Drive device

• US 6,761,028 B2
• Filed: 10/11/2002
• Issued: 07/13/2004
• Est. Priority Date: 10/15/2001
• Status: Expired due to Fees

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Bessho, Yuki, Takeuchi, Yukihisa, Takahashi, Nobuo
• Primary Examiner(s): Lazo, Thomas E.
• Application Number:
  US10/270,041
• Publication Number:
  US 20030131595A1
• Time in Patent Office: 641 Days
• Field of Search: 604/13, 605/33, 604/86, 604/73, 604/75, 604/15, 605/43, 310/328, 310/339
• US Class Current: 60/413
• CPC Class Codes: F04B 43/046 with piezoelectric drive
• CPC Class Codes: F15B 7/00 Systems in which the movement produced is definitely related to the output of a volumetric pump; Telemotors
• CPC Class Codes: F15C 5/00 Manufacture of fluid circuit elements; Manufacture of assemblages of such elements integrated circuits
• CPC Class Codes: F16K 2099/0076 using electrical discharge machining [EDM], milling or drilling
• CPC Class Codes: F16K 2099/0084 Chemistry or biology, e.g. "lab-on-a-chip" technology
• CPC Class Codes: F16K 2099/0092 Inkjet printers
• CPC Class Codes: F16K 99/0001 Microvalves microdevices B81B1/00; manufacture or treatment of devices or systems in or on a substrate B81C1/00; microfluidic structures B01L3/5027; micropumps F04B19/006
• CPC Class Codes: F16K 99/0011 Gate valves or sliding valves
• CPC Class Codes: F16K 99/0048 using piezoelectric means
• CPC Class Codes: F16K 99/0057 the fluid being the circulating fluid itself, e.g. check valves

Abstract

A drive device includes ceramic pumps which alternately pressurize and depressurize fluid within a fluid chamber on opposite sides of a movable body, to thereby move the movable body within the flow chamber. The flow chamber is connected via micro flow passages to an internal-pressure buffering chamber, which accommodates a compressible gas. When the pressure of the fluid is increased and decreased at high speed by the ceramic pumps, the micro flow passages exhibit a high passage resistance, so that the pressure within the channel does not escape to the internal-pressure buffering chamber, and the movable body moves freely. When the pressure of the fluid increases slowly due to the expansion of the fluid, the micro flow passages exhibit a low passage resistance, so that the fluid is led to the internal-pressure buffering chamber, and the pressure increase of the fluid is suppressed.

Claims

1. A drive device comprising:

a channel forming portion for forming a channel, the channel accommodating an incompressible operation fluid and a movable body made of a substance different from that of the operation fluid, and being substantially divided into two operation chambers by means of the movable body;

a pair of pumps each including a pump chamber communicating with the corresponding operation chamber and being filled with the operation fluid, an actuator provided for the pump chamber, and a diaphragm deformed by the actuator, the operation fluid within the pump chamber being pressurized or depressurized through deformation of the diaphragm;

an internal-pressure-buffering-chamber-forming portion for forming an internal-pressure buffering chamber which accommodates the operation fluid and a compressible fluid for pressure buffering; and

a micro flow passage for connecting the channel of the channel forming portion and the internal-pressure buffering chamber of the internal-pressure-buffering-chamber-forming portion, the micro flow passage exhibiting a high passage resistance against abrupt pressure change of the operation fluid within the channel, to thereby substantially prohibit passage of the operation fluid through the micro flow passage and exhibiting a low passage resistance against slow pressure change of the operation fluid within the channel, to thereby substantially permit passage of the operation fluid through the micro flow passage.

2. A drive device according to claim 1, wherein the actuator includes a film-type piezoelectric element consisting of a piezoelectric/electrostrictive film or an antiferroelectric film and electrodes;

and the diaphragm is formed of ceramic.

3. A drive device according to claim 2, wherein each of the diaphragms of the pumps forms part of the wall of each of the pump chambers and is disposed such that it has a membrane surface on the same plane;

wherein the channel of the channel forming portion is configured such that it defines a space having its longitudinal direction within a plane parallel to the membrane surface of the diaphragm;

wherein the micro flow passage of the micro flow passage portion is extended in the direction parallel to the membrane surface of the diaphragm; and

wherein the internal-pressure buffering chamber of the internal-pressure-buffering-chamber-forming portion is configured such that it defines a space having its longitudinal direction within a plane parallel to the membrane surface of the diaphragm and is disposed such that it communicates with the channel of the channel forming portion via the micro flow passage of the micro flow passage portion.

4. A drive device according to claim 1, wherein each of the diaphragms of the pumps forms part of the wall of each of the pump chambers and is disposed such that it has a membrane surface on the same plane;

wherein the channel of the channel forming portion is configured such that it defines a space having its longitudinal direction within a plane parallel to the membrane surface of the diaphragm;

wherein the micro flow passage of the micro flow passage portion is extended in the direction parallel to the membrane surface of the diaphragm; and

wherein the internal-pressure buffering chamber of the internal-pressure-buffering-chamber-forming portion is configured such that it defines a space having its longitudinal direction within a plane parallel to the membrane surface of the diaphragm and is disposed such that it communicates with the channel of the channel forming portion via the micro flow passage of the micro flow passage portion.