 13 of the body and the mounting member 15.
- the mounting member is primarily retain as an interference fit.
- peripheral portion 25 of the mounting member 15 is modified slightly in configuration so that the peripheral portion 25 corresponds closely to the configuration of the retaining formation 40 provided in the inside wall 26 of the body, such that no or minimal gap occurs between the adjoining faces of the peripheral portion 25 of the mounting member 15 and the inside wall 26.
- an aerobic or other adhesive to provide an oil seal may not be required.
- the tappet body 11 is not made of steel as with the prior art example as shown in figures 1 and 1A. Rather, the tappet body 11 is made from chilled grey cast iron so that the bearing surface 13 of the tappet body 11 is inherently much harder than steel, and more durable in use.
- Figure 3a shows a mounting member 15 which has a generally circular peripherally 25 without there being any interruptions. If the retaining groove in the inside wall 26 of the body 11 is sufficiently shallow, it is envisaged that such a mounting member 15 with a circular periphery 25 may be used as minimum deflection of the periphery 25 is required in order for the mounting member 15 to be inserted in the position shown in Figure 2a.
- the periphery 25 may be divided into peripheral segments 25a, 25b, 25c and 25d for example shown in Figure 3b.
- the segment portions 25a to 25d are separated by small notches 41 which permit greater deflection of the peripheral portion segments to 25a to 25d as the mounting member 15 is inserted in position.
- the tappet body 11 may be made of a hard material such as iron, this may be made of alternative materials.
- the bearing surface 13 of the tappet body 11 may need to be treated by some hardening process to give desired wear characteristics.
- other tappet body 11 need not be made of a similar material to the mounting member 15.
- the mounting member 15 is conveniently made as a pressing in steel, it may be made in other materials, and by alternative manufacturing techniques as desired. Although preferred it is not essential for the body 11 of the tappet assembly 10 to be cylindrical in configuration although this is most useful.
- the piston 17 need not have an internal recess as described in this example but other configurations are possible to both the piston assembly 16, and body 11 and mounting member 15 without departing from the scope of the invention.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Valve-Gear Or Valve Arrangements (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB9707387.8A GB9707387D0 (en) | 1997-04-11 | 1997-04-11 | Hydraulic tappet assembly |
GB9707387 | 1997-04-11 |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0870904A1 true EP0870904A1 (fr) | 1998-10-14 |
Family
ID=10810662
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP98106592A Withdrawn EP0870904A1 (fr) | 1997-04-11 | 1998-04-09 | Ensemble poussoir hydraulique |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0870904A1 (fr) |
GB (1) | GB9707387D0 (fr) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4124484C1 (fr) * | 1991-07-24 | 1993-01-14 | Fa. Carl Freudenberg, 6940 Weinheim, De | |
DE4138995A1 (de) * | 1991-11-27 | 1993-06-03 | Schaeffler Waelzlager Kg | Tassenstoessel mit hydraulischem ventilspielausgleich |
EP0770764A1 (fr) * | 1995-10-27 | 1997-05-02 | EATON AUTOMOTIVE S.p.A. | Poussoir hydraulique sans soudure muni d'un dispositif de siphon |
-
1997
- 1997-04-11 GB GBGB9707387.8A patent/GB9707387D0/en active Pending
-
1998
- 1998-04-09 EP EP98106592A patent/EP0870904A1/fr not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4124484C1 (fr) * | 1991-07-24 | 1993-01-14 | Fa. Carl Freudenberg, 6940 Weinheim, De | |
DE4138995A1 (de) * | 1991-11-27 | 1993-06-03 | Schaeffler Waelzlager Kg | Tassenstoessel mit hydraulischem ventilspielausgleich |
EP0770764A1 (fr) * | 1995-10-27 | 1997-05-02 | EATON AUTOMOTIVE S.p.A. | Poussoir hydraulique sans soudure muni d'un dispositif de siphon |
Also Published As
Publication number | Publication date |
---|---|
GB9707387D0 (en) | 1997-05-28 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): DE GB IT |
|
AX | Request for extension of the european patent |
Free format text: AL;LT;LV;MK;RO;SI |
|
AKX | Designation fees paid |
Free format text: DE GB IT |
|
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: 19990415 |