JPH0452072B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a rotary actuator suitable for driving a robot arm and other applications requiring small size and light weight.

``Prior Art'' Conventionally, electric motors, hydraulic motors, and oil or pneumatic cylinders have been generally used as actuators for driving robot arms and other devices. However, since these actuators are relatively large in shape and weight, it is not appropriate to install them at the tip of a robot arm. For example, when driving the tip of a robot arm, it is necessary to install them in the robot body far away from the tip of the arm. A motor or the like and the tip of the arm are connected by a belt, chain, rod, or other power transmission means.

``Problems to be Solved by the Invention'' Conventional drive actuators such as motors and cylinders have large weights and shapes as described above, so they cannot be used to drive, for example, the wrist part provided at the tip of a robot arm. In some cases, it is not possible to install an actuator at the wrist due to the large inertia.
It is necessary to place the actuator at the base of the arm, far away from the wrist, etc., and space is required to place the power transmission means between the wrist and the actuator, and the loss of power due to the long power transmission means is large. Moreover, there is a drawback that backlash and play in the power transmission means accumulate, making it impossible to obtain high positioning accuracy.

``Object of the Invention'' The present invention was made to solve the above problems, and its object is to obtain a rotary actuator that is small, lightweight, and has self-rotation controllability.

"Means for Solving the Problems" The main means adopted by the present invention to achieve the above object is that the above-mentioned rotary actuator has an output shaft rotatably supported by a housing. A swash plate member having a slope inclined at a predetermined angle with respect to the output shaft and fixed to the output shaft, and a plurality of actuators arranged around the output shaft so as to be able to move toward and away from the swash plate member. The member is subjected to shape memory processing so as to return to a memorized length in response to a change in temperature, and is disposed between the actuating member and the housing so that its shape change direction coincides with the output shaft direction. a shape memory alloy, a heating means disposed near the shape memory alloy for heating the shape memory alloy, and a heating means arranged in close proximity to the shape memory alloy to heat the shape memory alloy, and the heating means being operated in synchronization with rotation of the output shaft to heat the shape memory alloy The control means includes a control means that sequentially presses the actuating member against the swash plate member to continuously rotate the swash plate member together with the output shaft by changing the shape. The slope of the swash plate member among the above components may be one surface or a combination of multiple surfaces, but it is inclined at a constant angle with respect to the output shaft,
It may be formed on the front side or the back side of the swash plate member. In addition, the end of the actuating member may be in direct contact with the slope of the swash plate member, or may be in indirect contact via another link, etc., but this contact is due to the actuation of the shape memory alloy. When the member is in operation,
Usually there is intermittent contact. Further, the control means may be a contact type limit switch or the like, but it is usually constituted by an optical sensor or the like, or a rotary encoder or the like connected to the output shaft is employed. Further, the number of shape memory alloys heated simultaneously may be one or more. The output can be increased by using more than one.

"Operation" In the rotary actuator of the present invention, the corresponding shape memory alloy is heated by the heating means in synchronization with the rotational phase of the output shaft, contracts or expands, and moves the actuating member. This causes the actuating member to directly or indirectly drive the swash plate member. Since the heated shape memory alloy is shifted by the control means in accordance with the rotation of the output shaft, the rotation of the swash plate member and the output shaft to which it is attached continues.

``Embodiment'' Hereinafter, an embodiment embodying the present invention will be described with reference to the accompanying drawings.

Here, FIG. 1 is a front view showing a part of a rotary actuator in cross section according to an embodiment of the present invention;
Fig. 2 is a perspective view with the holding plate removed, Fig. 3 is a sectional view taken along the line A-A in Fig. 1, Fig. 4 is a wiring diagram of the heating means and control means that can use the same embodiment, and Fig. 5 6 is a perspective view of another example of the control means, FIG. 7 is a block diagram showing still another example of the control means, and FIG. 8 is a pulse generator. FIG. The following embodiments are merely specific examples of the present invention, and are not intended to limit the technical scope of the present invention.

In Fig. 1, reference numeral 1 denotes a housing, which is arranged in parallel at intervals and has shaft holes 2 a and 2 _a in the center, respectively.
A pair of bearing plates 3 _a and 3 _b provided with 2 _b , a connecting plate 4 whose both ends are fixed in a construction manner to the outer periphery of these bearing plates 3 _a and 3 _b , and a bearing plate 3 _b of bearing plate 3 _a . erected around the shaft hole 2 _a on opposing surfaces, parallel to the axis and spaced apart in the circumferential direction of the shaft hole 2 _a ,
It is composed of a plurality of supporting bars 5 having approximately the same length.

6 is a lever attached to the tip of each support bar 5 so as to be able to swing along its axis; 7 is a linear lever with both ends attached to one end of each lever 6 and the bearing plate 3 _a in a suspended manner. It is made of a shape memory alloy and is configured to return to its coiled or zigzag shape memory length when heated to a certain temperature (shape memory treatment temperature). Reference numeral 8 indicates an output shaft mounted on the bearing plates 3 _a , 3 _b inserted into the shaft holes 2 _a , 2 _b in a suspended manner and not movable in the axial direction, and 9 indicates the bearing plates 3 a , 3 _b .
Between 3 _{and 3b} , there is a rotary plate, which is an example of a swash plate member, in which the output shaft 8 is fixed through the center part, and the lever 6
The surface facing the output shaft 8 is an inclined surface 10 that is inclined with respect to the output shaft 8. As shape memory alloy 7,
Any Ti-Ni alloy or Cu-Al-Zn alloy can be used.

Reference numeral 11 denotes a holding plate fixed to the connecting plate 4 between the rotary plate 9 and the lever 6 so as not to touch them, and corresponds to the end of each lever 6 to which the shape memory alloy 7 is not attached. Through holes 12 are provided along the output shaft 8 at the positions, and a slide bar 13, which is an example of an actuating member, is inserted into each of the through holes 12 (see FIG. 2). Therefore, in this example, the shape memory alloy is indirectly attached to the slide bar 13 via the lever 6. When the shape memory alloy 7 is heated and contracts and the lever 6 swings, the rigid slide bar 13 is pushed by the lever 6 and can push the inclined surface 10 of the rotary plate 9. It is suitable that the end portion that comes into contact with the inclined surface 10 has a spherical shape.

14 is a switch operating body fixed to the output shaft 8 and protrudes from its outer periphery; 15 is a limit switch arranged in the circumferential direction of the output shaft 8; It is attached to the bearing plate _3a so as to be operable by the operating body 14 (see FIG. 3). A heater 16 is an example of a heating means attached to the support bar 5 near each shape memory alloy 7 so as to be able to heat it, and is connected to each of the limit switches 15, so that when the limit switch 15 is turned "ON" It is designed to generate heat when voltage is applied to it. Therefore, the operating body 14 and the limit switch 15 constitute a control means, the circuit diagram of which is shown in FIG. 4 together with the heater 16. By this control means, the operating body 14 is sequentially operated such that the lever 6 sequentially pushes the slide bar 13 located on a portion of the inclined surface 10 near the lever 6.

FIG. 4 is a circuit diagram of the limit switch 15 and the heater 16 as described above, in which the limit switch 15a and the heater _16a are connected in series through one contact of the changeover switch _17a , and the limit switch _15b and the heater _16b are connected in series through the changeover switch 17a. _b in series, and then in series via changeover switch 17. And each limit switch _15a , _15b
...15 _o are connected in parallel with each other, and
Each heater _16a , _16b ... _16o is also connected in parallel with each other, and they are connected in series via a power source 18 so that current flows only to the heater 16 connected to the limit switch 15 that is turned "ON". It's getting old. The other contact of the changeover switch 17 is
One heater 16 is skipped and connected to the adjacent heater 16.
19 is a power switch.

In the rotary actuator configured as described above, when the power switch 19 in FIG. 4 is turned on, the limit switch 15 _a in FIG.
is turned on by the operating body 14, the heater _16a generates heat, the corresponding shape memory alloy 7 is heated and contracts, and that force causes the shape memory alloy 7 to be attached. By swinging the lever 6, the slide bar 13 is pressed against the rotary plate 9. Since the surface of the rotary plate 9 is an inclined surface 10 inclined with respect to the output shaft 8, part of the force of the slide lever 13 is acts as a force to rotate the rotary plate 9 along the inclination direction, and rotates the output shaft 8 together with the rotary plate 9. When the output shaft 8 rotates together with the rotating plate 9, the operating body 14 turns the limit switch _15a "OFF", but then turns the next limit switch _15b "ON", so the heater 1
_6b heat-shrinks the shape memory alloy 7, and the lever 6 swings to slide the slide bar 13 and push the inclined surface 10 of the rotary plate 9. By repeating this operation, the output shaft 8 is continuously rotated together with the rotating plate 9. That is, by operating the heater 16 in synchronization with the rotation of the output shaft 8, this rotary actuator has so-called self-rotation controllability.

The shape memory alloy 7 that was heated and contracted returns to its original length as it cools, or loses its shrinking force, and the slide bar 13 and the lever at the protrusion of the swash plate 9 reversely move. 6 to return to its original position and release the lever 6 and slide bar 13. Then, the shape memory alloy 7 whose heating was stopped
The cooling may be natural cooling, but forced cooling such as by blowing air is suitable for increasing the rotational speed of the rotating body 9. When performing forced cooling, means other than the above-mentioned air cooling can also be employed.

As mentioned above, this rotary actuator obtains rotational force through the heating and cooling cycle of the shape memory alloy, but the structure is extremely simple, and the direction of shape change of the shape memory alloy 7 coincides with the direction of the output shaft 8. It is possible to reduce the size in the direction perpendicular to the output shaft 8 to make it smaller and lighter, and it also has self-rotation controllability, so if it is used, for example, for driving a wrist at the tip of a robot arm,
It can be attached to the tip of the arm to directly drive the wrist. Therefore, the starting torque is large, and the output per weight is several times larger than that of conventional motors, so it is possible to accurately operate the wrist portion and the like.

The slide bar 13 is connected to the lever 6 as shown in FIG.
It can also be rotatably attached to the end of the

FIG. 6 shows an example in which a photo answerer is used in place of the limit switch 15 in FIG. 1, and the heaters 16 are sequentially energized. A shielding plate 22 that is fixedly arranged opposite to each other in the axial direction of the shaft 8 and that shields the light emitting element 20 and the light receiving element 21.
is fixed to the output shaft 8, and a cutout 23 through which the light beam of the light emitting element 20 passes is formed in a part of the shielding plate 22.

In this example, when the output shaft 8 rotates together with the rotary plate 9, the shielding plate 22 also rotates and the position of the cutout 23 moves, and the light rays enter the light receiving element 2.
1 changes sequentially. Therefore, the heater 16 that is energized also changes sequentially, and the heater 1
6, heating can be controlled and reliability can be further improved.

When using a photo sensor as in this example, a shielding material 22 is provided in a part of the circumferential direction of the output shaft 8, and this causes the heater 16 corresponding to the light receiving element 21 whose light beam is blocked to generate heat. It is also possible.

FIG. 7 shows yet another embodiment of heating control by the heater 16, in which 24 is a pulse generator provided on the output shaft 8, and the pulse signal outputted by this is input to the binary counter 25. A decoder driver 26 converts the binary signal inputted from the binary counter 25 into an ON/OFF signal, outputs the signal, and sequentially heats the heater 16 via a control circuit (not shown). Although any configuration can be used as the pulse generator 24, for example, the one shown in FIG.
8 is a photo sensor 2 provided on the outer periphery of the disk 27
It outputs a signal each time it passes through 9. Instead of the photo sensor 29, a reed switch, a proximity switch, etc. can also be used. Also, the output shaft 8
The rotational position of the output shaft 8 may be detected by connecting a rotary encoder to the output shaft 8.

A plurality of heaters 16 can generate heat at the same time, and in this way, a larger rotational force can be obtained.

"Effects of the Invention" According to the present invention, in a rotary actuator having an output shaft rotatably supported by a housing,
a swash plate member having a slope inclined at a predetermined angle with respect to the output shaft and fixed to the output shaft; The actuating member is subjected to shape memory processing so as to return to the memorized length in response to a change in temperature, and is disposed between the actuating member and the housing so that the direction of shape change coincides with the direction of the output shaft. a heating means disposed near the shape memory alloy for heating the shape memory alloy; and a heating means disposed near the shape memory alloy to heat the shape memory alloy; By changing the shape of
A rotary actuator is provided, comprising control means for sequentially pressing the actuating member against the swash plate member to continuously rotate the swash plate member together with the output shaft, which has an extremely simple structure and has a shape memory. Since the direction in which the shape of the alloy changes coincides with the direction of the manual shaft, the size in the direction perpendicular to the output shaft can be suppressed to make it compact and lightweight, and it also has self-rotation controllability. Therefore, it can be installed and used at the tip of the robot's arm or almost any other location, and the load can be driven directly without using a power transmission means, making it possible to increase the starting torque. At the same time, power loss can also be reduced. Furthermore, there is an effect that the output to weight ratio can be several times larger than that of conventional actuators. Furthermore, since the shape memory alloy is provided on the housing side, it is easy to apply electricity, it is easy to perform forced cooling, and it is also easy to increase the rotation speed.

[Brief explanation of the drawing]

Fig. 1 is a front view showing a part of a rotary actuator according to an embodiment of the present invention in cross section, Fig. 2 is a perspective view with the retaining plate removed, and Fig. 3 is a sectional view taken along the line A-A in Fig. 1. , FIG. 4 is a wiring diagram of the heating means and control means that can be used in the same embodiment, FIG. 5 is a front view of another example of the support bar portion, and FIG. 6 is a perspective view of another example of the control means. 7 are block diagrams showing still another example of the control means, and FIG. 8 is a perspective view of the pulse generator. Explanation of symbols, 1... Housing, 5... Support bar, 6
... Lever, 7 ... Shape memory alloy, 8 ... Output shaft, 9 ... Rotating body (equivalent to swash plate member), 10 ...
Inclined surface, 11... Holding plate, 13... Slide bar (corresponding to an operating member), 14... Operating body (corresponding to a part of control means), 15... Limit switch (corresponding to a part of control means), 16... Heater (corresponding to heating means).

Claims (1)

[Scope of Claims] 1. A rotary actuator having an output shaft 8 rotatably supported by a housing 1, which has a slope 10 inclined at a predetermined angle with respect to the output shaft 8; a fixed swash plate member 9; a plurality of operating members 13 disposed around the output shaft 8 so as to be able to come into contact with and separate from the swash plate member 9; and return to a memorized length in response to a change in temperature. Shape memory processing is performed so that the shape change direction is aligned between the actuating member 13 and the housing 1, and the output shaft 8
a shape memory alloy 7 disposed to match the direction; a heating means 16 disposed close to the shape memory alloy 7 for heating the shape memory alloy 7; The heating means 1
6 to change the shape of the shape memory alloy 7, the operating member 13 is sequentially pressed against the swash plate member 9, and the swash plate member 9 is continuously rotated together with the output shaft 8; 15. A rotary actuator comprising: