Liquid feed pump and flow control device

• US 8,888,471 B2
• Filed: 08/28/2013
• Issued: 11/18/2014
• Est. Priority Date: 04/27/2011
• Status: Active Grant

• Current Assignee: CKD Corporation
• Original Assignee: CKD Corporation
• Inventors: Nitta, Shinichi
• Primary Examiner(s): LETTMAN, BRYAN MATTHEW
• Application Number:
  US14/012,820
• Publication Number:
  US 20130343909A1
• Time in Patent Office: 447 Days
• Field of Search: 417/413.1, 417/413.2, 417/395
• US Class Current: 417/413.2
• CPC Class Codes: F04B 43/046 with piezoelectric drive

Abstract

A liquid feed pump includes a pump housing, a diaphragm forming a pump chamber together with the recessed portion surface and partitioning the pump chamber from the hole, a reciprocating member reciprocatably inserted into the hole and reciprocating to press the diaphragm to deform, a driving member displacing the reciprocating member periodically in a direction of reciprocation, a seal portion sandwiching the diaphragm to seal the diaphragm in a position around an outer peripheral side of the recessed portion surface, a diaphragm receiving surface provided between the seal portion and the opening portion, and its contact area contacting the diaphragm decreases in response to an increase in the displacement of the reciprocating member to the recessed portion surface side and increases in response to an increase in the internal pressure of the pump chamber.

Claims

1. A liquid feed pump comprising:

a diaphragm including a central portion, a peripheral portion, and an intermediate portion therebetween;

a pump housing body including;

a recessed surface opposing the diaphragm;

a seal pressurization surface forming a first annular flat surface provided around the recessed surface, the seal pressurization surface opposing the peripheral portion of the diaphragm;

an intake passage having an opening in the recessed surface; and

a discharge passage having an opening in the recessed surface;

a reciprocating member having a cylindrical body and a convex surface at one end thereof, the convex surface having an apex at a center thereof and opposing a pump chamber with the central portion of the diaphragm interposed therebetween;

a driving member configured to periodically displace the reciprocating member with a variable amount in a reciprocative direction of the reciprocating member; and

a pump housing base including;

a columnar hole having an axis parallel to the reciprocative direction, the columnar hole accommodating and supporting the reciprocating member therein such that the convex surface of the reciprocating member facing the diaphragm;

a diaphragm receiving surface surrounding an opening of the columnar hole and opposing the recessed surface with the intermediate portion of the diaphragm interposed therebetween, the diaphragm receiving surface providing a contact area contacting the diaphragm, the contact area being decreased when a displacement of the reciprocating member toward the recessed surface increases, and increased when an internal pressure of the pump chamber increases; and

a seal receiving surface surrounding the diaphragm receiving surface so as to form a second annular flat surface opposing the first annular flat surface of the seal pressurizing surface, the peripheral portion of the diaphragm being hermetically sandwiched between the first and second annular flat surfaces so as to form the pump chamber between the diaphragm and the recessed surface,

wherein the driving member includes a piezoelectric actuator configured to set a displacement of the reciprocating member so as to provide two driving positions, the apex of the convex surface substantially aligning with the opening of the columnar hole in a non-driving state, the two driving positions including;

a high pressure driving position which allows the reciprocating member to reciprocate between the non-driving state and a position where a peripheral edge of the convex surface substantially aligns with the opening of the columnar hole and keeps the intermediate portion of the diaphragm in contact with and supported by the diaphragm receiving surface; and

a low pressure driving position which allows the cylindrical body of the reciprocating member to project from the opening of the columnar hole until the intermediate portion of the diaphragm separates from the diaphragm receiving surface.

2. The liquid feed pump according to claim 1, wherein the recessed surface has a shape corresponding to a shape of the diaphragm in a fully deformed state thereof in the low-pressure driving state,

and wherein the recessed surface includes:

an intake side groove extending from the opening of the intake passage toward a center of the recessed surface so as to communicate with the pump chamber, and

a discharge side groove extending from the opening of the discharge passage toward the center of the recessed surface so as to communicate with the pump chamber.

3. A flow control device for controlling a liquid feed pump, comprising:

the liquid feed pump according to claim 1; and

a control unit configured to control a discharge flow rate of the liquid feed pump by adjusting a voltage applied to the piezoelectric actuator.

4. The flow control device according to claim 3, wherein the control unit is configured to apply a pulse-shaped voltage to the piezoelectric actuator, and control the discharge flow rate of the liquid feed pump by adjusting a maximum value of the pulse-shaped voltage.

5. The flow control device according to claim 3, further comprising a pressure sensor configured to measure a discharge pressure of a fluid discharged from the discharge passage,

wherein the control unit is configured to restrict a stroke to be smaller than a predetermined value in accordance with the discharge pressure measured by the pressure sensor.

6. The flow control device according to claim 3, further comprising a flow rate sensor configured to measure a discharge flow rate of a fluid discharged from the discharge passage,

wherein the control unit is configured to restrict a driving frequency of a reciprocation of the reciprocating member to be lower than a predetermined value in accordance with the discharge flow rate measured by the flow rate sensor.

7. The flow control device according to claim 3, further comprising a flow rate sensor configured to measure a discharge flow rate of a fluid discharged from the discharge passage,

wherein the control unit is configured to provide an operation mode in which a driving period of a reciprocation of the reciprocating member is increased as the discharge flow rate measured by the flow rate sensor increases, and the driving period is reduced as the measured discharge flow rate reduces.

8. The flow control device according to claim 3, wherein the liquid feed pump includes a flow rate sensor configured to measure the discharge flow rate of the liquid feed pump,

wherein the control unit is configured to perform flow rate control by feeding back the discharge flow rate measured by the flow rate sensor at a plurality of measurement timings within each driving period of a reciprocation of the reciprocating member.