An intake valve for a combustion engine is described. The intake valve has a head portion that is designed to improve the flow of air-fuel mixture around the head portion and into the combustion chamber. The head portion has a beveled or rounded edge at the top surface. The angle changes from the underside surface to the top surface are rounded to prevent separation of the air-fuel mixture from the surface of the intake valve. In addition, the underside surface of the head portion has a plurality of helical grooves that induce a circular flow to improve mixing of the air-fuel mixture in the chamber. The helical grooves also improve heat exchange between the air-fuel mixture and the intake valve.

A hollow poppet valve (10) has an internal cavity (S) which comprises a diametrically large valve head cavity (S1) formed in a valve head (14) and a diametrically small stem cavity (S2) formed in a stem (12) in communication with the valve head cavity (S1). The stem cavity has a diametrically larger first portion (S21) near the end of the stem and a diametrically smaller second portion (S22) near the valve head. A step (17) is formed at the boundary of the first and the second portion of the stem cavity (S2). The internal cavity is loaded with a coolant to a level above the step, together with an inert gas. In response to a reciprocal motion of the valve, turbulent flows of coolant (F9) are created in the neighborhood of the step (17), facilitating active stirring of the coolant (19) in the cavity (S).

An improved membrane valve and method for manufacturing such membrane valve. The improved membrane valve can be used for transferring fluids or gases in hermetic or semi-hermetic compressors, including a method and system for manufacturing a membrane valve and a membrane valve with applications for use in several motors, particularly in hermetic or semi-hermetic compressors which use, as a refrigeration fluid, an appropriate type of gas thus promoting the refrigeration physical affect. A body and a membrane of the membrane valve are produced from substantially thin metallic plates separately in accordance to an available process and can be subjected to rounding in order to eliminate live corners, and then juxtaposed thus composing the valve, with the above mentioned membrane on one side, fitted to the body which is fixed through a connection process and, on the other side, left free to oscillate.