IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
UP-0222022
(2005-09-08)
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등록번호 |
US-7688168
(2010-04-23)
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발명자
/ 주소 |
- Taya, Minoru
- Cheng, Victor
- Sugandi, Harry
- Liang, Yuanchang
- Chen, Hsiuhung
- Wang, Chi-Yuan
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출원인 / 주소 |
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
5 인용 특허 :
21 |
초록
▼
Linear actuators (also known as an inchworm actuator) including a magnetically actuatable shape memory alloy (SMA) are described. The linear actuators include a bar and an actuator assembly, configured to achieve a linear displacement of the actuator assembly relative to the bar. A hybrid magnetic t
Linear actuators (also known as an inchworm actuator) including a magnetically actuatable shape memory alloy (SMA) are described. The linear actuators include a bar and an actuator assembly, configured to achieve a linear displacement of the actuator assembly relative to the bar. A hybrid magnetic trigger including an electromagnet and a permanent magnet is used to selectively attract the magnetically actuatable SMA toward the magnetic trigger. The motion of the magnetically actuatable SMA can be converted to a linear displacement. The magnetically actuatable SMA can be implemented using a SMA exhibiting both ferromagnetic and SMA properties, or by a ferromagnetic mass coupled with an SMA (i.e., a ferromagnetic SMA composite). Linear actuators including bars incorporating a ratchet mechanism, and featureless bars are described. A hydraulic system incorporating actuators including magnetically actuatable SMA membranes is also disclosed.
대표청구항
▼
The invention in which an exclusive right is claimed is defined by the following: 1. A linear actuator comprising a shaft and an actuator assembly configured to enable relative movement to occur between the shaft and the actuator assembly, the actuator assembly comprising: (a) a member configured t
The invention in which an exclusive right is claimed is defined by the following: 1. A linear actuator comprising a shaft and an actuator assembly configured to enable relative movement to occur between the shaft and the actuator assembly, the actuator assembly comprising: (a) a member configured to be magnetically actuated, actuation of the member causing the member to move from a first position to a second position, where the second position is closer to a magnetic field than the first position, the member comprising a shape memory alloy, such that when the shape memory alloy moves to the second position, a stress is applied to the shape memory alloy, and that stress, in combination with the shape memory alloy being exposed to a greater magnetic flux by virtue of being closer in proximity to the magnetic field in the second position as compared to the first position, causes a phase change in the shape memory alloy, from an initial relatively stiff austenitic state to a relatively softer martensitic state, the phase change resulting from a hybrid mechanism requiring both an applied stress and an exposure to a sufficiently strong magnetic field; and (b) a magnetic trigger configured to selectively actuate the member, the magnetic trigger controlling the magnetic field associated with the movement of the member to the second position. 2. The linear actuator of claim 1, wherein the shape memory alloy comprises a ferromagnetic shape memory alloy. 3. The linear actuator of claim 1, wherein the shape memory alloy is super elastic, and the member is configured so that when an intensity of the magnetic field is reduced to a level insufficient to actuate the member, the member automatically returns to the first position. 4. The linear actuator of claim 1, wherein the member further comprises a ferromagnetic mass coupled with the shape memory alloy such that the ferromagnetic mass and the shape memory alloy move together, the ferromagnetic mass being attracted to the magnetic trigger when the magnetic trigger is activated. 5. The linear actuator of claim 4, wherein the shape memory alloy comprises super elastic nickel titanium (NiTi) alloy. 6. The linear actuator of claim 1, wherein the magnetic trigger comprises a hybrid magnetic trigger including at least one permanent magnet and at least one electromagnet. 7. The linear actuator of claim 1, farther comprising a plurality of teeth movably mounted on the shaft and configured to control a direction of the relative movement between the shaft and the actuator assembly. 8. The linear actuator of claim 1, wherein the actuator assembly further comprises a plurality of clutches that control a direction of the relative movement between the shaft and the actuator assembly. 9. The linear actuator of claim 1, wherein the actuator assembly further comprises a second member configured to be magnetically actuated, the second member being disposed such that the member and the second member can be selectively actuated by the magnetic trigger, actuation of the member resulting in relative movement between the shaft and the actuator assembly in a first direction, and actuation of the second member resulting in relative movement between the shaft and the actuator assembly in a second direction. 10. The linear actuator of claim 9, wherein the actuator assembly further comprises additional magnetic triggers, such that the actuator assembly includes a plurality of magnetic triggers, each additional magnetic trigger being configured to selectively actuate the member and the second member, such that selective control of the plurality of magnetic triggers enables a stroke of the linear actuator to be controlled. 11. The linear actuator of claim 10, wherein the plurality of magnetic triggers are disposed between the member and the second member. 12. The linear actuator of claim 1, wherein the member comprises a first shape memory alloy coil spring, a second shape memory alloy coil spring, and a ferromagnetic mass, each shape memory alloy coil spnng being embedded in the ferromagnetic mass, such that each shape memory alloy coil spring and the ferromagnetic mass move as a single unit when the magnetic trigger is activated. 13. The linear actuator of claim 1, wherein the member is preloaded during assembly, such that the first position is associated with a preloaded state. 14. The linear actuator of claim 1, wherein the actuator assembly further comprises a second member configured to be magnetically actuated, and a second magnetic trigger configured to selectively actuate the second member, such that the actuation of the member by the magnetic trigger results in relative movement between the shaft and the actuator assembly in a first direction, and actuation of the second member by the second magnetic trigger results in relative movement between the shaft and the actuator assembly in a second direction. 15. A method for achieving a linear motion relative to a first member and a second member, comprising the steps of: (a) selectively securing at least a portion of the second member to the first member; (b) using a magnetic force to attract a magnetically actuatable portion of the second member to a magnetic portion of the second member, such that a distance separating the magnetically actuatable portion of the second member and the magnetic portion of the second member decreases, the magnetically actuatable portion of the second member comprising a shape memory alloy, a movement of the shape memory alloy from a first position to a second position applying a stress to the shape memory alloy, the stress and exposure to a magnetic field produced by the magnetic portion inducing a phase change in the shape memory alloy, the phase change occurring after the shape memory alloy begins to move in response to the magnetic force, the phase change comprising a change from an initial relatively stiff austenitic state to a relatively softer martensitic state, the shape memory alloy comprising at least one of: (i) a ferromagnetic shape memory alloy; and (ii) a ferromagnetic mass coupled to a shape memory alloy; and (c) interrupting the magnetic force attracting the magnetically actuatable portion of the second member to the magnetic portion of the second member, such that the distance separating the magnetically actuatable portion of the second member and the magnetic portion of the second member increases, the linear motion relative to the first member and the second member being achieved during at least one of the following: (i) while the distance separating the magnetically actuatable portion of the second member and the magnetic portion of the second member is decreasing; and (ii) while the distance separating the magnetically actuatable portion of the second member and the magnetic portion of the second member is increasing. 16. The linear actuator of claim 1, wherein movement of the member from the first position to the second position results in relative movement between the shaft and the actuator assembly. 17. The linear actuator of claim 1, wherein movement of the member from the second position to the first position results in relative movement between the shaft and the actuator assembly. 18. The method of claim 15, wherein: (a) the step of using a magnetic force to attract the magnetically actuatable portion of the second member to the magnetic portion of the second member comprises the step of energizing an electromagnet; and (b) the step of interrupting the magnetic force attracting the magnetically actuatable portion of the second member to the magnetic portion of the second member comprises the step of de-energizing the electromagnet. 19. A linear actuator comprising: (a) a shaft; and (b) an actuator assembly, actuation of the linear actuator resulting in a relative movement between the shaft and the actuator assembly, the shaft and actuator assembly being sized such that a linear extent of the shaft is greater than a linear extent of the actuator assembly, the shaft and actuator assembly being oriented such that the shaft extends throughout an inner volume of the actuator assembly and passes beyond at least one of a first end and a second end of the actuator assembly, the actuator assembly comprising: (i) a member configured to be magnetically actuated with a magnetic field, actuation of the member causing the member to move from a first position to a second position, where the second position is closer to the magnetic field than the first position, the member comprising a shape memory alloy; and (ii) a magnetic trigger configured to selectively actuate the member, the magnetic trigger controlling the magnetic field associated with the movement of the member to the second position. 20. A linear actuator comprising a shaft and an actuator assembly configured to enable relative movement to occur between the shaft and the actuator assembly, the actuator assembly comprising: (a) a member configured to be magnetically actuated, actuation of the member causing the member to move from a first position to a second position, where the second position is closer to a magnetic field than the first position, the member comprising a shape memory alloy; and (b) a magnetic trigger configured to selectively actuate the member, the magnetic trigger controlling the magnetic field associated with the movement of the member to the second position, a movement of the member from a first position to a second position applying a stress to the shape memory alloy, the stress and exposure to a magnetic field produced by the magnetic trigger inducing a phase change in the shape memory alloy, from an initial relatively stiff austenitic state to a relatively softer martensitic state. 21. A method for achieving a linear motion relative to a first member and a second member, comprising the steps of: (a) selectively securing at least a portion of the second member to the first member; (b) using a magnetic force to attract a magnetically actuatable portion of the second member to a magnetic portion of the second member, such that a distance separating the magnetically actuatable portion of the second member and the magnetic portion of the second member decreases, a movement of the magnetically actuatable portion of the second member from a first position to a second position applying a stress to a shape memory alloy portion of the second member, the stress and exposure to a magnetic field inducing a phase change in the shape memory alloy from an initial relatively stiff austenitic state to a relatively softer martensitic state, the shape memory alloy portion of the second member comprising at least one of: (i) a ferromagnetic shape memory alloy; and (ii) a ferromagnetic mass coupled to a shape memory alloy; and (c) interrupting the magnetic force attracting the magnetically actuatable portion of the second member to the magnetic portion of the second member, such that the distance separating the magnetically actuatable portion of the second member and the magnetic portion of the second member increases, the linear motion relative to the first member and the second member being achieved during at least one of the following: (i) while the distance separating the magnetically actuatable portion of the second member and the magnetic portion of the second member is decreasing; and (ii) while the distance separating the magnetically actuatable portion of the second member and the magnetic portion of the second member is increasing. 22. A linear actuator comprising a shaft and an actuator assembly configured to enable relative movement to occur between the shaft and the actuator assembly, the actuator assembly comprising: (a) a member configured to be magnetically actuated, actuation of the member causing the member to move from a first position to a second position, where the second position is closer to a magnetic field than the first position, the member comprising a shape memory alloy, wherein movement of the member from the first position to the second position is not due to a Martensite variant rearrangement; and (b) a magnetic trigger configured to selectively actuate the member, the magnetic trigger controlling the magnetic field associated with the movement of the member to the second position.
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