Hydraulic valve lifter for reciprocating internal combustion engines

Claim 2

An improved hydraulic valve lifter of the type having a lifter body with an axial bore, a base of the lifter body, a cam following face on the base for engagement by the lobe of a cam, a plunger axially displaceable within the axial bore of the lifter body between a first position close to the base of the lifter body and a second position remote from the base, the plunger being for acting on a push rod, a fluid receiving cavity in the axial bore of the lifter body and in series force relationship between the lifter body base and the plunger, and means for providing fluid to the fluid receiving cavity to lift the plunger in the axial bore of the lifter body, the improvement which comprises; a leak path means between the fluid receiving cavity and the outside of the valve lifter through the base of the lifter body and the cam following face, the leak path means being sufficient to prevent the cavity from filling with fluid from the fluid providing means during low to moderate engine speeds and thereby preventing the plunger from reaching its second position, but being restricted enough to allow the cavity to fill with fluid from the fluid providing means at a predetermined, greater engine speed and to thereby force the plunger into its second position.

Claim 3

The improvement claimed in claim 1 wherein the leak path is defined by a constantly open passage through the base opening where the cam lobe engages the cam following face.

Claim 4

An improved hydraulic valve lifter comprising: a. a lifter body having an axial bore, a base of the body at the bottom of the bore, and a cam follower face on the base for the lobe of a cam to engage; b. a plunger translationally disposed in the axial bore and having a first cavity therein, the bottom of the plunger defining with the wall of the axial bore of the lifter body and the base of the lifter body a second cavity for receipt of fluid passed from the first cavity, the fluid in the second cavity being to act in series in a valve train between the plunger and the lifter body and to translate the plunger in the axial bore from a first position proximate the base and a second, elevated position remote from the base; c. a check valve between the first and second cavities to pass the fluid from the first cavity to the second cavity and to prevent fluid from flowing from the second cavity to the first cavity; d. a plunger return spring between the body and the plunger to urge the plunger into an elevated position within the bore of the body; e. a push rod seat on the plunger for engaging a push rod; f. means for retaining the push rod seat, plunger, check valve and return spring in the bore of the body; and g. a leak path means between the second cavity and the outside of the valve lifter through the cam follower base to provide a controlled leak from the second cavity and prevent the second cavity from filling with the fluid passed from the first cavity and lifting the plunger to its fully elevated position during predetermined low to moderate engine speeds and to permit such filling of the second cavity above the predetermined engine speed to raise the plunger to its fully elevated position and provide the maximum effective length of the valve lifter.

Claim 5

An improved hydraulic valve lifter comprising: a. a lifter body having an axial bore, a base of the body at the bottom of the bore, and a cam follower face on the base for the lobe of a cam to engage; b. a plunger translationally disposed in the axial bore and having a first cavity therein, the bottom of the plunger defining with the wall of the axial bore of the lifter body and the base of the lifter body a second cavity for receipt of fluid passed from the first cavity, the fluid in the second cavity being to act in series in a valve train between the plunger and the lifter body and to translate the plunger in the axial bore from a first position proximate the base and a second, elevated position remote from the base; c. a check valve between the first and second cavities to pass the fluid from the first cavity to the second cavity and to prevent fluid from flowing from the second cavity to the first cavity; d. a plunger return spring between the body and the plunger to urge the plunger into an elevated position within the bore of the body; e. a push rod seat on the plunger for engaging a push rod; f. means for retaining the push rod seat, plunger, check valve and return spring in the bore of the body; and g. a leak path means between the second cavity and the outside of the valve lifter through the cam follower base to provide a controlled leak from the second cavity and prevent the second cavity from filling with the fluid passed from the first cavity and lifting the plunger to its fully elevated position during predetermined low to moderate engine speeds and to permit such filling of the second cavity above the predetermined engine speed to raise the plunger to its fully elevated position and provide the maximum effective length of the valve lifter.

Claim 6

The improved hydraulic valve lifter claimed in claim 3 wherein the leak path is a constantly open passage through the base for providing lubrication for the cam lobe and valve lifter at the interface between the two.