Actuator and clamp device using same

Patent metadata

Field	Value
Publication number	US-9573232-B2
Application number	US-201214237410-A
Country	US
Kind code	B2
Filing date	Mar 26, 2012
Priority date	Aug 8, 2011
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

A first piston for high load is inserted into a housing so as to be movable vertically, and a second piston for low load is inserted into a cylindrical hole of the first piston so as to be movable vertically. An output portion projects from the second piston to above the housing. A first spring for high load and a second spring for low load are mounted in a spring chamber defined by both pistons and. Both springs and are mounted so as to urge the first piston and the second piston upward. A switching mechanism disposed in the pressure fluid chamber at a side opposite to the spring chamber, connects the first piston selectively to the housing or the second piston.

First claim

The invention claimed is:

1. An actuator comprising:
a first piston, for high load, inserted into a housing so as to be movable in a direction of an axis;
a second piston, for low load, movably inserted into a cylindrical hole extending through the first piston in the direction of the axis, the second piston having, at a leading end portion thereof, an output portion projecting to an outside of the housing;
a pressure fluid chamber and a spring chamber formed by partitioning an inside of the housing by the first piston and the second piston;
a first spring, for high load, mounted in the spring chamber so as to urge the first piston toward the pressure fluid chamber side and received by a wall surface of the spring chamber;
a second spring, for low load, mounted in the spring chamber so as to urge the second piston toward the pressure fluid chamber side, the second spring having a lower end received by a lower wall of the housing; and
a switching mechanism having a plurality of engagement members arranged along an outer periphery of the second piston so as to be spaced apart from each other at predetermined intervals in a circumferential direction, the switching mechanism being disposed in the pressure fluid chamber so as to connect the first piston selectively to the housing or the second piston via the engagement members, wherein
the switching mechanism includes:
an outer peripheral straight surface and an engagement groove provided in an outer peripheral surface of the second piston in order from the pressure fluid chamber side toward the spring chamber side;
a first pressing portion provided in the first piston so as to press the engagement members toward the pressure fluid chamber side;
a second pressing portion provided in a peripheral wall of the pressure fluid chamber so as to receive therein the engagement members that are in a state of being in contact with the outer peripheral straight surface, the second pressing portion engaging the engagement members with the engagement groove when the second piston advances toward the pressure fluid chamber side; and
an inner peripheral straight surface provided in the peripheral wall of the pressure fluid chamber so as to come into contact with the engagement members that are in a state of being engaged with the engagement groove, and
the switching mechanism is configured such that the first piston is connected to the second piston via the engagement members and the connection between the first piston and the housing is releasable to allow the first piston to move in the direction of the axis relative to the housing when the second spring advances the second piston toward the pressure fluid chamber side by a predetermined stroke in a state where the first piston is connected so as to be received by the housing via the engagement members, during an actuator operating period when a pressure fluid in the pressure fluid chamber is discharged.

2. The actuator according to claim 1 , wherein
the engagement members are composed of engagement balls,
the first pressing portion has a first contact surface which comes into contact with each engagement ball from the spring chamber side,
the second pressing portion has a second contact surface which comes into contact with each engagement ball from the pressure fluid chamber side, and
an intersection angle of the first contact surface and the second contact surface is opened toward the second piston and is set within a range of 10 degrees to 25 degrees.

3. A clamp device using the actuator according to claim 2 , wherein the output portion projects in a direction toward the pressure fluid chamber,
a base portion of a clamp arm in a longitudinal direction thereof is supported by the leading end portion of the output portion so as to be swingable in a plane including the axis, and
one end portion of a link member is rotatably supported by a middle portion of the clamp arm in the longitudinal direction thereof, and another end portion of the link member is rotatably supported by the housing.

4. A clamp device using the actuator according to claim 2 , wherein the output portion projects in a direction toward the spring chamber, and
a clamp arm is fixed to the leading end portion of the output portion.

5. A clamp device using the actuator according to claim 1 , wherein the output portion projects in a direction toward the pressure fluid chamber,
a base portion of a clamp arm in a longitudinal direction thereof is supported by the leading end portion of the output portion so as to be swingable in a plane including the axis, and
one end portion of a link member is rotatably supported by a middle portion of the clamp arm in the longitudinal direction thereof, and another end portion of the link member is rotatably supported by the housing.

6. A clamp device using the actuator according to claim 1 , wherein the output portion projects in a direction toward the spring chamber, and
a clamp arm is fixed to the leading end portion of the output portion.

7. An actuator comprising:
a first piston, for high load, inserted into a housing so as to be movable in a direction of an axis;
a second piston, for low load, movably inserted into a cylindrical hole extending through the first piston in the direction of the axis, the second piston having, at a leading end portion thereof, an output portion projecting to an outside of the housing;
a pressure fluid chamber and a spring chamber formed by partitioning an inside of the housing by the first piston and the second piston;
a first spring, for high load, mounted in the spring chamber so as to urge the first piston toward the pressure fluid chamber side and received by a wall surface of the spring chamber;
a second spring, for low load, mounted in the spring chamber so as to urge the second piston toward the pressure fluid chamber side, the second spring having a lower end received by a lower wall of the housing; and
a switching mechanism having a plurality of engagement balls arranged along an outer periphery of the second piston so as to be spaced apart from each other at predetermined intervals in a circumferential direction, the switching mechanism being disposed in the pressure fluid chamber so as to connect the first piston selectively to the housing or the second piston via the engagement balls, wherein
the switching mechanism includes:
an outer peripheral straight surface and an engagement groove provided in an outer peripheral surface of the second piston in order from the pressure fluid chamber side toward the spring chamber side;
a first pressing portion provided in the first piston so as to press the engagement balls toward the pressure fluid chamber side;
a second pressing portion provided in a peripheral wall of the pressure fluid chamber so as to receive therein the engagement balls that are in a state of being in contact with the outer peripheral straight surface, the second pressing portion engaging the engagement balls with the engagement groove when the second piston advances toward the pressure fluid chamber side;
an inner peripheral straight surface provided in the peripheral wall of the pressure fluid chamber so as to come into contact with the engagement balls that are in a state of being engaged with the engagement groove; and
U-shaped grooves are formed in an upper portion of the first pressing portion so as to extend in a radial direction and be spaced apart from each other at predetermined intervals in the circumferential direction, and first contact surfaces that are in contact with the engagement balls from the spring chamber side are formed of bottom surfaces of the grooves, and
the switching mechanism is configured such that the first piston is connected to the second piston via the engagement bal

Assignees

• Yokota Hideaki
• Yonezawa Keitaro
• Kosmek Ltd

Inventors

• Yokota Hideaki
• Yonezawa Keitaro

Classifications

• B25B5/04 Primary

  with pivoted jaws · CPC title

• B25B5/062

  with clamping means pivoting around an axis parallel to the pressing direction · CPC title

• F15B15/204

  Control means for piston speed or actuating force without external control, e.g. control valve inside the piston (F15B11/02, F15B15/22 take precedence) · CPC title

• B25B5/06

  Arrangements for positively actuating jaws · CPC title

• B25B5/061

  with fluid drive (B25B5/087, B25B5/122 take precedence) · CPC title