actuator

Abstract

A shape memory alloy actuator (1) includes a first portion (2), a second portion (3), one or more heat sinks (2, 3, 35, 52), and one or more shape memory alloy wires (4, 5). The one or more shape memory alloy wires (4, 5) include a first segment of shape memory alloy wire (4). The one or more shape memory alloy wires (4, 5) are configured to move the second portion (3) relative to the first portion (2) within a range of motion. The first segment of shape memory alloy wire (4) is connected to the first portion (2) at a first end (6) via a first elastic element (7), and a second end (8) of the first segment of shape memory alloy wire (4) is connected to the second portion (3). The first elastic element (7) is configured such that, in response to a change in tension of the first segment of shape memory alloy wire (4), the increase or decrease in a first distance (d, d1) between the first segment of shape memory alloy wire (4) and at least one heat sink (2, 3, 35, 52) is greater than a change in a second distance (l, l1) between the first end and the second end (6, 8).

Description

[0001] field

[0002] This application relates to actuators, particularly actuators comprising one or more shape memory alloy (SMA) wires.

[0003] background

[0004] Actuators comprising one or more shape memory alloy (SMA) wires can be used, for example, in cameras, to move lens assemblies in a direction perpendicular to the optical axis, thereby providing optical image stabilization (OIS). For example, shape memory alloy wires operate based on transforming into an austenitic phase upon heating and reverting to a martensitic phase upon cooling.

[0005] WO2019 / 086855A1 describes a camera with an actuator assembly including a support platform, a movable platform supporting a lens assembly, an SMA cable connecting the support platform and the movable platform, a support member supporting the movable platform on the support platform, and two arms extending between the support platform and the movable platform.

[0006] Overview

[0007] According to a first aspect of the invention, a shape memory alloy actuator is provided, comprising a first portion, a second portion, one or more heat sinks, and one or more shape memory alloy wires. The one or more shape memory alloy wires include a first segment of shape memory alloy wire. The one or more shape memory alloy wires are configured to move the second portion relative to the first portion within a range of motion. The first segment of shape memory alloy wire is connected to the first portion at a first end via a first elastic element, and a second end of the first segment of shape memory alloy wire is connected to the second portion. The first elastic element is configured such that, in response to a change in tension of the first segment of shape memory alloy wire, an increase or decrease in a first distance between the first segment of shape memory alloy wire and at least one of the heat sinks is greater than a change in a second distance between the first end and the second end.

[0008] One or more shape memory alloy wires can be configured to move a second part relative to a first part within a range of motion and / or move a first part relative to a second part within a range of motion.

[0009] The first distance can be the average distance between the first segment of shape memory alloy wire and at least one heat sink.

[0010] In response to a change in tension in the first segment of the shape memory alloy wire, the first end can move a first displacement toward the second end and a second displacement perpendicular to the first displacement. The second displacement can be greater than the first displacement. The first displacement can correspond to a direction parallel to the first segment of the shape memory alloy wire before the tension change. The second displacement can correspond to a direction perpendicular to the first segment of the shape memory alloy wire before the tension change.

[0011] The first elastic element may include a portion extending in a direction oriented at an angle less than or equal to 45 degrees to the second distance.

[0012] When the first segment of shape memory alloy wire is just taut, the first elastic element may include a portion extending in a direction oriented at an angle less than or equal to 45 degrees to the first segment of shape memory alloy wire. The first elastic element may have bending resistance against a force applied in a direction corresponding to a first distance, where the force applied is less than the force applied in a direction corresponding to a second distance. The first elastic element may include a spring, or be in the form of a spring. The first elastic element may include a leaf spring, or be in the form of a leaf spring.

[0013] The second end of the first segment of shape memory alloy wire can be connected to the second part via a second elastic element.

[0014] The second elastic element can be configured such that, in response to a change in tension of the first shape memory alloy wire segment, the second end can move a third displacement toward the first end and a fourth displacement perpendicular to the third displacement. The fourth displacement can be greater than the third displacement. The third displacement can correspond to a direction parallel to the first shape memory alloy wire segment before the tension change. The fourth displacement can correspond to a direction perpendicular to the first shape memory alloy wire segment before the tension change. The third displacement can be parallel to the first displacement in the opposite direction. The fourth displacement can be parallel to or parallel to the second displacement in the opposite direction.

[0015] The second elastic element may include a portion extending in a direction oriented at an angle less than or equal to 45 degrees to the second distance.

[0016] When the first segment of shape memory alloy wire is just taut, the second elastic element may include a portion extending in a direction oriented at an angle less than or equal to 45 degrees to the first segment of shape memory alloy wire. The second elastic element may have bending resistance against a force applied in the direction corresponding to a first distance, where the force applied is less than the force applied in the direction corresponding to a second distance. The second elastic element may include a spring, or be in the form of a spring. The second elastic element may include a leaf spring, or be in the form of a leaf spring.

[0017] The first segment of shape memory alloy wire can be attached to the first elastic element and / or the second elastic element by crimping. The first segment of shape memory alloy wire can also be attached to the first elastic element and / or the second elastic element by laser welding.

[0018] For a given change in tension of the first segment of shape memory alloy wire, the change in the first distance can be greater than or equal to ten times the change in the second distance.

[0019] The change in the first distance can correspond to moving away from the first radiator in one or more radiators and towards the second radiator in one or more radiators.

[0020] A change in the first distance corresponding to movement towards the heat sink can cause a decrease in the average distance between the first shape memory alloy wire segment and the heat sink. A change in the first distance corresponding to movement away from the heat sink can cause an increase in the average distance between the first shape memory alloy wire segment and the heat sink.

[0021] The first part may include at least one radiator or support for at least one radiator. At least one of the one or more radiators may be mounted on the first part. At least one of the one or more radiators may be integral with the first part. At least one of the one or more radiators may correspond to a portion of the first part.

[0022] The second part may include at least one radiator or support for at least one radiator. At least one of the one or more radiators may be mounted on the second part. At least one of the one or more radiators may be integral with the second part. At least one of the one or more radiators may correspond to a portion of the second part.

[0023] One or more shape memory alloy wires may include another segment or more of shape memory alloy wires, each of which is constructed in the same manner as the first segment.

[0024] One or more shape memory alloy wires may include a first shape memory alloy wire and a second shape memory alloy wire. The second shape memory alloy wire may be configured to oppose.

[0025] The first segment of shape memory alloy wire. The tension of the first segment of shape memory alloy wire and the tension of the second segment of shape memory alloy wire can vary independently of the position of the second part within at least a portion of the range of motion.

[0026] The second shape memory alloy wire can be configured to resist the first shape memory alloy wire when the contraction of the first wire would cause the extension of the second wire, and vice versa. The first shape memory alloy wire can be resisted by the second shape memory alloy wire and one or more other shape memory alloy wires.

[0027] The shape memory alloy actuator may also include a third elastic element configured to resist the first segment of shape memory alloy wire.

[0028] The third elastic element can be configured to resist the first shape memory alloy wire when the contraction of the first shape memory alloy wire causes deformation of the third elastic element, and the deformation of the third elastic element increases the tension of the first shape memory alloy wire. The first shape memory alloy wire can be resisted by the third elastic element and one or more other elastic elements. The third elastic element may include a spring, or be in the form of a spring. The third elastic element may include a leaf spring or a coil spring, or be in the form of a leaf spring or a coil spring. Each of the other elastic elements may include a spring, or be in the form of a spring. Each of the other elastic elements may include a leaf spring or a coil spring, or be in the form of a leaf spring or a coil spring.

[0029] The device may include a shape memory alloy actuator and a controller. The controller may be configured to control the relative position of the first part and the second part. The controller may also be configured to control the cooling rate of the first shape memory alloy wire by adjusting the tension of the first part. Moving the first part of the shape memory alloy wire toward at least one heat sink may increase the cooling rate. Moving the first part of the shape memory alloy wire away from at least one heat sink may decrease the cooling rate.

[0030] Controlling the cooling rate of the first shape memory alloy wire segment by adjusting its tension can correspond to adjusting the tension of both the first and second segments without changing their relative positions. Moving the first segment toward at least one heat sink increases the cooling rate by increasing the heat flow from the first segment to the heat sink. Moving the first segment away from at least one heat sink decreases the cooling rate by reducing the heat flow from the first segment to the heat sink.

[0031] The device may also include a temperature sensing module configured to determine a temperature corresponding to the first segment of shape memory alloy wire. A controller may be configured to determine the temperature and adjust the distance between the first segment of shape memory alloy wire and at least one heat sink based on the temperature.

[0032] The temperature can be the temperature of the first shape memory alloy wire segment. The temperature can be the temperature of the shape memory alloy actuator. The temperature can be the temperature of the device. The temperature can be the ambient temperature. The temperature sensing module can be provided by the controller. The temperature sensing module can be separate from the controller. The temperature sensing module can be configured to determine (or estimate or calculate) the temperature of the first shape memory alloy wire segment based on historical power supplied to the first shape memory alloy wire segment and measurements of the ambient temperature. The temperature sensing module can be configured to determine the temperature of the first shape memory alloy wire segment based on its resistance. The device and / or temperature sensing module can include one or more ambient temperature sensors. Adjusting the distance between the first shape memory alloy wire segment and at least one heat sink can include adjusting the mean average distance.

[0033] The distance between the first segment of shape memory alloy wire and at least one heat sink, based on temperature regulation, may include retrieving a pre-calibrated distance corresponding to the temperature from a lookup table stored by the controller.

[0034] When the temperature lies between a pair of temperature values ​​stored in the lookup table, retrieving the precalibrated distance can include the distance inserted between a pair of precalibrated distances corresponding to the stored pair of temperature values.

[0035] Adjusting the distance between the first shape memory alloy wire segment and at least one heat sink based on temperature may include decreasing the distance between the first shape memory alloy wire segment and at least one heat sink in response to a determined increase in temperature. Adjusting the distance between the first shape memory alloy wire segment and at least one heat sink based on temperature may include increasing the distance between the first shape memory alloy wire segment and at least one heat sink in response to a determined decrease in temperature.

[0036] The controller can also be configured to reduce the distance between the first segment of shape memory alloy wire and at least one heat sink before the relative positions of the second and first parts change.

[0037] The controller can also be configured to increase the distance between the first segment of shape memory alloy wire and at least one heat sink after the relative position change of the second and first parts.

[0038] The controller can also be configured to adjust the distance between the first segment of shape memory alloy wire and at least one heat sink based on the relative position of the second part within the range of motion.

[0039] The controller can be configured to move the first segment of the shape memory alloy wire closer to at least one heat sink in response to the second portion being within 20%, 15%, 10%, or 5% of the boundary of the movement range. The percentage distance from the boundary of the movement range can be calculated based on the distance from the boundary as a percentage of the width of the movement range in the same direction. The percentage distance from the boundary of the movement range can also be calculated based on the distance from the boundary as a percentage of the maximum width of the movement range in any direction.

[0040] Adjusting the distance between the first shape memory alloy wire segment and at least one heat sink based on the relative position of the second portion within the movement range may include increasing the distance between the first shape memory alloy wire segment and at least one heat sink in response to the second portion moving closer to the center of the movement range. Adjusting the distance between the first shape memory alloy wire segment and at least one heat sink based on the relative position of the second portion within the movement range may also include decreasing the distance between the first shape memory alloy wire segment and at least one heat sink in response to the second portion moving further away from the center of the movement range.

[0041] One or more shape memory alloy wires may include another segment or more of shape memory alloy wires, each of the other segments being constructed in the same manner as the first segment, and wherein the controller is configured to control each of the other segments in the same manner as the first segment.

[0042] Optical image stabilization components for cameras may include shape memory alloy actuators or devices.

[0043] Autofocus components for cameras may include shape memory alloy actuators or devices.

[0044] According to a second aspect of the invention, a method for controlling a shape memory alloy actuator is provided. The shape memory alloy actuator includes a first portion, a second portion, one or more heat sinks, and one or more shape memory alloy wires, the one or more shape memory alloy wires including a first segment of shape memory alloy wire and a second segment of shape memory alloy wire, the second segment of shape memory alloy wire being configured to resist the first segment of shape memory alloy wire. The one or more shape memory alloy wires are configured to move the second portion relative to the first portion within a range of motion. The tension of the first segment of shape memory alloy wire and the tension of the second segment of shape memory alloy wire can vary independently of the position of the second portion within at least a portion of the range of motion. The first segment of shape memory alloy wire is connected to the first portion at a first end via a first elastic element, and the second end of the first segment of shape memory alloy wire is connected to the second portion. The first elastic element is configured such that, in response to a change in the tension of the first segment of shape memory alloy wire, an increase or decrease in a first distance between the first segment of shape memory alloy wire and at least one heat sink is greater than a change in a second distance between the first end and the second end. The method includes controlling the cooling rate of the first segment of shape memory alloy wire by adjusting the tension of the first segment of shape memory alloy wire. Moving the first segment of the shape memory alloy wire toward at least one heat sink increases the cooling rate. Moving the first segment of the shape memory alloy wire away from at least one heat sink decreases the cooling rate.

[0045] One or more shape memory alloy wires can be configured to move a second part relative to a first part within a range of motion and / or move a first part relative to a second part within a range of motion.

[0046] Controlling the cooling rate of the first shape memory alloy wire by adjusting the tension of the first shape memory alloy wire can correspond to adjusting the tension of the first shape memory alloy wire and the tension of the second shape memory alloy wire without changing the relative positions of the first and second parts.

[0047] The method may include features corresponding to any feature of the shape memory alloy actuator and / or device.

[0048] The second end of the first segment of shape memory alloy wire can be connected to the second part via a second elastic element.

[0049] The method may further include using a temperature sensing module to determine the temperature corresponding to the first segment of shape memory alloy wire. The method may also include adjusting the distance between the first segment of shape memory alloy wire and at least one heat sink based on the temperature.

[0050] Adjusting the distance between the first segment of shape memory alloy wire and at least one heat sink based on temperature may include retrieving a pre-calibrated distance between the first segment of shape memory alloy wire and at least one heat sink corresponding to that temperature from a lookup table.

[0051] Adjusting the distance between the first shape memory alloy wire segment and at least one heat sink based on temperature may include decreasing the distance between the first shape memory alloy wire segment and at least one heat sink in response to a determined increase in temperature. Adjusting the distance between the first shape memory alloy wire segment and at least one heat sink based on temperature may include increasing the distance between the first shape memory alloy wire segment and at least one heat sink in response to a determined decrease in temperature.

[0052] The method may also include reducing the distance between the first segment of shape memory alloy wire and at least one heat sink in response to a change in the relative positions of the second and first portions.

[0053] The method may also include increasing the distance between the first segment of shape memory alloy wire and at least one heat sink in response to the relative positions of the second and first segments being constant.

[0054] The method may also include adjusting the distance between the first segment of shape memory alloy wire and at least one heat sink based on the relative position of the second part within the movement range.

[0055] Adjusting the distance between the first shape memory alloy wire and at least one heat sink based on the relative position of the second part within the movement range may include increasing the distance between the first shape memory alloy wire and at least one heat sink in response to the second part moving closer to the center of the movement range, and decreasing the distance between the first shape memory alloy wire and at least one heat sink in response to the second part moving further away from the center of the movement range.

[0056] One or more shape memory alloy wires may include additional shape memory alloy wire segments. Each additional shape memory alloy wire segment may be constructed in the same manner as the first shape memory alloy wire segment. The method may also include controlling each additional shape memory alloy wire segment in the same manner as the first shape memory alloy wire segment. Brief description of the attached diagram

[0058] Some embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0059] Figures 1A to 1C The first SMA actuator is schematically shown;

[0060] Figure 2 The apparatus for controlling a general SMA actuator is shown schematically.

[0061] Figure 3 This is a flowchart of the first method for actively adjusting the cooling rate of a section of SMA line.

[0062] Figure 4 This is a flowchart of the second method for actively adjusting the cooling rate of a section of SMA line;

[0063] Figure 5 This is a flowchart of the third method for actively adjusting the cooling rate of a section of SMA line;

[0064] Figure 6 This is a flowchart of the fourth method for actively adjusting the cooling rate of a section of SMA line;

[0065] Figure 7 This is a flowchart of the fifth method for actively adjusting the cooling rate of a section of SMA line;

[0066] Figures 8A to 8C The second SMA actuator is schematically shown;

[0067] Figure 9A and Figure 9B The third SMA actuator is schematically shown;

[0068] Figures 10A to 10C The fourth SMA actuator is schematically shown;

[0069] Figure 11A and Figure 11B The fifth SMA actuator is schematically shown;

[0070] Figure 12 The sixth SMA actuator is schematically shown;

[0071] Figure 13 The seventh SMA actuator is schematically shown;

[0072] Figures 14A to 14C The eighth SMA actuator is schematically shown;

[0073] Figure 15 The ninth SMA actuator is schematically shown;

[0074] Figures 16A to 16C The displacement of a segment of SMA wire connected to an elastic bias element at one or both ends is shown;

[0075] Figure 17 An optical image stabilization (OIS) component is schematically shown; and

[0076] Figure 18 The second OIS component is shown schematically.

[0077] Detailed description

[0078] The heating rate of shape memory alloy (SMA) wires can be easily controlled, for example, by controlling the resistance heating I applied to the SMA wire. 2R is used to achieve this. In contrast, the cooling rate depends on the environment of the SMA line and on the heat flow through radiation, convection, and diffusion. The frequency response and switching time of SMA-based actuators may be limited by the cooling rate of the line.

[0079] The examples in this specification are based, at least in part, on the inventors' development of structures and methods that can increase the cooling rate of an SMA line by reducing the distance (or spacing) between the SMA line and a structure or other heat sink at a lower temperature. For example, a suitable heat sink can be any part of the actuator structure capable of conducting heat away from the SMA line.

[0080] While reducing the distance between the SMA wires and the heatsink can increase the heat flow from the SMA wires to the heatsink to allow for faster cooling, this also increases the power consumption required to maintain the SMA wires at the desired temperature. Some examples described in this specification can allow control of the tension of one or more SMA wires to actively influence the cooling rate by controlling the spacing (pitch) between the SMA wires and one or more heatsinks (which may simply correspond to portions of the actuator structure).

[0081] Examples of this specification include an elastic feature (e.g., a spring) that connects at least one end of the SMA wire to another part of the actuator, and allows changes in the tension of the SMA wire to move the SMA wire toward and / or away from a nearby heat sink.

[0082] The examples in this specification enable a reduction in the switching time of SMA actuators without excessively increasing power consumption. Other effects and advantages of the examples in this specification will become apparent from the description below.

[0083] Reference Figure 1A The first shape memory alloy (SMA) actuator 1 is shown.

[0084] The first SMA actuator 1 includes a first part 2 and a second part 3. The first part 2 and the second part 3 are configured to move relative to each other using one or more shape memory alloy wires (including at least a first SMA wire 4). Figure 1A The SMA actuator 1 shown also includes a second SMA line 5, but other examples may only require the first SMA line 4 (see [link to example]). Figures 14A to 14C and Figure 15 Part 2 and Part 3 can move relative to each other within the range of motion. For example, if the linear SMA actuator 1 has a center position x0, the range of motion can extend a distance Δx (also referred to as “stroke” Δx) to either side of the center position x0.

[0085] The first SMA line 4 and the second SMA line 5 can be made of any suitable SMA material, such as nitinol or other titanium alloy SMA materials. The first part 2 and / or the second part 3 can be formed of metal, such as stainless steel. The first part 2 and the second part 3 can be formed by any suitable method (including but not limited to machining, etching (e.g., laser or chemical etching), additive manufacturing, etc.). Some areas of the first part 2 and / or the second part 3 can be coated with an electrically insulating dielectric material to prevent short circuits through the first part 2 and / or the second part 3.

[0086] The first SMA wire 4 is heated by applying a first current I1 through it. The first SMA wire 4 has a resistance R1, and for the total heat flow J1 leaving the first SMA wire 4, the first SMA wire 4 will cause a temperature change until equilibrium is reached, such that I1... 2 R1 = J1. The balance can be affected by changing the first current I1, and also by affecting the total heat flux J1, as described below. As mentioned above, increasing the balance I1... 2 The heating side of R1 is simple, but increasing the heat flux J1 is much more complex. Controlling this increase in heat flux J1 is the subject of this specification.

[0087] The second SMA line 5 is heated by applying a second current I2 through it, which can be changed independently of the first current I1.

[0088] like Figure 1A As shown, the first end 6 of the first SMA wire 4 is connected to the first part 2 via a first elastic element 7. The second end 8 of the first SMA wire 4 is connected to the second part 3, for example, via a second elastic element 9. In other examples, the second end 8 may be connected to the second part 3 without the second elastic element 9 (see [link to example]). Figure 11A , Figure 11B , Figure 12 , Figure 13 and Figure 15 ).like Figure 1A As shown, the first SMA wire 4 can be attached to the first elastic element 7 and / or the second elastic element 9 via a crimp. Alternatively, the first SMA wire 4 can be attached to the first elastic element 7 and / or the second elastic element 9 via laser welding or any other technique suitable for connecting the material forming the first SMA wire 4 to the material forming the first elastic element 7 and the second elastic element 9.

[0089] exist Figure 1AIn the first SMA actuator 1 shown, the first end 10 of the second SMA line 5 is connected to the first part 2 via the third elastic element 11, and the second end 12 of the second SMA line 5 is connected to the second part 3 via the fourth elastic element 13. The second SMA line 5 is connected to the third elastic element 11 and / or the fourth elastic element 13 in the same manner as the first SMA line 4 is attached to the first elastic element 7 and / or the second elastic element 9.

[0090] The first SMA actuator 1 includes a heat sink in the form of a second portion 3. The second portion 3 can serve as a heat sink because it will typically have a larger thermal mass than the first SMA line 4 and the second SMA line 5, and / or sufficient thermal conductivity to transfer heat away from the first SMA line 4 and the second SMA line 5. For example, heat from the first SMA line 4 and the second SMA line 5 can be transferred to the second portion 3 via a combination of radiation, convection, and conduction. The heat can then diffuse through the second portion and dissipate into the environment through an area that is relatively larger than that of the first SMA line 4 and the second SMA line 5.

[0091] The first part 2 and the second part 3 remain in physical contact with each other. For example, the first SMA line 4 and the second SMA line 5 can be inclined such that the tension T in the first SMA line 4 and the second SMA line 5 pushes the first part 2 and the second part 3 together. Alternatively, additional structures and / or elastic structures (such as springs or armatures (not shown)) can push the first part 2 and the second part 3 together. The overall effect is to allow the first part 2 and the second part 3 to move relative to each other in a first direction x or in a plane defined by the first direction x and the second direction y, while restricting or preventing relative movement in a third direction z. The gap 14 between the opposing surfaces of the first part 2 and the second part 3 can include a support, such as, for example, one or more sliding body supports (not shown), ball supports (not shown), etc. The gap 14 may be absent, allowing the first part 2 and the second part 3 to slide in direct contact. Alternatively, the gap 14 may be empty, and the first part 2 and the second part 3 may slide through a support (not shown) or Figure 1A Other structural contacts outside the plane shown (e.g., displaced in the second direction y). When included, one or more support members (not shown) may be made of a suitable metal or alloy, such as phosphor bronze or stainless steel with a diamond-like carbon coating. The surfaces of the first part 2 and / or the second part 3 that contact the support members or provide surfaces for the support members may also be coated with a coating (e.g., diamond-like carbon) to reduce wear.

[0092] Figure 1AA first SMA actuator 1 is shown in a central or initial configuration (e.g., corresponding to actuator position x0). In the central configuration, the first SMA line 4 has a length l1 and is separated from the second part 3 by a distance d1 (sometimes referred to as the pitch). In the central configuration x0, the second SMA line 5 has the same length l1 and is separated from the second part 3 by the same distance d1. The distance d1 may be the average distance between the first SMA line 4 and the second part 3 in the form of a heat sink.

[0093] In the first SMA actuator 1, the second SMA line 5 is configured to resist the first SMA line 4. The second SMA line 5 resists the first SMA line 4 such that contraction (movement in the negative x-direction) of the first SMA line 4 forces the second SMA line 5 to extend, and vice versa. This arrangement of resisting first SMA line 4 and second SMA line 5 results in the tension T in the first SMA line 4 and second SMA line 5 being able to change independently of the relative positions of the first portion 2 and the second portion 3 within at least a portion of the movement range x0 ± Δx. This function will combine... Figure 1B and Figure 1C Further explanation.

[0094] In other examples, the first SMA line 4 can be resisted by an elastic element (such as a spring) instead of the second SMA line 5 (see [reference]). Figures 14A to 14C and Figure 15 ).

[0095] Also refer to Figure 1B The first SMA actuator 1 is shown as a second configuration 1b, in which the length of the first SMA line 4 and the length of the second SMA line 5 have been changed from l1 to l2, resulting in an increase in the tension T of the first SMA line 4 and the second SMA line 5.

[0096] This change in tension T is achieved by varying currents I1 and I2 to move the first SMA line 4 and the second SMA line 5 to a new equilibrium temperature. The change in temperature of the first SMA line 4 and the second SMA line 5 alters the equilibrium between the austenite and martensite phases, thus changing their length. Although the tension T has been increased, the relative positions of the first part 2 and the second part 3 remain within the central configuration x0.

[0097] The first elastic element 7 is configured such that, in response to a change in tension T of the first SMA line 4, the new distance d2 between the first SMA line 4 and the heat sink in the form of the second part 3 changes by an amount δd = |d1-d2|, which is greater than the change in length δl = |l1-l2| between the first end 6 and the second end 8. In this document, the interval between the first SMA line 4 and one or more heat sinks (e.g., the second part 3) can generally be referred to as the first distance d. In this document, the length of the first SMA line 4 can generally be referred to as the second distance l. The second to fourth elastic elements 9, 11, and 13 are constructed in the same manner as the first elastic element 7.

[0098] In the SMA actuator 1, the elastic elements 7, 9, 11, 13 are in the form of a crimping member having an inclined portion and an extension portion that provide a leaf spring, and are arranged such that an increased tension T causes the elastic elements 7, 9, 11, 13 to flex toward the second portion 3, thereby reducing the first distance d from d1 to d2.

[0099] However, the first to fourth elastic elements 7, 9, 11, and 13 are not limited to a specific implementation, and any type of elastic element can be replaced, as long as the change δd in the increase or decrease of the first distance d between the first SMA line 4 and at least one heat sink is greater than the corresponding change δl in the second distance l between the first end 6 and the second end 8. The same consideration applies to the second SMA line 5 and any other SMA line segments.

[0100] Instead of a crimping element, the elastic element described herein can be provided with any suitable means of holding the SMA wire.

[0101] The angles of the first to fourth elastic elements 7, 9, 11, and 13 can be changed, although typically to ensure that a change in tension T causes a greater change δd in the first distance d than the corresponding change δl in the second distance l, the angle of the crimping member providing the first to fourth elastic elements 7, 9, 11, and 13 should remain relatively shallow. For example, the angle of this crimping member is less than or equal to 45 degrees relative to the direction x or plane xy of the relative movement between the first part 2 and the second part 3. In other examples, the first SMA line 4 can also be rotated during use (see...). Figure 11A , Figure 11B , Figure 12 , Figure 13 and Figure 15 In this case, defining an angle of less than or equal to 45 degrees relative to the direction oriented along the length (second distance) l of the first SMA line 4 might be more practical. The latter case can be further defined by referring to a reproducible state of the first SMA line 4 (e.g., when the SMA line 4 is just taut, or corresponding to the center configuration x0).

[0102] Typically, the first to fourth elastic elements 7, 9, 11, and 13 can be replaced by any other elastic element that provides resistance to deformation in the direction corresponding to the first distance d (e.g., z), which is less than the resistance in the direction corresponding to the second distance l (e.g., x). It is important that the change δl relative to the second distance l (length) is amplified by the change δd in the first distance d, because movement toward / away from a radiator such as the second section 3 can be used to increase / decrease the cooling rate of the first SMA line 4. Furthermore, any component of the change δl in the second distance l (length) adapted by the elastic elements 7, 9, 11, and 13 (when resisting the relative movement of the first section 2 and the second section 3) represents a reduction in the range of motion x0 ± Δx (stroke range) of the SMA actuator 1, and ideally should be minimized. Some or all of the first to fourth elastic elements 7, 9, 11, and 13 can take the form of springs, such as leaf springs, bracket springs, coil springs, or shaped regions of compliant materials such as natural or synthetic rubber.

[0103] Preferably, for a given change ΔT in the tension of the first SMA line 4, the change δd at the first distance d can be greater than or equal to five times, or more preferably ten times, the change δl at the second distance l. Any type of elastic element capable of providing the above-described function can be used instead. Figure 1A and Figure 1B The elastic compression members 7, 9, 11, and 13 shown are illustrated.

[0104] Also refer to Figure 1C The SMA actuator 1 is shown in a third configuration 1c, in which the length of the first SMA line 4 has been changed (i.e. decreased) to l3, while the length of the second SMA line 5 has been changed (i.e. increased) to l4≠l3.

[0105] In the second configuration 1b and the third configuration 1c, the tension T in the first SMA line 4 and the second SMA line 5 is the same. However, in the third configuration 1c, the first part 2 and the second part 3 are offset from the center position x0 by a smaller amount δx than the range of motion, i.e., δx ≤ Δx.

[0106] Also refer to Figure 2 The device 15 is shown, which includes a general SMA actuator 16 and a controller 17.

[0107] A typical SMA actuator 16 includes at least a first SMA line 4 (e.g., see...). Figures 14A to 14C and Figure 15However, for any number N other SMA lines 19, a second SMA line 5, a third SMA line 18, etc., may be optionally included. Generally, the SMA actuator 16 can take the form of any of the SMA actuators 1, 28, 33, 34, 36, 37, 38, 41, 42 described herein.

[0108] Controller 17 includes processor 20, memory 21, one or more sensors 22, input / output (I / O) interface 23, current driver module 24, and resistance measurement module 25. Processor 20 may take the form of one or more general-purpose digital electronic central processing units (CPUs). Processor 20 may be a multi-core CPU. Memory 21 may include volatile memory and / or non-volatile memory. Typically, memory 21 may include a mixture of non-volatile memory for storing instructions and volatile memory used for the runtime of processor 20. In some examples, a combination or even all of the components of controller 17 may be provided by a single, appropriately constructed microcontroller, application-specific integrated circuit (ASIC), or similar device. For example, current driver module 24 and / or some or all of sensors 22 may be separate devices, while all other components of controller 17 are provided by a single device.

[0109] The current driver module 24 supplies a first current I1 to the first SMA wire segment 4. By adjusting the first current I1, the program executed by the processor 20 can control the temperature, and thus control the tension T and length l of the first SMA wire segment 4. Typically, a larger current I1 heats the first SMA wire segment 4, causing it to contract. The resistance R1 of the first SMA wire segment 4 is measured by the resistance measurement module 25. The current I1 is controlled using, for example, the resistance feedback control technique described in WO 2014 / 076463 A1, which is incorporated herein by reference. The current driver module 24 and the resistance measurement module 25 can be used to control currents I2, I3, ..., I... N The same number of SMA lines 4, 5, 18, and 19 are supplied as included in the general SMA actuator 16.

[0110] Sensor 22 may include, for example, one or more temperature sensors (not shown), gyroscope sensors (not shown), etc. For instance, a typical SMA actuator 16 may be connected to a lens (not shown) of a camera system, and feedback from the gyroscope sensor (not shown) may be used (using drive currents I1…, I…) N The positioning of the lens is controlled to stabilize the image focused by the lens.

[0111] I / O interface 23 provides communication and interface with other components of the device containing device 15. For example, device 15 may be included in a smartphone (not shown), and I / O interface 23 may provide communication with the smartphone's CPU (not shown).

[0112] The processor 20 of the controller 17 executes a control method to control the relative position of the first section 2 and the second section 3 of the general SMA actuator 16. The first SMA line 4 is resisted by a spring or other elastic element (see...). Figures 14A to 14C and Figure 15 In the example of a general SMA actuator 16, the configuration of the first SMA line 4 described above can provide advantageous effects, for example, as further described below, by increasing the cooling rate toward one or more edges of the motion range x0±Δx.

[0113] In the example of a typical SMA actuator 16, active adjustment of the cooling rate is possible. For the typical SMA actuator 16, the first SMA line 4 is resisted by one or more SMA lines, such as the second SMA line 5, the third SMA line 18, and another SMA line 19. For example, if the first SMA actuator 1 is used together with the controller 17. This is a result of independently changing the tension T and the actuator displacement δx within at least a portion of the motion range x0 ± Δx. In such an example, the control method executed by the processor 20 can control the relative displacement δx of the first section 2 and the second section 3, while additionally controlling (or at least influencing) the cooling rate of the SMA lines 4, 5, 18, and 19 by adjusting the tension T of each resisting group among the SMA lines 4, 5, 18, and 19. For example, moving segments 4, 5, 18, and 19 of the SMA line toward at least one heat sink increases the cooling rate (increases heat flow J), while moving segments 4, 5, 18, and 19 of the SMA line away from the heat sink decreases the cooling rate (decreases heat flow J).

[0114] In some examples, in addition to reducing the initial distance d (pitch) of segments 4, 5, 18, and 19 of the SMA wires, tension T can be used to bring segments 4, 5, 18, and 19 of the SMA wires into contact with a heat sink, for example, mounted on or protruding from the first part 2 or the second part 3, thereby further improving the cooling rate. In the case of contact with a heat sink, the heat sink should be electrically insulated / isolated to avoid control currents I1…, I… N Short circuit.

[0115] Actively adjusting the cooling rate can be useful in actuators 1 and 16 used in camera autofocus (AF) applications. For example, the transition time can be accelerated by increasing the cooling rate (increasing heat flux J) by offsetting segments 4, 5, 18, and 19 of the SMA line closer to one or more heat sinks. During other times when the AF system is idle, the cooling rate can be reduced (reducing heat flux J) to lower power consumption (requiring I). 2 R balances J to maintain the required temperature. Reducing power consumption means reducing heat generation, which also helps keep the ambient temperature of actuators 1 and 16 low until the displacement δx of actuator 1 is required. Additionally or alternatively, because segments 4, 5, 18, and 19 of the SMA line can be moved further away from the nearby heat sink, actively influencing the cooling rate can be used to reduce power consumption at low ambient temperatures.

[0116] The following describes another example of actively regulating the cooling rate (see Figures 3 to 6 ).

[0117] In the first SMA actuator 1, the function of the heat sink is provided by the physical structure of the second part 3. The heat sink is not limited to this, and the general actuator 16 may include one, two, or more heat sinks. The structure of either or both of the first part 2 and the second part 3 can serve as a heat sink. Furthermore, the housing (not shown) and / or other components of the general actuator 16 can serve as a heat sink. The heat sink may also be provided in the form of a protrusion integrally formed with or mounted to either the first part 2 or the second part 3 (see example...). Figure 18 (Radiator 52 in the specification). Typically, a radiator can be passive, using thermal mass and thermal conduction to dissipate the heat generated by segments 4, 5, 18, and 19 of the SMA line away from those segments. However, the examples in this specification are equally applicable to actively cooled radiators.

[0118] Passive tension regulation

[0119] In addition to the other effects described herein, a typical SMA actuator 16 (e.g., SMA actuator 1) can also provide passive tension regulation as described below.

[0120] In many SMA actuators, controller 17 advantageously adjusts the average drive current I1, ..., I2 supplied to segments 4, 5, 18, 19 of the SMA line according to the ambient temperature Θ. N The tension T of segments 4, 5, 18, and 19 of the SMA line is adjusted (relative to changes in ambient temperature Θ). However, this active tension adjustment requires temperature sensors, etc.

[0121] In an example of a general SMA actuator 16, passive tension regulation can be provided, wherein at least the first SMA line 4 moves closer to one or more heat sinks in response to an increase in its tension T. For a constant drive current I1, an increase in ambient temperature will readily lead to a temperature rise and thus an increase in the tension T of the first SMA line 4. This causes the first SMA line 4 to move closer to one or more heat sinks (e.g., the second section 3), and the resulting increase in cooling rate will tend to offset the temperature rise and thus offset the increase in tension T of the first SMA line 4 due to the increase in ambient temperature. The opposite applies to a decrease in ambient temperature. Although this has been described with respect to the first SMA line 4, it also applies to sections 4, 5, 18, and 19 of all SMA lines that may be included in the general SMA actuator 16.

[0122] In short, the introduction of elastic elements 7, 9, 11, and 13 can at least reduce the dependence of line tension on ambient temperature and thus reduce the need for active tension adjustment. Therefore, controller 17 may be able to use a temperature sensor with lower sensitivity and / or accuracy (and lower cost), or even omit the temperature sensor entirely (and disregard for ambient temperature).

[0123] The first method to actively regulate the cooling rate

[0124] Also refer to Figure 3 This demonstrates a first method for actively adjusting (or at least influencing) the cooling rate of the first SMA line 4.

[0125] As described above, the first method applies to the first SMA line 4, the contraction of which is resisted by one or more other SMA lines 5, 18, 19, such that the tension T in the SMA lines 4, 5, 18, 19 can be changed independently of the displacement δx between the first part 2 and the second part 3 (at least within a portion of the range of motion x0 ± Δx). The first SMA actuator 1 is an example of a general SMA actuator 16 to which the first method applies. The first method can be executed by a program executed by the processor 20 of the controller 17.

[0126] Simultaneously with the first method, controller 17 will continue to provide the function of controlling the relative displacement δx between the first part 2 and the second part 3.

[0127] One or more temperatures Θ corresponding to the first SMA line 4 are measured (step S1). For example, sensor 22 may include a temperature sensing module (not shown). Temperature Θ may include the ambient temperature Θ of a general SMA actuator 16 or a device containing a general SMA actuator 16. oAnd it can be directly measured by the temperature sensing module of sensor 22. Additionally or alternatively, the temperature Θ may include the temperature Θ of the first SMA line 4. 线 The temperature Θ of the first SMA line 4. 线 The processor 20 can use the power I1 supplied by the current driver 24 to the first SMA line 4. 2 The history of R1 and the ambient temperature Θ obtained by sensor 22 o The measurement results are used to determine (or estimate or calculate) the resistance R1. Additionally or alternatively, because the resistance R1 varies with temperature, when estimating the temperature Θ of the first SMA line 4... 线 At this time, the resistor R1 obtained from the resistance measurement module 25 can be used.

[0128] Check whether the temperature Θ corresponding to the first SMA line 4 has changed by δΘ (step S2). For example, the measured temperature Θ can be compared with a cache of one or more previously measured temperatures Θ. If there is no change in δΘ (step S2 | No), the controller 17 continues to monitor the temperature Θ corresponding to the first SMA line 4.

[0129] If there is a change δΘ in one or more temperatures Θ corresponding to the first SMA line 4 (step S2|Yes), then the tension T of the first SMA line 4 is adjusted according to the change δΘ (step S3).

[0130] The cooling rate of the first SMA line 4 can be adjusted (or at least affected) by moving it toward or away from one or more heat sinks by adjusting the tension T. This adjustment is provided by the flexure of the first elastic element 7, and by the flexure of the second elastic element 9 if present. Adjusting the first distance d between the first SMA line 4 and at least one heat sink corresponds to adjusting the average distance d along the length l of the first SMA line 4. Generally, the first distance d (line spacing) should be reduced at high temperature Θ to increase the cooling rate, and then reduced at low temperature Θ to reduce power consumption. An example of a specific control scheme is described below.

[0131] While the general SMA actuator 16 is still in use (step S4|Yes), the control loop is repeated.

[0132] Although the first SMA line 4 has been described, the first method applies to segments 4, 5, 18, and 19 of all SMA lines included in the general SMA actuator 16 controlled by the controller 17.

[0133] The second method of actively adjusting the cooling rate

[0134] Also refer to Figure 4This illustrates a second method for actively adjusting (or at least influencing) the cooling rate of the first SMA line 4. The second method represents an example of implementing the first method.

[0135] The second method applies to the first SMA line 4, whose contraction is resisted by one or more other SMA lines 5, 18, 19, such that the tension T in the SMA lines 4, 5, 18, 19 can be changed independently of the displacement δx between the first part 2 and the second part 3 (at least within a portion of the range of motion x0 ± Δx). SMA actuator 1 is an example of a general SMA actuator 16 to which the second method is applicable. The second method can be executed by a program executed by the processor 20 of the controller 17.

[0136] Simultaneously with the second method, controller 17 will continue to provide the function of controlling the relative displacement δx between the first part 2 and the second part 3.

[0137] One or more temperatures Θ are measured and / or calculated in the same manner as in the first method (step S1) (step S5). If the temperature δΘ does not change (step S6 | No), then the tension T of the first SMA line 4 is not modified, and when the general actuator 16 is in use (step S10 | Yes), the temperature Θ corresponding to the first SMA line 4 continues to be monitored (step S5).

[0138] In response to a measured change δΘ at one or more monitored temperatures Θ (step S6|Yes), the tension T(Θ) corresponding to the new temperature Θ is retrieved from a lookup table (not shown) (step S7). The lookup table stores pre-calibrated tension values ​​T(Θ) corresponding to a specific temperature Θ. Each pre-calibrated tension value T(Θ) corresponds to a specific first distance d, which depends on the specific mechanical compliance of the first elastic element 7 (and, if the second elastic element 9 is used, also on the second elastic element 9) in the direction parallel to and perpendicular to the length l (second distance). The temperature Θ used to reference the lookup table can be the ambient temperature Θ0, but is preferably the temperature Θ of the first SMA line 4. 线 When temperature Θ is located within a pair of pre-calibrated temperature Θs stored in a lookup table. a Θ b Between, the closest pre-calibration temperature Θ a Θ b It can be used.

[0139] Alternatively and optionally, the tension T(Θ) corresponding to temperature Θ can be calculated using the value corresponding to the pre-calibrated temperature Θ. a Θ b (where temperature Θ is between temperature Θ) a Θ b Between, Θ a <Θ<Θb Tension T a =T(Θ) a ), T b =T(Θ) b Perform interpolation (step S8).

[0140] The tension T of the first SMA wire segment 4 is adjusted to a value T(Θ) retrieved (or interpolated) using a lookup table (step S9). The tension T can be reduced by decreasing the drive current I1 to allow the first SMA wire segment to cool and extend along length l. Drive currents I2, I3, ..., I4 are supplied to the SMA wire segments 5, 18, 19 that resist the first SMA wire segment 4. N This also needs to be reduced to decrease the tension T without causing a change in the displacement δx between the first part 2 and the second part 3. The tension T can be increased by increasing the drive current I1 to cause the first SMA segment to contract along length l, while correspondingly increasing the drive currents I2, I3, ..., I4 supplied to the SMA segments 5, 18, 19 that resist the first SMA segment. N This is to prevent changes in displacement δx.

[0141] While the general actuator 16 is still in use (step S10|Yes), the control loop is repeated.

[0142] Although the first SMA line 4 has been described, the second method applies to segments 4, 5, 18, and 19 of all SMA lines included in the general SMA actuator 16 controlled by controller 17.

[0143] A third method for actively regulating the cooling rate

[0144] Also refer to Figure 5 This illustrates a third method for actively adjusting (or at least influencing) the cooling rate of the first SMA line 4. The third method represents an example of implementing the first method.

[0145] The third method applies to the first SMA line 4, whose contraction is resisted by one or more other SMA lines 5, 18, 19, such that the tension T in the SMA lines 4, 5, 18, 19 can be changed independently of the displacement δx between the first part 2 and the second part 3 (at least within a portion of the range of motion x0 ± Δx). The first SMA actuator 1 is an example of a general SMA actuator 16 to which the third method is applicable. The third method can be executed by a program executed by the processor 20 of the controller 17.

[0146] Simultaneously with the third method, controller 17 will continue to provide the function of controlling the relative displacement δx between the first part 2 and the second part 3.

[0147] In the same manner as the first and second methods (steps S1, S5), measure and / or calculate one or more temperatures (step S11).

[0148] In response to an increase in temperature δΘ>0 (step S12|Yes), the first distance d that separates the first SMA wire 4 from at least one heat sink included in the general SMA actuator 16 is reduced (S13). The first distance d can be reduced by increasing or decreasing the tension of the first SMA wire 4 according to the precise configuration of the first elastic element 7. The tension T of the other one or more SMA wires 5, 18, 19 resisting the first SMA wire 4 is correspondingly adjusted. (The following is in conjunction with...) Figure 8A and Figure 8B An example of a second SMA actuator 28 is described, in which the reduced tension T reduces the first distance d.

[0149] In response to a decrease in temperature δΘ < 0 (step S12 | No, step S14 | Yes), the first distance d separating the first SMA line 4 from at least one heat sink included in the general SMA actuator 16 is increased (S15). The first distance d can be increased or decreased by increasing or decreasing the tension T of the first SMA line 4 according to the precise configuration of the first elastic element 7. The tension T of the other one or more SMA lines 5, 18, 19 resisting the first SMA line 4 is adjusted accordingly.

[0150] While the general actuator 16 is still in use (step S16|Yes), the control loop is repeated.

[0151] Although the first SMA line 4 has been described, the third method is applicable to segments 4, 5, 18, and 19 of all SMA lines included in the general SMA actuator 16 controlled by controller 17.

[0152] Although described separately from the second method, the features of the second and third methods can be combined in any compatible manner. For example, the target change δd of the first distance can be based on the temperature change δΘ and optionally also on the current ambient temperature Θ. o or linear temperature Θ 线 Retrieved from the lookup table.

[0153] A fourth method to actively influence the cooling rate

[0154] Also refer to Figure 6 This illustrates a fourth method for actively regulating (or at least influencing) the cooling rate of the first SMA line 4. The fourth method involves regulating the cooling rate based on the activity of the general actuator 16 rather than in response to a constantly changing temperature Θ.

[0155] The fourth method can be applied to a first SMA line 4, the contraction of which is resisted by one or more other SMA lines 5, 18, 19, such that the tension T in the SMA lines 4, 5, 18, 19 can be changed independently of the displacement δx between the first part 2 and the second part 3 (at least within a portion of the range of motion x0 ± Δx). The first SMA actuator 1 is an example of a general SMA actuator 16 to which the fourth method can be applied. The fourth method can be executed by a program executed by the processor 20 of the controller 17.

[0156] Simultaneously with the fourth method, controller 17 will continue to provide the function of controlling the relative displacement δx between the first part 2 and the second part 3. The fourth method may be additionally or alternatively executed concurrently with or incorporated into any of the first to third methods.

[0157] The purpose of the fourth method is to increase the cooling rate of the first SMA line 4 just before the movement (displacement) of the general SMA actuator 16 begins, and thus increase the responsiveness of the first SMA line 4. Once the relative movement of the first part 2 and the second part 3 has stopped, the first SMA line 4 can be moved back to a larger first distance d (interval / spacing) to reduce the total power consumption.

[0158] The fourth method (step S17) is triggered by receiving a command that changes the relative displacement δx between the first part 2 and the second part 3. This command can be received via I / O interface 23 or generated internally by controller 17. For example, in an optical image stabilization implementation, processor 20 can generate this command in response to acceleration detected by the gyroscope of sensor 22.

[0159] Before or simultaneously with controlling segments 4, 5, 18, and 19 of the SMA line to shift the relative displacement δx of the first part 2 and the second part 3, the first distance d of the first SMA line segment 4 is reduced (step S18). The first distance d of the other one or more SMA lines 5, 18, and 19 that resist the first SMA line segment 4 is also adjusted accordingly.

[0160] The first SMA line 4 (and the resisting SMA lines 5, 18, 19) are kept at a reduced distance, while the first part 2 and the second part 3 are repositioned (step S19) until the necessary relative displacement δx (offset) has been obtained (step S20|Yes).

[0161] Once the movement is complete, the first distance d is reset to a larger stationary value in order to reduce power consumption (step S21).

[0162] In a simplified implementation of the fourth method, a fixed variation δd in the first distance d can be applied between the moving and stationary states. 移动 .

[0163] In other implementations, controller 17 may store two profiles of a first distance d that varies with the displacement δx within the motion range x0 ± Δx. For example, the first function d 静止 (δx) can be defined as the target distance d when the actuator is not moving, while the second function d 移动 (δx) is defined as the target distance d during actuator movement. For the displacement δx within the range of motion: x0-Δx≤δx≤x0+Δx, the function should satisfy d. 静止 (x)>d 移动 (x).

[0164] Starting from the first displacement δx1 (relative to the central configuration x0), the controller 17 can adjust the tension T from d 静止 (δx1) offset to d 移动 (δx1) (step S18), move the first part 2 and the second part 3 relative to each other to a second displacement δx2 (steps S19 & S20), and then adjust the tension T to move from d 移动 (δx2) offset to d 静止 (δx2)(Step S21).

[0165] While the general actuator 16 is still in use (step S22|Yes), the control loop is repeated.

[0166] Although the first SMA line 4 has been described, the fourth method is applicable to all SMA lines included in the general SMA actuator 16 controlled by the controller 17, including segments 4, 5, 18, and 19.

[0167] Although described separately from the first through third methods, the features of the first through fourth methods can be combined in any compatible manner.

[0168] The fifth method to actively influence the cooling rate

[0169] Also refer to Figure 7 A fifth method is shown for actively adjusting (or at least influencing) the cooling rate of the first SMA line 4. This fifth method involves adjusting the cooling rate based on the current displacement δx of the general SMA actuator 16 within the range of motion x0 ± Δx.

[0170] The fifth method can be applied to the first SMA line 4, whose contraction is resisted by one or more other SMA lines 5, 18, 19, such that the tension T in the SMA lines 4, 5, 18, 19 can be changed independently of the displacement δx between the first part 2 and the second part 3 (at least within a portion of the range of motion x0 ± Δx). The first SMA actuator 1 is an example of a general SMA actuator 16 to which the fifth method can be applied. The fifth method can be executed by a program executed by the processor 20 of the controller 17.

[0171] Simultaneously with the fifth method, controller 17 will continue to provide the function of controlling the relative displacement δx between the first part 2 and the second part 3. The fifth method may be additionally or alternatively executed simultaneously with or incorporated into any of the first to third and / or fourth methods.

[0172] The temperature change required to achieve a given change in displacement δx of the general SMA actuator 16 is typically much larger at the extremes of the motion range x0±Δx of the general SMA actuator 16 than near the central configuration x0. This is a result of the nonlinear behavior of the SMA material and may cause the motion rate of the general SMA actuator 16 to be relatively lower at the extremes of the motion range x0±Δx of the general SMA actuator 16 than near the central configuration x0. The purpose of the fifth method is to increase the cooling rate of the first SMA line 4 as the general SMA actuator 16 moves away from the central configuration x0 and moves towards the extremes of displacement δx and / or near the motion range x0±Δx, and thus increase the responsiveness of the first SMA line 4.

[0173] Whenever the general actuator 16 shifts (step S23|Yes), the controller 17 retrieves or calculates the new target tension T(δx) based on the current displacement δx of the general SMA actuator 16 (step S25).

[0174] Then, the current driver module adjusts the drive currents I1, I2, I3, ..., I... NOne, some, or all of them are used to adjust the tension T in the first SMA line 4 to a target tension T(x) related to the retrieved or calculated position (step S26). As described above, the first elastic element 7 (and any other elastic elements 9, 11, 13 used) causes a change in tension T, thereby also producing a change in the first distance d between the first SMA line 4 and at least one heat sink. The first distance d of one or more SMA lines 5, 18, 19 that resist the first SMA line 4 will change accordingly. In this way, the fifth method has the function of adjusting the first distance d between the first SMA line 4 and at least one heat sink based on the relative displacement δx of the first part 2 and the second part 3 within the range of motion x0 ± Δx.

[0175] The exact nature of the relationship between actuator displacement δx and tension T(x) (or the equivalent first distance d) can take any suitable form. For example, a fifth method could adjust the tension T(x) to increase the first distance d in response to a displacement δx of the center configuration x0 moving closer to the motion range x0±Δx between the first part 2 and the second part 3, and adjust the tension T(x) to decrease the first distance d in response to a displacement δx of the center configuration x0 moving away from the motion range x0±Δx. In this way, the cooling rate can be increased as it approaches the edge of the motion range x0±Δx to provide improved responsiveness of the first SMA line 4, and the cooling rate can be decreased as it approaches the center configuration x0 to minimize excess power consumption.

[0176] In another example, the displacement δx relative to the center position x0 can be checked against a threshold, which serves as a preset condition for adjusting the tension T and therefore the first distance d of the first SMA line 4 (step S24). For example, the distance Δx-δx to the edge of the range of motion can be compared with the threshold distance x. 阈值 Comparison. If the general SMA actuator 16 is already at the threshold distance x at the edge of the motion range x0±Δx. 阈值 If the movement is internal (step S24|Yes), the tension T can be adjusted to reduce the first distance d and increase the cooling rate of the first SMA line 4 (steps S25, S26). Threshold distance x 阈值 Any suitable value can be taken, such as 20%, 15%, 10%, or 5% of the range Δx.

[0177] While the general actuator 16 is still in use (step S27|Yes), the control loop is repeated.

[0178] Although the first SMA line 4 has been described, the fifth method is applicable to all SMA lines included in the general SMA actuator 16 controlled by the controller 17, including segments 4, 5, 18, and 19.

[0179] Although described separately from the first through fourth methods, the features of the first through fifth methods can be combined in any compatible manner.

[0180] Second SMA actuator

[0181] Also refer to Figure 8A This shows a second example of the SMA actuator 28.

[0182] Except that the first to fourth elastic elements 7, 9, 11, and 13 have been replaced by the fifth to eighth elastic elements 29, 30, 31, and 32, respectively, the second SMA actuator 28 is identical to the first SMA actuator 1. The second SMA actuator 28 is an example of a general SMA actuator 16. The first SMA line 4 is connected to the first part 2 via the fifth elastic element 29. Unlike the first elastic element 7, which moves the first SMA line 4 toward the heat sink in the form of the second part 3 in response to an increased tension T, the fifth elastic element 29 is configured to move the first SMA line 4 away from the second part 3 in response to an increased tension T.

[0183] Also refer to Figure 8B This illustrates a second configuration 28b corresponding to the second SMA actuator 28 when the first SMA line 4 and the second SMA line 5 are caused to contract by increasing the corresponding drive currents I1 and I2.

[0184] exist Figure 8A The initial or central configuration x0 is shown, where the first SMA line 4 and the second SMA line 5 have a length l1 and a first distance d1. Figure 8B In this configuration, the lengths of both the first SMA line segment 4 and the second SMA line segment 5 have been reduced to a shorter length l2. Therefore, the fifth to eighth elastic elements 29, 30, 31, and 32, which support the first SMA line segment 4 and the second SMA line segment 5, have all flexed upwards and away from the heat sink in the form of the second part 3 to a new distance d2. In this way, the cooling rate of the first SMA line segment 4 and the second SMA line segment 5 can be reduced in response to the increase in tension T in the opposing SMA line segments 4 and 5.

[0185] In the second configuration 28b, both the first SMA line 4 and the second SMA line have been caused to contract to the same length l2, thus eliminating net displacement δx. Of course, if the first SMA line 4 and the second SMA line were caused to contract to different lengths, then in addition to any change in tension T, a change in displacement δx would occur. Tension T and displacement δx can be changed independently of each other within at least a portion of the motion range x0 ± Δx of the second SMA actuator 28.

[0186] Except that the effect of tension T is reversed, the second SMA actuator 28 can be considered the same as the first SMA actuator 1.

[0187] The fifth elastic element 29 is configured such that, in response to a change δT in the tension T of the first SMA line 4, the new distance d2 between the first SMA line 4 and the heat sink in the form of the second part 3 changes by an amount δ. d =|d1-d2|, the quantity δ d =|d1-d2| is greater than the change in length δl between the first end 6 and the second end 8, which is δl =|l1-l2|.

[0188] The sixth to eighth elastic elements 30, 31, and 32 are constructed in a similar manner to the fifth elastic element 29.

[0189] In the second SMA actuator 28, the elastic elements 29, 30, 31, and 32 are in the form of a crimping member having an inclined portion and an extension portion providing a leaf spring, and are arranged such that an increased tension T causes the elastic elements 29, 30, 31, and 32 to flex away from the second portion 3, thereby increasing the first distance d from d1 to d2. However, the fifth to eighth elastic elements 29, 30, 31, and 32 are not limited to this implementation and can be replaced by any alternative elastic element that provides the appropriate function, such as, for example, a leaf spring, a bracket spring, a coil spring, a shaped region of a compliant material such as natural or synthetic rubber, etc. The considerations and alternatives discussed above regarding the first to fourth elastic elements 7, 9, 11, and 13 also apply to the fifth to eighth elastic elements 29, 30, 31, and 32.

[0190] Although the second SMA actuator 28 is shown as including a first SMA line 4 and a second SMA line 5, the general SMA actuator 16 may include up to N SMA line segments 4, 5, 18, and 19. Each SMA line segment 4, 5, 18, and 19 in the general SMA actuator 16 may be constructed in the same manner as the first SMA line 4 and the second SMA line 5 of the second SMA actuator 28.

[0191] like Figure 8C As shown, the fifth to eighth elastic elements 29, 30, 31, and 32 can be configured to hold the first SMA line 4 and the second SMA line 5, wherein the line holding portion / line connecting component (e.g., crimping member) of the elastic elements 29, 30, 31, and 32 is located inside the flexible portion and the second portion 3 of the elastic elements 29, 30, 31, and 32, rather than on the outside.

[0192] Third SMA actuator

[0193] Also refer to Figure 9AThe third SMA actuator 33 is shown. See also... Figure 9B The diagram shows a second configuration 33b of the third SMA actuator 33, in which the tension T of the first SMA line 4 and the second SMA line 5 has been relaxed and there is no net displacement δx.

[0194] In the first SMA actuator 1, the spring features of the first elastic element 7 and the second elastic element 9 extend beyond the length l of the first SMA line segment 4, and similarly apply to the second SMA line segment 5 and the corresponding elastic elements 11, 13. This configuration can result in an increase in the size of the first SMA actuator 1 and / or a decrease in the range of motion x0 ± Δx, because the maximum possible change in length (second distance) δl is related to the natural, stress-free length of the SMA lines segments 4, 5, 18, 19 (e.g., with the twinned martensite phase as a reference point).

[0195] The third SMA actuator 33 is designed to address these issues by rotating each of the first to fourth elastic elements 7, 9, 11, 13 by 180 degrees so that the corresponding spring features are within the length l of the first SMA line 4 or the second SMA line 5. The third SMA actuator 33 is an example of the general SMA actuator 16.

[0196] Special reference Figure 9A The central configuration x0 is shown, in which the first SMA line 4 and the second SMA line 5 are prestressed with tension T. See also: Figure 9B If the tension T is allowed to relax (by reducing the driving currents I1, I2), the first SMA line 4 and the second SMA line 5 extend from l1 to l2, while the first to fourth elastic elements 7, 9, 11, 13 relax toward a stress-free configuration, and in doing so, the first distance is reduced from d1 to d2.

[0197] Although the third SMA actuator 33 is shown as a modification of the SMA actuator 1, the second SMA actuator 28 can be modified in the same way so that the deformation of the fifth to eighth elastic elements 29, 30, 31, 32 occurs within the length l of the corresponding first SMA line 4 or second SMA line 5.

[0198] Despite Figure 9A and Figure 9B The diagram shows first to fourth elastic elements 7, 9, 11, and 13 in the form of spring-loaded fittings, as described above with respect to SMA actuator 1 and the second SMA actuator; however, any elastic element suitable for providing the described function may be substituted. In particular, any elastic element may be configured to accommodate deformation within the length l of the respective SMA line segments 4, 5, 18, and 19.

[0199] Although the third SMA actuator 33 shown includes a first SMA line 4 and a second SMA line 5, a general SMA actuator 16 may include up to N SMA line segments 4, 5, 18, and 19. Each SMA line segment 4, 5, 18, and 19 in the general SMA actuator 16 may be constructed in the same manner as the first SMA line 4 and the second SMA line 5 of the third SMA actuator 33.

[0200] Fourth SMA actuator

[0201] In the first to third SMA actuators 1, 28, and 33, the first SMA line 4 and the second SMA line 5 are constructed using elastic elements 7, 9, 11, 13, 29 to 32 to increase or decrease the first distance d from the heat sink in the form of the second part 3. In other examples, the associated heat sink may be provided by the first part 2, or may be mounted on or integrated with either the first part 2 or the second part 3.

[0202] This movement toward / away from a single radiator may provide an increased cooling rate only at one extreme of the tension T. However, the actuator can be designed so that movement away from the first radiator is also movement toward the second radiator.

[0203] Also refer to Figures 10A to 10C The fourth SMA actuator 34 is shown.

[0204] The fourth SMA actuator 34 is identical to the third actuator 33, except that the upper portion 35 extends from the first portion 2 to pass over the first SMA line segment 4 and the second SMA line segment 5. The upper portion 35 may be integrally formed as part of the first portion 2, or it may be a separate element attached or fixed to the first portion 2 in any way such that the upper portion 35 does not move relative to the first portion 2. The second portion 3 provides a first heat sink, and the upper portion 35, which moves with the first portion 2, provides a second heat sink. SMA line segments 4 and 5 are positioned between the second portion 3 and the upper portion 35.

[0205] The fourth SMA actuator 34 is configured such that the high tension T and low tension T in the opposing first SMA line 4 and second SMA line 5 will cause those portions of SMA lines 4 and 5 to move closer to or contact at least one heat sink.

[0206] For details, please refer to the following: Figure 10AIn the central configuration x0, the first SMA wire segment 4 and the second SMA wire segment 5 have a length l1. The SMA wire segments 4 and 5 are tensioned to a tension T by each other and corresponding elastic elements 7, 9, 11, and 13. The tension T is maintained using drive currents I1 and I2 to control the length l1 of the first SMA wire segment 4 and the second SMA wire segment 5. In the central configuration x0, the first SMA wire segment 4 is positioned a first lower distance dl1 from the first heat sink provided by the second part 3, and a first upper distance du1 from the second heat sink provided by the upper part 35. The second SMA wire segment 5 is constructed similarly to the first SMA wire segment 4.

[0207] Special reference Figure 10B The diagram illustrates a second configuration 34b of the fourth SMA actuator 34. In this second configuration 34b, the fourth actuator 34 remains in the central configuration x0, but the tension T is allowed to relax by reducing the drive currents I1 and I2 (and thus the temperature), allowing the first SMA line 4 and the second SMA line 5 to extend by a certain amount δl, to l2 = l1 + δl. Consequently, the elastic deformation of the elastic elements 7, 9, 11, and 13 will also relax, allowing the first SMA line 4 and the second SMA line 5 to move closer to the first heat sink provided by the second part 3 and further away from the second heat sink provided by the upper part 35. The change δd will result in the first lower distance becoming dl2 = dl1 - δd, and the first upper distance becoming du2 = du1 + δd.

[0208] Special reference Figure 10C The diagram illustrates a third configuration 34c of the fourth SMA actuator 34. In this third configuration 34c, the fourth actuator 34 remains in the central configuration x0, but the tension T increases by increasing the drive currents I1 and I2 (and thus the temperature), causing the first SMA line 4 and the second SMA line 5 to contract by a certain amount δl, to l3 = l1 - δl. Consequently, the elastic deformation of the elastic elements 7, 9, 11, and 13 also increases, causing the first SMA line 4 and the second SMA line 5 to move further away from the first heat sink provided by the second part 3 and closer to the second heat sink provided by the upper part 35. The change δd will cause the first lower distance to become dl3 = dl1 + δd, and the first upper distance to become du3 = du1 - δd.

[0209] In the same manner as the first to third SMA actuators 1, 28, 33, the tension T in the first SMA line 4 and the second SMA line 5 can be changed independently of the displacement δx between the first part 2 and the second part 3 of the fourth actuator 34, at least within a portion of the motion range x0 ± Δx.

[0210] Although the fourth SMA actuator 34 is shown as including a first SMA line 4 and a second SMA line 5, the general SMA actuator 16 may include up to N SMA line segments 4, 5, 18, and 19. Each SMA line segment 4, 5, 18, and 19 in the general SMA actuator 16 may be constructed in the same manner as the first SMA line 4 and the second SMA line 5 of the fourth SMA actuator 34.

[0211] In this way, segments 4, 5, 18, and 19 of the SMA line can be positioned between a pair of heat sinks so that any change in tension T can provide an increased cooling rate.

[0212] Fifth SMA actuator

[0213] The first to fourth SMA actuators 1, 28, 33, and 34 already include a first SMA line segment 4 and a second SMA line segment 5, which are connected at the first end 6, 10 and the second end 8, 12 via elastic elements 7, 9, 11, 13, 29 to 32. However, the general actuator 16 may include SMA line segments 4, 5, 18, and 19, which are connected via a single elastic element 7, 9, 11, 13, 29 to 32.

[0214] Also refer to Figure 11A The fifth SMA actuator 36 is shown.

[0215] Except for omitting the first elastic element 7 and the third elastic element 11, the fifth SMA actuator 36 is the same as the first SMA actuator 1. The first end 6 of the first SMA line 4 is directly or at least rigidly attached to the first part 2, and the first end 10 of the second SMA line 5 is directly or at least rigidly attached to the first part 2.

[0216] exist Figure 11A In the diagram, gap 14 is shown as omitted, wherein the first portion 2 and the second portion 3 are kept in contact by the angle of the first SMA line 4 and the second SMA line 5 and the tension in the first SMA line 4 and the second SMA line 5. This may sometimes be referred to as a "sliding" support. However, in a variant of the fifth SMA actuator 36, gap 14 does not need to be omitted, and any support suitable for allowing movement parallel to the first direction x or parallel to the plane defined by the first direction x and the second direction y can be used instead of the sliding support. For example, one or more ball bearings or cylindrical bearings may be provided between the first portion 2 and the second portion 3.

[0217] exist Figure 11AIn the configuration shown, the fifth SMA actuator 36 is located in the central configuration x0, and the first SMA line 4 and the second SMA line 5 have equal lengths l1 and form an equal angle with the first direction x. The first SMA line 4, the second SMA line 5, the second elastic element 9, and the fourth elastic element 13 are prestressed with tension T. The average first distance between the first SMA line 4 and the heat sink provided by the second part 3 is d1.

[0218] Also refer to Figure 11B The second configuration 36b of the fifth SMA actuator 36 is shown.

[0219] Without shifting relative to the central configuration x0, the tension T of the first SMA wire 4 and the second SMA wire 5 is increased by increasing the driving currents I1 and I2. The first SMA wire 4 is heated and contracts, causing its length (second distance) to change by a certain amount δl, from l1 to l2 = l1 - δl. This causes the second elastic element 9 to bend towards the first end 6, reducing the angle formed with the first direction x to... This has the effect of reducing the average first distance by a certain amount δd to d2 = d1 - δd. Figure 11A and Figure 11B In the example shown, the change in the average first distance is:

[0220]

[0221] The second SMA line 5 and the fourth elastic element 13 deform and flex in a manner corresponding to the first SMA line 4 and the second elastic element 7.

[0222] In the same manner as the first to fourth SMA actuators 1, 28, 33, 34, the tension T of the first SMA line 4 and the second SMA line 5 can be changed independently of the displacement δx of the fifth actuator 36, at least within a portion of the range of motion x0 ± Δx.

[0223] Although the fifth SMA actuator 36 is shown to include a first SMA line 4 and a second SMA line 5, a general SMA actuator 16 may include up to N SMA line segments 4, 5, 18, and 19. Each SMA line segment 4, 5, 18, and 19 in the general SMA actuator 16 may be constructed in the same manner as the first SMA line 4 and the second SMA line 5 of the fifth SMA actuator 36.

[0224] In the alternative SMA actuator (not shown), the second elastic actuator 9 and the fourth elastic actuator 13 can be replaced by the sixth elastic actuator 30 and the eighth elastic actuator 32, which are configured such that an increase in tension T will increase the average first distance d between the first SMA line 4 and the second SMA line 5 and the heat sink provided by the second part 3.

[0225] Sixth SMA actuator

[0226] Also refer to Figure 12 The sixth SMA actuator 37 is shown.

[0227] Except that the second elastic element 9 and the fourth elastic element 13 have been rotated such that the deformation of the second elastic element 9 and the fourth elastic element 13 will be within the length l of the corresponding first SMA line 4 and the second SMA line 5, the sixth SMA actuator 37 is the same as the fifth SMA actuator 36. The difference between the fifth actuator 36 and the sixth SMA actuator 37 is substantially equivalent to the difference between the first SMA actuator 1 and the third SMA actuator 33, except that increasing the tension will increase the average first distance d.

[0228] Alternatively and equivalently, the sixth SMA actuator 37 can be considered equivalent to starting from the third SMA actuator 33 and then replacing the first elastic element 7 and the third elastic element 11 with a direct or at least rigid connection to the first part 2.

[0229] In the same manner as the first to fifth SMA actuators 1, 28, 33, 34, and 36, the tension T of the first SMA line 4 and the second SMA line 5 can be changed independently of the displacement δx of the sixth actuator 37, at least within a portion of the motion range x0 ± Δx.

[0230] Although the sixth SMA actuator 37 is shown to include a first SMA line 4 and a second SMA line 5, a general SMA actuator 16 may include up to N SMA line segments 4, 5, 18, and 19. Each SMA line segment 4, 5, 18, and 19 in the general SMA actuator 16 may be constructed in the same manner as the first SMA line 4 and the second SMA line 5 of the sixth SMA actuator 37.

[0231] In an alternative SMA actuator (not shown), the second elastic actuator 9 and the fourth elastic actuator 13 can be replaced by the sixth elastic actuator 30 and the eighth elastic actuator 32.

[0232] Seventh SMA actuator

[0233] The fifth SMA actuator 36 and the sixth SMA actuator 37, and variations not shown, include each SMA line segment 4, 5, 18, 19 having a single elastic element 7, 9, 11, 13, 29 to 32 connecting the SMA line segments 4, 5, 18, 19 to the second portion 3 of the actuators 36 and 37. In other embodiments, the SMA line segments 4, 5, 18, 19 may be attached to the second portion 3 using a direct or at least rigid connection, while simultaneously being attached to the first portion 2 via the elastic elements 7, 9, 11, 13, 29 to 32.

[0234] For example, also refer to Figure 13 The seventh SMA actuator 38 is shown.

[0235] Except for omitting the second elastic element 9 and the fourth elastic element 13, the seventh SMA actuator 36 is the same as the first SMA actuator 1. The second end 8 of the first SMA line 4 is directly or at least rigidly attached to the second part 3, and the second end 12 of the second SMA line 5 is directly or at least rigidly attached to the second part 3.

[0236] exist Figure 13 In the diagram, gap 14 is shown as omitted, wherein the second portion 3 is held in place against one or more retaining lip features 39 by the angle of the first SMA line 4 and the second SMA line 5 and the tension in the first SMA line 4 and the second SMA line 5. This may sometimes be referred to as a "sliding" support. However, in a variation of the seventh SMA actuator 38, any support suitable for allowing movement parallel to the first direction x or parallel to the plane defined by the first direction x and the second direction y can be used instead of the sliding support. For example, one or more ball bearings or cylindrical bearings may be provided between the second portion 3 and the retaining lip features 39. The retaining lip features may be integrally formed with the first portion 2, or they may be separate from the first portion 2 but attached to the first portion 2 in a manner that prevents relative movement.

[0237] In the same manner as the first to sixth SMA actuators 1, 28, 33, 34, 36, and 37, the tension T of the first SMA line 4 and the second SMA line 5 can be changed independently of the displacement δx of the seventh actuator 38, at least within a portion of the motion range x0 ± Δx.

[0238] Although the seventh SMA actuator 38 is shown to include a first SMA line 4 and a second SMA line 5, a general SMA actuator 16 may include up to N SMA line segments 4, 5, 18, and 19. Each SMA line segment 4, 5, 18, and 19 in the general SMA actuator 16 may be constructed in the same manner as the first SMA line 4 and the second SMA line 5 of the seventh SMA actuator 38.

[0239] In an alternative SMA actuator (not shown), the second elastic element 9 and the fourth elastic element 13 can be replaced by the sixth elastic element 30 and the eighth elastic element 32.

[0240] In another embodiment (not shown), segments 4, 5, 18, and 19 of the SMA line can be connected to the first portion 2 at the first end 6 and 10 using elastic elements 7, 9, 11, 13, 29 to 32 or directly (rigidly) connected, while the second ends 8 and 12 can be connected to the second portion 3 using elastic elements 7, 9, 11, 13, 29 to 32 or directly (rigidly) connected.

[0241] SMA wire and spring actuator

[0242] The first to seventh SMA actuators 1, 28, 33, 34, 36, 37, and 38 have already used the second SMA line 5 to resist the contraction of the first SMA line 4. However, it is not necessary to use one or more SMA lines 5, 18, and 19 to resist the contraction of the first SMA line 4. Any of the first to seventh SMA actuators 1, 28, 33, 34, 36, 37, and 38 may be adapted to include a resilient biasing element 40. Figure 14A For example, a spring, the elastic biasing element 40 is arranged to resist the contraction of the first SMA line 4 and the tension T of the first SMA line 4. Such an actuator may be referred to as an "SMA line and spring" actuator, and represents an additional example of a general SMA actuator 16.

[0243] The SMA wire and spring actuator loses its ability to change the tension T of the first SMA wire 4 independently of the displacement δx relative to the central configuration x0. Nevertheless, elastic elements 7, 9, 11, 13, 29 to 32 can be added to the SMA wire and spring actuator and configured to provide an improvement in the cooling rate depending on the relative displacement δx between the first part 2 and the second part 3.

[0244] Also refer to Figure 14A This shows the eighth SMA actuator 41 in the central (or initial) configuration x0.

[0245] Except that the second SMA line 5 and the associated elastic elements 11 and 13 have been removed and replaced with an elastic biasing element 40 in the form of a helical spring, the eighth SMA actuator 41 is identical to the fourth SMA actuator 34. 偏置 The linear (following Hooke's law) spring constant. The first SMA line 4, the first elastic element 7, the second elastic element 9, and the elastic bias element 40 are in... Figure 14A The configuration shown is prestressed with tension T.

[0246] In most cases, the function of the eighth SMA actuator 41 is similar to that of the fourth SMA actuator 34. The obvious difference is that changing the tension T of the first SMA line 4 also necessarily leads to a displacement δx between the first part 2 and the second part 3 of the eighth SMA actuator 41.

[0247] For example, also refer to Figure 14B The second configuration 41b of the eighth SMA actuator 41 is shown.

[0248] In the second configuration 41b, the tension T in the first SMA line 4 has been allowed to decrease by reducing the drive current I1 (and lowering the temperature), thereby allowing the first SMA line 4 to extend until a new equilibrium is reached with the elastic bias element 40. The tension T is reduced by a certain amount δT = k 偏置 δx, this quantity involves the displacement δx of the eighth SMA actuator 41 multiplied by the spring constant k of the elastic bias element 40. 偏置 The first elastic element 7 and the second elastic element 9 also relax towards a stress-free state, and as described above, the first elastic element 7 and the second elastic element 9 are configured to cause the first SMA line 4 to move a certain amount δd = dl1 - dl2 = du2 - du1 towards the first heat sink provided by the second part 3 and away from the second heat sink provided by the upper part 35. It should be noted that the change in length δl = l2 - l1 will be slightly greater than the displacement δx, because some of the change in length δl is accommodated by the relaxation of the first elastic element 7 and the second elastic element 9.

[0249] Also refer to Figure 14C The third configuration 41c of the eighth SMA actuator 41 is shown.

[0250] In the third configuration 41c, the tension T in the first SMA wire 4 has been increased by increasing the driving current I1 (and raising the temperature), causing the first SMA wire 4 to contract until a new equilibrium is reached with the elastic bias element 40. The increase in tension T is constant, δT = k. 偏置 δx, this quantity involves the displacement δx of the eighth SMA actuator 41 multiplied by the spring constant k of the elastic bias element 40. 偏置The first elastic element 7 and the second elastic element 9 also deform upwards and inwards towards the upper part 35 and towards each other. This causes the first segment of the SMA line 4 to move away from the first heat sink provided by the second part 3 and towards the second heat sink provided by the upper part 35 by a certain amount δd = dl3 - dl1 = du1 - du3. It should be noted that the change in length δl = l3 - l1 will be slightly greater than the displacement δx, because some of the change in length δl is accommodated by the bending of the first elastic element 7 and the second elastic element 9.

[0251] In this way, when the eighth SMA actuator 41 approaches either extreme of the motion range x0±Δx, the first SMA line is brought closer to the first or second radiator (second part 3 or upper part 35), thereby increasing the cooling rate and improving responsiveness.

[0252] Despite Figures 14A to 14C The spring is shown as a helical spring, but the elastic biasing element 40 can be replaced by any biasing element capable of applying tension T to resist the contraction of the first SMA line 4. For example, the elastic biasing element 40 can take the form of a leaf spring, a bracket spring, a flexure, an area of ​​elastic material such as natural or synthetic rubber, or any other elastic biasing element capable of providing the above-described function.

[0253] Ninth SMA actuator

[0254] Any of the first to seventh SMA actuators 1, 28, 33, 34, 36, 37, and 38 may be adapted to operate as a wire-vs-spring actuator, instead of using the second SMA line 5 to resist the contraction of the first SMA line 4.

[0255] For example, also refer to Figure 15 The ninth SMA actuator 42 is shown.

[0256] Except that the second SMA line 5 is omitted and the contraction of the first SMA line 4 is resisted by an elastic bias element 40 in the form of a helical spring, the ninth SMA actuator is the same as the fifth SMA actuator 36.

[0257] Displacement of SMA segment ends

[0258] Also refer to Figure 16A The diagram shows an actuation diagram of the first SMA line 4, which has a fixed second end 8 and a first end 6 connected by a first elastic element 7.

[0259] The initial configuration is shown in solid lines, while the final configuration after adding tension T to the first SMA line 4 is shown in dashed lines and reference numerals 4b and 7b.

[0260] The total displacement of the first end 6 is transmitted via vector r The total displacement is described as including a first displacement r1 toward the second end 8 and a second displacement r2 perpendicular to the first displacement r1. The first displacement r1 corresponds to the distance moved in a direction parallel to the first segment of the SMA line 4 before the tension T changes, and the second displacement r2 corresponds to a direction perpendicular to the first segment of the SMA line 4 before the tension T changes.

[0261] An alternative expression of the function of the first elastic element 7 is that, in response to a change in tension T of the first SMA line 4, the first end 6 should move a second displacement r2, which is greater than the first displacement r1. Note that... Figure 16A (or Figure 16B , Figure 16C The example shown does not meet this condition; for visual purposes, the relative displacement in this example is exaggerated. This function also applies to any suitable elastic element 7, 9, 11, 13, 29 to 32.

[0262] Also refer to Figure 16B The diagram shows an actuation diagram of the first SMA line 4, which has a first end 6 connected by a first elastic element 7 and a second end 8 connected by a second elastic element 9.

[0263] The initial configuration is shown in solid lines, while the final configuration after adding tension T to the first SMA line 4 is shown in dashed lines and reference numerals 4b, 7b, and 9b.

[0264] The total displacement of the second end 8 is transmitted through vector h The total displacement comprises a third displacement h1 toward the first end 6 and a fourth displacement h2 perpendicular to the third displacement h1. The third displacement h1 corresponds to the distance moved in a direction parallel to the first SMA line 4 before the change in tension T, and the fourth displacement h2 corresponds to a direction perpendicular to the first SMA line 4 before the change in tension T. In response to a change in tension T of the first SMA line 4, the second end 8 should move the fourth displacement h2, which is greater than the third displacement h1. This function also applies to any suitable elastic elements 7, 9, 11, 13, 29 to 32.

[0265] The second displacement r2 and the fourth displacement h2 do not necessarily have to be in the same direction. For example, also refer to Figure 16C The diagram shows an actuation diagram of the first SMA line 4, which has a first end 6 connected by a first elastic element 7 and a second end 8 connected by a second elastic element 9.

[0266] Figure 16C The configuration is different Figure 16BThe configuration is as follows, because the second elastic element 9 has been flipped (mirrorized) about an axis parallel to the first direction x. The initial configuration is shown with solid lines, while the final configuration after increasing the tension T of the first SMA line 4 is shown with dashed lines and reference numerals 4b, 7b, and 9b.

[0267] In this configuration, the fourth displacement h2 is in the opposite direction to the second displacement r2 (parallel to the opposite direction). Such a configuration may still be useful for controlling the spacing of the first SMA line 4 (and thus the cooling rate). Figure 16C An example of a pair of heat sinks 52 configured to provide a variable average distance relative to the first SMA line 4 is also shown.

[0268] SMA Optical Image Stabilizer

[0269] Also refer to Figure 17 The image shows an optical image stabilization (OIS) component 43 for the camera.

[0270] OIS assembly 43 includes a first portion 2 in the form of a support platform 44 and a second portion 3 in the form of a lens holder 45. The lens holder 45 includes an annular aperture in which a lens 46 is supported. OIS assembly 43 is configured to allow lateral movement of the lens holder 45 and the supported lens 46 in a plane defined by a first direction x and a second direction y (in other words, defined by a first axis x and a second axis y), and rotation of the lens holder 45 about a third direction z (in other words, a third axis z). The third direction z is the optical axis of the lens 46. The lens 46 focuses an image onto an image sensor (not shown), and an additional lens (not shown) may be positioned above and / or below the lens 46 in the third direction z.

[0271] The lens bracket 45 is connected to the support platform using segments 471, 472, 473, and 474 arranged to form a lateral actuation arrangement. Examples of lateral actuation arrangements including four SMA lines are described in WO 2017 / 055788 A1 and WO 2019 / 086855 A1, which are incorporated herein by reference.

[0272] In operation, segments 471, 472, 473, and 474 of the SMA line are selectively driven to move the lens holder 45 relative to the support platform 44 in any lateral direction (i.e., in a direction perpendicular to the third z-axis and the optical axis (in the plane of the first x-axis and the second y-axis)). Further explanation is also provided in WO 2013 / 175197A1, which is incorporated herein by reference.

[0273] SMA line segments 471, 472, 473, and 474 are arranged in a loop at different angular positions around lens 46 to provide two pairs of mutually opposing SMA line segments 471, 472, 473, and 474 perpendicular to each other. The four SMA line segments 471, 472, 473, and 474 form a pair 471, 474 opposite to a pair 472, 473 along a first direction x, while a pair 471, 472 opposite to a pair 473, 474 along a second direction y. Therefore, each pair of opposing SMA line segments 471, 472, 473, and 474 can selectively drive the lens holder 45 and the supported lens 46 to move in one of two perpendicular directions within a plane encompassing the first direction x and the second direction y. Thus, segments 471, 472, 473, and 474 of the SMA line can be selectively driven in the plane of the first direction x and the second direction y to move the lens holder 45 relative to the support platform 44 to any position within the movement range x0±Δx, y0±Δy. The size of the movement range x0±Δx, y0±Δy depends on the geometry and contraction range of segments 471, 472, 473, and 474 of the SMA line within their normal operating parameter range.

[0274] Because the segments 471, 472, 473, and 474 of the SMA line form opposing pairs, the aforementioned method of actively influencing the cooling rate can be applied to the OIS component 43.

[0275] The drive signals for segments 471, 472, 473, and 474 of the SMA line can be generated and supplied by a controller 17 including a current driver module 24, which includes at least four outputs. Figure 2 Under the control of the process executed by processor 20, drive currents I1, I2, I3, and I4 are driven by current driver module 24 in response to the gyroscope sensor included in sensor 22. Figure 2 The output signal of the image sensor (not shown) is generated to drive the movement of the OIS component 43 to stabilize the image focused on the image sensor (not shown) by the lens 46, thereby providing OIS. The drive currents I1, I2, I3, I4 can be generated using, for example, the resistive feedback control technique described in WO 2014 / 076463A1, which is incorporated herein by reference.

[0276] During operation, the lens holder 45 moves orthogonally to the optical axis (in the xy plane) relative to an image sensor (not shown) offset from the lens 46 in the third direction z, thereby shifting the image on the image sensor (not shown). This can be used to provide optical image stabilization (OIS) by compensating for possible movement of the camera, which includes the OIS component 43, caused by factors such as hand shake.

[0277] In some examples, additional components such as springs, flexures, or similar resilient biasing elements (not shown) may be included in the OIS assembly 43 to bias the lens holder 45 toward the central configuration x0, y0. When such a resilient biasing element (not shown) is included, the lens holder 45 will tend toward the central configuration x0, y0 from any position displaced δx, δy relative to the central configuration x0, y0 without any lateral movement driving the OIS assembly 43. This helps ensure that the camera containing the OIS assembly 43 retains its image-capturing function, even without driving the SMA lines segments 471, 472, 473, 474. The magnitude of the lateral biasing force is kept low enough not to impede the OIS, while preferably high enough to center the OIS assembly 43 without driving.

[0278] A space 48 is provided between the support platform 44 and the lens holder 45 to allow a certain range of motion. End stops (not shown) may be provided to prevent excessive tension of the SMA cable segments 471, 472, 473, 474 in the event of an impact (e.g., due to falling to the floor) to the camera containing the OIS assembly 43. For visual purposes, Figure 17 The relative size of the space has been enlarged by 48.

[0279] The difference between OIS assembly 43 and a previous OIS assembly comprising four SMA lines lies in that each of the segments 471, 472, 473, and 474 of the four SMA lines is connected between the support platform 44 and the lens holder 45 using a pair of elastic elements 49 at either end. The elastic elements 49 are constructed as described above such that the segments 471, 472, 473, and 474 of the SMA lines can be translated in the third direction z (i.e., perpendicular to the xy plane) due to the increase and decrease of the tension T of the segments 471, 472, 473, and 474. The heat sink can be provided, for example, by the structure of the support platform 44, or by another structure arranged along the third direction z above the segments 471, 472, 473, and 474 of the SMA lines.

[0280] However, the elastic element 49 according to this specification is not limited to the displacement of the segments 471, 472, 473, 474 of the SMA line in a direction perpendicular to the motion plane of the general SMA actuator 16.

[0281] For example, also refer to Figure 18 The second OIS component 50 is shown.

[0282] Except that the elastic element 49 is replaced by an in-plane elastic element 51, the second OIS assembly 50 is identical to the first OIS assembly 43. The in-plane elastic element 51 is connected at one end to the support platform 44 or lens holder 45, and at the other end to one of the four SMA line segments 471, 472, 473, and 474. The connection between the in-plane elastic element 51 and the support platform 44 or lens holder 45 can be fixed or freely rotatable, for example, using... Figure 18 The pin joint shown is free to rotate. Unlike the elastic element 49, the in-plane elastic element 51 does not cause the segments 471, 472, 473, 474 of the SMA line to move toward and away from the support platform 44 and the lens bracket in the third direction z.

[0283] Instead, the in-plane elastic element 51 is configured to displace the segments 471, 472, 473, 474 of the SMA lines in the plane of the first direction x and the second direction y, so as to move them closer to or further away from the corresponding heat sinks 521, 522, 523, 524. The heat sinks 521, 522, 523, 524 may be extensions of the support platform 44, or they may be separate structures joined or mounted to the support platform 44. Preferably, the heat sinks 521, 522, 523, 524 will have relatively high thermal conductivity, for example, formed of a metallic material such as stainless steel. The heat sinks 521, 522, 523, 524 are arranged close to the segments 471, 472, 473, 474 of the corresponding SMA lines, and each heat sink includes main surfaces 531, 532, 533, 534 extending substantially parallel to the segments 471, 472, 473, 474 of the closest SMA lines.

[0284] Compared to a structure using a support platform 44 and / or a lens holder 45 to provide the heat sink, the arrangement of in-plane SMA segments 471, 472, 473, 474 displacements in the second OIS assembly 50 allows for greater control over the precise positioning of the heat sinks 521, 522, 523, 524. Furthermore, the in-plane SMA segments 471, 472, 473, 474 displacements help maintain a lower device size in the third direction (parallel to the optical axis of the lens 46).

[0285] Other variations

[0286] It should be understood that the above embodiments can have many other variations.

[0287] The SMA actuators 1, 28, 33, 34, 36, 37, 38, 41, 42, 43, and 50 described above have been shown as using elastic elements 7, 9, 11, 13, 29 to 32, 49, and 51 in the form of spring-loaded fittings. However, any elastic element 7, 9, 11, 13, 29 to 32, 49, and 51 in any SMA actuator 1, 28, 33, 34, 36, 37, 38, 41, 42, 43, and 50 can be replaced by any other structure suitable for providing the functions described above. For example, the elastic element can be provided by any type of spring, a flexure or arm formed of a metal or polymer material, a structure formed of an elastomeric material, etc.

[0288] Wire and spring SMA actuators 40, 42 have been shown, comprising a separate resilient biasing element 40 in the form of a helical spring. However, wire and spring SMA actuators 40, 42 are not limited to helical springs, and any other type of resilient biasing structure suitable for resisting the segment of the SMA wire can be used. Examples include leaf springs, bracket springs, flexures or arms formed of metal or polymer materials, structures formed of elastomeric materials, and so on. The resilient biasing element can be integrally formed as part of the first portion 2 and / or the second portion 3, for example, formed as a stainless steel flexure extending from the first portion 2.

[0289] Although not shown in the accompanying drawings, the second portion 3 of any of the SMA actuators 1, 28, 33, 34, 36, 37, 38, 41, 42, 43, and 50 may be provided with an end stop (not shown) to limit the lateral movement of the second portion 3 relative to the first portion 2. In this way, segments 4, 5, 18, 19, 471, 472, 473, and 474 of the SMA line can be protected against impacts.

[0290] Although the SMA actuators 1, 28, 33, 34, 36, 37, 38, 41, 42, 43, 50 described above are limited to movement in the plane of the first direction x and the second direction y, the same principle of using elastic elements 7, 9, 11, 13, 29 to 32, 49, 51 to control the cooling rate based on the spacing with one or more heat sinks can be applied to a general SMA actuator 16 that provides movement along any translational direction x, y, z and rotation about any direction x, y, z.

[0291] Although the foregoing description has been presented with reference to the first direction x, the second direction y, and the third direction z of a right-handed orthogonal Cartesian coordinate system, the present invention is not limited to the coordinate system used to describe it.

[0292] OIS components 43 and 50 do not need to be configured to support lens 46, and can be configured, for example, to support other types of optical elements, image sensors, the entire camera module, etc. OIS components 43 and 50 are not necessarily used in a camera.

[0293] The SMA actuators 1, 15, 28, 33, 34, 36, 37, 38, 41, 42, 43, and 50 described above can be used in any type of component including a first part and a second part that can move relative to the first part.

[0294] Part 2 can be a supporting structure. Part 3 can be a movable part.

[0295] It should be understood that, Figures 1A-1C , Figures 8A-8B , Figures 9A-9B , Figures 10A-10C , Figures 11A-11B , Figure 12 , Figure 13 Any of the embodiments shown (or any other similar embodiments) may be configured with Figures 14A-14C , Figure 15 The elastic bias element 40 (or any similar elastic bias element).

[0296] It should be understood that Figures 14A-14C , Figure 15 Any embodiment shown (or any other similar embodiment) may include a second SMA line 5 and a connection to... Figures 1A-1C , Figures 8A-8B , Figures 9A-9B , Figures 10A-10C , Figures 11A-11B , Figure 12 , Figure 13 The second segment of SMA line 5 is an elastic element (or any other similar component).

[0297] The aforementioned SMA actuator assembly includes an SMA wire. The term "shape memory alloy (SMA) wire" can refer to any element containing an SMA. An SMA wire can have any shape suitable for the purposes described herein. An SMA wire can be elongated and can have a circular cross-section or any other cross-section shape. The cross-section can vary along the length of the SMA wire. It is also possible that the length of the SMA wire (however defined) can be similar to one or more of its other dimensions. An SMA wire can be flexible, or in other words, it can be supple. In some examples, when connected in a straight line between two elements, the SMA wire can only exert tension to force the two elements together. In other examples, the SMA wire can bend around the element, and the SMA wire can apply a force to the element as it tends to straighten under tension. An SMA wire can be beam-like or rigid and capable of applying different forces (e.g., non-tension) to the element. An SMA wire may or may not include non-SMA (one or more) materials and / or (one or more) components. For example, an SMA wire may include an SMA core and a coating of non-SMA materials. Unless the context otherwise requires, the term "SMA line" can refer to any configuration of an SMA line that acts as a single actuating element, such that the single actuating element can be independently controlled to generate a force acting on the element. For example, an SMA line may comprise two or more sections of an SMA line arranged mechanically in parallel and / or in series. In some arrangements, an SMA line may be part of a larger segment of an SMA line. Such a larger segment of an SMA line may comprise two or more sections that can be individually controlled, thereby forming two or more SMA lines.

Claims

1. A shape memory alloy actuator, comprising: Part One; Part Two; One or more radiators; as well as One or more shape memory alloy wires, the one or more shape memory alloy wires including a first shape memory alloy wire, the one or more shape memory alloy wires being configured to move a second portion relative to the first portion within a range of motion; Wherein, the first segment of shape memory alloy wire is connected to the first part at the first end by a first elastic element, and the second end of the first segment of shape memory alloy wire is connected to the second part; The first elastic element is configured such that, in response to a change in the tension of the first shape memory alloy wire, the amount by which a first distance between the first shape memory alloy wire and at least one of the heat sinks increases or decreases is greater than a change in a second distance between the first end and the second end.

2. The shape memory alloy actuator according to claim 1, wherein, The one or more shape memory alloy wires are configured to move the second portion relative to the first portion within the range of motion and / or to move the first portion relative to the second portion within the range of motion.

3. The shape memory alloy actuator according to claim 1 or claim 2, wherein, The first elastic element includes a portion extending in a direction oriented at an angle less than or equal to 45 degrees to the second distance.

4. The shape memory alloy actuator according to any one of claims 1 to 3, wherein, The second end of the first shape memory alloy wire is connected to the second part via a second elastic element.

5. The shape memory alloy actuator according to claim 4, wherein, The second elastic element includes a portion extending in a direction oriented at an angle less than or equal to 45 degrees to the second distance.

6. The shape memory alloy actuator according to any one of claims 1 to 5, wherein, The change in the first distance corresponds to a movement away from the first radiator among the one or more radiators and toward the second radiator among the one or more radiators.

7. The shape memory alloy actuator according to any one of claims 1 to 6, wherein, The first part includes at least one of the heat sinks.

8. The shape memory alloy actuator according to any one of claims 1 to 7, wherein, The second part includes at least one of the heat sinks.

9. The shape memory alloy actuator according to any one of claims 1 to 8, wherein, The one or more shape memory alloy wires include another segment or more of shape memory alloy wires, each of which is constructed in the same manner as the first segment of shape memory alloy wire.

10. The shape memory alloy actuator according to any one of claims 1 to 9, wherein, The one or more shape memory alloy wires include the first shape memory alloy wire and the second shape memory alloy wire; The second shape memory alloy wire is configured to resist the first shape memory alloy wire. The tension of the first segment of shape memory alloy wire and the tension of the second segment of shape memory alloy wire can be changed independently of the position of the second part within at least a portion of the moving range.

11. The shape memory alloy actuator according to any one of claims 1 to 10, further comprising: A third elastic element is configured to resist the first segment of shape memory alloy wire.

12. A device for controlling a shape memory alloy actuator, comprising: The shape memory alloy actuator according to claim 10 or claim 11 when dependent on claim 10; as well as The controller is configured to: Control the relative positions of the first part and the second part; The cooling rate of the first shape memory alloy wire is controlled by adjusting the tension of the first section of the wire, wherein: Moving the first segment of shape memory alloy wire toward at least one of the heat sinks increases the cooling rate; and Moving the first segment of shape memory alloy wire away from at least one of the heat sinks reduces the cooling rate.

13. The apparatus of claim 12, further comprising a temperature sensing module configured to determine a temperature corresponding to the first segment of shape memory alloy wire; in, The controller is configured to: Determine the temperature; The distance between the first segment of shape memory alloy wire and at least one of the heat sinks is adjusted based on the temperature.

14. The apparatus according to claim 13, wherein, Adjusting the distance between the first segment of shape memory alloy wire and at least one of the heat sinks based on the temperature includes: Retrieve the pre-calibrated distance corresponding to the temperature from the lookup table stored by the controller.

15. The apparatus according to claim 13, wherein, Adjusting the distance between the first segment of shape memory alloy wire and at least one of the heat sinks based on the temperature includes: In response to determining an increase in temperature, the distance between the first segment of shape memory alloy wire and at least one of the heat sinks is reduced; In response to determining that the temperature has decreased, the distance between the first segment of shape memory alloy wire and at least one of the heat sinks is increased.

16. The apparatus according to any one of claims 12 to 15, wherein, The controller is also configured to reduce the distance between the first segment of shape memory alloy wire and at least one of the heat sinks before changing the relative positions of the second and first portions.

17. The apparatus according to any one of claims 12 to 16, wherein, The controller is also configured to increase the distance between the first segment of shape memory alloy wire and at least one of the heat sinks after changing the relative positions of the second and first portions.

18. The apparatus according to any one of claims 12 to 17, wherein, The controller is also configured to adjust the distance between the first segment of shape memory alloy wire and at least one of the heat sinks based on the relative position of the second portion within the range of motion.

19. The apparatus according to claim 18, wherein, Adjusting the distance between the first segment of shape memory alloy wire and at least one of the heat sinks based on the relative position of the second part within the movement range includes: In response to the second portion moving closer to the center of the movement range, the distance between the first segment of the shape memory alloy wire and at least one of the heat sinks is increased; In response to the second portion moving further away from the center of the movement range, the distance between the first segment of shape memory alloy wire and at least one of the heat sinks is reduced.

20. The apparatus according to any one of claims 12 to 19, wherein, The one or more shape memory alloy wires include another segment or more shape memory alloy wires, each of the other segments being constructed in the same manner as the first segment, and wherein the controller is configured to control each of the other segments in the same manner as the first segment.

21. An optical image stabilization assembly for a camera, the optical image stabilization assembly comprising an actuator according to any one of claims 1 to 11 or a device according to any one of claims 12 to 20.

22. An autofocus assembly for a camera, the autofocus assembly comprising an actuator according to any one of claims 1 to 11 or a device according to any one of claims 12 to 20.

23. A method for controlling a shape memory alloy actuator, the shape memory alloy actuator comprising: Part One; Part Two; One or more radiators; as well as One or more shape memory alloy wires, the one or more shape memory alloy wires comprising a first shape memory alloy wire and a second shape memory alloy wire, the second shape memory alloy wire being configured to resist the first shape memory alloy wire, the one or more shape memory alloy wires being configured to move the second portion relative to the first portion within a range of motion, wherein the tension of the first shape memory alloy wire and the tension of the second shape memory alloy wire are capable of changing independently of the position of the second portion within at least a portion of the range of motion; Wherein, the first segment of shape memory alloy wire is connected to the first part at the first end by a first elastic element, and the second end of the first segment of shape memory alloy wire is connected to the second part; Wherein, the first elastic element is configured such that, in response to a change in the tension of the first segment of shape memory alloy wire, the amount by which a first distance between the first segment of shape memory alloy wire and at least one of the heat sinks increases or decreases is greater than the change in a second distance between the first end and the second end. The method includes: The cooling rate of the first shape memory alloy wire is controlled by adjusting the tension of the first section of the wire, wherein: Moving the first segment of shape memory alloy wire toward at least one of the heat sinks increases the cooling rate; and Moving the first segment of shape memory alloy wire away from at least one of the heat sinks reduces the cooling rate.

24. The method according to claim 23, wherein, The one or more shape memory alloy wires are configured to move the second portion relative to the first portion within the range of motion and / or to move the first portion relative to the second portion within the range of motion.

25. The method according to claim 23 or 24, wherein, The second end of the first shape memory alloy wire is connected to the second part via a second elastic element.

26. The method according to any one of claims 23 to 25, further comprising: The temperature corresponding to the first segment of shape memory alloy wire is determined using a temperature sensing module; The distance between the first segment of shape memory alloy wire and at least one of the heat sinks is adjusted based on the temperature.

27. The method according to any one of claims 23 to 26, further comprising: In response to changing the relative positions of the second portion and the first portion, the distance between the first segment of shape memory alloy wire and at least one of the heat sinks is reduced.

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