Three-position stop type swing actuator

A three-position stop type swing actuator comprising:

• a casing;
• a main piston disposed in the casing to move in forward and backward directions due to a fluid pressure;
• an output shaft connected coaxially with said main piston and configured to rotate around an axis of the output shaft;
• a converting mechanism configured to convert a forward and backward motion of said main piston into a rotating and swinging motion of said output shaft;
• and
• a sub piston disposed in said casing to move said main piston less than a full stroke of said main piston in the forward direction;
• wherein:
• said converting mechanism comprises one of a first converting device configure to convert the forward and backward motion of said main piston into a rotating and swinging motion of the main piston and a second converting device configured to convert the forward and backward motion of said main piston into the rotating and swinging motion of said output shaft;
• said first converting device comprises at least one spiral groove formed on an outer periphery of said main piston and at least one pin fitted to said casing so as to be fitted to said at least one spiral groove;
• and
• said second converting device comprises one of a spiral groove formed on an outer periphery of said output shaft fitted with a pin fixed to said main piston and a screw with a lead angle larger than 45 degrees formed on the outer periphery of said output shaft meshed with a nut formed in the main piston.

A three-position stop type swing actuator comprising:

• a first cylinder hole provided within a casing in such a manner as to be communicated with each other, and having a small diameter and a large length in an axial direction;
• a second cylinder hole having a large diameter and a short length in an axial direction;
• a main piston arranged within said first cylinder hole in such a manner as to freely move in forward and backward directions in an axial direction;
• a sub piston having a large diameter portion sliding in an airtight manner within said second cylinder hole, and a small diameter portion sliding in an airtight manner within said first cylinder hole, and restricting a middle stop position of said main piston by said small diameter portion being brought into contact with said main piston;
• a first pressure chamber formed in one end surface side of said main piston;
• a second pressure chamber formed between another end surface of said main piston and a small diameter portion of said sub piston;
• a third pressure chamber formed in a side of a large diameter portion of said sub piston;
• an output shaft placed at a coaxial position with said main piston in said casing in such a manner as to be fixed in an axial direction and freely rotate around an axis;
• and
• a conversion and transmission mechanism converting a forward and backward motion of said main piston into a rotating and swinging motion of said output shaft so as to transmit to said output shaft.

A three-position stop type swing actuator comprising:

• a main piston arranged within a casing in such a manner as to freely move in forward and backward directions due to a fluid pressure;
• an output shaft placed at a coaxial position with said main piston in such a manner as to be fixed in an axial direction and freely rotate around an axis;
• a conversion and transmission mechanism converting a forward and backward motion of said main piston into a rotating and swinging motion of said output shaft so as to transmit to said output shaft;
• and
• a sub piston for restricting a middle stop position of said main piston, said sub piston having a stroke smaller than that of said main piston, a fluid pressure operating force larger than that of said main piston, and arranged within said casing in such a manner as to freely move in the forward and backward directions due to the fluid pressure and be capable of being brought into contact with said main piston;
• wherein:
• said conversion and transmission mechanism includes at least one of first converting means converting a forward and backward motion of said main piston into a rotating and swinging motion of said main piston and second converting means converting the forward and backward motion of said main piston into the rotating and swinging motion of said output shaft;
• and
• said first converting means is constituted by a spiral groove formed on an outer periphery of said main piston and a pin fitted to said casing so as to be fitted to said spiral groove, and said second converting means is constituted by a spiral groove formed on an outer periphery of said output shaft and a pin fixed to said main piston so as to be fitted to said spiral groove.

A three-position stop type swing actuator comprising:

• a main piston arranged within a casing in such a manner as to freely move in forward and backward directions due to a fluid pressure;
• an output shaft placed at a coaxial position with said main piston in such a manner as to be fixed in an axial direction and freely rotate around an axis;
• a conversion and transmission mechanism converting a forward and backward motion of said main piston into a rotating and swinging motion of said output shaft so as to transmit to said output shaft;
• and
• a sub piston for restricting a middle stop position of said main piston, said sub piston having a stroke smaller than that of said main piston a fluid pressure operating force larger than that of said main piston, and arranged within said casing in such a manner as to freely move in the forward and backward directions due to the fluid pressure and be capable of being brought into contact with said main piston;
• wherein:
• said conversion and transmission mechanism includes at least one of first converting means converting a forward and backward motion of said main piston into a rotating and swinging motion of said main piston and second converting means converting the forward and backward motion of said main piston into the rotating and swinging motion of said output shaft;
• and
• said first converting means comprises a spiral groove formed on an outer periphery of said main piston and a pin fitted to said casing so as to be fitted to said at least one spiral groove, and said second converting means comprises a screw having a lead angle larger than 45 degrees and formed on the outer periphery of said output shaft, and a nut formed in the main piston and meshed with the screw.