JPWO2019021604A1 - METHOD OF DRIVING ACTUATOR, ACTUATOR, AND METHOD OF MANUFACTURING ACTUATOR - Google Patents

Abstract

The present invention is a method for driving an actuator (1), comprising the following steps (a) and (b): (a) a step of applying tension to the actuator (1), wherein the actuator ( 1) comprises a fiber (110) and a cord (120), the fiber (110) being twisted around its long axis, the fiber (110) having the shape of a cylindrical coil The fiber (110) is shrunk along the central axis direction of the coil by heating and restored by heat dissipation, and the fiber (110) is formed of a crystalline polymer, and the fiber (110 ) Is fixed to one end of the cord (120), the other end of the fiber (110) is fixed to the other end of the cord (120), and the cord (120) is fixed to the fiber (110). Longer than natural length, tension Applied along the central axis of the coil such that the length of the fiber (110) is equal to the length of the cord (120), and (b) heating the fiber (110) The process of contracting. Thereby, the actuator (1) contracts at the time of heating at a predetermined contraction rate each time.

Description

  The present invention relates to a method of driving an actuator, an actuator, and a method of manufacturing the actuator.

  U.S. Pat. No. 5,956,015 discloses twist and pull actuators for coiled and non-coiled nanofiber yarns and polymer fibers.

  Non-Patent Document 1 discloses a coiled polymer fiber formed of linear low density polyethylene. According to Non-Patent Document 1, the coiled polymer fiber is shrunk by heating and restored by heat radiation. In Non-Patent Document 1, tension is applied to a coiled polymer fiber along its axial direction before heating, and the degree of contraction of the coiled polymer fiber at the time of heating depends on the magnitude of the applied tension (ie, heating It is disclosed that the length of the contracted coiled polymer fiber / the length of the restored actuator body due to heat radiation is different.

  U.S. Pat. No. 5,958,015 discloses an axially retractable actuator.

  Patent Document 3 discloses a shape memory alloy actuator and a massager. In the paragraph No. 0020 of Patent Document 3, it is disclosed that the actuator is provided with a cord-like stopper member made of an inelastic body that regulates the distance of the engagement portion of the rod-like member in the pressure application direction.

International Publication No. 2014/022667 U.S. Pat. No. 4,733,603 JP 2005-155388 A Patent No. 6111438 gazette

Maki Hiraoka et. al. “Power-efficient low-temperature woven coiled fiber actuator for wearable applications” Scientific Reports volume 6, Article number: 36358 (2016)

  An object of the present invention is to provide a method of driving an actuator that contracts upon heating with a predetermined contraction rate each time.

The method of driving an actuator according to the invention comprises the following:
A method of driving an actuator, comprising:
(A) applying tension to the actuator;
here,
The actuator comprises a fiber and a cord,
The fibers are twisted around their longitudinal axis,
The fibers are folded to have the shape of a cylindrical coil,
The fiber is shrunk along the central axis direction of the coil by heating, and restored by heat radiation,
The fiber is formed of a crystalline polymer,
One end of the fiber is fixed to one end of the cord,
The other end of the fiber is fixed to the other end of the cord,
The cord is longer than the natural length of the fiber,
Here, the natural length is a length of the fiber restored by heat radiation and not applied with the tension;
The tension is applied along the central axis of the coil such that the length of the fiber is equal to the length of the cord;
And (b) heating the fibers to shrink the fibers.

  In use of the actuator according to the invention, tension is applied to the coiled polymer fiber. The elongation of the coiled polymer fiber before heating depends on the tension. The shrinkage of coiled polymer fibers also depends on the tension.

  When tension is applied to the coiled polymer fiber along the central axis of the coil, the cord functions as a stopper, and the length of the coiled polymer fiber is equal to the length of the cord. Therefore, a constant tension is applied to the coiled polymer fiber each time before heating. Therefore, each time, the coiled polymer fiber shrinks at the same shrinkage rate upon heating. As a result, the actuator is always displaced by the same amount of contraction each time during heating.

  On the other hand, in the absence of cords, the tension applied to the coiled polymer fiber prior to heating can be different each time. Therefore, each time, the coiled polymer fiber does not necessarily shrink at the same shrinkage rate during heating. As a result, the actuator is not always displaced by the same amount of contraction each time during heating.

  The present invention provides a method of driving an actuator that contracts upon heating each time with a predetermined contraction rate.

FIG. 1 shows a schematic view of the actuator 1 according to the first embodiment. FIG. 2A shows a schematic view of the fiber 110 whose one end is fixed to the ceiling 170. FIG. 2B shows a schematic view of the fiber 110 with the weight 180 attached to the other end. FIG. 2C shows a schematic view of the fiber 110 during heating. FIG. 3 is a graph showing an example of the relationship between tension and contraction rate. FIG. 4A shows a schematic view of the actuator 1 whose one end is fixed to the ceiling 170. FIG. 4B shows a schematic view of the actuator 1 to which the tension 400 is applied. FIG. 4C shows a schematic view of the actuator 1 at the time of heating. FIG. 5 shows a schematic view of the actuator 1 according to the second embodiment. FIG. 6 shows a schematic view of a massage device 6 according to a third embodiment. FIG. 7A shows a schematic view of a state where the massage device 6 is attached to the thigh 800 before heating. FIG. 7B shows a schematic view of a state where the massage device 6 is attached to the thigh 800 at the time of heating. FIG. 8 shows a schematic view of a massage device 6 according to the fourth embodiment. FIG. 9A shows a schematic view of untwisted and unfolded fiber 9111a. 9B is a schematic view showing a cross section of the fiber 9111a taken along line 9B-9B in FIG. 9A. FIG. 10A is a schematic view showing the state of the fiber 110 before heating in the TMA device. FIG. 10B is a schematic view showing the state of the fiber 110 at the time of heating in the TMA device. FIG. 11 shows a schematic view of a test apparatus used in the evaluation of cycle characteristics. FIG. 12 shows a schematic view of a twisted and folded fiber 9111 c in Patent Document 4. FIG. 13A shows a schematic view of a crystalline polymer to which no tension is applied. FIG. 13B shows a schematic view of a crystalline polymer under tension.

First Embodiment
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic view of the actuator 1 according to the first embodiment. The actuator 1 according to the first embodiment includes a fiber 110, a cord 120, a first fixed terminal 130a, and a second fixed terminal 130b.
(Method of manufacturing actuator 1)
Hereinafter, a method of manufacturing the actuator 1 according to the present invention will be described.

  For details of the method of manufacturing the fiber 110, refer to Patent Document 4 prior to the present patent application. Patent document 4 (i.e. patent 6111438), U.S. patent application 15 / 245,145 corresponding to patent document 4, Chinese patent application 201680000857.0, and European patent application 16767126.2 are incorporated herein by reference. The fiber 110 is disclosed in Non-Patent Document 1. The term "fibers 110" as used herein corresponds to the term "fibers" as used in said patent.

  The code 120 is prepared as follows.

  First, as shown in FIG. 2A, one end of the fiber 110 is fixed to the ceiling 170. The fibers 110 are made of a crystalline polymer.

  Next, as shown in FIG. 2B, a weight 180 is attached to the other end of the fibers 110. Thereby, tension T1 is applied to the fiber 110. The length L11 of the fiber 110 at this time is measured.

  Next, as shown in FIG. 2C, when the fibers 110 are heated using the heater 301, the fibers 110 shrink. The length L21 of the fiber 110 at this time is measured. As the heater 301, for example, a heater using near infrared radiation or a hot air blower which blows hot air on a coil can be used.

  The shrinkage factor D1 (i.e., L21 / L11) is calculated based on the length L21 of the fiber 110.

  In this way, the relationship between tension T1 and shrinkage D1 is investigated.

  Similarly, for each of a plurality of tensions (T2, T3, T4, ...) different from the tension T1, the relationship between the tension and the contraction rate is examined.

  From the above, the relationship between tension and contraction rate is grasped. Table 1 shows an example of the relationship.

  FIG. 3 is a graph showing an example of the relationship between tension and contraction rate.

  The contraction rate of the fiber 110 is considered to have a local minimum value at a certain tension (T3 in FIG. 3), as shown in FIG. This is because if the tension is too small or the tension is too large, it is considered that the contraction rate of the fiber 110 is large. Here, "the contraction rate of the fiber 110 is large" means that the contraction amount of the fiber 110 at the time of heating is small with respect to the length of the fiber 110 to which the tension before heating is applied.

  If the tension is too low, the gaps between the coils of the fibers 110 having a coil shape are narrow. Therefore, it is considered that there is little room for the fibers 110 to shrink when the fibers 110 are heated, and the shrinkage rate of the fibers 110 is large.

  FIG. 13A shows a schematic view of the crystalline polymer in the fiber 110 where no tension is applied. The fibers 110 are made of a crystalline polymer. The crystalline polymer includes crystals 1301 of the crystalline polymer, and a polymer chain 1302 which is an amorphous component connecting the crystals 1301 with each other. The fiber 110 contracts using the thermal movement of the polymer chain 1302 as a driving source. As shown in FIG. 13A, in the untensioned state, the polymer chain 1302 is slack.

  FIG. 13B shows a schematic view of the crystalline polymer in the fiber 110 to which an excessive tension (T6 in FIG. 3) is applied. When the tension is too high, the polymer chains 1302 connecting the crystals 1301 are not loosened, and the polymer chains 1302 are stretched. This restricts the movement of the polymer chain 1302, and the shrinkage factor of the fiber 110 is considered to be large.

  Next, referring to Table 1, the length of the cord 120 is determined according to the predetermined contraction rate (ie, the desired contraction rate). For example, when the contraction rate D1 is selected as a desired contraction rate, the cord 120 having a sufficient length is cut to prepare a cord 120 having a length of L11. As described above, the cord 120 whose length is adjusted is obtained based on the contraction rate of the fiber 110 when the fiber 110 to which tension is applied in advance is heated.

  Next, both ends of the cord 120 are fixed to both ends of the fiber 110 using the first fixed terminal 130 a and the second fixed terminal 130 b (for example, round crimp terminals).

  Thus, the actuator 1 shown in FIG. 1 is obtained.

(Fiber 110)
For details of the fibers 110, refer to US Pat.

  As disclosed in that patent, the fibers 110 can be comprised of coiled polymeric fibers formed from linear low density polyethylene.

  The fiber 110 having the shape of a coil is shrunk along the central axis of the coil by heating and is restored by heat dissipation. In other words, the fibers 110 are reversibly stretchable. As an example, when the fiber 110 applied with a stress of 10 MPa at its one end is heated to 90 degrees Celsius, the fiber 110 shrinks by about 23%. As the fibers 110 cool to room temperature, the fibers 110 recover to their original length. As also disclosed in Patent Document 4, the fibers 110 can be heated to a temperature of, for example, 30 degrees Celsius or more and 100 degrees Celsius or less. Unlike the disclosure of Patent Document 4, in the present invention, as long as the fiber 110 having a coil shape can be produced by twisting, crystalline polymer other than linear low density polyethylene as a material of the coiled polymer fiber Can also be used. For example, the material of the coiled polymer fiber may be polyethylene (eg, low density polyethylene or high density polyethylene), nylon (eg, nylon 6, nylon 6, 6 or nylon 12) or polyester.

(Code 120)
The cords 120 are provided adjacent to the fibers 110.

  The cord 120 is longer than the natural length of the fiber 110. Here, the natural length of the fiber 110 means the length of the fiber restored by heat radiation and to which no tension is applied. As mentioned above, the length of the cord 120 is adjusted based on the shrinkage factor of the fiber 110 when the fiber 110 to which tension is previously applied is heated.

  The cord 120 is made of a material that does not substantially stretch by application of tension or heating. Here, “substantially does not expand and contract” means that the amount of expansion and contraction of the cord 120 is as small as negligible as compared with the amount of expansion and contraction of the fiber 110. The cords 120 include, for example, electric wires, metal wires, or threads.

(First Fixed Terminal 130a and Second Fixed Terminal 130b)
The first fixing terminal 130 a is used to fix one end of the fiber 110 to one end of the cord 120. Similarly, the second fixed terminal 130 b is used to fix the other end of the fiber 110 to the other end of the cord 120.

For example, a fork type crimp terminal or a round crimp terminal may be used as the first fixed terminal 130a and the second fixed terminal 130b.
(Method of driving actuator 1)
First, as shown in FIG. 4A, the first fixed terminal 130a is fixed to the ceiling 170.

  Next, as shown in FIG. 4B, tension 400 is applied to the fiber 110 along the central axis direction of the coil of the fiber 110 so that the length of the fiber 110 is equal to the length of the cord 120. Ru. At this time, the code 120 is stretched. FIG. 4B shows a case where a cord 120 having a length of L11 is used. That is, according to Table 1, FIG. 4B shows the case where D1 is selected as the desired contraction rate.

  Next, as shown in FIG. 4C, the fibers 110 are heated by the heater 301, and the fibers 110 contract along the central axis direction of the coil. At this time, the cord 120 is loosened. According to Table 1, the length of the fiber 110 at this time is L21, and a desired contraction rate D1 is obtained.

  Then, when the heating is stopped, the fibers 110 expand along the central axis direction of the coil due to heat radiation, and return to the original shape shown in FIG. 4B. In other words, the fibers 110 are restored by heat radiation.

  These contractions and restorations can be repeated.

  As described above, by stretching the fiber 110 before heating the fiber 110 so that the length of the fiber 110 is equal to the length of the cord 120, a constant tension is applied to the fiber 110 each time before heating. . Therefore, each time, the fibers 110 shrink at the same shrinkage rate during heating. As a result, each time the actuator 1 is heated, it is displaced by the same displacement every time.

  If the length of the fiber 110 before heating is approximately equal to the length of the cord 120, that is, even if the cord 120 is slightly loose, the fiber 110 shrinks when the fiber 110 is heated with a desired shrinkage ratio. Here, “the cord 120 is slightly loose” means that the length of the cord 120 in the direction of the central axis of the coil is 98% or more of the length when the cord 120 is stretched, and the cord It means that 120 is smaller than its length when stretched.

Of course, if the actuator 1 does not have a cord 120, the tensile stress may be too small or too large, and the tension applied to the fibers 110 before heating may be different each time. Therefore, the fibers 110 do not always shrink at the same shrinkage rate during heating each time. As a result, the actuator 1 is not always displaced by the same amount of contraction each time during heating.
Second Embodiment
FIG. 5 shows a schematic view of the actuator 1 according to the second embodiment. The actuator 1 according to the second embodiment further comprises a heating device.

  The heating device comprises heating wire 501 and power source 502.

  The heating wire 501 is spirally wound around the fiber 110 so as to be in contact with the outer peripheral portion of the fiber 110.

  The heating wire 501 is made of, for example, a metal or a conductive polymer. Examples of heating wire shapes are threads or thin plates. In order to increase the strength of the heating wire 501, the side surface of the heating wire 501 may be coated using a film made of a stretchable resin, for example, a thermoplastic resin.

The power source 502 is used to supply power to the heating wire 501. The heating wire 501 generates heat when power is supplied. The fibers 110 are thereby heated.
Third Embodiment
In the third embodiment, a massage device 6 equipped with the actuator 1 according to the second embodiment is described.

  FIG. 6 shows a schematic view of a massage device 6 according to a third embodiment.

  The massage device 6 comprises the actuator 1 and the coupler 601 according to the second embodiment.

  The coupler 601 comprises a pair of connectors. For example, a surface fastener may be used as the connector 601. In this case, one connecting portion 601a has a hook surface having a large number of hook-like protrusions on the surface, and the other connecting portion 601b has a loop surface having a large number of loop-like protrusions on the surface. By pressing the hook surface against the loop surface, one coupling portion 601 a is coupled to the other coupling portion 601 b. Adjustment of the connection position of the other connection portion 601 b with respect to the one connection portion 601 a is possible.

  The first fixed terminal 130a is connected to one of the connection portions 601a using, for example, a bolt and a nut (not shown). Similarly, the second fixed terminal 130 b is connected to the other connecting portion 601 b.

  The massage device 6 is worn on the human body by connecting one of the connecting portions 601 a to the other connecting portion 601 b. By stretching the fibers 110 so that the length of the fibers 110 is equal to the length of the cords 120 during installation, a constant tension is applied to the fibers 110 each time before heating. Therefore, each time, the fibers 110 shrink at the same shrinkage rate during heating. As a result, each time the actuator 1 is heated, it is displaced by the same amount of contraction each time.

  7A and 7B show the usage of the massage device 6. FIG. In FIGS. 7A and 7B, the massage device 6 is provided with six actuators 1. Moreover, in FIG. 7A and 7B, the cord 120, the 1st fixed terminal 130a, the 2nd fixed terminal 130b, the heating wire 501, and the power supply 502 are abbreviate | omitted.

  FIG. 7A shows a state in which the massage device 6 is attached to the thigh 800 before heating. The heating causes the fibers 110 of each actuator 1 to contract. As a result, as shown in FIG. 7B, a force is generated to tighten the thigh 800 toward the inside of the thigh 800.

  It should be noted that if the length of the fiber 110 before heating is approximately equal to the length of the cord 120, that is, even if the cord 120 is slightly loose, the fiber 110 shrinks when the coil is heated with a desired shrinkage ratio. In addition, the massage device 6 may be attached to a site other than the thigh 800, for example, a calf.

It is necessary to apply a desired tension to the actuator 1 each time the massage device 6 is worn on the human body, but when the actuator 1 does not have the cord 120, the tension applied to the fibers 110 before heating is different each time there is a possibility. This is because the length of the actuator 1 before heating when tension is applied is not constant. Therefore, the fibers 110 do not always shrink at the same shrinkage rate during heating each time. As a result, the actuator 1 is not always displaced by the same amount of contraction each time during heating.
Fourth Embodiment
FIG. 8 shows a schematic view of a massage device 6 according to the fourth embodiment. The massage device 6 according to the fourth embodiment has the same configuration as that of the massage device 6 according to the third embodiment except that three massages 1 are provided. In addition, in FIG. 8, the heating wire 501 and the power supply 502 are abbreviate | omitted. In this case, for example, even when one cord 120 is stretched and the other two cords 120 are slightly slackened, it is possible to obtain approximately a desired contraction rate.

  Each actuator 1 does not need to have the cord 120, and the massage device 6 may have at least one cord 120.

(Example)
The invention will be described in more detail below with reference to examples.
(Example)
(Experimental example 1A)
<Fabrication of Fiber 110>
According to the disclosure content of Patent Document 4 (ie, Patent No. 6111438), the inventors obtained a fiber 9111c (see FIG. 12) having a coil shape. In the following, the fibers 9111 c are also referred to as fibers 110. The natural length of the fiber 110, ie, the length L3, was 100 mm. The cross-sectional area of the fiber 110 before coiling, that is, the area S of the cross-section perpendicular to the direction of the central axis 9111LA of the fiber 9111a (see FIGS. 9A and 9B) was 0.0113 mm ² .
Understanding the relationship between tensile stress and shrinkage
The amount of shrinkage of the fibers 110 was measured using a Thermomechanical Analysis (TMA) device.

  Specifically, first, as shown in FIG. 10A, one end and the other end of the fiber 110 are fixed to the chuck portions 401 and 402 of the TMA device, respectively, and a load of 3.5 g is applied to the fiber 110, that is, 3 MPa The tensile stress was applied to the fiber 110 through the chuck portion 401 and the probe 403 by the tension generating unit 404 until the tensile stress was applied. The length L11 of the fiber 110 at this time was 105.3 mm.

  In the present specification, tensile stress is defined by the following formula (I).

Tensile stress (Pa) = F / S (I)
Here, F indicates the tension applied to the fibers 110, and S indicates the cross-sectional area of the fibers 110 before coiling (see FIG. 10B).

  The fibers 110 were then heated by the heater 405. The heating for 1200 seconds changed the temperature of the fibers 110 from 30 ° C. to 70 ° C.

  As shown in FIG. 10B, the fibers 110 are shrunk by heating. The maximum contraction amount ΔL of the fiber 110 at the time of heating was measured by the displacement detection unit 406. The amount of contraction ΔL was 5.26 mm. Here, the contraction amount ΔL is defined by the following formula (II).

Contraction amount ΔL = L11−L21 (II)
Here, L11 indicates the length of the fiber 110 before heating to which a tensile stress is applied, and L21 indicates the length of the fiber 110 at the time of heating. The contraction rate of the actuator 1 was 0.95.
(Experimental example 1B)
An experiment similar to that of Example 1A was conducted, except that a tensile stress of 7 MPa (i.e., a load of 8.1 g) was applied to the fiber 110 according to Example 1A.

The fiber 110 had a length of 112.5 mm when a tensile stress of 7 MPa was applied to the fiber 110 before heating. The amount of shrinkage ΔL when the fibers 110 were heated was 7.87 mm, and the percentage of contraction of the fibers 110 was 0.93.
(Experimental example 1C)
An experiment similar to that of Example 1A was conducted, except that a tensile stress of 10 MPa (i.e., a load of 11.5 g) was applied to the fiber 110 according to Example 1A.

The fiber 110 had a length of 117.9 mm when a tensile stress of 10 MPa was applied to the fiber 110 before heating. The amount of shrinkage ΔL when the fibers 110 were heated was 10.61 mm, and the percentage of contraction of the fibers 110 was 0.91.
(Experimental example 1D)
An experiment similar to that of Example 1A was conducted, except that a tensile stress of 12 MPa (i.e., a load of 13.8 g) was applied to the fiber 110 according to Example 1A.

The fiber 110 had a length of 121.4 mm when a tensile stress of 12 MPa was applied to the fiber 110 before heating. The amount of shrinkage ΔL when the fibers 110 were heated was 12.14 mm, and the percentage of contraction of the fibers 110 was 0.90.
(Experimental example 1E)
An experiment similar to that of Example 1A was conducted, except that a tensile stress of 14 MPa (i.e., a load of 16.2 g) was applied to the fiber 110 according to Example 1A.

The fiber 110 had a length of 125 mm when a tensile stress of 14 MPa was applied to the fiber 110 before heating. The amount of shrinkage ΔL when the fibers 110 were heated was 10.62 mm, and the percentage of contraction of the fibers 110 was 0.915.
(Experimental example 1F)
An experiment similar to that of Example 1A was conducted, except that a tensile stress of 30 MPa (i.e., a load of 34.6 g) was applied to the fiber 110 according to Example 1A.

The fiber 110 had a length of 153.5 mm when a tensile stress of 30 MPa was applied to the fiber 110 before heating. The amount of shrinkage ΔL when the fibers 110 were heated was 10.43 mm, and the percentage of contraction of the fibers 110 was 0.932.
(Experimental example 1G)
An experiment similar to that of Example 1A was conducted, except that a tensile stress of 40 MPa (i.e., a load of 46.1 g) was applied to the fiber 110 according to Example 1A.

The fiber 110 had a length of 171.4 mm when a tensile stress of 40 MPa was applied to the fiber 110 before heating. The amount of shrinkage ΔL when the fibers 110 were heated was 8.57 mm, and the percentage of contraction of the fibers 110 was 0.95.
(Experimental example 1H)
An experiment similar to that of Example 1A was conducted, except that a tensile stress of 50 MPa (i.e., a load of 57.6 g) was applied to the fiber 110 according to Example 1A.

  The fiber 110 had a length of 189.3 mm when a tensile stress of 50 MPa was applied to the fiber 110 before heating. The amount of shrinkage ΔL when the fibers 110 were heated was 7.57 mm, and the percentage of contraction of the fibers 110 was 0.96.

  The experimental results of Experimental Examples 1A to 1H are shown in Table 2.

  As shown in Table 2, the contraction rate of the actuator 1 at the time of heating was different depending on the magnitude of the tensile stress applied to the actuator 1 before the heating.

  Specifically, as shown in Table 2, when the tensile stress is too small (that is, in the case of Experimental Example 1A) or when the tensile stress is too large (that is, in the case of Experimental Examples 1G and 1H), the shrinkage rate is Remained high at around 0.95. That is, the ratio of the amount of contraction of the fibers 110 at the time of heating to the length of the fibers 110 before heating was small. On the other hand, when the tensile stress was 7 MPa to 30 MPa (that is, in the case of Experimental Examples 1B to 1F), the contraction rate was lower than 0.95. That is, the ratio of the amount of contraction of the fiber 100 at the time of heating to the length of the fiber 110 before heating was large.

As described above, the relationship between the tensile stress and the contraction rate was grasped.
<Production of Code 120>
As the cord 120, a wire (purchased from Junkosha) was used.

  The length of the cord 120 was determined as follows, with reference to the relationship between tensile stress and shrinkage described above. As an example, a shrinkage factor of 0.90 was chosen as the desired shrinkage factor. Referring to Table 2, the length L11 of the fiber before heating (ie, 121.4 mm) corresponding to the shrinkage rate was determined as the length of the cord 120.

  By cutting the wire of sufficient length, a cord 120 adjusted to have a length equal to the length L11 (ie, 121.4 mm) was produced.

As described above, the cord 120 whose length is adjusted is obtained based on the contraction rate of the fiber 110 when the fiber 110 to which tension is applied in advance is heated.
<Fixation of fiber 110 and cord 120>
A round first crimped terminal was used as the first fixed terminal 130a. The round second crimp terminal was used as the second fixed terminal 130 b. The wire barrel portion 131a of the first crimp terminal was crimped using crimping pliers so that one end of the fiber 110 and one end of the cord 120 were aligned, and one end of the fiber 110 and one end of the cord 120 were fixed. Similarly, the other end of the fiber 110 and the other end of the cord 120 were fixed using a second crimp terminal.

The actuator 1 was obtained as described above.
<Confirmation of contraction rate of actuator 1>
As in Example 1A, except that tensile stress was applied to the actuator 110 so that the length of the fiber 110 was equal to the length of the cord 120 (ie, 121.4 mm) before heating. The contraction amount of 1 was measured, and the contraction rate was calculated. The contraction amount ΔL was 12.14 mm, and the contraction ratio of the actuator 1 was 0.90. This result was consistent with the result of Experimental Example 1D shown in Table 2.

  As described above, by applying a predetermined tension so that the length of the fiber 110 is equal to the length of the cord 120 before heating the actuator 1 according to the present embodiment, the actuator 1 is displaced at a desired contraction rate at the time of heating I was able to.

  When the actuator 1 is applied to the massage device 6, it is desirable that the contraction rate of the actuator 1 be lower than 0.95 in order to obtain a higher massage effect.

  From the above, in order to obtain a contraction rate lower than 0.95, it is necessary to apply a desired tensile stress (that is, 7 MPa or more and 30 MPa or less in the above-mentioned experiment) to the actuator 1.

In Experimental Examples 1A to 1H, as described above, the fiber 110 having a natural length of 100 mm was used. Therefore, according to Table 2, in order to apply a tensile stress of 7 MPa or more and 30 MPa or less, the cord 120 having a length of 112.5% or more and 153.5% or less of the natural length of the fiber 110 may be used .
<Confirmation of cycle characteristics>
The cycle characteristics of each of the actuators 1 of Experimental Examples 1C, 1D, and 1E were confirmed by the following operation test.
(Actuator 1 of Experimental Example 1C)
FIG. 11 shows a schematic view of a test apparatus used in the evaluation of cycle characteristics.

  The first fixed terminal 130 a was fixed to the ceiling 170. A weight 180 of 11.5 g was attached to the second fixed terminal 130 b. The weight 180 stretched the cords 120 and applied 10 MPa to the fibers 110 as shown in FIG. On the side of the actuator 1, a coats heater 1201 (purchased from Sakaguchi Heat Transfer Co., Ltd., trade name "NSP01") used to heat the fiber 110, and a fan 1202 used to cool the fiber 110 were disposed. An enclosure (not shown) was provided around the test apparatus to reduce the effects of external influences such as air flow. Also, in order to measure the temperature in the vicinity of the fiber 110, a fiber (not shown) that does not expand or contract due to heating is provided in the vicinity of the fiber 110, and a thermocouple (purchased from Adachi Keiki Co., Ltd.) under the trade name "SF "-K-100-ANP" (not shown) was attached.

  Next, the cycle of heating and cooling of the fiber 110 was repeated 10,000 times.

  Specifically, first, the fibers 110 were heated by the coats heater 1201 for 4.8 seconds. Since the heat source area of the Coats heater 1201 is 130 mm, the whole of the fiber 110 can be heated substantially uniformly. By heating, the temperature near the fibers 110 changed from 30 ° C. to 70 ° C.

  Next, after heating, the Coats heater 1201 was moved away from the fibers 110 by an air cylinder (not shown), and the wind of the fan 1202 cooled the fibers 110. The cooling time was 15 seconds. Cooling changed the temperature in the vicinity of the fibers from 70 ° C. to 30 ° C.

  These heating and cooling were alternately repeated 10,000 times. During the operation test, the amount of contraction of the fibers 110 was monitored by irradiating the lower surface of the weight 180 with a laser beam using a laser displacement system 190 (purchased from Keyence Corporation, trade name “IL-100”).

After the above-mentioned operation test, the length of the fiber 110 was 100.3 mm. The rate of change of the length of the fiber 110 after the operation test was 0.3% with respect to the natural length L3 (ie, 100 mm) of the fiber 110 before the operation test.
(Actuator of Experimental Example 1D)
The experiment was conducted in the same manner as the above-mentioned operation test except that 13.8 g weight 180 was used, ie 12 MPa was applied to the fiber 110. As a result, the length of the fiber 110 was 101 mm. The change rate of the length of the fiber 110 after the operation test was 1%.
(Actuator of Experimental Example 1E)
The experiment was conducted in the same manner as the above-mentioned operation test except that a weight of 16.2 g 180 was used, that is, 14 MPa was applied to the fiber 110. As a result, the length of the fiber 110 was 104 mm. The change rate of the length of the fiber 110 after the operation test was 4%.

  The results of the performance test are shown in Table 3.

  The rate of change of the total length of the actuators 1 of Experimental Example 1C and Experimental Example 1D is 1% or less, and their cycle characteristics, that is, durability are excellent. On the other hand, the change rate of the total length of the actuator 1 of Experimental Example 1E is as high as 4%, and its durability is inferior.

  The actuators 1 of Experimental Examples 1A, 1B, and 1F to 1H have not been subjected to the operation test. The greater the tensile stress, the greater the rate of change of the overall length. Therefore, it is estimated from the results of Experimental Example 1C that the change rate of the total length of the actuator 1 in Examples 1A and 1B is 0.3% or less. Moreover, it is estimated that the change rate of the full length of the actuator 1 of Example 1F-1H is 4% or more from the result of Experimental example 1E.

  From the above, from the viewpoint of the durability of the actuator 1, the tensile stress is preferably 12 MPa or less. Furthermore, in order to achieve both a low shrinkage rate and excellent durability, it is desirable that the tensile stress be 7 MPa or more and 12 MPa or less.

  In Experimental Examples 1A to 1H, as described above, the fiber 110 having a natural length of 100 mm was used. Therefore, according to Table 3, in order to apply a tensile stress of 7 MPa or more and 12 MPa or less, a cord having a length of 112.5% or more and 125% or less of the natural length of the fiber 110 may be used.

  The actuator according to the invention can be used as an artificial muscle. An example of a product comprising an actuator according to the invention is a massage device that can be worn on the human body.

This massage device comprises:
Actuator,
A coupler comprising a pair of coupling parts, and a heating device,
Here, the actuator comprises a fiber and a cord,
The fibers are twisted around their longitudinal axis,
The fibers are folded to have the shape of a cylindrical coil,
The fiber is shrunk along the central axis direction of the coil by heating, and restored by heat radiation,
The fiber is formed of a crystalline polymer,
One end of the fiber is fixed to one end of the cord,
The other end of the fiber is fixed to the other end of the cord,
The cord is longer than the natural length of the fiber,
Here, the natural length is a length of the fiber restored by heat radiation and not applied with the tension;
One end of the actuator is connected to one of the pair of connecting parts,
The other end of the actuator is connected to the other of the pair of coupling portions,
The other connection place of the pair of connection parts with respect to one of the pair of connection parts is adjustable,
The tension is applied to the fiber, and the fiber is stretched so that the length of the fiber is equal to the length of the cord, and one of the pair of connecting portions is connected to the other of the pair of connecting portions. , The massage device is attached to the human body, and
The fiber to which the tension is applied shrinks by being heated by the heating device.

DESCRIPTION OF SYMBOLS 1 Actuator 6 Massage apparatus 110 Fiber 111a One coiled polymer fiber 111b Another coiled polymer fiber 120 Cord 130a 1st fixed terminal 130b 2nd fixed terminal 131a, 131b Wire barrel part 170 Ceiling 180 Weight 301 Heater 400 Tension 401, 402 chuck part 403 probe 404 tension generation part 405 heater 406 displacement detection part 501 heating wire 502 power source 601 coupler 601 a, 601 b connection part 800 thigh 1201 coats heater 1202 fan 1301 crystal 1302 polymer chain

Claims (20)

A method of driving an actuator, comprising the steps of: (a) applying tension to the actuator;
here,
The actuator comprises a fiber and a cord,
The fibers are twisted around their longitudinal axis,
The fibers are folded to have the shape of a cylindrical coil,
The fiber is shrunk along the central axis direction of the coil by heating, and restored by heat radiation,
The fiber is formed of a crystalline polymer,
One end of the fiber is fixed to one end of the cord,
The other end of the fiber is fixed to the other end of the cord,
The cord is longer than the natural length of the fiber,
Here, the natural length is a length of the fiber restored by heat radiation and not applied with the tension;
The tension is applied along the central axis of the coil such that the length of the fiber is equal to the length of the cord, and (b) the fiber is heated to shrink the fiber How to possess. The method according to claim 1, wherein
The length of the cord is adjusted based on the shrinkage of the fiber when the fiber is pre-tensioned and heated.
Method. The method according to claim 1, wherein
The length of the cord is adjusted based on the length L0 of the fiber obtained from the shrinkage factor D of the fiber represented by the following formula (I):
L0 = L1 / D (I)
Here, L0 indicates the length of the fiber when a tension T of a predetermined value is applied along the central axis direction of the coil before heating the fiber, and L1 indicates a tension T of the predetermined value. Indicate the length of the fibers when the fibers are shrunk by heating the fibers while maintaining
Method. The method according to claim 1, wherein
(1) tension T of a predetermined value applied to the fiber along the central axis direction of the coil before heating the fiber and (2) tension T of the predetermined value along the central axis direction of the coil The length L0 of the fiber when applied
(3) the length L1 of the fiber when the fiber is shrunk while maintaining the tension T at the predetermined value when the fiber is heated (3)
(4) Shrinkage rate D = L1 / L0,
The length of the cord is adjusted to a length equal to the length L0 of the coil from which the contraction rate D is obtained, based on a table in which (1) to (4) are associated.
Method. The method according to claim 1, wherein
The fibers consist of linear low density polyethylene and the following formula (I) is satisfied:
D / d <1 (I)
here,
D represents the average diameter of the cylindrical coil, and d represents the diameter of the fiber,
Method. The method according to claim 1, wherein
In the step (b), the fibers are heated to a temperature of more than 30 degrees Celsius and not more than 70 degrees Celsius.
Method. The method according to claim 1, further comprising the step of: (c) cooling and restoring the fiber after the step (b). The method according to claim 7, wherein
In the step (c), the fibers are cooled to a temperature of 30 degrees Celsius or less.
Method. The method according to claim 7, wherein
The step (b) and the step (c) are repeated,
Method. The method according to claim 1, wherein
The following formula (II)
7 MPa ≦ (the tension / cross sectional area of the fiber) ≦ 30 MPa (II)
How is satisfied. The method according to claim 1, wherein
The following formula (III)
7 MPa ≦ (Tension / Cross-sectional area of the fiber) ≦ 12 MPa (III)
How is satisfied. The method according to claim 1, wherein
The cord has a length greater than or equal to 112.5% and less than or equal to 153.5% of the natural length of the fiber,
Method. The method according to claim 1, wherein
The cord has a length greater than or equal to 112.5% and less than or equal to 121.4% of the natural length of the fiber.
Method. An actuator, comprising:
Fiber, and cord,
here,
The fibers are twisted around their longitudinal axis,
The fibers are folded to have the shape of a cylindrical coil,
The fiber is shrunk along the central axis direction of the coil by heating, and restored by heat radiation,
The fiber is formed of a crystalline polymer,
One end of the fiber is fixed to one end of the cord,
The other end of the fiber is fixed to the other end of the cord, and the cord is longer than the natural length of the fiber,
Here, the natural length is a length of the fiber restored by heat radiation and not subjected to the tension.
Actuator. The actuator according to claim 14, wherein
The length of the cord is adjusted based on the shrinkage of the fiber when the fiber is pre-tensioned and heated.
Actuator. The actuator according to claim 14, wherein
The fiber is made of linear low density polyethylene, and the following formula (II)
D / d <1 (II)
here,
D represents the average diameter of the cylindrical coil, and d represents the diameter of the fiber,
Is satisfied,
Actuator. The actuator according to claim 14, wherein
The cord has a length greater than or equal to 112.5% and less than or equal to 153.5% of the natural length of the fiber,
Actuator. The actuator according to claim 14, wherein
The cord has a length greater than or equal to 112.5% and less than or equal to 121.4% of the natural length of the fiber.
Actuator. The actuator according to claim 14, wherein
The apparatus further comprises a heating device capable of heating the fiber.
Actuator. Claims 1. A method of manufacturing an actuator comprising a fiber and a cord, comprising the steps of: (a) obtaining the cord having a length determined according to the shrinkage factor desired for the fiber;
here,
The fibers are twisted around their longitudinal axis,
The fibers are folded to have the shape of a cylindrical coil,
The fiber is shrunk along the central axis direction of the coil by heating, and restored by heat radiation,
The length of the cord is determined with reference to the relationship between the tension previously applied to the fiber before heating and the shrinkage of the fiber during heating.
The shrinkage factor of the fibers is equal to the ratio of the length of the fibers shrunk by heating to the length of the fibers restored by heat dissipation, and
The cord is longer than the fiber restored by heat dissipation, and (b) the actuator is obtained by fixing both ends of the cord to both ends of the fiber.
How to possess.

Images