Liquid flow rate controller

• US 6,491,659 B1
• Filed: 03/02/2000
• Issued: 12/10/2002
• Est. Priority Date: 03/02/2000
• Status: Expired due to Fees

• Current Assignee: I'M Co., Ltd.
• Original Assignee: I'M Co., Ltd.
• Inventors: Miyamoto, Isshin
• Primary Examiner(s): Nguyen, Anhtuan T.
• Assistant Examiner(s): LAM, ANN Y
• Application Number:
  US09/517,816
• Time in Patent Office: 1,013 Days
• Field of Search: 604/30, 604/65, 604/66, 604/67, 604/31, 604/131, 604/246, 604/256, 604/253, 604/250
• US Class Current: 604/30
• CPC Class Codes: A61M 2205/14 Detection of the presence or absence of a tube, a connector or a container in an apparatus
• CPC Class Codes: A61M 2205/3306 Optical measuring means
• CPC Class Codes: A61M 39/28 Clamping means for squeezing flexible tubes, e.g. roller clamps tube strippers A61M1/83
• CPC Class Codes: A61M 39/281 Automatic tube cut-off devices, e.g. squeezing tube on detection of air
• CPC Class Codes: A61M 5/16804 Flow controllers
• CPC Class Codes: A61M 5/16813 by controlling the degree of opening of the flow line
• CPC Class Codes: A61M 5/1689 Drip counters

Abstract

A liquid flow rate detector and controller having a microprocessor that senses the rate of drops falling in a monitoring balloon on a fluid tube. A light emitter/detector diode pair detects drops as they fall in the balloon, which are timed by the microprocessor. The device has first and second switches manufactured in a single small unit made of thin laminates. Each switch comprises an electrode and a contact point, mutually facing across a gap in the layers. The lamina on at least one side of each switch is elastic. External force flexes the elastic layer, causing it to bend across the gap, causing the electrode and the contact point to touch. A fluid tube is inserted in a narrow channel between the first switch and a movable wedge. A stepper motor under control of the microprocessor moves the wedge to press the fluid tube against the first switch until the contacts close. This indicates that the fluid tube is completely flattened and closed. The microprocessor then retracts the wedge a predetermined distance from the closed point and monitors the rate of drops falling in the drip balloon. The movement of the wedge is precisely controlled by the microprocessor to achieve a desired drop rate. The second switch senses the presence of a fluid tube in the narrow channel to allow initialization of the process.

Claims

1. An intravenous feeding control device comprising:

a limit switch having a contact point and an electrode to detect a pressure applied to a medical fluid tube;

a wedge that presses the medical fluid tube into the limit switch;

drive means for moving the wedge to push and release the medical fluid tube;

control means electrically connected to the limit switch and the drive means for controlling the drive means to close and open the medical fluid tube.

2. The intravenous feeding control device of claim 1 further comprising:

a storage hollow in the front of intravenous feeding control device to receive an intravenous balloon.

3. The intravenous feeding control device of claim 2 wherein the storage hollow is elongated, and has an axis that is slanted between 10 and 20 degrees from a vertical path of fluid drops falling in the balloon.

4. An intravenous feeding control device of claim 1 comprising;

a combination of light emission element and light detect element to detect a drop of medical fluid in an intravenous balloon.

5. A liquid flow rate controller comprising:

a case;

a channel in the case, having a narrow portion for holding a liquid transfer tube, and a wide portion for holding a liquid drip monitoring balloon attached to the tube;

a light emitter and light detector on opposite sides of the wide portion of the channel for sensing drops of liquid falling in the balloon;

a movable wedge;

a limit switch;

the wedge and limit switch on opposite sides of the narrow portion of the channel;

drive means for moving the wedge toward the limit switch to compress the liquid tube against the limit switch;

the light detector and limit switch electronically connected to a microprocessor for input thereto;

the drive means connected to the microprocessor for control by the microprocessor;

control logic in the microprocessor for moving the wedge toward the limit switch until the limit switch is closed, then reversing the wedge and making positional adjusatents thereto as required to achieve a given rate of detection of drops by the light detector.

6. The liquid flow rate controller of claim 5 further comprising:

a tube presence detection switch in the case;

the tube presence detection switch electronically connected to the microprocessor for input thereto;

a lever projecting partly into the narrow portion of the channel apart from the wedge;

the lever contacting and closing the tube presence switch when a tube is inserted in the narrow portion of the channel;

whereby the microprocessor is informed of the presence of a tube in the narrow portion of the channel.

7. The liquid flow rate controller of claim 5 wherein the wide portion of the channel is elongated, and has an axis that is slanted between 10 and 20 degrees from vertical as defined by a path of drops of liquid falling in the balloon.

8. A liquid flow rate controller comprising:

a case having a channel with a narrow portion for accepting a fluid tube, and a wide portion for accepting a drip balloon;

a light emitter and a light detector on opposite sides of the wide channel portion, the light detector producing an electronic signal when a drop of fluid falls between the light emitter and detector;

a movable wedge protruding transversely into the narrow channel portion by a variable amount to press against the fluid tube with a respectively variable force;

a motor controlling the amount of protrusion of the wedge into the narrow channel portion;

a limit switch in the narrow channel portion opposite the wedge, activated by a threshold amount of lateral deflection of the fluid tube caused by the force exerted transversely on the tube by the wedge;

a tube presence detection switch in the narrow channel portion apart from the wedge, the tube presence detection switch activated by the presence of a fluid tube inserted in the narrow channel portion;

a control panel on the case, having input switches and a display panel;

an electronic logic device connected electronically to the control panel, limit switch, tube presence detection switch, motor, and light detector, the electronic logic device programmed to detect the signal rate from the light detector and to control the motor to achieve a selected signal rate from the light detector;

whereby a fluid tube having an in-line drip balloon can be placed in the channel and the rate of a fluid flowing through the tube is controlled as desired.

9. The liquid flow rate controller of claim 8, wherein the limit switch and tube presence detection switch are part of a switch assembly made by laminating layers of material, including at least a spacer sandwiched between a substrate and a membrane, the membrane being flexible, the spacer having at least first and second openings, within each of which an electrode is attached to the substrate and an opposed contact point is attached to the membrane, thus defining the limit switch and tube presence detection switch respectively, whereby the flexible membrane can be externally depressed at either of said switches, causing the respective contact point to touch the opposed electrode.

10. The switch assembly of claim 9, further comprising a flexibility adjustment layer bonded externally to the membrane over one of said switches to increase the pressure required to activate said one of said switches.

11. The liquid flow rate controller of claim 8, further comprising a lever extending across part of the narrow channel portion, the lever being pushed aside when a tube is inserted in the narrow channel portion, and the lever depressing the second limit switch when a tube is inserted in the narrow channel portion.

12. The liquid flow rate controller of claim 8 wherein the wide portion of the channel is elongated, and has an axis that is slanted between 10 and 20 degrees from vertical as defined by a path of drops of liquid falling in the balloon.