EP0568157B1 - Low-mass, direct-acting hydraulic valve-lifter - Google Patents
Low-mass, direct-acting hydraulic valve-lifter Download PDFInfo
- Publication number
- EP0568157B1 EP0568157B1 EP93201203A EP93201203A EP0568157B1 EP 0568157 B1 EP0568157 B1 EP 0568157B1 EP 93201203 A EP93201203 A EP 93201203A EP 93201203 A EP93201203 A EP 93201203A EP 0568157 B1 EP0568157 B1 EP 0568157B1
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- EP
- European Patent Office
- Prior art keywords
- baffle
- shell
- hydraulic valve
- wall
- lifter according
- Prior art date
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Classifications
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- 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
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- 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
- F01L2301/00—Using particular materials
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- 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
- F01L2303/00—Manufacturing of components used in valve arrangements
Definitions
- This invention relates to hydraulic valve-lifters (HVL's) for engines and, in more particular embodiments, to direct-acting HVL's of light weight for use in relatively high-speed overhead cam (OHC) automotive engines and the like.
- HVL's may also be referred to as hydraulic tappets and sometimes are called hydraulic-lash adjusters, and direct-acting hydraulic valve-lifters (DAHVL's) are sometimes called bucket tappets, however these various names are not necessarily of equivalent scope.
- this invention relates to a follower for a hydraulic valve-lifter as specified in the preamble of claim 1, for example as disclosed in DE-A-3623638.
- a camshaft 18 supported in an aluminium camshaft carrier 11 has cams 22, each of which directly engages a DAHVL (tappet 23) that in turn engages the stem 34 of a poppet valve conventionally carried in a cylinder head, not shown, to actuate the valve.
- Each lifter 23 includes a cup-like follower having a cam-engaging alloy cast iron upper end 24 diffusion-bonded to a cold-formed steel baffle shell including an annular outer wall (skirt 26) and an inwardly-supported central wall 27.
- the central wall includes a radial supporting baffle and an axial annular cylinder portion in which a hydraulic element assembly (HEA) (hydraulic-lash adjuster 28) is reciprocably supported.
- the HEA is supplied with hydraulic fluid (engine oil) through an annular oil feed chamber 30 which is fed at its lower edge through an opening 32 via an external groove 31.
- the follower construction is thin-walled to maintain a low reciprocating weight for the lifter 23 as is desirable for operation at higher engine speeds.
- the chamber 30 is filled with a significant volume of oil which increases the reciprocating mass of the lifter in operation.
- the oil in the chamber 30 may drain from the lifter when the engine is stopped so that, upon starting, the oil supply must again fill the chamber 30 before a dependable feed of oil is again provided to the HEA 28. During this period, the HEA must rely upon an internal oil reservoir for its oil supply.
- air may enter the system such as through draining of the chamber 30 when the engine is stopped or foaming of the oil supply during engine operation. This air may enter the HEA through an inlet from the chamber 30, resulting in unwanted tappet noise and/or improper valve actuation for an extended period until the air is removed from the lifter by escape through the clearances apart from or along with the escaping oil.
- a hydraulic valve-lifter according to the present invention is characterised by the features specified in the characterising portion of claim 1.
- the present invention involves direct-acting hydraulic valve lifters (DAHVL's) which utilize the foam filler and other features of the aforementioned European patent application 91202790.1 (EP-A-0 485 007) whilst providing improvements in the cam follower construction that can reduce mass and complexity with potentially lower manufacturing cost.
- DASHVL's direct-acting hydraulic valve lifters
- a follower having an optional single-piece shell combined with a light plastics baffle retained by the foam filler for low mass and cost; suitable for use with conventional hydraulic element assemblies (HEA's) or other piston arrangements.
- HSA's hydraulic element assemblies
- a preferred polymer material for the baffle having low mass and good stability characteristics.
- a riser chamber that provides a fluid inlet path and sufficient volume for maintaining pressure under cold flow. This can be formed as part of the plastics baffle and/or within the supporting foam.
- Lifter 10 generally indicates a preferred embodiment of direct-acting hydraulic valve lifter (DAHVL) according to the present invention.
- Lifter 10 is somewhat similar in its general construction to the tappets or lifters described in the previously cited U.S.patent 4,745,888 and in European patent application 91202790.1 (EP-A-0 485 007) and is adapted to be reciprocably mounted between a cam 11 and a stem 12 of a cylinder poppet valve in an engine 14 in a conventional manner as shown, for example, in the cited U.S patent.
- the lifter 10 comprises a cam follower 15 and a hydraulic element assembly (HEA) 16.
- the follower 15 includes a cup-like outer shell 18, an inner baffle 19 and a foam filler 20.
- the shell 18 has an annular skirt-like outer wall 22 with an open bottom end 23 and a cam-engaging head 24 closing the upper end.
- the head 24 is often referred to as a foot for consistency with other valve-lifters, including historical direct-acting types, in which the lifter rides on top of the cam).
- the head 24 may be formed of steel integral with the outer wall 22.
- the head 24 may be separately formed and attached to the wall 22 in any suitable manner such as, for example, by diffusion-bonding or laser- welding.
- the shell outer wall 22, as shown in Figure 1 is of circular cross-section centred on an axis 26, however it may be oval, rectangular or another suitable shape, if desired. Between its ends, an inwardly-extending annular groove 27 is formed, as by rolling or machining. An oil inlet opening 28 passes through the shell 18 on the upper side of the groove 27, as shown in Figure 1.
- the baffle 19 is formed separately from the shell 18, and is of a suitable lightweight material and construction and is retained in the upper portion of the shell 18.
- Baffle 19 includes an upstanding inner wall 30 that preferably extends to the head 24 of the shell 18.
- the upper portion of the wall 30 forms an annular recess 31 similar to a counterbore in appearance.
- the wall 30 defines an inner cylinder 32 which is preferably of circular cross-section to receive therein a conventional HEA.
- a flange 34 extends outwards from the cylinder, preferably at the bottom of the wall 30. In the illustrated embodiment, the flange 34 extends radially for part of its diameter and then slopes downwards to engage the shell outer wall 22 inwards of the oil groove 27.
- the raised central portion of the flange 34 provides clearance for associated valve train components.
- the flange includes a fill hole 35 and a smaller vent hole 36 to be later discussed.
- auxiliary wall means defining a riser chamber 38 extending axially along the inner wall 30 from the flange 34 to the head 24 of the shell.
- the wall means include spaced lateral walls 39 and 40 that extend radially outwards from the inner wall 30, and a boundary wall 42 that connects outer edges of the lateral walls 39,40 between the inner and outer walls 30, 22 to define the outer extent of the riser chamber 38.
- Walls 39, 40, 42 also engage the inner side of the head 24 and extend to the flange 34 below.
- An inlet hole 43 through the boundary wall 42 near the flange 34 is aligned with the opening 28 in the wall 22.
- the shell 18 and the baffle 19 define an annular first space 44 between the inner and outer walls.
- This space is filled with a foam filler 20 except for the riser chamber 38 which is open to the passage of oil.
- a passage 46 formed through the foam between the inlet opening 28 and the inlet hole 43 allows oil flow from the oil groove 27 into the riser chamber 38.
- a slot 47 through the upper portion of the inner wall 30 connects the riser chamber 38 with a second space 48 within the inner wall and a shallow recess 50 in the head 24 permits oil to flow from the chamber 38 through the slot 47 and recess 50 to an inner reservoir 51 in the HEA.
- the HEA comprises a closed end piston 52 internally carrying a plunger 54 engagable with the head 24 and having a check-valve-controlled orifice 55 that allows one-way oil flow from the reservoir 51 to a pressure chamber 56 between the piston and plunger.
- Re-circulation holes 58 in the plunger 54 and clearance means formed as a flat on the piston or as a groove 60 across the cylinder 32 surface provide optional re-circulation and vent means as described and claimed in the aforesaid European patent application 91202790.1 (EP-A-0 485 007).
- FIG. 4 Another optional feature shown in Figure 4, which shows an enlarged view of the circled area 4 of Figure 1, is a crush edge 62 at the lower outer edge of the baffle flange 34. Formed as a sharp edge 62 (shown in dashed lines) in the plastics material prior to assembly, the edge 62 is deformed by interference fitting within the smaller inner diameter of the outer wall 22 adjacent the oil groove 27. This tight-fitting, crushed edge 62 forms a seal against the escape of the foam filler during its installation in the follower first space 44.
- Figure 5 shows a DAHVL 63 similar to that of Figure 1 wherein like numerals designate like parts.
- a modified follower 64 A two-piece shell 66 is provided having a thin steel outer wall 67 attached, such as by diffusion-bonding, to an alloy cast iron head 68.
- the two-piece construction is optional and similar to prior commercial valve lifters such as that shown in the aforementioned U.S. patent 4,745,888.
- a baffle 70 similar to that of Figures 1-4 is also provided having two other modifications.
- An inner wall 71 has at its upper end a lip 72 extending outwards and engaging an inner side of the head 68. The lip can assist in preventing leakage of foam into the second space 48 containing the HEA 16.
- a modified riser chamber 74 is also formed by providing an outward extension 75 from the lower portions of auxiliary walls 76 to form an enlarged inlet portion 78. This extends the riser chamber 74 outward and further reduces resistance to fluid flow from the inlet opening 28 to the second space 48.
- the joint between the baffle 70 and the outer wall 67, at the location of the riser chamber inlet portion 78, is sealed against oil leakage by the close fitting of the parts and, optionally, by a crushed edge 62 forming seal means as shown in Figure 4.
- seal means could be provided as seal means to control leakage at this joint.
- seals as resilient rings or gaskets could be used around the baffle edges to control foam leakage during filling.
- FIG. 6 illustrates another embodiment of follower 80 for a DAHVL according to the present invention.
- the shell 18 is optionally like that of Figure 1 but baffle 82 is modified to eliminate auxiliary walls. Instead, a lost core 83 is applied during manufacture as shown in Figures 6-8.
- the core 83 fits within the annular recess 31 of the inner wall 30 of baffle 82 closing the upper part of the second space 48.
- a small radial segment 84 of the core extends through the slot 47 in the wall 30 out to the outer wall 22 and down to the flange 34 of the baffle at the inlet opening 28 to prevent the inflow of foam filler 20 to the cored volume during the filling process.
- the core is subsequently removed, as will be discussed later, forming a riser chamber 86 in the first space that is bordered by the foam filler 20 and connects the inlet opening 28 with the second space 48.
- oil admitted through the opening 28 passes through the riser chamber 38, 74, 86, slot 47 and recess 50 to the reservoir 51. From there, it is allowed to pass through the check-valved orifice 55 and to refill the pressure chamber 56 at each cycle as the HEA 16 operates to adjust the valve-lash in known manner, urging the follower head 24, 68 lightly against the cam 11 and the HEA piston 52 against the valve stem 12. Then, as the rotating cam 11 forces the follower 15, 64, 80 downwards, the HEA piston 52 opens the valve by forcing down the stem 12 and spring seat 87 against the force of the spring 88, further cam rotation again allowing the valve to close and the replacement of oil which has leaked from the pressure chamber 56.
- the riser chamber 38, 74, 86 is made with sufficient cross-section transverse to the direction of oil flow to avoid substantial resistance to cold oil flow and to encourage normal filling of the pressure chamber even under cold starting conditions when the oil is more viscous.
- the recirculation holes 58 and vent groove 60 operate to minimize the entry of oil-entrained air into the reservoir 51.
- the shell 18 may be cold-formed from a conventional hardenable steel with the oil groove 27 being roll-formed or machined therein as desired.
- the baffle 19 is preferably moulded of a low- mass polymer plastics material having good dimensional control, thermal expansion stability and chemical resistance.
- a presently preferred example is Fortron@ 6165, a highly glass-reinforced and mineral-filled polyphenylene sulphide (PPS) moulding material available from Hoechst Celanese, Engineering Plastics Division, Summit, New Jersey, U.S.A.
- PPS polyphenylene sulphide
- the groove 60 if used, may be moulded into the cylinder 32, or the cylinder 32 and groove 60 may be machined for clearance control if desired.
- the baffle 19 may be made from any suitable material which selected, for example, from among the thermoplastic and thermosetting reinforced and filled engineering plastics materials.
- suitable material selected, for example, from among the thermoplastic and thermosetting reinforced and filled engineering plastics materials.
- needed or desired characteristics of such baffle materials are durability in a lubricating oil environment at temperatures from -40° to 150 ° C., a coefficient of linear thermal expansion closely matched to the mating metallic components, resistance to lubricating oil contaminants and an ability to be moulded with close tolerance and low warp.
- the foam filler After assembly of the baffle 19 into the shell 18, the foam filler is installed as a liquid into the first space 44 through a nozzle inserted into the fill hole 35 in the flange 34.
- the filler foams and hardens in place, with air escaping from the space 44 through the vent hole 36. Leakage of foam into the second space 48 and the riser chamber 38 may be prevented if necessary by pressurizing these spaces through the inlet hole 43, the bottom of the cylinder 32 being sealed off during the process.
- the joints may be adequately sealed by engagement of the baffle and shell members, possible with the aid of crush edges such as 62 acting as seal means.
- foam filler After hardening, the foam filler has sufficient strength and adhesion to retain the plastics baffle in position within the shell under engine operating conditions.
- a preferred selection of foam filler material is a modified polyurethane foam provided by System-Chardonol Division of Cook Composites and Polymers Co. (formerly the Freeman Chemical Company) of port Washington, Wisconsin, U.S.A. and having a mix ration of 100 parts by weight Chempol@ 030-A944-70 resin to 200 parts by weight Chempol@ 030-2416 Isocyanate.
- a preferred process for assembling the lifter follower includes the following steps:
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Description
- This invention relates to hydraulic valve-lifters (HVL's) for engines and, in more particular embodiments, to direct-acting HVL's of light weight for use in relatively high-speed overhead cam (OHC) automotive engines and the like. HVL's may also be referred to as hydraulic tappets and sometimes are called hydraulic-lash adjusters, and direct-acting hydraulic valve-lifters (DAHVL's) are sometimes called bucket tappets, however these various names are not necessarily of equivalent scope. In particular, this invention relates to a follower for a hydraulic valve-lifter as specified in the preamble of claim 1, for example as disclosed in DE-A-3623638.
- It is known in the art relating to overhead cam (OHC) internal combustion engines to provide a direct-acting hydraulic valve-lifter (DAHVL) that is contacted by a cam and directly actuates one or more valves of the engine. One such arrangement which has been used in production engines is shown in United States patent 4,745,888 issued May 24, 1988.
- In that patent disclosure, a
camshaft 18 supported in analuminium camshaft carrier 11 hascams 22, each of which directly engages a DAHVL (tappet 23) that in turn engages thestem 34 of a poppet valve conventionally carried in a cylinder head, not shown, to actuate the valve. Eachlifter 23 includes a cup-like follower having a cam-engaging alloy cast ironupper end 24 diffusion-bonded to a cold-formed steel baffle shell including an annular outer wall (skirt 26) and an inwardly-supportedcentral wall 27. The central wall includes a radial supporting baffle and an axial annular cylinder portion in which a hydraulic element assembly (HEA) (hydraulic-lash adjuster 28) is reciprocably supported. The HEA is supplied with hydraulic fluid (engine oil) through an annularoil feed chamber 30 which is fed at its lower edge through anopening 32 via anexternal groove 31. - The follower construction is thin-walled to maintain a low reciprocating weight for the
lifter 23 as is desirable for operation at higher engine speeds. However, thechamber 30 is filled with a significant volume of oil which increases the reciprocating mass of the lifter in operation. Also, the oil in thechamber 30 may drain from the lifter when the engine is stopped so that, upon starting, the oil supply must again fill thechamber 30 before a dependable feed of oil is again provided to the HEA 28. During this period, the HEA must rely upon an internal oil reservoir for its oil supply. In addition, air may enter the system such as through draining of thechamber 30 when the engine is stopped or foaming of the oil supply during engine operation. This air may enter the HEA through an inlet from thechamber 30, resulting in unwanted tappet noise and/or improper valve actuation for an extended period until the air is removed from the lifter by escape through the clearances apart from or along with the escaping oil. - Co-pending European patent application Serial No.91202790.1 (EP-A-0 485 007) discloses DAHVL's in which oil is displaced from the
chamber 30 by oil-resistant foam which reduces the operating reciprocating mass of the lifter and supports or assists in supporting the axial cylinder portion of the central wall that in turn supports the HEA. Reference to that patent application, which is incorporated herein by reference, as well as to corresponding applications elsewhere will further explain the background of the additional features included in the present invention. - A hydraulic valve-lifter according to the present invention is characterised by the features specified in the characterising portion of claim 1.
- The present invention involves direct-acting hydraulic valve lifters (DAHVL's) which utilize the foam filler and other features of the aforementioned European patent application 91202790.1 (EP-A-0 485 007) whilst providing improvements in the cam follower construction that can reduce mass and complexity with potentially lower manufacturing cost. Among the improved features of the invention are:
- A follower having an optional single-piece shell combined with a light plastics baffle retained by the foam filler for low mass and cost; suitable for use with conventional hydraulic element assemblies (HEA's) or other piston arrangements.
- A preferred polymer material for the baffle having low mass and good stability characteristics.
- A riser chamber that provides a fluid inlet path and sufficient volume for maintaining pressure under cold flow. This can be formed as part of the plastics baffle and/or within the supporting foam.
- Sealing and assembly means and methods for reliability and efficiency of manufacture.
- These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings; in which:-
- Figure 1 is a cross-sectional view of an engine valve train incorporating a direct-acting hydraulic valve-lifter (DAHVL) having a riser chamber and other features according to the present invention;
- Figure 2 is a top view of a plastics baffle member shown in Figure 1;
- Figure 3 is a pictorial view of the plastics baffle member shown in Figures 1 and 2;
- Figure 4 is an enlarged view of the circled portion of Figure 1 showing an optional "crush edge" sealing feature;
- Figure 5 is a cross-sectional view of an alternative embodiment of the invention, having other optional features;
- Figure 6 is a cross-sectional view of another embodiment of follower formed with a lost core shown prior to removal;
- Figure 7 is a top end view of a baffle for the embodiment of Figure 6 showing the lost core in place prior to assembly into a shell; and
- Figure 8 is a pictorial view of the baffle of Figures 6 and 7 with the lost core in position for assembly.
- Referring now to Figures 1-4 of the drawings in detail,
numeral 10 generally indicates a preferred embodiment of direct-acting hydraulic valve lifter (DAHVL) according to the present invention.Lifter 10 is somewhat similar in its general construction to the tappets or lifters described in the previously cited U.S.patent 4,745,888 and in European patent application 91202790.1 (EP-A-0 485 007) and is adapted to be reciprocably mounted between acam 11 and astem 12 of a cylinder poppet valve in anengine 14 in a conventional manner as shown, for example, in the cited U.S patent. - The
lifter 10 comprises acam follower 15 and a hydraulic element assembly (HEA) 16. Thefollower 15 includes a cup-likeouter shell 18, aninner baffle 19 and afoam filler 20. - The
shell 18 has an annular skirt-likeouter wall 22 with anopen bottom end 23 and a cam-engaging head 24 closing the upper end. (Thehead 24 is often referred to as a foot for consistency with other valve-lifters, including historical direct-acting types, in which the lifter rides on top of the cam). For some applications, thehead 24 may be formed of steel integral with theouter wall 22. However, where an alloy cast iron or other head material is preferred, thehead 24 may be separately formed and attached to thewall 22 in any suitable manner such as, for example, by diffusion-bonding or laser- welding. The shellouter wall 22, as shown in Figure 1, is of circular cross-section centred on anaxis 26, however it may be oval, rectangular or another suitable shape, if desired. Between its ends, an inwardly-extendingannular groove 27 is formed, as by rolling or machining. An oil inlet opening 28 passes through theshell 18 on the upper side of thegroove 27, as shown in Figure 1. - The
baffle 19 is formed separately from theshell 18, and is of a suitable lightweight material and construction and is retained in the upper portion of theshell 18. Baffle 19 includes an upstandinginner wall 30 that preferably extends to thehead 24 of theshell 18. The upper portion of thewall 30 forms anannular recess 31 similar to a counterbore in appearance. Below the recess, thewall 30 defines aninner cylinder 32 which is preferably of circular cross-section to receive therein a conventional HEA. Aflange 34 extends outwards from the cylinder, preferably at the bottom of thewall 30. In the illustrated embodiment, theflange 34 extends radially for part of its diameter and then slopes downwards to engage the shellouter wall 22 inwards of theoil groove 27. The raised central portion of theflange 34 provides clearance for associated valve train components. The flange includes afill hole 35 and asmaller vent hole 36 to be later discussed. - Along one side of the
inner wall 30 and aligned with the inlet opening 28 are auxiliary wall means defining ariser chamber 38 extending axially along theinner wall 30 from theflange 34 to thehead 24 of the shell. In the Figure 1-4 embodiment, the wall means include spacedlateral walls inner wall 30, and aboundary wall 42 that connects outer edges of thelateral walls outer walls riser chamber 38. Walls 39, 40, 42 also engage the inner side of thehead 24 and extend to theflange 34 below. Aninlet hole 43 through theboundary wall 42 near theflange 34 is aligned with the opening 28 in thewall 22. - When assembled, the
shell 18 and thebaffle 19 define an annularfirst space 44 between the inner and outer walls. This space is filled with afoam filler 20 except for theriser chamber 38 which is open to the passage of oil. Apassage 46 formed through the foam between the inlet opening 28 and theinlet hole 43 allows oil flow from theoil groove 27 into theriser chamber 38. Aslot 47 through the upper portion of theinner wall 30 connects theriser chamber 38 with asecond space 48 within the inner wall and ashallow recess 50 in thehead 24 permits oil to flow from thechamber 38 through theslot 47 and recess 50 to aninner reservoir 51 in the HEA. - The features of the HEA form no part of the present invention since they are of known conventional form or are disclosed in the prior co-pending European patent application 91202790.1 (EP-A-0 485 007). Detailed discussion of the HEA is not therefore required. In general, however, the HEA comprises a closed end piston 52 internally carrying a
plunger 54 engagable with thehead 24 and having a check-valve-controlledorifice 55 that allows one-way oil flow from thereservoir 51 to apressure chamber 56 between the piston and plunger.Re-circulation holes 58 in theplunger 54 and clearance means formed as a flat on the piston or as agroove 60 across thecylinder 32 surface provide optional re-circulation and vent means as described and claimed in the aforesaid European patent application 91202790.1 (EP-A-0 485 007). - Another optional feature shown in Figure 4, which shows an enlarged view of the circled
area 4 of Figure 1, is a crush edge 62 at the lower outer edge of thebaffle flange 34. Formed as a sharp edge 62 (shown in dashed lines) in the plastics material prior to assembly, the edge 62 is deformed by interference fitting within the smaller inner diameter of theouter wall 22 adjacent theoil groove 27. This tight-fitting, crushed edge 62 forms a seal against the escape of the foam filler during its installation in the followerfirst space 44. - Figure 5 shows a DAHVL 63 similar to that of Figure 1 wherein like numerals designate like parts. Several optional features are included in a modified
follower 64. A two-piece shell 66 is provided having a thin steelouter wall 67 attached, such as by diffusion-bonding, to an alloycast iron head 68. The two-piece construction is optional and similar to prior commercial valve lifters such as that shown in the aforementioned U.S. patent 4,745,888. - A
baffle 70 similar to that of Figures 1-4 is also provided having two other modifications. Aninner wall 71 has at its upper end alip 72 extending outwards and engaging an inner side of thehead 68. The lip can assist in preventing leakage of foam into thesecond space 48 containing theHEA 16. A modifiedriser chamber 74 is also formed by providing anoutward extension 75 from the lower portions ofauxiliary walls 76 to form anenlarged inlet portion 78. This extends theriser chamber 74 outward and further reduces resistance to fluid flow from the inlet opening 28 to thesecond space 48. - In this Figure 5 embodiment, the joint between the
baffle 70 and theouter wall 67, at the location of the riserchamber inlet portion 78, is sealed against oil leakage by the close fitting of the parts and, optionally, by a crushed edge 62 forming seal means as shown in Figure 4. However, it does not have the additional sealing effect of the foam filler at this location as does the Figure 1-4 embodiment. If desired, other types of seals could be provided as seal means to control leakage at this joint. Also, such seals as resilient rings or gaskets could be used around the baffle edges to control foam leakage during filling. - Figure 6 illustrates another embodiment of
follower 80 for a DAHVL according to the present invention. Theshell 18 is optionally like that of Figure 1 but baffle 82 is modified to eliminate auxiliary walls. Instead, a lostcore 83 is applied during manufacture as shown in Figures 6-8. The core 83 fits within theannular recess 31 of theinner wall 30 ofbaffle 82 closing the upper part of thesecond space 48. Asmall radial segment 84 of the core extends through theslot 47 in thewall 30 out to theouter wall 22 and down to theflange 34 of the baffle at the inlet opening 28 to prevent the inflow offoam filler 20 to the cored volume during the filling process. The core is subsequently removed, as will be discussed later, forming ariser chamber 86 in the first space that is bordered by thefoam filler 20 and connects the inlet opening 28 with thesecond space 48. - In operation of the described embodiments, oil admitted through the opening 28 passes through the
riser chamber slot 47 andrecess 50 to thereservoir 51. From there, it is allowed to pass through the check-valved orifice 55 and to refill thepressure chamber 56 at each cycle as theHEA 16 operates to adjust the valve-lash in known manner, urging thefollower head cam 11 and the HEA piston 52 against thevalve stem 12. Then, as the rotatingcam 11 forces thefollower stem 12 andspring seat 87 against the force of thespring 88, further cam rotation again allowing the valve to close and the replacement of oil which has leaked from thepressure chamber 56. - Under warmed-up engine operation, oil flows freely into the inlet passages. However, the
riser chamber groove 60, if provided, operate to minimize the entry of oil-entrained air into thereservoir 51. - In manufacture of a lifter follower as in Figures 1-4, the
shell 18 may be cold-formed from a conventional hardenable steel with theoil groove 27 being roll-formed or machined therein as desired. - The
baffle 19 is preferably moulded of a low- mass polymer plastics material having good dimensional control, thermal expansion stability and chemical resistance. A presently preferred example is Fortron@ 6165, a highly glass-reinforced and mineral-filled polyphenylene sulphide (PPS) moulding material available from Hoechst Celanese, Engineering Plastics Division, Summit, New Jersey, U.S.A. Thegroove 60, if used, may be moulded into thecylinder 32, or thecylinder 32 andgroove 60 may be machined for clearance control if desired. - Alternatively, the
baffle 19 may be made from any suitable material which selected, for example, from among the thermoplastic and thermosetting reinforced and filled engineering plastics materials. Among the needed or desired characteristics of such baffle materials are durability in a lubricating oil environment at temperatures from -40° to 150 ° C., a coefficient of linear thermal expansion closely matched to the mating metallic components, resistance to lubricating oil contaminants and an ability to be moulded with close tolerance and low warp. - After assembly of the
baffle 19 into theshell 18, the foam filler is installed as a liquid into thefirst space 44 through a nozzle inserted into thefill hole 35 in theflange 34. The filler foams and hardens in place, with air escaping from thespace 44 through thevent hole 36. Leakage of foam into thesecond space 48 and theriser chamber 38 may be prevented if necessary by pressurizing these spaces through theinlet hole 43, the bottom of thecylinder 32 being sealed off during the process. However, the joints may be adequately sealed by engagement of the baffle and shell members, possible with the aid of crush edges such as 62 acting as seal means. - After hardening, the foam filler has sufficient strength and adhesion to retain the plastics baffle in position within the shell under engine operating conditions. A preferred selection of foam filler material is a modified polyurethane foam provided by System-Chardonol Division of Cook Composites and Polymers Co. (formerly the Freeman Chemical Company) of port Washington, Wisconsin, U.S.A. and having a mix ration of 100 parts by weight Chempol@ 030-A944-70 resin to 200 parts by weight Chempol@ 030-2416 Isocyanate.
- At present, a preferred process for assembling the lifter follower includes the following steps:
- 1. Provide a follower shell and plastics baffle as described above, both of which should be clean and dry.
- 2. Heat the shell to 66 ° C (150°F). This helps to assure proper expansion and correct physical and mechanical properties of the cured foam.
- 3. Assemble the baffle into the shell, orienting the baffle riser chamber with the shell inlet opening.
- 4. In a fixture, clamp the baffle in the shell and seal the baffle at the shell inner diameter.
- 5. Mix the two-part foam and inject through the baffle foam fill hole.
- 6. When foam expansion begins, apply air pressure to baffle interior volume to prevent foam seepage thereinto.
- 7. Heat the follower assembly with the clamped baffle at 66 ° C (150 ° F) until the foam is cured and set.
- 8. When complete, remove the baffle from the clamping fixture.
- Manufacture of the Figure 5 embodiment can be essentially as above, whilst the embodiment of Figures 6-8 differs in the previously described use of the lost
core 83. Any suitable core material can be used which can be removed after assembly of the lifter follower. Possible examples are oil or water-soluble foam materials, ice, etc. Whilst the invention has been described by reference to certain preferred embodiments, it should be understood that numerous changes could be made to the disclosed embodiments within the scope of the following claims.
Claims (15)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US87762392A | 1992-05-01 | 1992-05-01 | |
US877623 | 1992-05-01 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0568157A1 EP0568157A1 (en) | 1993-11-03 |
EP0568157B1 true EP0568157B1 (en) | 1995-03-01 |
Family
ID=25370356
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP93201203A Expired - Lifetime EP0568157B1 (en) | 1992-05-01 | 1993-04-27 | Low-mass, direct-acting hydraulic valve-lifter |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0568157B1 (en) |
JP (1) | JP2535127B2 (en) |
CA (1) | CA2094993A1 (en) |
DE (1) | DE69300068T2 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19913287A1 (en) * | 1999-03-24 | 2000-09-28 | Schaeffler Waelzlager Ohg | Lightweight mechanical valve pushrod, in which cavity of cup-shaped casing is filled with metal foam |
DE19913290A1 (en) * | 1999-03-24 | 2000-09-28 | Schaeffler Waelzlager Ohg | Switchable cam tracker for engine valve drive, with at least one web forms in sectors or completely of injectable foam material |
US6557518B1 (en) * | 2002-01-18 | 2003-05-06 | General Motors Corporation | Cylinder deactivation apparatus |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3437478A1 (en) * | 1984-10-12 | 1986-04-17 | INA Wälzlager Schaeffler KG, 8522 Herzogenaurach | AUTOMATICALLY HYDRAULICALLY ADJUSTING VALVE |
DE3623638C2 (en) * | 1986-07-12 | 1994-02-24 | Schaeffler Waelzlager Kg | Automatically hydraulic valve lifter |
DE4026793A1 (en) * | 1990-08-24 | 1992-03-05 | Freudenberg Carl Fa | HYDRAULIC VALVE COMPENSATION COMPENSATION ELEMENT FOR INTERNAL COMBUSTION ENGINES |
US5119774A (en) * | 1990-11-08 | 1992-06-09 | General Motors Corporation | Direct acting hydraulic valve lifter |
-
1993
- 1993-04-27 CA CA002094993A patent/CA2094993A1/en not_active Abandoned
- 1993-04-27 EP EP93201203A patent/EP0568157B1/en not_active Expired - Lifetime
- 1993-04-27 DE DE69300068T patent/DE69300068T2/en not_active Expired - Fee Related
- 1993-04-30 JP JP5104637A patent/JP2535127B2/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
EP0568157A1 (en) | 1993-11-03 |
DE69300068T2 (en) | 1995-08-10 |
JP2535127B2 (en) | 1996-09-18 |
CA2094993A1 (en) | 1993-11-02 |
JPH07269314A (en) | 1995-10-17 |
DE69300068D1 (en) | 1995-04-06 |
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