Patent ID: 6125886
Filing Date: 2000-10-03
Classification: F15B,F16K,Y10T

Abstract:
A pilot valve comprising:a valve body having a spring chamber and a spool hole communicating therewith;a push rod movably attached to the valve body;a fluid chamber, at least a part of which is formed in the valve body;a spool movably attached to the spool hole, one end surface of the spool forming a portion of an interior surface of the fluid chamber;a spring bearing member movably provided in the spring chamber relatively to the valve body;a first spring member provided between the valve body and the spring bearing member for elastically biasing the push rod in a projecting position through the spring bearing member;a second spring member provided between the spring bearing member and the spool for elastically biasing the spool in a direction apart from the push rod; andan operation lever for pressing the push rod,the spool including:a first spool portion having a small pressure receiving area of a pressure receiving part;a second spool portion having a large pressure receiving area of a pressure receiving part; anda notch provided between the first spool portion and the second spool portion,the pilot valve having a structure in which when the push rod is set in the projecting position, the first spool portion of the spool blocks communication of a primary pressure side passage with a secondary pressure side passage and the notch of the spool causes the secondary pressure side passage to communicate with a tank passage, and when the push rod is pressed by the operation lever, the spool is moved by action of the second spring member, the notch of the spool causes the primary pressure side passage to communicate with the secondary pressure side passage, and a pressure fluid flowing in the secondary pressure side passage acts on the pressure receiving parts of the first and second spool portions,wherein the fluid chamber is provided on an outside of one end of the spool, the fluid chamber communicating with a tank line through a throttle passage having a throttle portion.