Lash adjuster

A lash adjuster comprising:na cylinder having a base;a plunger that is movable up and down in contact with an internal peripheral surface of the cylinder, the plunger having a base wall, and a valve hole being provided in the base wall of the plunger;a low-pressure chamber provided in the plunger;a high-pressure chamber provided in a lower end part of the cylinder;a return spring provided in the high-pressure chamber, the return spring having a coil diameter, a top section, and a bottom section; anda non-return valve that opens and closes the valve hole, wherein the low-pressure chamber holds operating oil and the high-pressure chamber is filled with the operating oil,wherein the high-pressure chamber and the low-pressure chamber are separated by the base wall of the plunger,wherein the return spring is a compression coil spring arranged in the high-pressure chamber such that a longitudinal axis of the return spring is parallel with an up-down direction,wherein the return spring biases the plunger in an upwards direction,wherein the coil diameter of the return spring is largest at an uppermost end of the return spring and becomes progressively smaller from the top section to the bottom section,wherein the non-return valve is a valve member provided in the high-pressure chamber, andwherein the valve member is a single body that includes a retainer part and an elastic bending piece, the retainer part being fixed to the base wall of the plunger and the elastic bending piece being operable to open and close the valve hole by bending in the up-down direction.

A lash adjuster comprising:na cylinder having a base;a plunger that is movable up and down in contact with an internal peripheral surface of the cylinder, the plunger having a base wall, and a valve hole being provided in the base wall of the plunger;a low-pressure chamber provided in the plunger;a high-pressure chamber provided in a lower end part of the cylinder;a return spring provided in the high-pressure chamber, the return spring having a coil diameter, a top section, and a bottom section; anda non-return valve that opens and closes the valve hole,wherein each of the low-pressure chamber and the high-pressure chamber is configured to hold operating oil,wherein the high-pressure chamber and the low-pressure chamber are separated by the base wall of the plunger,wherein the return spring is a compression coil spring arranged in the high-pressure chamber such that a longitudinal axis of the return spring is parallel with a longitudinal axis of the plunger,wherein the return spring biases the plunger in an upwards direction,wherein the coil diameter of the return spring is largest at an uppermost end of the return spring and becomes progressively smaller from the top section to the bottom section,wherein the non-return valve is a valve member provided in the high-pressure chamber, andwherein the valve member is a single body that includes a retainer part and an elastic bending piece, the retainer part being fixed to the base wall of the plunger and the elastic bending piece being operable to open and close the valve hole by bending in an up-down direction.