Note: Descriptions are shown in the official language in which they were submitted.
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ENGINE MONITOR AND RECORDER
FIELD OF THE INVENTION
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This invention relates to turbine engine monitoring
equipment.
BACKGROUND_OF THE INVENTION
It has previously been proposed to monitor the
temperature of a turbine engine, particularly at
over-temperature levels, and one such over-temperature
monitoring system is disclosed in U.S. Patent No.
3,931,619. Another system of this general type is
disclosed in the copending patent application of Geoffrey
Hancock, U.S. Patent Application Serial No. 197,008,
filed October 14, 1980, now U.S. Patent No. 4,315,296 and
assigned to the assignee of the present invention. In
these prior arrangements, predetermined weighting
characteristics were established and alarm signals were
energized when the turbine engine exceeded such
predetermined overall limits. These control systems
characteristically involve a summation function in which
the time at some very high tempera~ure would be equated
to a longer time at a slightly lower temperature, and the
sum of the weighted factors would be employed to provide
an output indication which would give a rough indication
of the over-temperature stress or damage to the turbine
engine which may have occurred~
However, it would be desirable to have a more
accurate indication of the precise amount o~ time that
3~ the turbine engine has been operated, and that it has
been operated at particular temperature levels. In
addition, supplemental information such as the number of
times that the engine has started is also relevant in
determining whether periodic maintenance of the engine is
appropriate. Further, in the analysis of the maintenance
status of a turbine engine or the reason for certain
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anomalies in engine performance, it is frequently
desirable to be ahle to determine the details of the
recent past history of the operation of the engine in
greater detail than has been possible heretofore.
Accordingly, the present invention is intended to
overcome the shortcomings of the prior art systems and to
provide the more complete historical information of the
type outlined hereinabove.
SUMMARY OF THE INVENTION
In accordance with a specific illustrative embodi-
ment of the invention, each turbine engine of a multi-
engine aircraft is provided with an engine mounted
electronics unit including a data-processor, and a
permanent non-volatile memory unit which may be
electronically erased and updated. Inputs to the
engine-mounted unit include a thermocouple input, or
input ~rom same other type of temperature sensor, for
providing a continuous indication of the temperature of
the turbine engine. The analog temperature input
information is converted to digital form and is compared
with a certain preset temperature ranges or channels,
which confirm to an address or a location in the
non-volatile memory in which temperature information
relative to the particular temperature channel is stored.
The previously stored digital information is withdrawn
from storage and is updated with the supplemental
information, and the revised time information for the
particular temperature channel is then returned to the
non-volatile storage unit. Located remote from the
engine unit, eithsr in a portable service unit or in a
cockpit mounted unit, is an additional microprocessor,
and a digital display, along with switches for calling up
the desired temperature information and having it
displayed. The digital information may be transmitted
serially from the non-volatile memory in the engine-
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mounted unit to the remote display unit. With this
arrangement, only a few wires need be connected from each
of the engine mounted units to the remote electronics.
In accordance with a broader aspect of the
invention, a turbine engine monitoring and recording
system includes an engine-mounted electronic circuit unit
having a data-processor and a non-volatile memory, a
thermocouple mounted on the engine for supplying
temperature data to said engine mounted unit; and
additional electronic circuitry remote from the turbine
engine including an additional data-processor and display
arrangements. Circuit means are included in the engine
mounted electronic circuit unit for storing information
indicating the number of times the turbine engine has
been operated, and the length of time that the turbine
engine has been operated within each o~ a plurality of
discreet temperature ranges; and switching means are
provided in association with the remote electronic unit
for ordering and displaying selected information relative
to the length of time the engine has been operated in
selected ones of the temperature channels.
Other objects, features and advantages of the
invention will bacome apparent from a consideration of
the following detailed description and from the
accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a block circuit diagram illustrating
the system of the present invention;
Figure 2 is a schematic showing of a two-engine
aircraft in which the propellers are powered by turbine
engines;
Figure 3 is an exterior view of the engine mounted
electronic unit;
Figure 4 shows a display and switching panel which
may be mounted either on the dashboard in the airplane
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cockpi-t, or in a remote portable test unit;
Figures 5A and 5B are circuit diagrams indicating
the actual circuitry included within the engine moun-ted
electronics units;
Figure 6 shows the electronics included in the
remote unit;
Figures 7A and 7B are a detailed circuit diagram
showing the amplification and analog-to-digital
conversion circuitry which modifies the input temperature
signal from the th~rmocouple;
Figure 8 is a plot indicating the over-temperature
ranges for a typical turbine engine, with the allowable
time at each temperature level being plotted agains
turbine temperature.
DETAILED DESCRIPTION
Referring more particularly to the drawings, Figure
1 essentially shows the engine mounted electronic unit,
with only the thermocouple 12 and the remote electronic
unit 14 with its associated display 16 being
schematically shown to the right in Figure 1 outside of
the electronic connections 18, 20 and 22.
The input from thermocouple 12 is processed in unit
24 which includes an operational amplifier 26 which
receives and amplifies the sig~al from thermocouple 12,
and the analog to digital converter 28 which provides 10
binary digits or bits as an output signal indicating the
temperature level. An over-temperature alarm signal is
routed on lead 30 through connector 18 to the remote unit
14 where over-temperature alarm lights 32 signal
excessive temperature for the left or the right engine.
The electronic unit 34 includes a data-processor
having a central processing unit 36. A random access
memory 38 and a program read-only memory 40. A
non-volatile memory 42 is employed to store cumulative,
long-term temperature information of the history of the
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turbine engine with which the electronic unit is
associated, as more fully described below.
Now, on the following page a typical table of
temperature channel specifications is set forth. This
temperature specification table includes the channels of
information which may be obtained and displayed in the
display unit 16. More speciically, the temperature
channel specifications as set forth in table I indicate a
discrete set of temperature bands. Thus, for example,
temperature channel 3 relates to the temperature range
between 819.5C. and 830.8C. Included in the PROM 40 is
a table indicating these temperature bands and limits as
set forth in Table I. The in~ormation from the analog-
to-digital converter 28 as supplied to the input/output
circuit 44 over bus 46 is periodically sampled and
compared with the temperature bands as set forth in Table
I and as included in the PROM 40. Within the non-
volatile memory 42 are a set of memory storage locations
corresponding respectively to each of the many channels
included in table I. Following the comparison step
mentioned above, the channel or channels which are
involved are identified, and the information is withdrawn
from memory 42 and held in local storage, and is
incremented by a time interval corresponding to the
processing and sampling rate of the microprocessor 34.
The modified or incremented information is then returned
to the storage unit 42.
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The foregoing steps are set forth in s]ightly
different format in table II:
TABLE II
1. Periodic Sampling of Temperature Input
2. Digital to Analog Conversion
3. Comparator Step.
4. Identification of Memory Locations for Time
0 Information for Each Specific Temperature Range
5. Withdrawal of Stored Information From All
Channels Lower Than the Indicated Temperature Channel.
6. Incrementing of Data from these Memory
Locations
7. Return of Modified Channel Information to
Memory Storage Locations in Non-Volatile Memory.
8. For (A) Channels, an Allowable Time Period is
Substracted From the Increment by Which the Stored Time
is Increased.
When inormation is ordered up by the actuation of
one of the switches 48 associated with the remote
electronics and display unit 14, the information is
transmitted from the non-volatile memory on the data bus
50 to the 8 bit storage and shift register unit 52. The
information is then transmitted serially on lead 54 to
the output driver 58 and is transmitted on lead 60 to the
remote electronics and display unit 14,16.
The power supply 62 is conventional and merely
converts from the 24 volt aircraft power supply to the
plus and minus 12 volts required for operation of the
electronic circuitry and to the +5 volt signal required
for certain of the additional circuits.
Figure 2 is showing of a prop jet aircraft in which
the aircraft 64 is driven by the propeller 66 powered
from the turbine engine 68. The aircraft 64 is of course
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a twin-engine plane, with the other engine being located
beyond the main fuselage. In Figure 2 the one engine-
mounted electronics unit 70 is shown, and there is of
course another one mounted in the left engine. The
circuitry as shown in Figure 1 is that which is included
within the unit 70, while the thermocouple 12 (which may
represent a series of thermocouples) is mounted adjacent
to the engine 68, normally near the exhaust or at an
inter-stage location of this engine. The single remote
10unit 14 with the associated display 16 and switches 48,
may be mounted within the cockpit compartment, or may be
a portable test unit provided for maintenance and repair.
In either case, both of the two engine mounted units are
connected to a single remote unit 14, 16.
15Figure 3 shows the exterior configuration of an
engine mounted unit 70 including the terminal plugs 72
and 74.
Figure 4 shows the display which may be part of the
instrument display in the cockpit or may be included on
the portable test unit which may be used for ground
servicing. The display panel 76 includes the digital
display 7~, the over-temperature alarm si~nals 80 and 82
for the left and the right engines, respectively, the
self-test switch and signal 84, the push-button switches
8~ and 88 for the left and the right engines, respec-
tively, and the channel selection switches 90. At the
left hand end of the row of channel selection switches 90
is the additional switch 92 designated ~'start cycles",
and depressing this pushbutton switch causes a number to
appear on the display unit 78 representing the number of
times that the temperature of the engine has risen to a
temperature above 300C. a very low temperature for a
turbine engine, and then returned to a temperature below
this level. The switch 94 may be used with each channel
and indicates either the total time over limits ("TOL",
which refers to the length of time beyond the manu-
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facturers rated time of operation in the particular
temperature band); and the switch position designated
"TRT" which indicates the total running time over the
minimum temperature of the band under consideration.
Now, turning to Figures 5A and 5B, this is a
somewhat more detailed showing of the circuit of Figure
1. More specifically, the output from the thermocouple
is applied to the terminals 102 at the input to the
analog circuit 104. Incidentally, this analog circuit
104 will be shown in greater detail in connection with
Figure 7, and serves to compensate and amplify the
temperature signal provided by the thermocouple. The
output from the analog circuitry 104 is applied to the
analog-to~digital converter 28. The output leads 46 from
the analog to-digital converter supply a ten bit
conversion of the temperature level to the microprocessor
chip 106, ~hich for example may be an Intel chip such as
the 8035 or the 8048. The ROM 108 includes sequential
instructions for the operation of the microprocessor 106
and for the periodic sampling of temperature data.
Incidentally, in addition to just temperature data, other
inputs may could be ~rovided to the engine mounted
electronic unit, such as overtorque and overspeed warning
functions; and these could be converted from analog input
signals to digital signals, multiplexed with the input
temperature signals, supplied to the microprocessor, and
eventually ordered up for display by depressing push-
buttons such as the switches 48 as shown in Figure 1 and
the switches 90 and 92 in Figure 4.
Three buses which are included in Figure 5 include
the data bus 110, the address bus 112, and the control
bus 114; and data carried on the data bus 110 may be
supplied to or from the microprocessor 106, and to or
from the EEPROM 42 which is a non-volatile memory unit,
in accordance with instructions provided on the address
bus 112. The letters "EAROM" stand for "Electrically
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Alternable Programmable Read-Only Memory". The latch 116
buffers between the data and the address buses and the
memory 42 and the microprocessor 106. It may be noted
that the serial transmission line or port 118 included in
the control bus 114 is employed to direct serial output
signals to the output driver 58 which amplifies the data
which has been ordered up by depressing selected keys or
switches on the display unit, and transmits this data on
a serial basis over output lead 120. The lead 122
connects the data lead 118 to the output driver 58~ It
is to be noted that a parallel data transmission is also
feasable, but serial is more economical cabling.
It is also noted that the lead 30 connected from
the analog circuitry 104 extends in due course to the
remote warning lamp 80', pri.me, which appears as light 80
in Figure 4. This signal is actuated when the
temperature exceeds the maximum temperatures as shown in
Figure 7, to be discussed in greater detail below.
Figure 6 shows the remote circuitry which may be
either cockpit mounted, or be included in a ground
portable model which may be selectively plugged in to the
engine mounted units on the left and the right engines.
Figure 6 includes the microprocessor 124 and the display
driver 126 in addition to a fi~e-digit display 78 and the
switches 90, 92, 128 and 130. Additional switches
include the self-test switch 84 and the power on and off
switches 132 and 134.
When one of the temperature channel switches 90,
together with one of the switches 128 or 130 is selected,
the appropriate interrogation signal is supplied from
microprocessor 124 (which includes memory) over lead 136
through amplifier 138 to the interrogation lead 140 which
is connected to the interrogation input lead 142 included
in the control bus 114. The appropriate information is
then ordered up from the non-volatile memory 42 and is
transmitted in serial form over leads 118, 122, and 120
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to input lead 144 to -the microprocessor c'hip 124 in the
remote unit. The display driver 126 is then energized in
accordance with conventional and known digital data-
processing techniques to display the transmitted data on
the display 78.
Turning now to Figures 7A and 7B, this input
circuit has a thermocouple input to the terminals 146,
and a digital temperature output at the ar right-hand
side of Figure 7 at the leads 148 from the analog to the
digital converter unit 28. The circuitry includes the
thermocouple cold-junction temperature compensation
bridge 150 and the differential amplifier 152. The
output signal from th~ differential amplifier 152 is
amplified by operational amplfier 154 which provides at
its output a substantially linear voltage representing
the temperature of the turbine engine. Incidentallyt a
constant current source 156 is included in the circuitry
to control emitter current flow in differential amplifier
152. The operational amplifier 158 drives the over-
temperature alarm light 80 or 82 as shown in Figure 4.
The operational amplifier 160 couples the output from
- operational ampli~ier 154 to the analog-to-digital
converter 28. Incidentally, the levels for the
temperature alarm signal and for the input to the analog-
to-digital converter are established by the potentio-
meters 162 and 164, respectively. These may of course be
adjusted and calibrated to give the desired signal at the
proper temperature levels, and to accommodate slight
variations in thermocouple output or in the amplification
provided by the input circuitry, for example. The output
leads 148 at the right-hand side of Figure 7 are coupled
to the 10 bit data bus 46 as shown in Figure lo
Now, turning to Figure,8, this drawing indicates a
typical manufacturer's diagram of over-temperature
conditions which may be damaging to the turbine engine in
the event that they last longer than certain predeter-
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mined limits. First, it may be noted that the horizontal
axis of the plot inicates the time in seconds, and the
vertical axis of the plot is the temperature in de~rees
centigrade. The temperature scale has two different
plots, one designated T-4 and the other designated T-5.
The reason for the diEferent scales involves the
different temperatures at successive points along the
turbine engine, from T-l at the engine inlet to T-6 or
T-7 at the exhaust. The thermocouple may be located at
any of several points at or following the combustion
zone, to indicate the engine operating temperature, but
the temperatures sensed at these various points will vary
significantly, from the turbine inlet point to the
turbine inter stage temperature point, to the exhaust
zone, and the circuitry must be ad]usted to correspond to
the actual physical locations of the thermocouple along
the turbine engine.
Now, re~erring to Figure 8 in more detail, the area
indicated by the designation "Area A" in Figure 8 is a
permitted area. This means, for example, that at a T-5
temperature of 930C., just over the 925C. initial point
in the characteristic, the engine may be operated ~or 10
seconds and not be damaged or require maintenance.
However, beyond ~his time interval, when it goes into
"Area B", certain inspection steps ~hould be taken.
Similarly, for Areas C and D, successive more complete
inspections and overhaul may be required. ~ore
specifically, for Area B it is recommended that the cause
of the over-temperature be determined and corrected and
that the engine be visually inspected through the exhaust
ports of the power turbine blades and through the exhaust
duct, turning vanes where appropriate; and a record
should be made in the engine log book. For Area C, a hot
section inspection should be performed; the compressor
blades should be stretch checked without removing the
blades from the disk; and a fluorescent penetran~
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inspection should be made of the compressor turbine and
power turbine discs and blades without removing the
blades from the disks. For Area D, the engine should be
returned to an overhaul facility, the compressor turbine
blades and power turbine blades must be discarded, and
both of the turbine discs must be subjected to a stretch
check and fluorescent penetrant inspection.
Concerning the "time over limits" channels such as
3A and 4A, on each occasion when the engine temperature
goes up to an elevated level and remains there for more
than the indicated time interval, this time period beyond
the allowable time period is recorded and added to that
previously stored in the non-volatile memory. Thus, for
example, i~ an engine were allowed to remain in channel
5A for 10 seconds, and it actually remained at a
temperature above the minimal level for channel 5~ for 15
seconds, then 5 seconds would be added to the value
stored in the non-volatile memory for channel 5A.
In conclusion, it is to be understood that the
foregoing is a description of one illustrative, preferred
embodiment of the invention. Other electronic circuit
arrangements for implementing the functions described
hereinabove may be employed. By way of example, but not
of limitation, other logic chips may be employed to
implement the indicated function without departing from
the spirit and scope of the invention; a series of
thermocouples, resistance thermometers, optical
temperature sensors, or any other means for measuring
teperature, located at desired points along the turbine
engine may be used instead of the schematic indication of
a single thermocouple as shown in the drawing; and it is
to be expected that the values as set forth in Table I
and in Figure 8 will vary from one turbine engine to
another and tha-t these are merely representative of
particular engines under consideration. Also, dif-
ferences in display and switching arrangements are
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expected between cockpit mounted and portable test units,
and when one or multiple engine planes are involved, and
the arrangements of Figs. 4 and 6 show typical varia-
tions. Accordingly, the present inventiOn is not limited
to the particular system as shown in the present drawings
and as described in this specification.
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