Power plants – Pressure fluid source and motor – Pulsator
Reexamination Certificate
2001-11-20
2004-04-13
Lazo, Thomas E. (Department: 3745)
Power plants
Pressure fluid source and motor
Pulsator
C060S476000, C091S525000, C092S048000
Reexamination Certificate
active
06718766
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a pump-integrated flexible actuator, such as one that can be used in a pet robot which is generally in contact with human beings, a work robot used to perform agricultural tasks, such as holding pieces of fruit which have irregular shapes and which are likely to be damaged, as well as various other varied uses.
2. Description of Related Art
An actuator that holds objects is known, which is disclosed in, for example, Japanese Unexamined Patent Application Publication Nos. 5-172118 and 5-164112, in which a cylindrical elastic member that includes a plurality of pressure chambers is provided. The cylindrical elastic member is bent by controlling fluid pressure which acts on each pressure chamber, thereby holding or pressing the object (this art is hereinafter referred to as a “first related art”).
An actuator that is different from the first related art is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2-17204, in which a driving source and a pump are assembled in a hydraulic cylinder (this art is hereinafter referred to as a “second related art”).
Since the cylindrical elastic member that is included in the actuator according to the first related art is soft, the actuator can softly contact human beings and objects.
However, this actuator must be provided with a pump for supplying work fluid and piping for feeding the work fluid to the pressure chambers that are disposed outside of the cylindrical elastic member. Therefore, there is a problem in that the size of the actuator increases. There is another problem in that the pipes block the movement of joints of a robot when the robot uses this actuator as, for example, an arm. Therefore, it is difficult to use the actuator for a pet robot or the like because the robot must be provided with a number of sensors and complex mechanisms, since delicate movements that are similar to those of a living creature are required of such a pet robot.
The actuator according to the second related art, in which a pump and piping are not exposed to the exterior, cannot softly contact human beings and objects because driving members, such as a piston rod, are hard. It is therefore difficult to use the actuator for a pet robot or an agricultural work robot for holding pieces of fruit and other objects.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a pump-integrated flexible actuator, in which the size of the actuator, which has a simple configuration, is reduced. It is also an object of the invention to provide an actuator that softly contacts human beings when the actuator is used as a pet robot, and that can reliably hold objects when the actuator is used as an agricultural work robot.
The present invention provides a pump-integrated flexible actuator which includes a movable unit provided with a plurality of fluid chambers that have fluid sealed therein, the movable unit being movable with the fluid chambers being deformed by a transfer of the fluid between the fluid chambers; a pump unit integrated with the movable unit, that transfers the fluid between the plurality of fluid chambers; and a pump driver that controls driving of the pump unit. The plurality of fluid chamber that have fluid sealed therein are preferably disposed parallel to each other. According to the invention, an actuator having a simple configuration and a reduced size, in which a movable unit of the actuator is capable of operation, is obtainable.
The movable unit is preferably provided with at least one long and narrow deformable tube that forms the plurality of fluid chambers that have fluid sealed therein, and a flexible core disposed parallel to the tube, that restricts expansion of the tube in a longitudinal direction thereof. The movable unit is preferably provided with at least two long and narrow tubes, which are capable of expansion and contraction, disposed parallel to each other, each tube forming the fluid chamber, and a flexible core disposed between the tubes, that restricts expansion of each tube in a longitudinal direction thereof. According to the invention, the movable unit can be reliably deformed in a manner that is similar to a living creature because the core restricts expansion in a longitudinal direction of each tube and allows expansion in a widthwise direction thereof when the core bends while maintaining the tubes in parallel with each other.
The tube, which is disposed at a side of the movable unit to be brought into contact with an object when a pressing force and a holding force of the movable unit act on the object, is preferably made of a soft and elastic material. According to the invention, the object can be pressed and held without being scratched because the tubes are made of a soft material and contact the object softly in a state in which a plurality of plane-contact portions of action are provided.
When a soft member covers the pump unit, the actuator becomes safer because hard parts are not exposed to the exterior.
The fluid that is sealed in the fluid chambers is preferably a liquid, and an outer cover having a liquid-absorbing function preferably covers the movable unit at the periphery thereof. According to the invention, the liquid does not leak to the exterior because it is absorbed by the outer cover even when the liquid leaks from the movable unit.
The pump-integrated flexible actuator preferably further includes a depressurization mechanism which reduces inner pressure of one of the plurality of fluid chambers by having the plurality of fluid chambers communicate with each other when the inner pressure of the one of the plurality of fluid chambers increases to an abnormal level. According to the invention, when an excessive external force is applied to the movable unit and pressure in one of a plurality of the fluid chambers is thereby increased to an abnormal level, the depressurization mechanism reduces the increased pressure in the fluid chamber, thereby avoiding explosion of the fluid chamber, whereby a fail-safe mechanism against an excessive external force can be provided.
The core is preferably formed with a signal wire or an electrical wire connected between the pump unit and the pump driver. According to the invention, the signal wires and the electrical wires are prevented from becoming damaged, which enables electric shocks and the like to be avoided.
The pump driver is preferably disposed in the movable unit which seals liquid therein so that the pump driver is in contact with the liquid. According to the invention, the pump driver is cooled because heat generated by the pump driver is absorbed by the liquid, and a more compact actuator is obtainable by virtue of the pump driver disposed inside the movable unit.
The pump-integrated flexible actuator preferably further includes a reservoir that stores a predetermined amount of fluid; and a supply member that controls supply of the fluid stored in the reservoir to each fluid chamber of the movable unit. According to the invention, the work fluid in the reservoir is supplied into the fluid chambers by operating the supply member and the inner pressure of the fluid chambers is thereby increased, whereby the movable unit can be made to be rigid. With this arrangement, when the actuator is used as a component for, for example, a pet robot, the actuator can move into a state in which the pet robot is tense other than the state in which the actuator is bent with an operation of the pump unit.
Two pump units are preferably integrated with the movable unit at respective longitudinal ends of the movable unit, and the two pump units preferably simultaneously operate to transfer fluid between the plurality of fluid chambers. According to the invention, the actuator can be moved quickly by increasing the bending speed of the movable unit with the two pump units transferring the fluid between a plurality of the fluid chambers.
Each pump unit is preferably provided with a detachable connecting part, such that when a pair of
Seto Takeshi
Takagi Kunihiko
Lazo Thomas E.
Oliff & Berridg,e PLC
Seiko Epson Corporation
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