JPH0231409B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling the air pressure in a closed space such as an airplane cabin, and in particular to monitoring and testing each component to improve the reliability of its operation and ensure the safety and comfort of passengers in the closed space. This invention relates to a digital in-flight pressure control system that can increase pressure.

Air pressure regulation in the passenger cabin (hereinafter also referred to as the cabin) is an important element in providing a comfortable environment for passengers and crew members and in ensuring safe flight of the airplane. Most airplanes today fly at altitudes of 35,000 feet (approx.
10,670 m) or more, and the cabin pressure control device used for such an airplane must satisfy the following conditions. In other words, sufficient oxygen is supplied to passengers without causing unpleasant sudden changes in cabin pressure that are felt to the human ear, and without creating an excessively large difference between cabin pressure and outside pressure, while also providing adequate oxygen to the aircraft components. It is important not to give any force.

With conventional cabin pressure control systems, one crew member periodically measures the cabin altitude (pressure) (cabin pressure, or cabin pressure, contrasts with the flight altitude, so it is convenient to express it in terms of the altitude that produces the cabin pressure. (hereinafter referred to as the "cabin altitude"), the rate of change in the readings of the measuring instrument and the rate of change in the readings of the airplane's altimeter are compared to determine whether the device is operating normally. I needed to check. In addition, in many conventional systems, the cabin pressure is determined by the take-off runway altitude, cruising altitude, and landing altitude based on sea level, but the cabin pressure may change rapidly, and as a result, the ears of passengers and crew may be affected by the air pressure. There was a danger that the change would cause discomfort.

Furthermore, conventional systems have been unreliable because they lack the self-monitoring and testing capabilities and flight data required by modern airplanes.

This minimizes crew effort, maintains constant cabin pressure regardless of changes in the aircraft's altitude and environment, and provides high safety and reliability for monitoring and testing critical components. It was strongly desired to provide an in-flight pressure control device.

According to the present invention, there is provided a safe and reliable cabin pressure control device that eliminates the above-mentioned drawbacks of conventional devices, can be applied to the latest model airplanes, and provides a comfortable environment for passengers and crew. be done.
The only operations that require manual input to the device are selecting the landing runway altitude and the maximum rate of change of cabin pressure before takeoff. Also, there is no need to change during the flight unless the landing site is changed. The device of the present invention can minimize changes in cabin pressure independently of changes in airplane altitude and external pressure. The logic circuitry of the device can also automatically perform adjustment actions according to the airplane's flight plan to eliminate passenger and crew discomfort due to low pressure at high altitudes.

The system of the present invention includes a cruise altitude control system that maintains a constant cabin altitude (pressure) when flying over a range of altitude changes of up to ±500 feet. When the cruise altitude controller detects that the airplane's altitude change is within a predetermined limited range, the cabin pressure controller functions to fix the cabin altitude according to the schedule and maintain the cabin altitude at the predetermined cabin altitude. Therefore, until the airplane rises or descends to a predetermined height from the altitude at which cruise control is performed, or until the difference between the cabin pressure and the outside pressure reaches a predetermined limit, slight turbulence, changes in outside airflow, etc. The cabin altitude (pressure) can be kept constant independently of the accompanying altitude changes of the airplane. When the cruising altitude of the airplane changes beyond a predetermined range, the fixed state of the cruising altitude control device is released and the cabin altitude (pressure) is increased or decreased at a predetermined rate to the value in the schedule corresponding to the new altitude. .

Hereinafter, the present invention will be explained along with preferred embodiments.

The cabin pressure control system according to the present invention shown in FIG. 1 includes a mode selector 12 for selecting an operating mode, and the mode selector 12 sends signals indicating the operating state of the airplane before takeoff, during takeoff, and during landing. Furthermore, a signal indicating inspection on the ground after landing is given to the OR gate 14. OR gate 1
4 inputs a signal from mode selector 12
A signal is output to the OR gate 16. When in automatic operating mode, an automatic flight control circuit 18 also sends a signal to the OR gate 16 to control cabin pressure based on external pressure, landing altitude, and actual cabin pressure. On the other hand, a signal Pc indicating the actual pressure inside the aircraft is inputted to the automatic flight control circuit 18 via the A/D converter 22 by the in-flight pressure sensor 20 that detects the pressure inside the aircraft. In addition to the signals from the automatic flight control circuit 18, the logic circuit 19 also receives signals from the automatic flight control circuit 18.
A signal indicating the maximum allowable pressure difference between the pressure outside the machine and the actual pressure inside the machine is input, and an output signal is output to the OR gate 16 and the control circuit 26. Limiting circuit 26 also receives the output signal from OR gate 16. The output signal of the logic circuit 19 indicates the actual pressure difference between the internal pressure and the external pressure, or the maximum allowable differential pressure between the internal pressure and the external pressure. In the logic circuit 26,
A predetermined rate of change in cabin pressure in accordance with the operating mode of the airplane selected by operating mode selector 12 is calculated. The D/A converter 28 is a logic circuit 26
It inputs the digital output signal from , and outputs to the adder circuit 30 an analog signal P _cc representing the predetermined rate of change in the cabin pressure. Output of cabin pressure sensor 20
The analog differentiator 32 receiving P _c differentiates the actual cabin pressure signal and sends a signal indicating the actual rate of change of the cabin pressure to the amplifier 34, and the amplifier 34 adds the signal P _CA indicating the actual rate of change to the adding circuit 30. Output to. On the other hand, the adder circuit 30 sends a signal representing the difference between the predetermined rate of change and the actual rate of change in the internal pressure to the amplifier 36, and the amplifier 36 itself inputs a signal representing the difference in the rate of change and sends the signal to the adder circuit 38. Output.

On the other hand, a signal representing the speed of the drive motor 42 is also input to the addition circuit 38 from the tachometer 40 via the speed demodulation circuit 44 . The output signal of adder circuit 38 is amplified in error amplifier 46 to provide an error signal for driving drive motor 42. More specifically, in accordance with the error signal, either the valve open switch 48 or the valve close switch 50 is actuated to operate the drive motor 42. The drive motor 42 controls the valve 52, determines the flow rate of air from inside the machine, and adjusts the pressure inside the machine.

If a failure occurs in the circuit described above, the drive motor 42 will be controlled via the standby control circuit 53 having the same configuration as the circuit described above.

The block diagram of FIG. 2 shows the flow of input and output signals from a central processing unit 54 (hereinafter simply referred to as CPU) for controlling valve 52 (not shown in FIG. 2). ± from the power supply 60 to the cabin pressure sensor 20
A voltage of 15V is applied, and the internal pressure is detected and a signal P _C indicating the detected value is sent to the channel CH-O of the analog multiplexer 56. On the other hand, the analog multiplexer 56 inputs a plurality of analog signals and selectively converts them into digital signals to the CPU 54.
send a signal to. Also, the output signal P _C from the in-machine pressure sensor 20 is input to the first input terminal of the adder 58;
An offset voltage from the power supply 60 is applied to the input terminal of
V _OFFSET1 , and filter 64 is connected to the third input terminal.
A substantially linear signal P _LIN indicating the landing runway altitude is inputted from the voltage divider 62 via the respective voltage dividers 62 . The voltage divider 62 divides the input voltage V _REF from the reference voltage source 65 and generates a signal.
Output P _LIN . Adder 58 outputs signal P _LIN and cabin pressure
A signal P _DIF representing the difference from P _C is output and sent to an amplifier 66 . The amplifier 66 inputs and amplifies the signal P _DIF and outputs it to the input channel CH− of the analog multiplexer 56.
Send to 1. Further, an input signal P _CSIM of the in-machine pressure control device, which simulates the in-machine pressure during the bench test, is sent to the input terminal 67 of the in-machine pressure sensor 20. The signal _{P_LIN} from filter 64 is also sent to input channel CH-2 of analog multiplexer 26.

Also, the channel CH of analog multiplexer 56
-3 is sent a signal representing a predetermined maximum rate of change in cabin pressure. That is, the voltage divider 68 is the reference voltage source 6
The voltage V _REF from 5 is divided and sent to channel CH-3 of analog multiplexer 56 via filter 70 .

Channel CH− of analog multiplexer 56
Reference numeral 4 checks the ±15V output voltage of the power supply 60, inputs a signal from the bench test switch 72, and commands the CPU 54 to set the operation to the bench test mode. The output voltage of the power supply 60 +15V is connected to channel CH-4 through a resistor 74, and the output voltage of the power supply 60 is
The output voltage of -15V is also applied to channel CH-4 through resistor 76.

Channel CH− of analog multiplexer 56
5 includes a drive motor 40 (not shown in FIG. 2).
A signal representing the speed of is input. Adder 7
8 inputs the output signal from the speed demodulation circuit 44 (not shown in FIG. 2) via the amplifier 79 and the reference voltage from the reference voltage source 65 via the amplifier 82;
The output signal is outputted to channel CH-5 of analog multiplexer 56 via amplifier 83.

Also, the channel CH of analog multiplexer 56
A signal representing a predetermined rate of change in the cabin pressure P _CC is input to channel CH-6, and an actual rate of change in the cabin pressure P _CAB is input to channel CH-7.

On the other hand, the channels of analog multiplexer 56
CH-8 and CH-9 have a drive motor 40
A signal indicating that valve 52 (not shown in FIG. 2) is open and a signal indicating that valve 52 is closed by drive motor 40 (not shown in FIG. 2) are provided, respectively. is input. Channel CH-10 receives a reference voltage from a reference voltage source 65.
V _REF and an internal reference ground signal are input to channel CH-11, respectively. Channel CH-1
2, CH-14 and CH-15 are spare terminals.
In addition, channel CH-13 receives an output signal from a voltage drop monitoring circuit 84 that monitors the 5V output voltage from power supply 60.

In order to read out the analog signal input to a specific channel of the analog multiplexer 56,
CPU 54 first addresses that particular channel via latch circuit 86. As a result, the analog multiplexer 56 outputs the output voltage to the adder circuit 90 via the buffer amplifier 92. CPU
Data from DATA terminal 54 is transferred to DATA bus 8.
5 and a data buffer amplifier 88 to a latch circuit 86. The four output terminals of the latch circuit 86 are connected to the address terminals of the analog multiplexer 56.
selectively addresses input channels CH-0 to CH-16.

CPU 54 also outputs a digital signal representing a predetermined voltage to D/A converter 28 via latch circuit 86. The D/A converter 28 receives a voltage input from the reference voltage source 65 via the amplifier 94.
Converts a digital input signal to a corresponding analog voltage based on V _*REF . Inverter 96 inverts the analog output voltage from D/A converter 28 and sends the inverted voltage V _D/A to addition circuit 90 , comparison circuit 97 and sample holding circuit 98 .

Summing circuit 90 also receives an offset voltage V _OFFSET2 and outputs a voltage representing the difference between the input voltage of the addressed channel of analog multiplexer 56 and the output voltage of D/A converter 28. On the other hand, the A/D comparator circuit 100 is an adder circuit 90
, and outputs a digital signal indicating whether the output voltage of the adder circuit 90 is positive or negative to the input terminal 7 of the input buffer 101 .

According to other embodiments of the invention, further input buffers 102, 103 may be provided. In this case, the input buffers 102 and 103 supply digital signals representing the state of predetermined flight variable data to the CPU 54 in order to determine the predetermined conditions of the cabin pressure control system. For example, in order to check whether the output of the inverter 96 exceeds 5V, the comparison circuit 9
The output terminal DAC1 of 7 can be connected to the input terminal 0 of the input buffer 102.

In the illustrated embodiment, each input buffer 101,
102 and 103 contain eight data bits 0-7.
and a digital read signal that allows each data bit to be selectively input to CPU 54. Under the control of the CPU 54, each input buffer 101-103 is addressed using digital read signals from each output terminal 4, 3, 2 of the address decoder 104 shown in FIG.

In order to read the addressed channel of the analog multiplexer 56, the CPU 54 operates to output a digital read signal 1 from the output terminal 4 of the address decoder 104 to the input terminal of the input buffer 101 (see FIG. 2B); The buffer 101 operates to input the signal from the A/D comparison circuit 100 to the CPU 54.

The CPU 54 determines the output voltage of the analog multiplexer 56 using a continuous approximation method. The output of the A/D comparison circuit 100 is connected to the analog multiplexer 56.
If the voltage V _D/A is higher than the output voltage of the second predetermined voltage, the CPU 54 outputs a digital signal representing a second predetermined voltage to the D/A converter 28 via the latch circuit 86.

In the above operation, the CPU 54 outputs a signal that approximates the output of the analog multiplexer 56 within specified tolerances.
is repeated until it is generated. CPU 54 will read each channel of analog multiplexer 56 in the manner described above. Furthermore, Batsuhua 1
Other information supplied to the CPU 54 via 01, 102, and 103 will be explained below.

The present invention is configured to input information regarding flight variables to a cabin pressure control system based on one or more computers on board an airplane. In the illustrated embodiment, multiplexer 108 is connected to first and second computers 110,112. The CPU 54 determines which of the computers 110 and 112 should input data to the in-flight pressure control device, and sends a computer selection signal from the CPU 54 to the output terminal 7 of the output buffer 113 shown in FIG.
to the selection input terminal of multiplexer 108.

Referring to FIGS. 2A, 2B, 2C, and 3, a data input circuit 116 for inputting onboard data is connected to an output terminal of multiplexer 108, and a selected computer 110 is connected to the output terminal of multiplexer 108.
Alternatively, the information word from 112 is input and conditioned. Usually, each information word consists of 32 bits and is data transmitted using a return-to-zero recording method. The first 8 bits constitute the identification code of the transmitted information word, the other bits represent flight data. Data input circuit 11
6 stores all 32-bit data, and then sends the interrupt signal to the input terminal for interrupt requests of the CPU 54 via the OR gate 117 and flip-flop 118.
Send to IRQ.

Referring to FIG. 3, address decoder 120
is connected to the memorizable terminal MR of the CPU 54, the address decoder 121 is connected to the address decoder 120, and the address decoder 104 is connected to the address decoder 12.
1, respectively, and this allows the CPU 54
may selectively address other components of the cabin pressure control system. A read/shift input terminal and a reset input terminal of data input circuit 116 are connected to output terminal 5 of address decoder 104 and output terminal 3 of address decoder 120, respectively.
OR gate 117 is also time frame generator 1
26 inputs a periodically generated output signal which provides an interrupt operation of the CPU 54.

The CPU 54 provides a restart frame signal to the time frame generator 126 via the output terminal 2 of the address decoder 120, thereby starting the operation of the time frame generator 126. The output signal FMG of time frame generator 126 is sent to input terminal 7 of input buffer 103 and flip-flop 128. When an electrical failure occurs in the cabin pressure control device, a disconnection signal is sent from the CPU 54 to the flip-flop 128 and the second flip-flop 130 via the output buffer 113. In response, an automatic failure signal is output from the flip-flop 128 to the output terminal 1 of the input buffer 101, and the CPU 54 outputs an automatic failure signal to the output terminal 1 of the input buffer 101.
8 operations can be monitored.

When there is no fault in the cabin pressure control device and a signal representing the removal of a previously existing fault is input to the CPU 54, a fault removal signal is sent from the CPU 54 to the flip-flop 128 via the output terminal 7 of the address decoder 104, and the flip-flop 128 A signal is output to another flip-flop 130. The flip-flop 130 also has an address decoder 1.
A relay activation signal is also input from the CPU 54 through the output terminal 7 of the CPU 20. In response to these signals, flip-flop 130 activates relay drive logic circuit 13.
Outputs a signal that activates 4. When relay drive logic 134 is activated, relay drive logic 134 sends a relay on signal to input terminal 1 of input buffer 103 . To suitably operate the cabin pressure control system, a time frame generator 12 is required.
6. Sequentially turn on flip-flop 128 and flip-flop 130 to turn on relay drive logic circuit 1.
34, but if a failure occurs in the cabin pressure control device, the above-mentioned operation is interrupted and control of cabin pressure by the cabin pressure control device is stopped.

A signal output from the reset circuit 136 to reset or turn on the cabin pressure control device 10 is input to the flip-flop 118, the one-shot multivibrator 138, and the AND gate 140. The output signal from is input. When the set time in one-shot multivibrator 138 is reached, a reset signal is sent from AND gate 140 to the reset terminal of CPU 54. When the CPU 54 is reset, the initial values of the control parameters are set and the cabin pressure control system is placed in the ground operating mode. The reset circuit 136 resets the voltage from the reference voltage source 65.
Powered by V _REF and a 5V voltage from power supply 60.

The CPU 54 has two operating levels: foreground and background. The foreground level is used to provide data and functions that need to be processed according to timing constraints.The functions implemented here include reading information from the data input circuit 116, inputting the cabin pressure measurement, etc. This includes updating, updating the output pressure rate of change, and performing certain high-priority tests. On the other hand, the background level is used to provide functions that do not need to be updated according to timing constraints, and the functions implemented here include infrequent tests and flight mode parameters that require extensive calculations. It will be done. CPU 54 is usually time frame generator 1
26. Time frame generator 126 is 50
When generating an interrupt signal every millisecond, the CPU54
responds to the interrupt signal and enters the foreground processing mode. When the calculation regarding the foreground is completed, the CPU 54 outputs the input terminal of the interrupt request.
The remaining time in the 50 millisecond time frame is returned to background calculation mode until a new timing frame interrupt signal is input to IRQ.

Unless an activation signal is input to the OR gate 117 from the data input circuit 116, the CPU 54 performs normal operation within a predetermined time frame, in which case the CPU 54 is returned to the foreground processing mode and the data stored in the data input circuit 116 is returned to the foreground processing mode. It is necessary to process the data words. A read/shift signal is input from the CPU 54 to the read/shift input terminal of the data input circuit 116 via the output terminal 5 of the address decoder 104, and the data word stored in the data input circuit 116 is transferred via the data bus 85.
It is input to the CPU 54.

The data input circuit 116 inputs a variety of information, but three of them are particularly important in the cabin pressure control system: altitude corrected according to atmospheric pressure, absolute altitude, and their atmospheric pressure correction.
When controlled by the CPU 54, absolute altitude information is obtained to monitor and adjust the pressure difference between the outside and inside pressures to determine the preferred rate of change in cabin pressure as a function of the airplane's planned altitude. There is a need to. Also, using the altitude corrected according to the atmospheric pressure, the CPU 54 determines the cabin pressure necessary for preparation for landing.

CPU 54 decodes the identification code of the data word input from data input circuit 116 and determines whether such data word is appropriate for operation of the cabin pressure control system. If the entered data word is correct, CPU 54 stores said word and calculates a new rate of change in cabin pressure. After storing the data word, a reset signal is sent from the CPU 54 to the reset input terminal of the data input circuit 116 via the terminal 3 of the address decoder 120.
16 further inputs a signal from the multiplexer 108 and is put into a memorizable state.

When the CPU 54 is unable to perform foreground work in a predetermined period, a decoder enable signal is input from the CPU 54 via the output terminal 1 of the address decoder 121, and the one-shot multivibrator 141, which performs input/output operations,
A signal is output to the memorizable input terminal MR of the CPU 54, and the one-shot multivibrator 141
The foreground work is enabled by the CPU 54 until the set time in .

As is clear from the above, FIGS. 2 and 3 show in detail the function of the circuit shown in _FIG . When V _D/A is calculated and a trigger signal is sent from the output terminal 2 of the output buffer 113 to the sample holding circuit 98, the sample holding circuit 98 reads the output signal from the inverter 96 and holds the output signal for a predetermined time. A signal _P〓CC representative of a predetermined rate of change in cabin pressure passed from sample holding circuit 98 through filter circuit 140' is sent to channel CH-6 of analog multiplexer 56 and amplifier 144. On the other hand, the adder circuit 30 receives the output signal of the amplifier 144, the output signal P/ _CA of the amplifier 34, and the output signal from the amplifier 146 as an offset voltage obtained by amplifying the output voltage V _REF from the reference voltage source 65.

Addition circuit 148 also inputs a predetermined rate of change _P〓CA of the in-machine pressure signal and voltage V _REF , and outputs to buffer amplifier 150 a signal representing the actual rate of change in in-machine pressure that has been changed by voltage V _REF . The buffer amplifier 150 inputs the output signal P _CAB to channel CH-7 of the analog multiplexer 56.

A signal representing the difference between the predetermined rate of change and the actual rate of change in the cabin pressure is sent from the adder circuit 30 to the adder circuit 38 via the lead/lag compensation circuit 156. On the other hand, the speed demodulation circuit 44 receives an energizing voltage of 115 VAC from the power supply 60 and signals TACH HI and TACH LO from the tachometer 40 (see FIG. 1). Amplifier 79 amplifies the output signal from velocity demodulation circuit 44 and inputs it to adder circuit 38 . Summing circuit 38 generates a speed error signal for controlling the operation of drive motor 42 (not shown).

FIG. 2 also shows details of the valve open switch 48 and valve close switch 50 of FIG. 1st
A speed error signal is input from the error amplifier 46 to the second threshold circuits 152 and 154. The threshold circuit 152 receives the digital signal.
AND data 156, one threshold value circuit 154
outputs digital signals to AND data 158, respectively. Also, AND gates 156 and 158 have
Output terminal 4 of output buffer 113 from CPU 54
A drivable signal is inputted via. Threshold circuit 152 activates threshold circuit 15 when the positive speed error signal rises to a predetermined level, for example 1.25V.
The output level of the threshold circuit 152 is switched from low to high, and the output level of the threshold circuit 152 is switched from high to low when the positive speed error signal drops to a predetermined level, for example, 1.05V.
On the other hand, the threshold circuit 154 switches the output level of the threshold circuit 154 from low to high when the negative speed error signal drops below a predetermined level, for example, -1.25V, and also causes the negative speed error signal to reach a predetermined level. For example, the output level of the threshold circuit 154 is configured to switch from high to low when the voltage rises to -1.05V or higher. The AND gate 156 receives the high level signal from the threshold circuit 152 and the CPU
When a drive enable signal is input from 54, AND gate 156 outputs a command signal for opening the valve by a motor to input terminal 5 of input buffer 103 and relay 160 made of a semiconductor. relay 16
0 has an electro-optical configuration that does not respond to inappropriate input.

On the other hand, the relay 168 is connected to the relay drive logic circuit 134.
controlled by That is, when relay 168 is in the on position, relay 1
68 to the drive motor 42 shown in FIG.
A voltage is sent through the motor to open the valve.
The input terminal of the A/D converter 172 is the relay 16
0 and bleeder resistor 170, and the valve opening DC signal from A/D converter 172 is connected to channel CH of analog multiplexer 56.
- Sent to 8.

Furthermore, when the AND gate 158 receives the high level signal from the threshold circuit 154 and the drive enable signal from the CPU, it connects the input terminal 6 of the input buffer 103 and another relay 17 made of a semiconductor.
A command signal to close the valve is output by the motor to No. 4. This causes the relay 168 to send a suitable voltage to the drive motor 42 (see FIG. 1) through a circuit consisting of the relay 174 connected in parallel with the bleeder resistor 182 to the drive motor 42 (see FIG. 1) to cause the motor to close the valve.
The input terminal of A/D converter 184' is relay 1
74 and bleeder resistor 182, and the DC output signal from A/D converter 184' is connected to channel CH of analog multiplexer 56.
Sent to -9.

As shown in FIG. 3, data is sent from the CPU 54 to output buffers 113 and 184 via a data buffer amplifier 88 on a data bus 85.
Output buffers 113 and 184 are 8-bit data terminals 0 to 184, respectively, which control each component of the cabin pressure control device.
7. Under the control of the CPU 54, the output buffer 11 is output using the digital write signals from the output terminals 4 and 5 of the address decoder 120, respectively.
3,184 are activated. The data bits from output terminals 0 and 1 of output buffer 113 are used during bench test mode of the cabin pressure control system. The data bits from output terminals 2, 4, 5, and 7 of output buffer 113 are used as described above in connection with the circuit operation of FIG. On the other hand, in the illustrated embodiment, output terminal 3 of output buffer 113
is a spare terminal, and the output signal of output terminal 6 is the first
The figure shows whether the valve 52 is in a closed or open state.

Data bits at output terminals 0-7 of output buffer 184 control display panel 186 shown in FIG. The data bits from output terminals 0 to 7 are respectively indicated by an indicator light 187 indicating a selector failure, an indicator light 188 indicating a power off, an indicator light 189 indicating a control circuit failure, and an indicator light 1 indicating a landing gear failure.
90, an indicator light 191 that indicates a low inflow amount, an indicator light 192 that indicates a drive motor failure, an indicator light 193 that indicates a non-fault state, and an indicator light 194 that indicates a confirmation mode.
will be sent and displayed.

Referring again to FIG. 2, the input buffer 101
Digital signals to be sent to the CPU 54 are input to input terminals 0 to 7 of the CPU 54 . More specifically, input terminal 0 has an output buffer 18 in the self-test mode.
A no-failure signal for confirming the operation of the input/output terminals of this device is inputted from the output terminal 6 of No. 4. An automatic failure signal is inputted to the input terminal 1 from the flip-flop 128 during the self-test mode to confirm a series of operations by each frame, fault removal, and operation relay of the flip-flop 128. Also, using the automatic failure signal, the display panel 1 is activated by the CPU 54.
The status of indicator light 208 at 86 (see FIG. 4) is monitored. On the other hand, a signal input from self-test switch 196 of display panel 186 to input terminal 2 is used to start the built-in test sequence. A reset signal from a reset switch 197 of the display panel 186 is input to the input terminal 3 of the input buffer 101. Further, a signal from a confirmation switch 198 and a signal from a press test switch 199 of the display panel 186 are input to the input terminals 4 and 5, respectively. Furthermore, a drivable signal for performing an operation test within the device and an output signal from the A/D comparison circuit 100 are inputted to the input terminals 6 and 7, respectively, from the output terminal 4 of the output buffer 113.

On the other hand, a no-fault signal is input to input terminal 0 of the input buffer 102 from an indicator light 193 indicating that there is no fault. Input terminals 1 to 6 also contain signals from the valve 52 (see Figure 1), a signal from the confirmation switch 198 connected to the relay 168, a signal indicating lowering by manual control, and a signal when the device is in automatic control mode. An auto-enable signal, a landing gear signal, and a door close signal indicating the presence or absence of the vehicle are input, respectively. An interrupt signal for interrupting the operation of the CPU 54 is connected to the input terminal 7 of the input buffer 102 in the data input circuit 11.
It is input from 6. By selecting the signal input to the input terminal 7 of the input buffer 102,
CPU 54 determines whether an interrupt signal has been sent from data input circuit 116.

The input terminal 0 of the input buffer 103 has a D/A
Signals for partially testing converter 28
DAC1 is input from the comparator circuit 97. The input signals to the input terminals 1, 5, 6, and 7 have already been described above. In the case of this embodiment, input terminals 2 and 3 are reserve terminals, and a no-fault signal is input to input terminal 4 from an indicator light 193 indicating that there is no fault.

According to the invention, two modes are possible for controlling the valve 52: an automatic mode and a manual mode. When in automatic mode, valve 52 is activated according to a program that controls the cabin pressure in response to detected cabin pressure.
is positioned. On the other hand, in the manual mode, referring to FIG. 4, the flow rate from the valve 52 is manually adjusted by the manual operation knob 201 on the display panel 186. Also, the altitude selector 202 of the display panel 186
-1000 to +15000 feet (approximately -305 to +
A landing runway altitude within the range between 4580 m) is selected. A high resolution tape display 204 displays the altitude selected by the altitude selector 202.

Furthermore, the selector 206 on the display panel 186 is
30 to 1200 feet above sea level (approx. 9 to 366 feet per minute during descent)
m) and a maximum rate of change in altitude for the airplane over the range of 50 to 2000 feet above sea level per minute of climb. Display 2
08 is lit when an automatic failure signal is generated from the CPU 54.

Indicator 212 on display panel 186 indicates the position of valve 52. Furthermore, the mode selector 214 allows selection of either automatic mode or manual mode, and allows adjustment of the cabin pressure. When in manual mode, the pilot can use manual operating knob 201 to control the position of valve 52 to adjust the flow rate. On the other hand, in automatic mode, two cabin pressure control devices 10
One is to control the cabin pressure in the manner described above,
The other one is placed in a standby state and in this case inputs all the input signals necessary for controlling the cabin pressure, but unless one cabin pressure control device 10 fails, the other one will not be connected to the drive motor 4.
2, so as not to send a control signal to the terminal.

According to the present invention, in automatic mode, the only actions required by the pilot are to select the landing runway altitude and to achieve the maximum rate of change of cabin pressure before takeoff. There is no need to change during the flight unless the destination is changed. According to the present invention, the cabin pressure is controlled according to an automatic schedule showing a group of curves showing the relationship between the airplane cabin altitude (pressure) and the airplane altitude. An example of such an automatic planning table is shown in FIG.

According to FIG. 5, passengers feel extremely comfortable because pressure changes in the cabin are kept low independent of changes in the altitude of the airplane. For a given airplane, the actual cabin altitude (pressure) plan is created so that the minimum rate of change in cabin altitude (pressure) corresponds to the airplane's theoretical maximum rate of climb while the airplane climbs toward its maximum altitude. Cabin altitude (pressure) when in automatic mode
The rate of change is determined by the lesser of the altitude (pressure) rate of change value in the automatic planning table and a predetermined limit value for the altitude (pressure) rate of change, e.g., per minute while the airplane is climbing.
In the case of 500 feet (approximately 152 m) and 300 feet (approximately 91 m) per minute during descent, the latter is controlled according to the value of 300 feet (approximately 91 m) per minute.

According to the present invention, the cruising altitude is controlled and the apparent cabin altitude (pressure) is indicated according to the cabin pressure.
is kept constant during cruising, and changes in cabin altitude (pressure) are kept within a predetermined range. That is, when it is detected that the rate of change in airplane altitude over a predetermined period of time exceeds a predetermined value (unit: feet) per minute, the cabin altitude (pressure) set in the automatic plan will be adjusted to the predetermined cabin altitude (pressure). Fixed. The predetermined cabin altitude (pressure) is the altitude at which the airplane is from the cruise controlled altitude.
It is maintained until the aircraft is ascended or descended 500 feet or until the pressure difference between the interior and exterior pressures reaches a predetermined critical level. To determine when an airplane has reached cruising altitude, it is generally preferable to use a 500-foot (approximately 152 m) rise and fall in 2 minutes as a reference value. When the cruising altitude of the airplane changes and greatly exceeds ±500 feet (approximately ±152 m) from the required cruise control altitude, the cabin altitude (pressure) is unfixed under the control of the CPU 54 and the cabin altitude (pressure) returns to the predetermined level. It is raised or lowered by the rate of change. When the airplane descends more than 1000 feet per minute, the descent logic circuit in the CPU 54 is activated.
During this time, the logic circuits associated with the automatic planning table are deenergized.

When CPU 54 receives a landing gear signal representative of flight from input buffer 102, the autoplan command circuit and cruise control logic are energized. The predetermined cabin altitude (pressure) is the greater of the autoplanned value and the landing roll altitude, unless overridden by a circuit that operates to prevent excessive differences between cabin and external pressures. It will be done.

The cabin altitude (pressure) value based on the automatic planning table is set so that, for example, the airplane can ascend rapidly while keeping the difference between the inside and outside pressures at a predetermined level. Since an airplane can climb more rapidly with less payload, the pilot may select a cabin altitude with a climb limit value that is different from the airplane's actual rate of climb. It has a function to maintain the differential pressure within the limit pressure so as not to exceed it.

If the airplane starts taxiing with the fuselage door open, the valve 52 will be fully open and no power will be supplied. Therefore, the cabin altitude (pressure) is approximately equal to the external pressure regardless of the amount of inflow introduced into the cabin. Referring to Figure 6, when the door is closed,
The pressure drop through valve 52 reduces the normal cabin altitude (pressure) to a value of, for example, 40 feet (approximately 12.2 m) less than the runway altitude. In addition, the cabin altitude (pressure) immediately before takeoff changes at a rate of 300 feet (approximately 91.4 m) per minute to a level equivalent to 150 feet (approximately 45.7 m), which is less than the final runway altitude. After takeoff, the cabin altitude (pressure) is controlled at 500 feet (approximately 152 m) per minute until the cabin altitude (pressure) is controlled by the above-mentioned cruising altitude logic circuit.
It is reduced by the value of .

The operation of the automatic control logic circuit and the automatic planning circuit will be explained using a typical flight from Los Angeles to Chicago, which takes off and lands at approximately sea level. Referring to Figure 7, a flight from Los Angeles to Chicago took off from Los Angeles at a runway altitude of 126 feet (approximately 38.4 m), climbed to an altitude of 37,000 feet (approximately 11,300 m) in 17 minutes, and remained at that altitude for a while. and then ascended to an altitude of 42,000 feet (approximately 12,800 m) in 7 minutes.
Cruising at 43,000 feet (approx. 13,100 m) for about 3 hours,
Next, descend to an altitude of 20,000 feet (approximately 6,100 m) in 15 minutes, maintain this altitude of 20,000 feet (approximately 6,100 m) for 5 minutes, and then descend to an altitude of 666 feet (approximately 203 m).
Descend to an altitude of 10 minutes. The pilot selects a landing altitude of 666 feet (approximately 203 meters) before takeoff, and there is no need to reset the altitude during flight.

Meanwhile, during takeoff, the cabin altitude (pressure) increases at a rate of 380 feet (approximately 116 meters) per minute according to an automatic schedule. The cabin altitude (pressure) is maintained at the value specified in the planning chart for the duration of the airplane's altitude of 37,000 feet (approximately 11,300 m);
m) to 42,000 feet (approximately 12,800 m), the cabin altitude (pressure) will rise again at a rate of approximately 230 feet (approximately 70.0 m) per minute according to the value specified in the schedule. The airplane is at an altitude of 42,000 feet (approximately
During the cruise, the cabin altitude (pressure) is maintained at a cruising altitude (pressure) of 8,000 feet (approximately 2,440 m).

When the plane descends 1000 feet (approximately 305 meters),
Cabin altitude (pressure) is automatic plan value and landing altitude 666
feet (approximately 203 m), whichever is greater, begins to decline. If the rate of decrease in the plan value exceeds 300 feet (approx. 91.0 m) above sea level per minute,
The cabin altitude (pressure) is reduced at a rate limited by that value. If the airplane is held at an altitude of 20,000 feet (approximately 6,100 meters), the cabin altitude (pressure) will continue to decrease at a rate proportional to the limit until it reaches an altitude of 42,000 feet.
When it reaches feet (approximately 12,800m), it reaches the plan value.

As the airplane descends again, the cabin altitude (pressure) drops at a planned rate of approximately 220 feet above sea level per minute, resulting in a cabin altitude (pressure) of 486 feet (approximately 148 m) (80 feet less than the landing altitude). (about
24.4m). After landing, the cabin altitude (pressure) increases at a rate of 600 feet (approximately 183 m) per minute until valve 52 is fully opened. Pilots in such airplanes do not have to adjust the apparatus of the present invention, and the rate of change of cabin altitude (pressure) is maintained within a range that is comfortable for the passengers.

[Brief explanation of drawings]

FIG. 1 is a simplified block diagram of an embodiment of the in-flight pressure control system according to the present invention, FIGS. 2A to 2C are detailed diagrams of the block diagram of FIG. 1, and FIG. 3 is a diagram of the CPU input shown in FIG. A block diagram showing the status of output signals by function, Fig. 4 is a front view of the display panel used in the device shown in Figs. 2A to 2C, and Fig. 5 is a flight plan table showing the relationship between cabin altitude and airplane altitude. Figure 6 is a graph showing changes in cabin altitude (pressure) until the airplane door is closed and takeoff. Figure 7 is a graph showing an example of an airplane altitude plan and the accompanying cabin altitude plan. . 10... Cabin pressure control device, 12... Mode selector, 14, 16... OR gate, 18... Automatic flight control circuit, 19... Logic circuit, 20... Cabin pressure sensor, 22... A/D converter , 26...
Limiting circuit, 28...D/A converter, 30...
Addition circuit, 32...Analog differentiator, 34, 36
... Amplifier, 38 ... Addition circuit, 40 ... Tachometer, 42 ... Drive motor, 44 ... Speed demodulation circuit, 46 ... Error amplifier, 48 ... Valve open switch, 50 ... Valve close switch, 52 ... ...Valve, 5
3...Standby control circuit, 54...CPU, 56...
Analog multiplexer, 58... Adder, 60
...Power supply, 62...Voltage divider, 64...Filter,
65...Reference voltage source, 66...Amplifier, 68...
Voltage divider, 70...filter, 72...switch,
74, 76...Resistor, 78...Adder, 79,
82, 83...Amplifier, 84...Voltage drop monitoring circuit, 85...Data bus, 86...Latch circuit,
88...Data buffer amplifier, 90...Addition circuit, 92...Buffer amplifier, 94...Amplifier,
96...Inverter, 97...Comparison circuit, 98...
...Sample holding circuit, 100...A/D comparison circuit, 1
01, 102, 103...Input buffer, 104
... Address decoder, 108 ... Multiplexer, 110, 112 ... Air data computer, 113 ... Output buffer, 116 ... Data input circuit, 117 ... OR gate, 118 ... Flip-flop, 120, 121 ... Address decoder , 126...Time frame generator, 1
28,130...flipflop, 134...
Relay drive logic circuit, 136...reset circuit,
138... One shot multivibrator, 140... AND gate, 140'... Filter circuit, 141... One shot multivibrator, 144, 146... Amplifier, 148...
... Addition circuit, 150 ... Buffer amplifier, 15
2,154...threshold circuit, 156,158...
... Lead/lag compensation circuit, 160, 168... Relay, 170... Bleeder resistor, 172... A/
D converter, 174... Relay, 182... Bleeder resistor, 184... Output buffer, 186
...Display panel, 188, 190, 192, 19
3,194... Indicator light, 196... Self test switch, 197... Reset switch, 198...
... Confirmation switch, 199 ... Press test switch, 201 ... Manual operation knob, 202 ... Altitude selector, 204 ... Tape display, 206 ... Selector, 208, 212 ... Display, 214 ...
Mode selector, 184'...A/D converter.

Claims (1)

[Claims] 1 A device for setting a landing runway altitude selector to generate a landing altitude signal indicating a predetermined landing altitude, and a device for setting an automatic rate of change limit selector to generate a landing altitude signal indicating a predetermined maximum permissible rate of change in cabin air pressure. a device for generating a rate-of-change signal; a device for detecting the air pressure in the cabin to generate a signal indicative of the actual air pressure in the cabin; and a device for generating an actual rate-of-change signal indicative of the actual rate of change of the air pressure in the cabin. a device, a device for inputting a signal indicating external pressure, the landing altitude signal, the actual rate of change signal,
A device for controlling air pressure in an aircraft, comprising a maximum rate of change signal and a device responsive to external pressure to adjust the position of a valve for regulating air pressure in the cabin.