Flow rate control apparatus and blood pressure monitor
A flow rate control apparatus includes a flow rate detection unit that detects the flow rate of a fluid flowing through a solenoid valve, a correlation storage unit that stores a correlation between a flow start point voltage at which the fluid starts to flow through a sample solenoid valve, which has substantially the same characteristic as the solenoid valve, and a limit voltage at which the sample solenoid valve is fully open, and a control unit that, when starting control of the flow rate of the fluid, changes the driving voltage of the solenoid valve, obtains the driving voltage at a time when the start of flowing of the fluid is detected as the flow start point voltage, and uses the correlation for the sample solenoid valve to set the driving voltage of the solenoid valve within a range between the flow start point voltage and the limit voltage.
1. A flow rate control apparatus for controlling a flow rate of a fluid by opening and closing a solenoid valve using a driving voltage, comprising:
a flow rate detection unit configured to detect the flow rate of the fluid flowing through the solenoid valve;
a correlation storage unit storing, for a sample solenoid valve which is a different valve from the solenoid valve and has substantially the same characteristic as the solenoid valve, a correlation between a flow start point voltage of the sample solenoid valve at which the fluid starts to flow through the sample solenoid valve and a limit voltage of the sample solenoid valve at which the sample solenoid valve is fully open; and
a control unit configured to, when starting control of the flow rate of the fluid, change the driving voltage of the solenoid valve, obtain the driving voltage at a time when the flow rate detection unit detects a start of flowing of the fluid as the flow start point voltage, use the correlation for the sample solenoid valve based on the flow start point voltage of the solenoid valve to obtain a limit voltage of the solenoid valve at which the solenoid valve is fully open through conversion, and thereafter set the driving voltage of the solenoid valve within a range between the flow start point voltage of the solenoid valve and the limit voltage of the solenoid valve.
2. The flow rate control apparatus according to claim 1 , wherein
the correlation for the sample solenoid valve stored by the correlation storage unit includes the correlation at a time when a plurality of pressures of the fluid are set.
3. The flow rate control apparatus according to claim 2 , comprising:
a pressure sensor configured to detect a pressure of the fluid,
wherein the control unit detects the pressure of the fluid at a control start time using the pressure sensor at the control start time,
when the pressure of the fluid at the control start time takes a value other than those of the plurality of pressures that give the correlation stored in the correlation storage unit, the control unit uses interpolation or extrapolation based on the correlation corresponding to the plurality of pressures to obtain a correlation between the flow start point voltage of the solenoid valve and the limit voltage of the solenoid valve corresponding to the pressure of the fluid at the control start time, and
the control unit uses the obtained correlation when obtaining the limit voltage of the solenoid valve through conversion based on the flow start point voltage of the solenoid valve.
4. The flow rate control apparatus according to claim 3 , wherein
the control unit detects the pressure of the fluid after the control start time using the pressure sensor in a control period, and
when the pressure of the fluid after the control start time changes from the pressure of the fluid at the control start time, based on the correlation corresponding to the plurality of pressures, the control unit obtains the flow start point voltage of the solenoid valve and the limit voltage of the solenoid valve through conversion.
5. The flow rate control apparatus according to claim 4 , wherein the correlation for the sample solenoid valve includes a relationship at a time when a plurality of varied ambient temperatures are set.
6. A blood pressure monitor comprising:
a cuff for compressing a measurement site;
a solenoid valve for adjusting a pressure of the cuff; and
the flow rate control apparatus according to claim 4 .
7. The flow rate control apparatus according to claim 3 , wherein the correlation for the sample solenoid valve includes a relationship at a time when a plurality of varied ambient temperatures are set.
8. A blood pressure monitor comprising:
a cuff for compressing a measurement site;
a solenoid valve for adjusting a pressure of the cuff; and
the flow rate control apparatus according to claim 3 .
9. The flow rate control apparatus according to claim 2 , wherein the correlation for the sample solenoid valve includes a relationship at a time when a plurality of varied ambient temperatures are set.
10. A blood pressure monitor comprising:
a cuff for compressing a measurement site;
a solenoid valve for adjusting a pressure of the cuff; and
the flow rate control apparatus according to claim 2 .
11. The flow rate control apparatus according to claim 1 , wherein the correlation for the sample solenoid valve includes a relationship at a time when a plurality of varied ambient temperatures are set.
12. The flow rate control apparatus according to claim 11 , comprising:
a temperature sensor configured to detect an ambient temperature of the solenoid valve,
wherein the control unit detects the ambient temperature of the solenoid valve after a control start time using the temperature sensor in a control period, and
when the ambient temperature of the solenoid valve after the control start time changes from the ambient temperature at the control start time, based on the correlation corresponding to the plurality of ambient temperatures, the control unit obtains the flow start point voltage of the solenoid valve and the limit voltage of the solenoid valve through conversion.
13. A blood pressure monitor comprising:
a cuff for compressing a measurement site;
a solenoid valve for adjusting a pressure of the cuff; and
the flow rate control apparatus according to claim 12 .
14. A blood pressure monitor comprising:
a cuff for compressing a measurement site;
a solenoid valve for adjusting a pressure of the cuff; and
the flow rate control apparatus according to claim 11 .
15. A blood pressure monitor comprising:
a cuff for compressing a measurement site;
a solenoid valve for adjusting a pressure of the cuff; and
the flow rate control apparatus according to claim 1 .