An actuator having two frames, each frame including a distal end member, a proximal pivot end member or proximal end pivot point, and at least two elongated side members connected between the distal end member and the proximal pivot end member of that frame. A flexure is disposed between an end of the pivot end member of the first frame and an end of the pivot end member of the second frame. A first longitudinal span member is disposed between the distal end member of the second frame and the pivot end member of the first frame, and a second longitudinal span member is disposed between the distal end member of the first frame and the pivot end member of the second frame. At least one of the first and second longitudinal span members is an expansive element having a longitudinal axis along which dimensional strain can be induced in response to an applied stimulus. This expansive element extends in a state of compression between the corresponding distal and proximal pivot end members, with the longitudinal axis of the element in a plane parallel to side members of the first and second frames. The one or both of the longitudinal span members that are expansive elements can be, e.g., a magnetostrictive element, an electrostrictive element, or a piezoelectric element. The actuator provides many of the characteristics required to achive optimal mass efficiency for a given set of actuator materials; and further provides advantages of high bandwidth, linearity, and large stroke performance advantages. As a result, the actuator can be adapted to many applications and can accommodate a range of engineering constraints.

High-efficiency, large stroke electromechanical actuator

A drug delivery device includes a pressurized reservoir in communication with a flow path to an outlet. The flow path includes two normally-closed valves and a flow restriction. A pressure measurement arrangement measures a differential fluid pressure between two points along the flow path which span at least part of the flow restriction, one of the points being between the valves. A controller selectively opens the valves to deliver a defined quantity of the liquid medicament to the outlet.

Drug delivery device and method

A bi-stable memory element (1) comprises a base contact (3), and a bridging contact (8), both made from an electrically conductive material. The bridging contact (8) is dimensioned so as to have two stable positions, in one of which the bridging contact (8) is in contact with the base contact (3), and in the other of which the bridging contact (8) is spaced apart from the base contact (3). Deflection means (4, 5) deflects the bridging contact (8) from one stable position to the other.

Bi-stable memory element

This paper proposes a compact ultrasonic motor with low manufacturing costs, a simpler driving circuit, and scalability. The stator of the motor presented in this paper consists of a hollow metal cylinder, whose outside surface was flattened on two sides at 90 degrees to each other, on which two rectangular piezoelectric plates were bonded. Because the cylinder has a partially square/partially circular outside surface, the stator has two degenerated bending modes that are orthogonal to each other. A wobbling motion is generated on the cylinder when only one piezoelectric plate is excited at a frequency between the two orthogonal bending modes. A rod through a pair of ferrules was used as the rotor of this motor. The prototype motor, whose stator was 2.4 mm in diameter and 10 mm in length, operated at 69.5 kHz, was experimentally characterized, and a maximum torque of 1.8 mNm was obtained.

A piezoelectric motor using two orthogonal bending modes of a hollow cylinder

Ultrasonic devices having transducer assembly including a stack of alternating electrodes and piezoelectric elements. A mounting device having a first and second end is adapted to receive ultrasonic vibration from the stack and transmit it from the first to the second end. A bolt including a head and shaft is configured to threadedly engaged the mounting device. The transducer assembly includes a deformable pressure element having a central opening that permits insertion of the shaft therethrough, and has a convex side facing the bolt head and a concave side facing the stack in a non-deformed state, but, in a deformed state, applies compression forces to the stack based on the deformation. The deformable pressure element may alternately include a surface area, in its deformed state, substantially equivalent to the surface area of a piezoelectric element and/or a first and second beveled surface defining the concave side.

Ultrasonic medical device and method

A mechanical amplification structure has a pair of L-shaped lever arms mounted for rotational motion about individually associated pivot points on a frame. An elongated transducer (e.g. piezoelectric or electrostrictive) expands or contracts responsive to electrical signals, the transducer being coupled to swing the lever arms about the pivot points. Thus an excursion distance between the swinging ends of the lever arms is equal to the expansion or contraction of the transducer multiplied by an effective length of the lever arms. An elastic support is coupled between the swinging ends of the arms to experience controlled mechanical excursions responsive to the electrical signals. A mechanical actuator is mounted on the elastic support for giving a mechanical action in response to an operation of the actuator means. As shown, the actuator is a printing needle in one embodiment and a relay contact in another embodiment.

Mechanical amplification mechanism combined with piezoelectric elements

A piezoelectric ultrasonic motor, which uses longitudinal and torsional composite vibration, is examined in order to obtain high torque characteristics with small diameter. Piezoelectric ceramic elements, oscillating in both longitudinal and torsional modes, respectively, are used as piezoelectric stiffened modes having high electromechanical coupling factors k/sub 33/ and k/sub 15/, respectively. It is found that the resonant frequencies for longitudinal mode and torsional mode could coincide with each other in the ultrasonic motor, according to finite element method analysis and experimental measurement. The motor operating in both resonant vibrations indicated good performance. The 20-mm diameter motor exhibited 4 kgfcm maximum torque, 450 r/min maximum rotational speed, 40% maximum efficiency, and quick responsiveness, within 2.5 ms. >

Piezoelectric ultrasonic motor using longitudinal-torsional composite resonance vibration

An ultrasonic motor has a longitudinal-torsional composite transducer, a stator constituted by an ultrasonic vibrator sandwiching the transducer, and a rotor urged against the stator. The stator excites longitudinal-torsional ultrasonic vibrations to rotate the rotor by a frictional force. The motor includes a vibration adjusting rod for matching resonance frequencies of longitudinal and torsional ultrasonic vibrations of the stator with each other.

Ultrasonic motor and method of adjusting the same

A piezoelectric transducer for a printing pin of a dot-matrix or an armature of a relay drives a mechanical amplification mechanism having a base plate with a reference wall that is to be fixed to a frame. An elongated piezoelectric transducer element extends in the direction of its expansion between the base plate and a lever arm. A lever arm has a first end portion coupled to an end of the piezoelectric transducer element, which is remote from the base plate. The lever arm is fixed to the second portion of the base plate by a fulcrum member located at a position near the first end. A band spring has one end coupled between the second end portion of the lever arm and the base plate. An actuating element is fixed to substantially a central portion of the spring. The actuating element may be either a printing pin of a dot-matrix or the moving contact of a relay.

Mechanical amplification mechanism for electromechanical transducer

A piezoelectric ultrasonic motor, which uses longitudinal and torsional composite vibration of a cylindrical resonator, was investigated. It was found that the resonant frequencies for longitudinal mode and torsional mode could coincide with each other in the cylindrical resonator, according to finite element analysis and experimental measurement. The motor using both resonant vibrations showed good performance. The 20-mm-diameter motor exhibited a 4 kgf-cm maximum torque, a 450-r.p.m maximum rotational speed, and a 40% maximum efficiency. >

Tadao Uchikawa

Papers

Mechanical amplification mechanism combined with piezoelectric elements

Piezoelectric ultrasonic motor using longitudinal-torsional composite resonance vibration

Ultrasonic motor and method of adjusting the same

Mechanical amplification mechanism for electromechanical transducer

Piezoelectric ultrasonic motor using longitudinal-torsional composite vibration of a cylindrical resonator