Patent ID: 11920686
Assignee: MAKITA CORPORATION
Field: Machine tools (Mechanical engineering)
Classification: CPC F  B | IPC B  F

Claim 0:
1. A pneumatic tool, comprising:
a chamber configured to store compressed air; and
a relief valve in fluid communication with the chamber,
wherein:
the relief valve includes:
an airflow channel that includes, in seriatim, from an inlet of the airflow channel to an outlet of the airflow channel:
an inflow channel (i) in communication with the chamber and (ii) having a first constant cross section;
a tapered section that (i) begins at an outlet of the inflow channel and (ii) has a cross-section that gradually increases from the outlet of the inflow channel to an outlet of the tapered section; and
an outflow channel that (i) begins at the outlet of the tapered section and (ii) has a second constant cross section that is larger than the first constant cross section;

a valve stem (i) configured to slide along the inflow channel and the tapered section, (ii) having an annular groove in an outer circumference of a slide portion of the valve stem that is configured to slide along the inflow channel and the tapered section and (iii) having an air release channel; and
an O-ring (i) in the annular groove and (ii) being configured to seal the inflow channel when the slide portion is in the inflow channel;
the O-ring and the airflow channel are configured such that the O-ring is in a compressed state when the O-ring is in the inflow channel and in an uncompressed state when the O-ring is in the tapered section;
wherein the air release channel includes an inlet that is open to an inner circumferential chamber of the annular groove and an outlet that is open to the outflow channel when the slide portion is in the tapered section; and
the air release channel is configured to allow at least a portion of the compressed air in the inner circumferential chamber and flowing between a wall surface of the annular groove and an inner circumferential surface of the O-ring to be discharged from the inner circumferential chamber to the outflow channel due to (i) movement of the O-ring from the inflow channel to the tapered surface and (ii) change of the O-ring from the compressed state to the uncompressed state due to an internal pressure of the chamber.