Liquid Dosing Arrangement

• US 20080077079A1
• Filed: 12/21/2004
• Published: 03/27/2008
• Est. Priority Date: 12/21/2004
• Status: Abandoned Application

• Current Assignee: Maquet Critical Care AB (Getinge AB)
• Original Assignee: Maquet Critical Care AB (Getinge AB)
• Inventors: Slettenmark, Bruno
• Application Number:
  US11/792,748
• Publication Number:
  US 20080077079A1
• Time in Patent Office: Days
• US Class Current: 604/65
• CPC Class Codes: A61M 2206/22 eliminating pulsatile flows, e.g. by the provision of a dampening chamber
• CPC Class Codes: A61M 5/14593 the diaphragm being actuated by fluid pressure
• CPC Class Codes: A61M 5/1486 the bags being substantially completely surrounded by fluid
• CPC Class Codes: A61M 5/16813 by controlling the degree of opening of the flow line
• CPC Class Codes: A61M 5/16881 Regulating valves on-off valves, e.g. clamps A61M39/28
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence

Abstract

A liquid dosing arrangement has a liquid supply system with a first pressure sensor for measuring a first pressure p₁; a liquid delivery system, with a second pressure sensor for measuring a second pressure p₂; and an injection valve, which is arranged so that the liquid is supplied through a restricting member in the injection valve and let through the restricting member by a pulsed opening and closing valve mechanism. The pressure drop, and the dimensions of the restricting member in the injection valve, are selected to make the velocity ν of the liquid flowing through the restricting member is high enough to make the flow of liquid through the liquid delivery system independent of the viscosity of the liquid.

Claims

1. A liquid dosing arrangement, comprising:

a liquid supply system comprising a first pressure sensor that measures a first pressure p₁;

a liquid delivery system comprising a second pressure sensor that measures a second pressure p₂; and

an injection valve between the liquid supply system and the liquid delivery system comprising a restricting member through which said liquid flows, and a pulsed opening and closing valve mechanism that operates said restricting member with opening pulses having frequency f_o and width t_o, wherein the pressure drop Δ

p over the injection valve (2) is Δ

p=p₁−

p₂;

with the pressure drop Δ

p, and the dimensions (b, d₁) of the restricting member in the injection valve making the velocity ν

of the liquid flowing through the restricting member sufficiently high to make the flow Φ

of liquid through the liquid delivery system essentially independent of the viscosity of the liquid.

2. The liquid dosing arrangement according to claim 1, wherein the restricting member in the injection valve is formed by at least one orifice in an orifice plate.

3. The liquid dosing arrangement according to claim 2, wherein the restricting member in the injection valve is formed by a plurality of orifices in an orifice plate.

4. The liquid dosing arrangement according to claim 2, wherein the at least one orifice (22) is approximately circular, and has a diameter d₁ of less than 300 μ

m.

5. The liquid dosing arrangement according to claim 1 comprising an expansion chamber downstream of the injection valve.

6. The liquid dosing arrangement according to claim 1, further comprising a pressure regulating system supplied with respective signals from the first and second pressure sensors, said pressure regulating system generating a regulating signal therefrom, and a pressure regulator supplied with said regulating signal that regulates the first pressure p₁ in the liquid supply system to keep Δ

p constant.

7. The liquid dosing arrangement according to claim 1, further comprising a low pass filter arranged to filter the signal from the second pressure sensor.

8. The liquid dosing arrangement according to claim 6, wherein the pressure regulating system comprises a first comparator device, to which the respective signals from the pressure sensors are fed, and which calculates the pressure drop Δ

p, and a second comparator device, which compares the pressure drop Δ

p, generated by the first comparator device, with a preset reference value Δ

p_ref for the pressure drop, the output from said second comparator device being the regulating signal for the pressure regulator.

9. The liquid dosing arrangement according to claim 1 comprising an alarm that is activated when the second pressure p₂ measured by the second pressure sensor exceeds a preset value p_max.

10. The liquid dosing arrangement according to claim 1 comprising a flow sensor in the liquid supply system and an alarm that is activated when a flow measured by the flow sensor deviates beyond preset values.

11. (canceled)

12. A method of dosing liquid in a liquid dosing arrangement comprising a liquid supply system, a liquid delivery system, and an injection valve between the liquid supply system and the liquid delivery system, the method comprising the steps of:

measuring a first pressure p₁ in the liquid supply system with a first pressure sensor;

measuring a second pressure p₂ in the liquid delivery system with a second pressure sensor; and

supplying liquid through a restricting member in the injection valve by a pulsed opening and closing valve mechanism with opening pulses having frequency f_o and width t_o, the pressure drop Δ

p over the injection valve being Δ

p=p₁−

P₂; and

selecting the pressure drop Δ

p=p₁−

p₂ over the injection valve, and the dimensions (b, d₁) of the restricting member in the injection valve, so that the velocity ν

of the liquid flowing through the restricting member insufficiently high to make the flow Φ

of liquid through the liquid delivery system essentially independent of the viscosity of the liquid.

13. The method of dosing liquid according to claim 12, comprising providing an expansion chamber downstream of the injection valve.

14. The method of dosing liquid according to claim 12 comprising filtering a signal from the second pressure sensor in a low pass filter.

15. The method of dosing liquid according to claim 12 comprising the steps of:

feeding respective signals from the first and second pressure sensors to a pressure regulating system; and

feeding an output of the regulating system as a regulating signal to a pressure regulator that regulates the first pressure p₁ in the liquid supply system to keep Δ

p constant.

16. The method of dosing liquid according to claim 12 comprising activating an alarm when the second pressure p₂ measured by the second pressure sensor exceeds a preset value p_max.

17. The method of dosing liquid according to claim 12 comprising activating an alarm when the flow measured by a flow sensor in the liquid supply system deviates beyond preset values.

18. An apparatus for intravenous infusion comprising

a liquid dosing arrangement comprising a liquid supply system comprising a first pressure sensor that measures a first pressure p₁, a liquid delivery system comprising a second pressure sensor that measures a second pressure p₂, and an injection valve between the liquid supply system and the liquid delivery system comprising a restricting member through which said liquid flows, and a pulsed opening and closing valve mechanism that operates said restricting member with opening pulses having frequency f_o and width t_o, wherein the pressure drop Δ

p over the injection valve (2) is Δ

p=p₁−

p₂; and

a liquid delivery interface connected to said liquid delivery system and configured to interact with a patient to deliver said liquid to the patient.