Composite tappet

Claim 2

A composite engine part, comprising: a metal cam-engaging shim providing a cam seat for abuttingly engaging and being driven by an overhead cam; a thermoplastic, amide-imide resinous polymeric tappet having a disc with a top defining a countersunk recess for receiving said cam-engaging shim and a bottom providing a valve seat for abuttingly engaging and reciprocatingly driving a valve, an elongated annular skirt depending downwardly from said disc and cooperating with said valve seat to provide a valve-spring receiving chamber for receiving a valve spring retainer, and an annular rim providing a cam guide rail extending integrally upwardly from said disc in a direction generally opposite said skirt to substantially contain said cam, said cam-guide rail cooperating with said top of said disc and said cam-engaging shim to form a composite cam seat chamber; and said amide-imide tappet and said cam-engaging shim maintaining their structural shapes, integrity and relationship at engine operating conditions.

Claim 3

A composite engine part in accordance with claim 1 wherein said skirt and said rim have flush outer surfaces in coplanar alignment with each other for reciprocatingly sliding against a cylinder wall and said upwardly-extending cam-guide rail defines a pair of diametrically-opposed oil grooves.

Claim 4

A composite engine part in accordance with claim 1 wherein said metal comprises aluminum.

Claim 5

A composite engine part in accordance with claim 1 wherein said metal comprises steel.

Claim 6

A composite engine part in accordance with claim 1 wherein said tappet comprises a reaction product of a trifunctional carboxylic acid compound and at least one diprimary aromatic diamine.

Claim 7

A composite engine part in accordance with claim 5 wherein said tappet comprises at least one of the following moieties: ##STR10## wherein one carbonyl group is meta to and one carbonyl group is para to each amide group and wherein Z is a trivalent benzene ring or lower-alkyl-substituted trivalent benzene ring, R 1 and R 2 are different and are divalent aromatic hydrocarbon radicals of from 6 to about 10 carbon atoms or two divalent aromatic hydrocarbon radicals of from 6 to about 10 carbon atoms joined directly or by stable linkages selected from the group consisting of --O--, methylene, --CO--, --SO 2 --, and --S-- radicals and wherein said R 1 and R 2 containing units run from about 10 mole percent R 1 containing unit and about 90 mole percent R 2 containing unit to about 90 mole percent R 1 containing unit and about 10 mole percent R 2 containing unit.

Claim 8

A composite engine part in accordance with claim 6 wherein R 1 is ##STR11##

Claim 9

A composite engine part in accordance with claim 6 wherein Z is a trivalent benzene ring, R 1 is ##STR12## and wherein the concentration range runs from about 30mole percent of the R 1 containing units and about 70 mole percent of the R 2 containing units to about 70 mole percent of the R 1 containing units and about 30 mole pecent of the R 2 containing units.

Claim 10

A composite engine part in accordance with claim 6 wherein said tappet comprises from 40% to 100% by weight amide-imide resinous polymer.

Claim 11

A composite engine part in accordance with claim 9 wherein said tappet comprises from 65% to 75% by weight amide-imide resinous polymer.

Claim 12

A composite engine part in accordance with claim 6 wherein said tappet comprises a fibrous reinforcing material selected from the group consisting essentially of graphite and glass.

Claim 13

A composite engine part in accordance with claim 11 wherein said tappet comprises from 10% to 50% by weight graphite.

Claim 14

A composite engine part in accordance with claim 12 wherein said tappet comprises from 30% to 34% by weight graphite.

Claim 15

A composite engine part in accordance with claim 11 wherein said tappet comprises 10% to 60% by weight glass.

Claim 16

A composite engine part in accordance with claim 14 wherein said tappet comprises 30% to 34% by weight glass.

Claim 17

A composite engine part in accordance with claim 11 wherein said fibrous reinforcing material has a polymeric sizing that substantially maintains its structural integrity at engine operating conditions.

Claim 18

A composite engine part in accordance with claim 11 wherein said tappet comprises not greater than 3% by weight polytetrafluoroethylene.

Claim 19

A composite engine part in accordance with claim 17 wherein said tappet comprises from 1/2% to 1% by weight polytetrafluoroethylene.

Claim 20

A composite engine part in accordance with claim 11 wherein said tappet comprises not more than 6% by weight titanium dioxide.

Claim 21

A process for forming a composite engine part, comprising the steps of: inserting a core in a generally tappet-shaped cavity of a mold providing a die to define a generally tappet-shaped molding chamber; injection molding a thermoplastic, amide-imide resinous polymer to form a generally tappet-shaped blank having an annular skirt for receiving a valve-spring retainer, a generally circular disc extending across said skirt, and a cam-guide rail extending generally opposite said skirt for substantially containing a cam, said injection molding including injecting said amide-imide polymer into said tappet-shaped cavity through a sprue at a location generally opposite said core to generally fill said molding chamber and substantially minimize knit lines in said amide-imide tappet-shaped blank; allowing said tappet-shaped blank to cool below its plastic deformation temperature; removing said core from said die; post curing said amide-imide tappet-shaped blank by solid state polymerization to enhance the strength and integrity of said amide-imide tappet-shaped blank; countersinking a recess in said disc; and placing a metal shim in said recess to provide a cam seat for engaging said being driven by said cam.

Claim 22

A process for forming a composite engine part, comprising the steps of: inserting a core in a generally tappet-shaped cavity of a mold providing a die to define a generally tappet-shaped molding chamber; injection molding a thermoplastic, amide-imide resinous polymer to form a generally tappet-shaped blank having an annular skirt for receiving a valve-spring retainer, a generally circular disc extending across said skirt, and a cam-guide rail extending generally opposite said skirt for substantially containing a cam, said injection molding including injecting said amide-imide polymer into said tappet-shaped cavity through a sprue at a location generally opposite said core to generally fill said molding chamber and substantially minimize knit lines in said amide-imide tappet-shaped blank; allowing said tappet-shaped blank to cool below its plastic deformation temperature; removing said core from said die; post curing said amide-imide tappet-shaped blank by solid state polymerization to enhance the strength and integrity of said amide-imide tappet-shaped blank; countersinking a recess in said disc; and placing a metal shim in said recess to provide a cam seat for engaging said being driven by said cam.

Claim 23

A process in accordance with claim 20 including grinding said tappet-shaped blank, and cutting diametrically-opposed oil grooves in said cam-guide rail.

Claim 24

A process in accordance with claim 20 wherein said amide-imide polymer is prepared by reacting a trifunctional carboxylic acid compound with at least one diprimary aromatic diamine.

Claim 25

A process in accordance with claim 22 wherein said amide-imide polymer comprises one of the following moieties: ##STR13## wherein one carbonyl group is meta to and one carbonyl group is para to each amide group and wherein Z is a trivalent benzene ring or lower-alkyl-substituted trivalent benzene ring, R 1 and R 2 are different and are divalent aromatic hydrocarbon radicals of from 6 to about 10 carbon atoms or two divalent aromatic hydrocarbon radicals of from 6 to about 10 carbon atoms joined directly or by stable linkages selected from the group consisting of --O--, methylene, --CO--, --SO 2 --, and --S-- radicals and wherein said R 1 and R 2 containing units run from about 10 mole percent R 1 containing unit and about 90 mole percent R 2 containing unit to about 90 mole percent R 1 containing unit and about 10 mole percent R 2 containing unit.

Claim 26

A process in accordance with claim 23 wherein R 1 is ##STR14##

Claim 27

A process in accordance with claim 23 wherein Z is a trivalent benzene ring, R 1 is ##STR15## and wherein the concentration range runs from about 30mole percent of the R 1 containing units and about 70 mole percent of the R 2 containing units to about 70 percent of the R 1 containing units and about 30 mole percent of the R 2 containing units.

Claim 28

A process in accordance with claim 23 wherein said polymer comprises from 10% to 50% by weight graphite fibers.

Claim 29

A process in accordance with claim 26 wherein said polymer comprises from 30% to 34% by weight graphite fibers.

Claim 30

A process in accordance with claim 23 wherein said polymer comprises from 10% to 60% by weight glass fibers.

Claim 31

A process in accordance with claim 28 wherein said polymer comprises from 30% to 34% by weight glass fibers.