Abstract:
A device or actuator includes a first component made of Shape Memory Alloy (SMA) that applies force to a second component of the device to provide a controllable actuator. The SMA component is selectively energized by using active electric current through it.

Description:
FIELD 
     The present invention relates to actuators. More specifically, the present invention relates to actuators with components made of a shape memory alloy. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
     Typical motor vehicles employ various types of actuators. For example, actuators are employed as hydraulic valves, mechanical piston actuators, clutching mechanisms in the operation of the vehicle&#39;s transmission, engine, motorized seats, and any other device or apparatus that requires a physical movement of a component to engage or disengaged the device or apparatus. 
     Recently, certain actuators employ shape memory alloys to impart an actuation force. Shape memory alloys have the desirable property of becoming rigid when heated above a transition temperature, such that the component formed of the shape memory alloy contracts, thereby imparting the actuation force. To remove the actuation force, however, the shape memory alloy must cool before the alloy can be heated again to engage the actuator. 
     SUMMARY 
     A device or actuator includes a first component made of Shape Memory Alloy (SMA) that applies force to a second component of the device to provide a controllable actuator. The SMA component is selectively energized by applying an active electric current through it. The device or actuator itself can be either a hydraulic or mechanical mechanism. More than one SMA component can be employed to provide faster return mechanisms. 
     The devices using multiple SMA components are either antagonistic or non-antagonistic based on the type of usage of the SMA components. Antagonistic devices use the multiple SMA components to act on the same component of the device in opposite directions and are selectively energized to provide to and fro actuation. The non-antagonistic devices use the multiple SMA components to act on different component in the actuator to still produce the same functional effect of the actuator 
     Further features, advantages, and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the drawings: 
         FIG. 1  is schematic view of a hydraulic control valve in accordance with the principles of the present invention; 
         FIG. 2  is a schematic view of yet another hydraulic control valve in accordance with the principles of the present invention; 
         FIG. 3  is a schematic view of a hydraulic valve in accordance with the principles of the present invention; 
         FIG. 4  is a schematic view of a mechanical piston actuator in accordance with the principles of the present invention; 
         FIG. 5  is a schematic view of yet another mechanical piston actuator in accordance with the principles of the present invention; 
         FIGS. 6A-6D  are schematic views of another hydraulic valve in accordance with the principles of the invention; and 
         FIGS. 7A and 7B  are schematic views of yet another hydraulic valve in accordance with the principles of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     Referring now to  FIG. 1 , an antagonistic device, an actuator embodying the principles of the present invention is illustrated therein and designated as  10 . The actuator operates as a hydraulic control spool valve  12  with three spool sections  14 ,  16  and  18  that reciprocates in a bore  20  between two stops  32  and  34 . The actuator  10  further includes an inlet port  22 , two outlet control ports  24  and  26  and an exhaust port  28 . As the valve  12  moves back and forth between the two stops  32  and  34  the spool sections  14 ,  16 , and  18  selectively open and close the inlet port  22  and the control ports  24  and  26  to control the flow of a hydraulic fluid from the inlet port to the outlet ports to actuate a mechanism connected and in communication with the control ports  24  and  26 . Positioned between the stop  32  and the spool section  14  is a biasing member  29  attached at one end to the spool section  14  and at the other end to a shuttle  35 , and positioned between the stop  34  and the spool section  18  is another biasing member  30  attached at one end to the spool section  18  and at the other end to a shuttle  37 . The biasing members  29  and  30  can be coil springs as shown in  FIG. 1  or any other suitable component that biases the spool section  14  away from the stop  32  and biases the spool section  18  away from the stop  34 , respectively. The shuttle  35  is connected to a wire  36  that is attached to a stationary member  40 , such as, for example, a rigid fixture in the transmission housing. And the shuttle  37  is connected to a wire  38  that is attached to the stationary member  40 . 
     Each of the wires  36  and  38  are formed of a shape memory alloy. Shape memory alloys have the desirable property of becoming rigid, that is, returning to a remembered state, when heated above a transition temperature. A shape memory alloy suitable for the wires  36  and  38  is Ni—Ti available under the more commonly known name Nitinol. When this material is heated above the transition temperature, the material undergoes a phase transformation from martensite to austenite, such that the material returns to its remembered state. The transition temperature is dependent on the relative proportions of the alloying elements Ti and Ni (Ni—Ti) and the optional inclusion of alloying additives. Note that any other suitable shape memory alloy may be used for the valve member  25  such as Ag—Cd, Au—Cd, Au—Cu—Zn, Cu—Al, Cu—Al—N, Cu—Zn, Cu—Zn—Al, Cu—Zn—Ga, Cu—Zn—Si, Cu—Zn—Sn, Fe—Pt, Fe—Ni, In—Cd, In—Ti, and Ti—Nb. 
     As noted above, in this particular implementation, the wires  36  and  38  are made from Nitinol with a desired transition temperature. Thus, when the temperature of the wires  36  and  38  is less than the transition temperature, the wires  36  and  38  are in the martensitic state. And when the temperature of either wire  36  or  38  is heated such that its temperature exceeds the transition temperature, the alloy in the wire  36  or  38  transforms to austenite, such that the wire returns to its remembered state, which in this case is a contracted state. 
     In some implementations, the wires  36  and  38  may be complemented by biasing members  42  and  44  that extend between the shuttle  35  and the stationary member  40  and between the shuttle  37  and the stationary member  40 , respectively. The biasing members  42  and  44  may be made of a shape memory alloy, as well. Alternatively, in some arrangements, the actuator  10  includes only the biasing members  42  and  44  made of shape memory alloy and not the wires  36  and  44 . 
     When the actuator  10  is in use, a current is applied to either the wire  36  or the wire  38  to actuate the hydraulic controller. Specifically, when a current is applied to the wire  36 , the wire is heated above the transition temperature so that the shape memory alloy in the wire  36  transforms to austenite causing the wire  36  to contract. This contraction along with the bias force imparted by the biasing member  29  moves the shuttle  35  towards to the left and consequently pulls the valve  12  towards the left as well. The motion of the valve  12  to the left extends the biasing member  30 . 
     When the current is removed from the wire  36  and a current is applied to the wire  38 , the shape memory alloy in the wire  36  returns to the martensitic state and the alloy in the wire  38  transforms to austenite. Hence, the wire  36  relaxes while the wire  38  contracts. Accordingly, the shuttle  37  as well as the valve  12  moves to the right compressing the biasing member  30  and extending the member  29 . Thus, by applying a desired current to either the wire  36  or  38 , the valve  12  and hence the sections  14 ,  16 , and  18  are moved back and forth within the bore  20  to selectively open and close the inlet port  22 , the exhaust port  28 , and the outlet control ports  24  and  26 . Using both the wires  36  and  38  could speed up the to and fro motion of the valve  12 . Recall, that in certain implementations, the actuator  10  includes biasing members  42  and  44  in addition to or instead of the wires  36  and  38 . These biasing members  42  and  44  can be formed of a shape memory alloy such that a current can be applied selectively to the members to  42  and  44  to actuate the hydraulic control valve in a manner similar to that described above in reference to the wires  36  and  38 . 
     Referring now to  FIG. 2 , an antagonistic device, there is shown an actuator  100  arranged as a hydraulic control valve. The actuator  100  includes a valve  112  with three spool sections  114 ,  116 , and  118  that reciprocates in a bore  120  between two ends  132  and  134 . The actuator  100  further includes an inlet port  122 , two outlet control ports  124  and  126  and an exhaust port  128 . As the valve  112  moves back and forth between the two ends  132  and  134  the spool sections  114 ,  116 , and  118  selectively open and close the inlet port  122  and the control ports  124  and  126  to control the flow of a hydraulic fluid from the inlet port to the outlet ports to actuate a mechanism connected and in communication with the control ports  124  and  126 . Positioned between the end  132  and the spool section  114  is a stationary member  135  to which one end of a biasing member  129  is attached. The other end of the biasing member  129  is attached to the spool section  114 . Similarly, a stationary member  137  is positioned between the end  134  and the spool section  118 . One end of a biasing member  130  is attached to the stationary member  137  and the other end is attached to the spool section  118 . The biasing members  129  and  130  are formed of a smart member alloy as described above and can be coil springs as shown in  FIG. 2  or any other suitable compressible component. 
     When the actuator  100  is in use, a current is applied to either the biasing member  129  or  130  to actuate the hydraulic control valve. Specifically, when a current is applied to the biasing member  129 , the biasing member is heated above the transition temperature so that the shape memory alloy in the biasing member  129  transforms to austenite causing the biasing member  129  to contract. This contraction along with the bias force imparted by the biasing member  130  on the spool section  118  moves the valve  112  towards the left. The motion of the valve  12  to the left extends the biasing member  130 . 
     When the current is removed from the biasing member  129  and a current is applied to the biasing member  130 , the shape memory alloy in the biasing member  129  returns to the martensitic state and the alloy in the biasing member  130  transforms to austenite. Hence, the biasing member  129  returns to its relaxed state while the biasing member  130  contracts. Accordingly, the valve  112  moves to the right compressing the biasing member  130  and extending the member  129 . Thus, by applying a desired current to either the biasing member  129  or  130 , the valve  112  and hence the sections  114 ,  116 , and  118  are moved back and forth within the bore  120  to selectively open and close the inlet port  122 , the exhaust port  128 , and the outlet control ports  124  and  126 . 
     Turning now to  FIG. 3 , an antagonistic device, there is shown an actuator configured as a hydraulic valve  200 . The valve  200  includes a valve  212  with two spool sections  214  and  216  that reciprocates in a bore  220  between two ends  232  and  234 . The valve  200  further includes an inlet port  222 , an outlet port  224 , and an exhaust port  228 . As the valve  212  moves back and forth between the two ends  232  and  234 , the spool sections  214  and  216  selectively open and close the inlet port  222  and the outlet port  224  to control the flow of a hydraulic fluid from the inlet port to the outlet port to actuate the valve  200 . Positioned between the end  232  and the spool section  214  is a stationary member  235  to which one end of a biasing member  229  is attached. The other end of the biasing member  229  is attached to the spool section  214 . Similarly, a stationary member  237  is positioned between the end  234  and the spool section  216 . One end of a biasing member  230  is attached to the stationary member  237  and the other end is attached to the spool section  216 . The biasing members  229  and  230  are formed of a smart member alloy as described previously and can be coil springs as shown in  FIG. 3  or any other suitable component that biases the spool section  214  away from the end  232  and biases the spool section  216  away from the end  234 , respectively. 
     When the valve  200  is in use, a current is applied to either the biasing member  229  or  230  to actuate the valve. Specifically, when a current is applied to the biasing member  229 , the biasing member is heated above the transition temperature so that the shape memory alloy in the biasing member  229  transforms to austenite causing the biasing member  229  to contract. This contraction along with the bias force imparted by the biasing member  230  moves the valve  212  towards the left. The motion of the valve  212  to the left extends the biasing member  230 . 
     When the current is removed from the biasing member  229  and a current is applied to the biasing member  230 , the shape memory alloy in the biasing member  229  returns to the martensitic state and the alloy in the biasing member  230  transforms to austenite. Hence, the biasing member  229  returns to its relaxed state while the biasing member  230  contracts. Accordingly, the valve  212  moves to the right compressing the biasing member  230  and extending the member  229 . Thus, by applying a desired current to either the biasing member  229  or  230 , the valve  212  and hence the sections  214  and  216  are moved back and forth within the bore  220  to selectively open and close the inlet port  222 , the exhaust port  228 , and the outlet port  224 . 
     In another implementation shown in  FIG. 4 , an actuator is arranged as a mechanical piston actuator  300 . The piston actuator  300  includes a valve  312  with three spool sections  314 ,  318 , and  320  that reciprocates in a bore  319  between two ends  322  and  324 . The piston actuator  300  further includes an arm  316  connected to the spool section  314 . The arm  316  is configured to engage, for example, a clutching mechanism  317  to activate and deactivate the clutching mechanism  317  as the valve  312  and hence the arm  316  moves back and forth between the two ends  322  and  324 . Positioned between the end  322  and the spool section  318  is a shuttle  348 . One end of a biasing member  326  is attached to the shuttle  348  and the other end of the biasing member  326  is attached to the spool section  318 . Similarly, a shuttle  338  is positioned between the end  324  and the spool section  320 . One end of a biasing member  328  is attached to the shuttle  338  and the other end of the biasing member  328  is attached to the spool section  320 . The biasing members  326  and  328  can be coil springs as shown in  FIG. 4  or any other suitable compressible component. 
     The piston actuator  300  further includes a wire  330  and a wire  332 , both of which are made of a shape memory alloy as described earlier. One end of the wire  330  is attached to a stationary anchor  334  and the other end of the wire  330  is attached to a stationary anchor  336 . A section  340  approximately near the middle of the wire  330  is attached to the shuttle  338 , such that any contraction of the wire  330  pulls the shuttle  338  away from the end  324 . One end of the wire  332  is attached to a stationary anchor  342  and the other end of the wire  332  is attached to a stationary anchor  344 . A section  346  approximately near the middle of the wire  332  is attached to the shuttle  348  such that any contraction of the wire  332  pulls the shuttle  348  away from the end  322 . 
     When the piston actuator  300  is in use, a current is applied to either the wire  330  or  332  to actuate the mechanical piston actuator. Specifically, when a current is applied to the wire  330 , the wire is heated above the transition temperature so that the shape memory alloy in the wire  330  transforms to austenite causing the wire  330  to contract. This contraction pulls the shuttle  338  against the biasing member  328 , which in turn applies a biasing force on the spool section  320  of the valve  312 , thereby moving the section  314  of the valve  312  along with the arm  316  towards the left. 
     When the current is removed from the wire  330  and a current is applied to the wire  332 , the shape memory alloy in the wire  330  returns to the martensitic state and the alloy in the wire  332  transforms to austenite. Hence, the wire  330  returns to its relaxed state while the wire  332  contracts. Accordingly, the wire  332  pulls on the shuttle  348  against the biasing member  326 , which in turn applies a biasing force on the spool section  318  of the valve  312 , thereby moving the section  314  along with the arm  316  towards the right. Thus, by applying a desired current to either wire  330  or  332 , the valve  312  and hence the arm  316  are moved back and forth to selectively engage the arm  316  with the clutching mechanism  317 . 
     In yet another implementation shown in  FIG. 5 , an actuator is arranged as a mechanical piston actuator  400 . The piston actuator  400  includes a valve  412  with three spool sections  414 ,  418 , and  420  that reciprocates in a bore  419  between two ends  430  and  432 . The piston actuator  400  further includes an arm  416  connected to the spool section  414 . The arm  416  is configured to engage, for example, a clutching mechanism  417  to activate and deactivate the clutching mechanism  417  as the valve  412  and hence the arm  416  move back and forth between the two ends  430  and  432 . Positioned between the end  430  and the spool section  418  is a stationary member  435  to which one end of a biasing member  426  is attached. The other end of the biasing member  426  is attached to the spool section  418 . Similarly, a stationary member  437  is positioned between the end  432  and the spool section  420 . One end of a biasing member  428  is attached to the stationary member  437  and the other end is attached to the spool section  420 . The biasing members  426  and  428  are formed of a smart member alloy as described above and can be coil springs as shown in  FIG. 5  or any other suitable compressible component. 
     When the piston actuator  400  is in use, a current is applied to either the biasing member  426  or  428  to actuate the mechanical piston actuator. Specifically, when a current is applied to the biasing member  426 , the biasing member is heated above the transition temperature so that the shape memory alloy in the biasing member  426  transforms to austenite causing the biasing member  426  to contract. This contraction along with the bias force imparted by the biasing member  428  on the spool section  420  moves the valve  412  and hence the arm  416  towards the left. 
     When the current is removed from the biasing member  426  and a current is applied to the biasing member  428 , the shape memory alloy in the biasing member  426  returns to the martensitic state and the alloy in the biasing member  428  transforms to austenite. Hence, the biasing member  426  returns to its relaxed state while the biasing member  428  contracts. Accordingly, the valve  412  and hence the arm  416  move to the right. Thus, by applying a desired current to either the biasing member  426  or  428 , the arm  416  is moved back and forth so that it selectively engages with the clutching mechanism  417 . 
     Referring now to  FIGS. 6A-6D , a non-antagonistic device, there is shown an actuator configured as a hydraulic valve  500 . The valve  500  includes a sleeve  514  positioned within a housing  510 . The sleeve  514  is arranged to reciprocate within the housing  510 . The valve  500  further includes a spool valve  520 , with two enlarged sections  524  and  526 , which reciprocates within the sleeve  514 . The valve  500  is provided with an inlet port  502 , an outlet control port  504 , and three exhaust ports  505 ,  506 , and  516 . As the sleeve  514  moves back and forth within the housing  510  and as the spool valve  520  moves back and forth within the sleeve  514 , the inlet port  502 , the outlet port  504 , and the exhaust ports  505 ,  506 ,  516  are selectively opened and closed to control the flow of a hydraulic fluid from the inlet port  502  to the outlet port  504  to actuate the valve  500 . 
     The valve  500  further includes a pair of biasing members  529  and  530 . Movement of the sleeve  514  towards the left relative to the sleeve  510  compresses the biasing member  529 , and movement of the spool valve  520  towards the right relative to sleeve  514  compresses the biasing member  530 . The biasing members  529  and  530  can be coil springs as shown in  FIG. 6  or can be any other suitable compressible component. 
     The valve  500  also includes two wires  508  and  516  formed from a shape memory alloy as described previously. One end of the wire  508  is attached to an anchor  515  and the other end is attached to the sleeve  514 . One end of the wire  516  is attached to an anchor  518  and the other end of the wire  516  is attached to the spool valve  520 . 
     When the valve  500  is in use, a current is applied to either the wire  508  or the wire  516  or to both wires to actuate the valve. Note that when current is not being applied to the wires  508  or  516 , the control port  504  exhausts to the exhaust port  506 , as shown in  FIG. 6A . When a current is applied to the wire  508  the wire is heated above the transition temperature so that the shape memory alloy in the wire  508  transforms to austenite causing the wire  508  to contract. This contraction pulls the sleeve  514  towards the left, which compresses the biasing member  529 . Accordingly, as depicted in  FIG. 6B , the inlet port  502  opens to the control port  504 . 
       FIG. 6C  depicts the valve  500  when a current is applied to the wire  516  in addition to a current being applied to the wire  508 . As such, the alloy in the wire  516  transforms to austenite, causing the wire  516  to contract. The contraction of the  516  pulls the spool valve  520  to the right, which compresses the biasing member  530 . Hence, when current is applied to both the wire  508  and the wire  516 , the control port  504  exhausts to the exhaust ports  505  and  516 . 
     When the current is removed from the wire  508 , the shape memory alloy in the wire  508  returns to the martensitic state. Hence, the wire  508  relaxes, and the biasing member  529  imparts a force on the sleeve  514 , which moves the sleeve towards the right, as shown in  FIG. 6D . When the valve  500  is in this configuration, the control port  504  is again opened to the inlet port  502 . Accordingly, by applying a desired current to either the wire  508  or  516 , or to both wires, the inlet port  502  and the outlet port  504  are selectively opened and closed to control the flow of a hydraulic fluid through the valve  500  to actuate the valve. 
     Referring now to  FIGS. 7A and 7B , a device with only one SMA component, there is shown another actuator configured as a hydraulic valve  600 . The valve  600  includes a spool valve  612  with two spool sections  614  and  616  that reciprocates in a housing  620 . The valve  600  further includes an inlet port  622 , an outlet control port  624 , and an exhaust port  628 . As the spool valve  612  moves back and forth between ends  633  and  638 , the spool sections  614  and  616  selectively open and close the inlet port  622  and the outlet port  624  to control the flow of a hydraulic fluid from the inlet port to the outlet port to actuate the valve  600 . Positioned between the end  633  of the housing  620  and the spool section  616  is a biasing member  629 . Although the biasing member  629  is shown as a coiled spring in  FIGS. 7A and 7B , the biasing member  629  any other suitable component that biases the spool section  616  away from the end  633 . 
     The valve  600  also includes a wire  630  made of a shape member alloy as described earlier. One end of the wire  630  is attached to a stationary anchor  632  and the other end of the wire  630  is attached to a stationary anchor  634 . A section  636  approximately near the middle of the wire  630  is attached to the end  638  of the enlarged spool  614  such that any contraction of the wire  630  pulls the spool valve  612  towards the end  633  of the housing  620 , thereby compressing the biasing member  629 . 
     When the valve  600  is in use, a current is applied to the wire  630  to actuate the valve. Hence, the wire  630  is heated above the transition temperature so that the shape memory alloy in the wire  630  transforms to austenite causing the wire  630  to contract. This contraction pulls the spool valve  612  towards the end  633  of the housing  620  such that the control port  624  opens to the inlet port  622 , as shown in  FIG. 6B . 
     When the current is removed from the wire  630  the wire  630  returns to the martensitic state. Hence, the wire  630  returns to its relaxed state, and the biasing member  629  pushes the spool valve  612  away from the end  633  of the housing  620 . Accordingly, when the current to the wire  630  is turned off, the control port  624  exhausts to the exhaust port  628  as shown in  FIG. 7B . Thus, by selectively applying a desired current to the wire  630 , the spool valve  612  moves up and down within the housing  620  to selectively open and close the inlet port  622  and the outlet control port  624 . 
     A particular feature of the actuators described with reference to  FIGS. 1 through 7  is an increased actuation frequency achieved by employing opposing components made of shape memory alloy. Specifically, each of the actuators described above includes a shape memory alloy wire and/or a biasing member that engages the valve or piston actuator by imparting a force on a component in the valve or piston actuator in one direction and may include another shape memory alloy component that disengages the valve or piston actuator by imparting a force on the component in an opposing direction. Hence, each actuator can be quickly engaged or disengaged by selectively applying a current to each of the two opposing shape memory alloy members. The actuators may include a single shape memory alloy component. Alternatively, the actuators may include multiple shape memory alloy components. The actuators with multiple shape memory alloy components can be antagonistic; that is, the shape memory alloy components work against each other as they each impart a force on a particular moving component in the actuator. In some arrangements, the multiple shape memory alloy components are non-antagonistic; that is, the shape memory alloy components may act independently on different moving components of the actuator. 
     The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.