Maquet Servo ventilator 900 C, Руководство по обслуживанию

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26
= Not valid for SV 900 E
= Not valid for SV 900 D
Insp. pressure ref. level (PC board no 5)
The block outputs are INSP. PRESSURE REFERENCE
LEVEL (V25:3) and the negative going INSP. PRESSURE
REFERENCE (V18:1).
At SIMV + CPAP MODE (V27:12), both block outputs
correspond to PEEP LEVEL (V25:2) coming from PC
board no 4.
In the modes SIMV + PRESS. SUPPORT, PRESS
CONTR. and PRESS SUPPORT, both block outputs
correspond to the sum of PEEP LEVEL and INSP. PRESS
LEVEL (V21:14).
During SIMV +PRESS SUPPORT and PRESS
SUPPORT and CAP modes (V20:14) at INSP. PRESS
LEVEL front panel settings below 8 cm H
2
O, the negative
going INSP PRESS. REFERENCE LEVEL is increased
(V21:7) with 1 cm H
2
O,
When the button GAS CHANGE is activated, the block
GAS CHANGE PRESSURE REF. LEVEL delivers a voltage
corresponding to +20 cm H
2
O at the negative going INSP.
PRESSURE REFERENCE output (V18:1).
Insp. press. level compensator
(PC board no 5)
During PRESSURE REG. INSP. TIME the INSP. PRESSURE
LEVEL COMPENSATOR connects the sum of the negative
going INSP. PRESSURE REFERENCE and AIRWAY
PRESSURE (E) during MID. INSP. TIME PULSE (switch
V47), to the integrator V36/C20. From the integrator the
signal is fed to the INSP PRESS. ERROR CALCULATOR
where com pensation for deviations in actual pressure
value, with respect to desired pressure level, takes place.
At mode change, START UP RESET pulse resets the
integrator (V46).
Second half insp. time (PC board no 7)
A positive going pulse is generated when the time elapsed
during the present INSPIRATION is equal to half of the total
time of the foregoing INSPIRATION.
Mid. insp. time pulse (PC board no 5)
The positive front edge of the pulse generated in SECOND
HALF INSP. TIME will trigger a pulse (V1, V16) which is fed
to INSP. PRESSURE LEVEL COMPENSATOR.
Start insp. time marker (PC board no 5)
A pulse is generated at the beginning of the inspira tion
time, This pulse is used for the derivating circuit in the
block INSP. PRESS. ERROR CALCULATOR, in the block
INSP. PRESSURE ERROR AMPLIFICATION SELECTION
and in the block END INSP. INDICATOR.
Insp. pressure error calculator
(PC board no 5)
The actual AIRWAY PRESSURE (I) value (via R95) is added
to the differentiated AIRWAY PRESSURE (E) value (via
C18/R135/V28), together with the integrated AIRWAY
PRESSURE (E) compensation value from INSP. PRESSURE
LEVEL COMPENSATOR (V36:6 via R94) and the negative
going INSP. PRESSURE REFERENCE (V18:1 via R93)
resulting in the INSP. PRESSURE ERROR SIGNAL (V19:8)
to the ERROR SIGNAL SELECTOR.
Insp. press. error ampl. selection
(PC board no 5)
This stage selects the gain depending on selected mode
and timing signals.
Error signal selector (PC board no 5)
This electronic switch (V26, V27) selects the INSP.
PRESSURE ERROR SIGNAL for the pressure servo loop
and the INSP. FLOW ERROR SIGNAL for the flow servo
loop (see introduction chapter “Regulation of inspira tion”).
Voltage controlled oscillator
(PC board no 6)
The VOLTAGE CONTROLLED OSCILLATOR converts the
error signal into a pulse sequence (speed signal at V5 via
V3:7, 8) with a variable frequency which is propor tional
to the error signal voltage. In addition, there is a direction
signal (at V4 via V3:1) which, depending on the polarity of
the error signal, decides whether the motor should step
forward (opening) or backward (closing).
Electronic unit – Regulation of inspiration