Actuator

Patent metadata

Field	Value
Publication number	US-10154895-B2
Application number	US-201615245145-A
Country	US
Kind code	B2
Filing date	Aug 23, 2016
Priority date	Aug 4, 2015
Publication date	Dec 18, 2018
Grant date	Dec 18, 2018

Abstract

The present invention provides an actuator, comprising a fiber and a temperature regulator capable of at least one of heating and cooling the fiber. The fiber is twisted around a longitudinal axis thereof. The fiber is folded so as to have a shape of a cylindrical coil. The fiber is formed of linear low-density polyethylene. The following mathematical formula (I) is satisfied: D/d<1 (I), where D represents a mean diameter of the cylindrical coil; and d represents a diameter of the fiber.

First claim

The invention claimed is:

1. An actuator, comprising:
a fiber; and
a temperature regulator capable of at least one of heating and cooling the fiber, wherein:
the fiber is twisted around a longitudinal axis thereof,
the fiber is folded so as to have a shape of a cylindrical coil,
the fiber is formed of linear low-density polyethylene,
the following mathematical formula (I) is satisfied:
D/d< 1  (I)

where
D represents a mean diameter of the cylindrical coil; and
d represents a diameter of the fiber,

the fiber has a density of not less than 0.915 g/cm 3 and not more than 0.925 g/cm 3 ,
the fiber has a weight-average molecular weight of not less than 50 kg/mol and not more than 200 kg/mol,
the fiber is composed of ethylene monomer units each represented by the chemical structural formula —(CH 2 —CH 2 ) n —, where n is a natural number, and α-olefin monomer units each represented by the chemical structural formula—(CH 2 —CHR) m —, where m is a natural number, and R represents a hydrocarbon group,
each of the α-olefin monomer units has a carbon number of not less than 4 and not more than 8, and
a molar ratio of the α-olefin monomer units to the ethylene monomer units is not less than 2.5% and not more than 3.5%.

2. The actuator according to claim 1 , wherein
the longitudinal axis of the fiber accords with a rotation direction of the cylindrical coil.

3. The actuator according to claim 1 , wherein
one end of the fiber is a fixed end; and
the other end of the fiber is extendable along an axis direction of the cylindrical coil.

4. The actuator according to claim 1 , further comprising:
a base; wherein
the base comprises a protrusion;
one end of the fiber is fixed to the protrusion; and
the other end of the fiber is extendable along an axis direction of the cylindrical coil.

5. The actuator according to claim 4 , wherein
the other end of the fiber is provided with at least one of a plate-like slider, a pulley, and a guide tube; and
the least one of the plate-like slider, the pulley, and the guide tube is slidable on the base along the axis direction of the cylindrical coil.

6. The actuator according to claim 1 , further comprising:
a base; wherein
the temperature regulator is located between the base and the fiber; and
the temperature regulator has a shape of a plate.

7. The actuator according to claim 1 , wherein
the temperature regulator comprises a controller and a metal film;
the fiber is coated with the metal film; and
the controller supplies electric energy to the metal film.

8. The actuator according to claim 7 , further comprising:
a base; wherein
the temperature regulator further comprises a Peltier element;
the Peltier element is located between the base and the fiber; and
the Peltier element has a shape of a plate.

9. The actuator according to claim 1 , wherein the following mathematical formula (I) is satisfied:
(Displacement Rate DR) ≥0.38×10 −2 /° C  (I)

where
(Displacement Rate DR) is equal to (x−y)/(x·ΔT)

where
x represents a length of the fiber along an axis direction of the cylindrical coil before the fiber is heated;
y represents a length of the fiber along the axis direction of the cylindrical coil after the fiber is heated; and
ΔT represents a temperature difference of the fiber between before and after the fiber is heated.

10. A method for extending and contracting a fiber; the method comprising:
(a) heating the fiber to contract the fiber, wherein
the fiber is twisted around a longitudinal axis thereof,
the fiber is folded so as to have a shape of a cylindrical coil,
the fiber is formed of linear low-density polyethylene,
the following mathematical formula (I) is satisfied:
D/d<1  (I)

where
D represents a mean diameter of the cylindrical coil; and
d represents a diameter of the fiber,

the fiber has a density of not less than 0.915 g/cm 3 and not more than 0.925 g/cm 3 ,
the fiber has a weight-average molecular weight of not less than 50 kg/mol and not more than 200 kg/mol,
the fiber is composed of ethylene monomer units each represented by the chemical structural formula —(Ch 2 —CH 2 ) n —, where n is a natural number, and α-olefin monomer units each represented by the chemical structural formula —(CH 2 —CHR) m —, where m is a natural number, and R represents a hydrocarbon group,
each of the α-olefin monomer units has a carbon number of not less than 4 and not more than 8,
a molar ratio of the α-olefin monomer units to the ethylene monomer units is not less than 2.5% and not more than 3.5%, and

the fiber is contracted along an axis direction of the cylindrical coil; and
(b) cooling the fiber to extend the fiber,
wherein the fiber is extended along the axis direction of the cylindrical coil.

11. The method according to claim 10 , wherein
in the step (a), the fiber is heated to a temperature of more than 30 degrees Celsius and not more than 100 degrees Celsius.

12. The method according to claim 10 , wherein
in the step (b), the fiber is cooled to a temperature of not more than 30 degrees Celsius.

13. The method according to claim 10 , wherein
the step (a) and the step (b) are repeated.

14. The method according to claim 10 , wherein
in the step (a), the following mathematical formula (I) is satisfied:
(Displacement Rate DR) ≥0.38×10 −2 /° C.  (I)

where
(Displacement Rate DR) is equal to (x−y)/(x·ΔT)

where
x represents a length of the fiber along the axis direction of the cylindrical coil before the fiber is heated;
y represents a length of the fiber along the axis direction of the cylindrical coil after the fiber is heated; and
ΔT represents a temperature difference of the fiber between before and after the fiber is heated.

Assignees

• Panasonic Ip Man Co Ltd
• Panasaonic Intellectual Property Managemeent Co Ltd

Inventors

• Hiraoka Maki
• Asai Katsuhiko
• Kaneko Yuriko
• Arase Hidekazu
• Omote Atsushi

Classifications

• B29C53/14

  Twisting {(for textile fibres D01H)} · CPC title

• B29C55/005

  characterised by the choice of materials · CPC title

• A61L2430/30

  for muscle reconstruction · CPC title

• A61F2230/0069

  cylindrical · CPC title

• B29K2023/0633

  LDPE, i.e. low density polyethylene · CPC title