Measuring head for diagnostic instruments and method
This invention relates to a measuring head which comprises an intake, an outlet, a mouthpiece and an electrically controlled proportional valve. The intake may be connected to a pressurized gas reservoir. The outlet releases exhaled gas and excess gas into the ambient. A mouthpiece provides gas to a subject and accepts exhaled gas from the subject. The electrically controlled, proportional valve is pneumatically connected between said intake and said mouthpiece for controlling the gas flow from said intake to said mouthpiece and said outlet. The invention further relates to a method for controlling a gas flow from the intake to the outlet.
1. A measuring head for diagnosing a pulmonary condition of a subject using a pressurized gas reservoir, comprising:
an intake for being connected to the pressurized gas reservoir;
an outlet for releasing exhaled gas and excess gas into the ambient;
a mouthpiece for providing gas to the subject for inhalation and accepting exhaled gas from said subject, said mouthpiece being pneumatically connected to said outlet and comprising a flow sensor for measuring the flow of said inhaled gas by and exhaled gas from said subject;
an electrically controlled, proportional valve, which is pneumatically connected between said intake and said mouthpiece for controlling the gas flow from said intake to said mouthpiece and said outlet;
a computer being electrically connected to said flow sensor and said proportional valve; said computer being programmed for adjusting said proportional valve, such that the gas flow delivered by said proportional valve is higher than the inspired gas flow.
2. The measuring head of claim 1 , further including a pressure sensor for measuring the pressure of said inhaled gas by and exhaled gas from said subject.
3. The measuring head of claim 1 , wherein said electrically controlled, proportional valve comprises a plurality of on/off solenoid valves.
4. The measuring head of claim 3 , wherein a ratio of the flows through said open solenoid valves at a predetermined pressure difference between said intake and said ambient is approximately a power of two.
5. The measuring head of claim 1 , wherein said measuring head comprises a pressure sensor which is pneumatically connected to a connection tube between said intake and said proportional valve.
6. A method for controlling a gas flow from an intake to an outlet and a mouthpiece by measuring head, the method comprising:
generating an electrical signal having a monotonic dependence from the gas flow caused by inhaling of a subject; and
controlling an opening of a proportional valve between said intake and said outlet and said mouthpiece by said signal such that the gas flow delivered by said proportional valve is higher than the inspired gas flow.
7. The method of claim 6 , wherein said electrical signal is generated by a flow sensor and said flow sensor measures the gas flow through said mouthpiece.
8. The method of claim 6 , further including measuring a pressure at said intake.
9. The method of claim 8 , further comprising:
closing said outlet; and
obtaining a two-dimensional gas flow array while said outlet is closed by:
applying several different pressure values at said intake;
performing the following at each pressure value:
adjusting several different openings at said proportional valve; and
measuring of the gas flow through said mouthpiece.
10. The method of claim 9 , further comprising:
obtaining an estimated gas flow through said intake based on a two-dimensional gas flow array, the pressure at said intake and the opening of said proportional valve; and
adjusting the opening of said proportional valve such that said estimated gas flow exceeds said gas flow caused by inhaling.
11. A pulmonary diagnostic instrument, comprising:
a measuring head comprising:
an intake for being connected to a pressurized gas reservoir;
an outlet for releasing exhaled gas and excess gas into the ambient;
a mouthpiece for providing gas to a subject and accepting exhaled gas from said subject, said mouthpiece being pneumatically connected to said outlet; said mouthpiece comprising a flow sensor for measuring the flow of said inhaled gas by and exhaled gas from said subject; and
an electrically controlled, proportional valve pneumatically connected between said intake and said mouthpiece for controlling the gas flow from said intake to said mouthpiece and said outlet;
the pulmonary diagnostic instrument further comprising:
a computer being electrically connected to said flow sensor and said proportional valve; said computer being programmed such that it suitable for adjusting said proportional valve such that the gas flow delivered by said proportional valve is higher than the inspired gas flow.
12. A measuring head, comprising:
an intake for being connected to a pressurized gas reservoir, said intake being pneumatically connected to a junction;
an outlet for releasing exhaled gas and excess gas into the ambient, said outlet being pneumatically connected to the junction;
a mouthpiece for providing gas to a subject for inhalation and accepting exhaled gas from said subject, said mouthpiece being pneumatically connected to said outlet, said mouthpiece comprising a flow sensor for measuring the flow of said inhaled gas by and exhaled gas from said subject; and
an electrically controlled, proportional valve, which is pneumatically connected between said intake and said mouthpiece for controlling the gas flow from said intake to said mouthpiece and said outlet.