U.S. patent number 3,779,673 [Application Number 05/249,441] was granted by the patent office on 1973-12-18 for fluid stepper motor.
This patent grant is currently assigned to The Bendix Corporation. Invention is credited to Charles J. Ahern, Walter F. Datwyler, Jr., Rex W. Presley.
United States Patent |
3,779,673 |
Ahern , et al. |
December 18, 1973 |
FLUID STEPPER MOTOR
Abstract
A stepper motor of the type in which fluidic logic cooperates
with a fluidic actuator to produce a rapid high torque positional
displacement of the actuator's output member, the fluidic logic in
response to an input command to change the position of the
actuator's output member from a first position to second position
generates a sequential set of coded signals operative to stepwise
drive the output member of the actuator in either direction until
the logic generates a coded signal corresponding to the position
commanded by the input.
Inventors: |
Ahern; Charles J. (Lathrup
Village, MI), Datwyler, Jr.; Walter F. (Royal Oak, MI),
Presley; Rex W. (Livonia, MI) |
Assignee: |
The Bendix Corporation
(Southfield, MI)
|
Family
ID: |
22943491 |
Appl.
No.: |
05/249,441 |
Filed: |
April 24, 1972 |
Current U.S.
Class: |
418/61.1;
235/201PF |
Current CPC
Class: |
F03C
2/08 (20130101) |
Current International
Class: |
F03C
2/08 (20060101); F03C 2/00 (20060101); G06m
001/12 (); F01c 001/02 (); F03c 003/00 () |
Field of
Search: |
;418/61
;235/21R,21FS,21PF |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Croyle; Carlton R.
Assistant Examiner: Vrablik; John J.
Claims
I claim:
1. A fluid stepper motor comprising:
fluid logic means including a control means for providing a
selected position input command, said fluid logic means further
including means to sequentially generate a series of position coded
signals and means responsive to said coded signals for generating a
decoded position signal, wherein said position coded signals are
sequentially generated until said means for decoding generates a
particular decoded signal predetermined by selected input command;
and
fluid actuator means including an output member, said output member
operative to assume each of a series of corresponding
predeterminable positions in response to generation of said series
of position coded signals by said fluid logic means, whereby said
output member moves sequentially through said series of
corresponding predeterminable positions to a position corresponding
to said position input command.
2. The stepper motor as claimed in claim 1 wherein said fluid
actuator means comprises:
a housing defining a fluid chamber therein;
a rotatably mounted output member;
a ring member eccentrically disposed in said fluid chamber,
drivingly engaged with said housing at one point and with the
output member at another point; and
means for orbiting said ring member in said fluid chamber, about
the axis of said output member, said means including means for
applying fluid pressure in defined regions between said ring member
and housing members, to generate fluid forces acting thereon,
whereby said orbiting of said ring member rotatably drives said
output member with relation to said housing.
3. The stepper motor as claimed in claim 2 wherein said means for
orbiting said ring member in said fluid chamber comprises:
a plurality of vanes flexibly connecting said ring member with said
housing, dividing the space between said ring member and said
housing into a plurality of isolated regions of equal angular size;
and
a plurality of apertures in said housing for conducting said fluid
signals generated by said fluidic logic to said isolated regions,
generating a fluid force on the circumference of said ring
member.
4. The stepper motor as claimed in claim 1 wherein said fluidic
logic means comprises:
clock means, operative to generate oscillating fluid signals of a
predeterminable magnitude at a predeterminable frequency and said
clock means further including means responsive to an inhibit signal
to stop generating said oscillating fluidic signals.
phase generator means responsive to the oscillating signals from
said clock means for generating a repetitious set of sequentially
phase coded signals.
code generator means responsive to the phase coded signals
generated by said phase generator means for generating a repetitive
set of sequentially position coded signals, each position coded
signal is indicative of a corresponding predeterminable position of
said output member and each sequential position coded signal is
indicative of a corresponding sequentially adjacent position of
said output member in a predeterminable direction;
decoder means responsive to said position coded signals generated
by said code generator means for generating decoded signals,
wherein each said decoded signal corresponds to an associated
position coded signal.
a step selector, responsive to said input command for said output
member to move from one position to a second position and to the
decoded signals generated by said decoder means, for generating an
inhibit signal when said decoded signal to said input command said
inhibit signal communicated to said clock means causes said clock
to stop.
5. The stepper motor as claimed in claim 4 wherein the fluidic
logic further comprises a cycle selector means operative to cause
the fluid logic to generate a complete set of coded signals in
response to an input command, said cycle selector means is a
momentary fluidic switch operative to terminate the inhibit signal
generated by the step selector for a period of time sufficient for
the code generator means to generate at least one sequential
position coded signal.
6. The stepper motor as claimed in claim 4 wherein said fluidic
logic further comprises a mode selector responsive to an input
command operative to terminate the inhibit signals generated by the
step selector causing said fluid logic to generate repetitive sets
of sequentially coded signals, said mode selector comprises a
two-position fluidic switch, responsive to an input command
operative to terminate the inhibit signal generated by the step
selector.
7. The stepper motor as claimed in claim 4 wherein said fluidic
logic further comprises a reset switch, responsive to an input
command, operative to reset said phase generator means to generate
a predeterminable phase coded signal and to reset said code
generator means to generate a predeterminable position coded
signal.
8. The stepper motor as claimed in Claim 4 wherein said clock means
comprises:
a variable frequency fluidic oscillator; and
a gateable fluidic amplifier.
9. The stepper motor as claimed in claim 8 wherein said gateable
amplifier comprises a means responsive to the oscillating fluidic
signals generated by said variable frequency oscillator for
generating a first and a second output signal, and said means
includes a second input responsive to said inhibit signal generated
by said step selector, operative to terminate the response of said
gateable amplifier to the signals generated by said variable
frequency oscillator.
10. The stepper motor as claimed in claim 8 wherein said variable
frequency fluidic oscillator comprises:
fluidic means responsive to input signals operative to generate an
output signal; and
feedback means, responsive to said output signal, operative to
communicate said output signal to the input of said fluidic means
responsive to an input signal, said feedback means delaying said
output signal communicated to said input a predeterminable period
of time.
11. The stepper motor as claimed in claim 10 wherein said feedback
means comprises:
constriction means operative to impede the output signal generated
by said fluidic means responsive to input signals;
capacitor means, for accumulating said impeded output signal,
whereby the output signal impeded by said constriction means and
accumulated by said capacitor means is delayed prior to being
communicated to the input of said means responsive to an input,
causing the output of said means to oscillate and generate said
oscillating fluidic signals.
12. The stepper motor as claimed in claim 4 wherein said phase
generator means comprises:
bistable means having a pair of stable states responsive to input
signals operative to switch from one stable state to the other and
generate output signals; and
input means, responsive to oscillating signals generated by said
clock means and the output signals generated by said bistable means
operative to generate signals, said signals communicated to said
bistable means are operative to cause said bistable means to
generate a repetitive set of sequentially phase coded signals.
13. The stepper motor as claimed in claim 12 wherein said means
responsive to the oscillating signal generated by said clock
comprises:
first means having a plurality of first means elements responsive
to said first output signal generated by said clock means,
operative to generate an output signal; and
second means having a plurality of second means elements responsive
to said second output signal generated by said clock means
operative to generate an output signal, said plurality of second
means elements is equal in number to said first means elements.
14. The stepper motor as claimed in claim 13 wherein said bistable
means comprises a plurality sequentially responsive bistable
elements equal in number to the sum of said first means elements
and said second means elements, the sequentially responsive
bistable elements are alternately associated with said first means
elements and said second means elements, and each bistable element
has at least one input for each of said bistable elements' stable
states, the output signal generated by the first bistable element
of said plurality of bistable elements is communicated to the input
of the associated first means element, the output signal generated
by the sequentially responsive bistable element is communicated to
the input of the associated said second means element and the
output signals generated by the successive sequentially responsive
bistable elements are connected alternately to the inputs of
successive alternating first means elements and second means
elements, the signal generated by said first means element
associated with the first sequentially responsive bistable element
is communicated to an input of said associated bistable element and
is further communicated to an input of the next sequentially
responsive bistable element, the output from the second means
element associated with the sequentially responsive bistable
element is communicated to the alternate input of said second
associated bistable element and one of the inputs of the next
sequentially responsive bistable element, the outputs of the
successive alternating first means elements and second means
elements are alternatively communicated in like manner to the
successively responsive bistable elements, with the output of the
last second means element communicated to the input of the last
sequentially responsive bistable element and further communicated
to the alternate input of the first sequentially responsive
bistable element forming a cyclic code generator operative to cause
the bistable elements to generate a repetitive set of sequentially
phase coded signals in response to the signals generated by said
clock means.
15. The stepper motor as claimed in claim 4 wherein said code
generator means comprises:
bistable means, responsive to input signals operative to generate
an output signal; and
input means responsive to said phase coded signals and the signals
generated by said bistable means operative to generate an output
signal, said output signal is operative to activate said bistable
means to generate said repetitive set of sequentially position
coded signals.
16. The stepper motor as claimed in claim 15 wherein said input
means further comprises:
a second input means, responsive to the phase coded signals
generated by the phase generator means and signals generated by
said bistable means, operative to generate output signals, said
signals operative to cause said code generator means to generate
sequential sets of coded signals, the sequence of said coded
signals being opposite to the sequence of coded signals generated
by said bistable means in response to the signals generated by said
first input means; and
a direction selector, having two positions, switchable from one
position to the other in response to an input command, said first
position operable to apply fluid power to said first input means
causing said code generator to generate a repetitive set of
sequentially coded signals which sequentially step in a
predeterminable direction, and said second position operable to
apply fluid power to said second input means, causing said code
generator to generate a repetitive set of coded signals which
sequentially step in the opposite direction.
17. The stepper motor as claimed in claim 16 wherein said direction
selector further comprises a third position, said third position
operative to remove fluid power from said first input means and
said second input means disabling said code generating means.
18. The stepper motor as claimed in Claim 15 wherein said bistable
means comprises a plurality of sequentially responsive bistable
elements, each of said bistable elements has a pair of mutually
exclusive stable states, switchable from one state to the other in
response to input signals, and is operative to generate a first
output signal indicative that said bistable element is in its first
stable state and a second output signal indicative that said
bistable element is in its second state and said coded signal
generated by said bistable means is a predeterminable number of
sequentially responsive bistable elements generating an output
signal indicative of the second bistable state, and the remaining
bistable elements generating an output signal indicative of the
first bistable state.
19. fluidic element operative to switch said sequentially
responsive bistable element to its second state, said signal is
also communicated to the input of a second bistable element, which
responsively precedes said associated bistable element by a number
of bistable elements equal to the number of elements in said
predeterminable number of bistable elements generating output
signals indicative of the second bistable state, said output signal
generated by said fluidic element is operative to switch said
responsively preceding bistable element to its first state, whereby
the plurality of active elements, in response to a coded signal
generated by the phase generator means and signals generated by the
associated bistable elements is operative to sequentially step the
coded signal generated by said code generator one bistable element
in the sequentially responsive direction.
20. The stepper motor as claimed in claim 19 wherein said bistable
elements are bistable fluidic flip-flops and said active fluidic
elements are fluidic NOR amplifiers.
21. The stepper motor as claimed in claim 19 wherein said fluidic
logic further comprises an interface means responsive to the
position coded signals generated by said code generator means
operative to amplify said position coded signals and communicate
said amplified position coded signals to said fluid actuator, said
interface includes means operative to buffer said code generator
from signals generated in said fluid actuator.
22. The stepper motor as claimed in claim 21 wherein said interface
comprises a plurality of fluid actuated two position three-way
valves, equal in number to said plurality of bistable elements in
said code generator, each valve in said plurality of valves is
associated with an associated bistable element in said code
generator means, said valves operative to transmit fluid power to
said fluid actuator in response to the position coded signals
generated by said code generator means.
23. The stepper motor as claimed in claim 19 wherein said decoder
comprises a plurality of decoder elements, equal in number to said
plurality of bistable elements in said code generator means, each
decoder element responsive to an output signal generated by an
associated bistable element in said code generator, and further
responsive to an output signal of a sequentially responsive
bistable element in said code generator means, operative to
generate a decoded signal indicative of the existing states of said
associated bistable element and said sequentially responsive
bistable element.
24. The stepper motor as claimed in claim 23 wherein said bistable
elements in said code generator means generate a first output
signal having a logic ONE signal indicative that said bistable
element is in said first stable state and a logic ZERO signal
indicative that said bistable element is in said second bistable
state and a second output signal having a logic ONE signal
indicative that said bistable element is in said second stable
state and a logic ZERO signal indicative that said bistable element
is in said first bistable state, and wherein said decoder elements
are fluidic OR logic amplifiers responsive to said first output
signals generated by said associated bistable elements and said
second output signals generated by said sequentially responsive
bistable elements, operative to generate a signal in response to a
logic ONE signal and terminate said signal in response to
simultaneous logic ZERO signals whereby said OR amplifiers generate
a signal when the associated bistable element and said sequentially
responsive bistable element are in the same bistable state and when
said associated bistable element is in the second bistable state
and the sequentially responsive bistable element is in the first
bistable state, and said OR amplifier is operative to terminate
said signal when the associated bistable element is in the first
bistable state and the sequentially responsive bistable element is
in the second bistable state.
25. The stepper motor as claimed in claim 23, wherein said step
selector comprises:
a selector means, having a plurality of positions, each position
communicating with an associated decoder element, said selector
means switchable from one position to another, in response to an
input command, for the actuator output member to move from a first
position to a second position, operative to transmit the decoded
signal generated by the decoder element; and
an inhibit signal generator, responsive to the signal transmitted
by said selector means, operative to generate an inhibit signal
when the signal transmitted by the selector means is terminated
indicating the code generator means has generated a coded signal
corresponding to the particular coded signal predetermined by the
selected input command.
26. The stepper motor as claimed in claim 25 wherein said selector
means is a multiposition fluidic switch including a single output
port and a plurality of input ports equal in number to the
plurality of said decoder elements in the decoder wherein each
input port is associated with an associated decoder element, said
fluidic switch operative to selectively connect said output port
with a predeterminable input port of said plurality of input ports
in response to said selected input command whereby the signal
generated by the associated decoder element of said predeterminable
input port is conducted to said output port.
27. The stepper motor as claimed in claim 25 wherein said inhibit
signal generator is a monostable fluidic amplifier responsive to
the signal generated by the decoder element associated with the
predetermined input port of said selector means operative to
generate a signal which is the inverse of the signal generated by
said decoder element, whereby the monostable amplifier responding
to the signal generated by the decoder element transmitted by the
selector means generates an inhibit signal when the code generator
generates a coded signal corresponding to the selected input
command.
28. In combination with a fluid actuator having an output member
and means operative to displace said output member to a plurality
of positions in response to a set of coded input signals wherein
each coded signal of said set of input signals is operative to
displace the output member to a predeterminable position the
improvement comprising:
clock means operative to generate alternating fluidic signals of a
predeterminable magnitude and frequency, said clock means includes
means responsive to an input signal operative to stop said clock
means from generating said alternating signals;
a phase code generator means generating a repetitious set of
sequentially phase coded signals in response to the signals
generated by said clock means;
a position code generator means generating a repetitive set of
sequentially position coded signals in response to the phase coded
signals generated by said phase generator means, each position
coded signal corresponds to a predeterminable portion of said
output member and each sequential position coded signal of said set
of sequentially position coded signals generated by said position
code generator means corresponds to a sequentially adjacent
position of the output member in a predeterminable direction;
a decoder means generating a sequential set of decoded signals in
response to the signals generated by said position code generator
means, each decoded signal of said sequential set of decoded
signals corresponds to an associated position coded signal; and
a step selector responsive to an input command to displace the
output member of the fluid actuator from a first predeterminable
position to second predeterminable position including means
responsive to the decoded signals generated by said decoder means
operative to generate a signal when the decoded signal corresponds
to the input command, said signal generated by said step selector
communicated to said clock is operative to cause said clock to
stop.
29. The combination as claimed in claim 28 wherein aid clock means
comprises:
a fluidic oscillator generating oscillating fluidic signals;
and
a monostable fluidic amplifier responsive to the oscillating
signals generated by said fluidic oscillator, operative to generate
a pair of mutually exclusive output signals, said monostable
fluidic amplifier includes input means operative to terminate
response of said monostable fluidic amplifier to the signals
generated by said fluidic oscillator.
30. The combination as claimed in Claim 28 wherein said phase
generator means comprises:
bistable amplifier means having a pair of stable states responsive
to input signal operative to switch from one stable state to the
other and generate output signals; and
phase amplifier means responsive to the signals generated by said
clock means and the signals generated by said bistable amplifier
means operative to activate said bistable amplifier means
generating a repetitive set of sequentially phase coded
signals.
31. The combination as claimed in claim 28 wherein said code
generator means comprises:
bistable means responsive to input signals operative to generate
output signals;
code amplifier means responsive to said phase coded signals and the
signals generated by said bistable means operative to activate said
code bistable means generating a repetitive set of sequentially
positioned coded signals.
32. The combination as claimed in claim 31 wherein said position
code generator means further comprises:
second code amplifier means responsive to said phase coded signals
and the signals generated by said code bistable means operative to
activate said code bistable generating a second sequential set of
position coded signals, the directional sequence of said second set
of coded signals being opposite to the sequence of the coded signal
generated by the code bistable means in response to the signals
generated by said first code amplifier means; and
a direction selector having two mutually exclusive positions,
switchable from one position to the other in response to an input
command, said first position operative to apply fluid power to said
first code amplifier means operative to cause said code generator
to generate a repetitive set of sequentially position coded signals
which sequentially step in a predtermined direction and said second
position operative to apply fluid power to said second code
amplifier means operative to cause said code generator to generate
a repetitive set of sequentially position coded signals which
sequentially step in the opposite direction.
33. The combination as claimed in claim 32 wherein the improvement
further comprises an interface means, responsive to the position
coded signals generated by said code generator means operative to
amplify said position coded signals and communicate said amplified
position coded signals to said fluid actuator said interface
further includes means to buffer said code generator means from
said fluid actuator.
34. The combination as claimed in claim 28 wherein said decoder
comprises a plurality of decoder amplifiers responsive to the order
of the position coded signals generated by said position code
generator means operative to operate a set of sequentially decoded
signals corresponding to the position coded signal generated by
said position code generator means.
35. The combination as claimed in claim 28 wherein said step
selector means comprises:
a selector means having a plurality of positions, each position
corresponding to a predeterminable position of said output member,
said selector means switchable from a first position to a second
position by an input command for said output member of the fluid
actuator to be displaced from a first predeterminable position to a
second predeterminable position, said selector means transmitting
said decoded signal corresponding to a predeterminable position
coded signal generated by the said decoder; and
an inhibit signal generating means responsive to the signal
transmitted by said selector means generating a signal when said
predeterminable decoded signal transmitted by the said selector
means indicates the code generator means has generated a coded
signal corresponding to said second predetermined position, said
signal generated by said inhibit signal generating means operative
to stop said clock means.
36. The combination according to claim 28 wherein the fluid logic
further comprises:
a cycle selector means operative to cause the fluid logic to
generate one complete set of position coded signals in response to
an input command;
a mode selector means responsive to an input command operative to
termiante said inhibit signals generated by said step selector
causing said fluid logic to generate repetitive sets of
sequentially position coded signals; and
a reset means operative to cause said fluidic logic to generate a
position coded signal corresponding to a predeterminable position
of said output member.
Description
BACKGROUND OF THE INVENTION
The use of stepping motors in positioning control systems is well
known in the prior art. The bulk of the prior art uses
electro-mechanical position control systems with electrically
driven stepper motors. However, various types of fluid stepping
motors have been developed in the past to perform specific
functions. One type of fluidic stepping motor converts the
substantially constant rotary output motion of a fluid motor into
intermittent rotary output motion by means of fluidic actuated
pawls engaging a ratchet wheel attached to the output member of the
fluid motor. This type of fluidic stepping motor is described in
U.S. Pat. No. 3,616,979. Another type of fluidic stepping motor is
discussed in U.S. Pat. No. 2,978,889 in which a number of fluid
driven pistons sequentially drive a ratchet wheel. The pistons are
systematically actuated so that the output member attached to the
ratchet wheel driven through a precise angle. Another type of fluid
operated stepper motor is described in U.S. Pat. No. 3,411,413 in
which a vane in a closed chamber is caused to step from one
position to another by applying fluidic pressure to one side of the
vane and venting the other side. The vane rotates to the desired
position where the pressure on both sides of the vane are
equalized. Another type of system is illustrated by the fluidic
numerical communicator described in U.S. Pat. No. 3,561,676. The
system incorporates a fluid driven rotatable member having a face
with a plurality of coded slots which when sensed provide a coded
fluidic signal indicative of the position of the rotating member.
These coded signals from the sensors are communicated to a
comparator which compares these coded signals with the input
command and generates a signal when the coded signal and the
command are identical. The generated signal activates a pawl which
stops the rotating member in the desired position. This device is
capable of translating the given input signal into a
predeterminable mechanical position. A more sophisticated type of
positioning control system is illustrated in U.S. Pat. No.
3,606,817. The positioning control system compares the actual
position of the mechanically driven device with the input command
and drives the device to the position indicated by the input
command. The position of the driven device is determined by a set
of transducers which produce a coded signal indicative of the
existing position of the driven device. This signal is compared
with the input command in a comparator which generates a signal to
drive a fluidic motor until the output position agrees with the
input command.
For the most part, the stepper motors found in the prior art
require sensors to determine the position of the output member and
are not capable of producing high output torques. This inability to
generate high output torques is also found in the
electro-mechanical stepper motors wherein the stepper motors are
electrically activated. The object of this invention is to provide
a stepper motor which overcomes many of the problems of the prior
art devices. This motor is capable of producing a high output
torque with accurate positional displacements and can be applied to
machine tools for accurate and rapid positioning of the workpiece
without employing feedback sensors. Beside positioning
applications, this stepper motor finds use in indexing, counting,
cutting, and many other standard control needs. The use of fluidic
logic provides for easy interfacing with fully automatic
systems.
SUMMARY OF THE INVENTION
The invention is a fluid actuator driven by fluidic logic to form a
stepper motor with a high output torque and accurate positional
displacements. The fluidic logic generates a sequential set of
coded signals which drive the output members of the fluid actuator
in sequential steps of equal magnitude in a predeterminable
direction. Each coded signal generated by the fluidic logic
corresponds to a predeterminable position of the output member of
the fluidic actuator, and each sequential coded signal corresponds
to the sequential position of the output member. In addition to
generating the sequential sets of coded signal, the logic generates
a decoded signal which corresponds to both the generated coded
signal and the position of the output member of the fluid actuator.
This decoded signal is used in conjunction with a step selector to
cause the stepper motor to sequentially step to a desired step or
position, in response to an input command to the step selector. The
fluid actuator is of the rotary type in which a ring element is
orbited within a stationary reaction chamber about an output
member. The ring element is orbited by a force vector generated by
the fluidic signals received from the fluidic logic. This force
vector is indexed about the circumference of the ring element in
equal angular increments by the sequential set of fluidic signals
generated by the fluidic logic. The orbiting member drives the
output member through angular increments proportional to the
angular displacement of the orbiting member.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing the basic elements of the stepper
motor.
FIG. 2 is a sectional side view of the fluid actuator.
FIG. 3 is a sectional front view of the fluid actuator.
FIG. 4 is an enlarged view of a section of FIG. 3.
FIG. 5 is a fluidic schematic showing the details of a preferred
embodiment of the fluidic clock.
FIG. 6 is a fluidic schematic showing the details of a preferred
embodiment of the phase generator.
FIG. 7 is the symbol for a fluidic bistable flip flop element.
FIG. 8 is a table giving the sequence of coded signals generated by
the phase generator, at the output terminals A, B and C.
FIG. 9 is a fluidic schematic showing the details of a preferred
embodiment of the code generator, decoder and the step selector
switch.
FIG. 10 is a table illustrating the sequence of the 9 sets of coded
signals generated by the code generator at the output terminals
V.sub.1 through V.sub.9.
FIG. 11 is a fluidic schematic showing the details of a preferred
embodiment of the interface and the fluid actuator.
FIG. 12 is a fluidic schematic showing the details of a preferred
embodiment of the step selector and inverter amplifier.
FIG. 13 is a fluidic diagram of the direction selector.
FIG. 14 is a fluidic diagram of the reset switch.
The essential elements of the stepper motor are shown in the block
diagram of FIG. 1 in which the Stepper Motor 10 consists of Fluidic
Logic 11 generating a repetitive set of sequentially coded signals
which drive the Output Member 13 of a Fluidic Actuator 12 in a
stepwise manner to a predeterminable position. The functional
operation of the Stepper Motor 10 is controlled by input commands
to the Fluidic Logic 11. The embodiment illustrated in FIG. 1 shows
a stepper motor provided with six inputs to the Fluidic Logic 11
which may be manual inputs from a human operator or may be
programmed inputs from a control device not shown. The Step
Selector 14 is a position control corresponding to the desired
position of the Output Member 13 of the Fluidic Actuator 12.
Movement of the Step Selector to a desired position causes the
Fluidic Logic 11 to generate sequential sets of coded signals which
drive the fluid actuator Output Member 13 to the selected position.
When the set of signals generated by the Fluid Logic corresponds to
the selected position, an inhibit signal is generated which stops
the Fluid Logic from generating the next sequential set of signals.
Activation of the Cycle Selector 15 directs the Fluidic Logic 11 to
generate one complete cycle of sequentially coded signals. The
response of the Fluidic Actuator 12 to one complete cycle of coded
signals may correspond to one full revolution of the Output Member
13, or may be some multiple or submultiple thereof as will be
discussed later with reference to the Fluidic Actuator 12. The Mode
Selector 16 has two positions, the "run" position which terminates
the response of the Fluidic Logic 11 to the inhibit signal of the
Step Selector 14, and the "step" position in which the operation of
the fluidic logic is controlled by the signal from the Step
Selector 14. The Direction Selector 17 is illustrated as having
three input positions, the "Hold" position prevents the operation
of the Fluidic Logic 11 irrespective of the input commands to the
Step Selector 14, Cycle Selector 15 or Mode Selector 16; the
"Clockwise" (CW) position operative to cause the Fluidic Logic 11
to generate a repetitive set of sequentially coded signals which
drive the Output Member 13 of the Fluidic Actuator 12 in one
direction; and the "Counter Clockwise" (CCW) position operative to
drive the Output Member 13 in the opposite direction. The Rate
Control 18 controls the frequency or rate at which the sequential
coded signals are generated by the fluid logic.
The Clock 19 is a variable frequency fluidic oscillator which
generates a mirrored pair of output signals. The frequency of the
output signals generated by the clock is controlled by the Rate
Control 18. The "on-off" function of the clock is controlled by the
inhibit signal generated by the Position Selector 14. The receipt
of an inhibit signal will cause the clock to stop.
The phase Generator 20 responds to the signals from the Clock 19
and generates a repetitive set of sequential phase coded signals.
The Code Generator 21 responds to the phase coded signals generated
by Phase Generator 20 and generates a repetitive set of sequential
position coded signals corresponding to the signals required by the
Fluidic Actuator 12 to drive the Output Member 13 to a
predeterminable position. The output signals of the Code Generator
21 are sequentially coded so that the successive sets of coded
signals correspond to the signals required to move Output Member 13
of the actuator one step at a time in the desired direction. Each
successive signal drives the Output Member 13 one more step in the
desired direction.
The Code Generator 21 is also controlled by the signals from the
Direction Selector 17. A "clockwise" signal generated by the
Direction Selector 17 causes the Code Generator 21 to generate a
set of signals which will sequentially step the output of the
actuator in one direction, a counter clockwise signal received from
the Direction Selector 17 will cause the code generator to generate
a set of signals which will sequentially step the output of the
actuator in the opposite direction.
The Interface 22 amplifies the position coded signals generated by
the Code Generator 21 and transmits the amplified signals to the
Fluidic Actuator 12 increasing the fluidic power driving the
actuator. The position coded signals from the Code Generator 21 are
also communicated to the Decoder 23 which generates a decoded
signal corresponding to the position coded signals being
transmitted to the fluid actuator. The decoded signal is
transmitted to the Step Selector 14 which responds to the selected
decoded signal and generates an inhibit signal when the decoded
signal is indicative of the position selected by the input command.
The Position Indicator 24 also responds to the signals generated by
the code generator and generates a visual indication of the
position of the actuator output as represented by the coded
signals.
The Reset 25 is an auxiliary control which resets the Phase
Generator 20 and the Code Generator 21 so that their outputs are
predeterminable coded signals. These predeterminable coded signals
may correspond to the first signal of the repetitive set of coded
signals generated by the respective generators or may be signals
which correspond to any other predeterminable position of the
Actuator Output Member 13.
The Fluid Actuator 12 is illustrated in FIGS. 2 and 3 as a rotary
actuator of the type in which a ring member is orbited within a
stationary reaction member and about an output member. The ring
member is driven to orbit the output member by the force vector
generated by the set of fluidic signals received from the Fluidic
Logic 11. The force vector is indexed about the circumference of
the ring member by the sequential signals from the fluidic logic
causing the ring member to orbit the output member causing the
output member to rotate. The Fluid Actuator 12 has a Housing 26
with an Integral Stationary Gear 27 forming a Chamber 28 within the
Housing 26. A ring member shown as a Ring Gear 29 and an output
member shown as the Output Gear 30 are internally contained within
the Chamber 28 by the Front Plate 31 and Rear Plate 32 of the
Housing 26. The Output Member 13 of the Fluidic Actuator 12 is
shaft eccentrically attached to the Output Gear 30. The Output
Member 13 is rotatably attached to the Front Plate 31 and Rear
Plate 32 of the Housing 26 by Bearing Means 33 and 34 secured
respectively to the Front Plate 31 and Rear Plate 32 so that the
rotational axis of the Output Member 13 is concentric with the
Chamber 28. The Ring Gear 29 has an external set of Teeth 35 equal
in number to the number of teeth on the Stationary Gear 27 and are
configured to mate therewith. The effective external diameter of
the Ring Gear 29 is less than the effective diameter of the
Stationary Gear 27 so that the Ring Gear is free to move laterally
or orbit inside the stationary gear, but not rotate within the
Chamber 28. The Ring Gear 29 also has an internal set of Teeth 36
configured to mate with the teeth of the Output Gear 30. This type
of fluidic actuator is sufficiently known in the art, that a
detailed description of its operation is not required. It is
sufficient to state that the orbiting of the ring gear within the
confines of the stationary gear will cause the output gear to
rotate in a direction opposite to the orbital rotation of the ring
gear at a rate which is proportional to the difference in the
number of mating teeth on the Output Gear 30 and the Ring Gear 29.
The Displacement Chamber 37 between the Stationary Gear 27 and the
Ring Gear 29 is subdivided isolated Compartments 38 by Vanes 39 as
shown in the enlarged section of the fluid actuator illustrated in
FIG. 4. Each Compartment 38 is capable of being individually
pressurized through an associated Inlet 40 through the Rear Plate
32 of the Housing 26. The Ring Gear 29 has Fluid Passages 41 which
communicate between the individual Inlets 40 and the associated
Compartment 38. Pressurizing a set of adjacent compartments will
generate a force vector operative to move the ring gear in a radial
direction away from the pressurized compartments. This force vector
may be caused to rotate by pressurizing an adjacent compartment at
one end of the set of pressurized compartments and venting to air
the last pressurized compartment at the opposite end of the
pressurized set. The adding of one pressurized compartment while
venting another at the opposite end of the previous pressurized set
causes the force vector to rotate through an angle equal to the
angular size of each compartment. Rotation of the force vector also
causes the ring gear to orbit through an equal angle.
The embodiment illustrated in FIG. 3 has the displacement chamber
divided into 9 compartments of equal angular size, however, the
number of compartments in equally operative devices may be more or
less. Referring to the illustrated 9 compartment fluidic actuator,
a high force vector is generated when 4 adjacent compartments are
pressurized and the remaining 5 are vented to air. This force
vector can be rotated through one revolution in nine equal steps by
pressuring an adjacent chamber and venting the one at the opposite
end of the pressurized set as discussed above. This sequence
establishes the code shown in FIG. 10 which lists the chambers
which are to be pressurized for a desired position of the Ring Gear
27. It is recognized that other codes can be generated which will
produce operative force vectors.
The fluidic logic is operative to generate the illustrated code in
the sequence shown so that the Output Member 13 of the fluid
actuator will rotate through a precise angle for each sequential
coded signal generated by the fluid logic.
The speed or the frequency at which the coded signals are generated
by the fluidic logic is controlled by the fluidic clock. The output
signal of an active Fluidic Amplifier 51 illustrated as an OR/NOR
amplifier in FIG. 5 is fed back to one of the inputs of the
amplifier by means of the Constriction 52 and the Fluidic Capacitor
53. The Constriction 52 and Capacitor 53 cooperate to delay the
signal generated at the output of the Fluidic Amplifier 51 before
it is capable of activating the input and terminating the output
signal. This closed fluidic loop oscillates at a predeterminable
frequency controlled by the fluidic properties of the Fluidic
Amplifier 51, the Constriction 52 and the Fluidic Capacitor 53. The
OR output signal from the amplifier is transmitted to an input of a
second Fluidic Amplifier 54, also illustrated as an OR/NOR fluidic
amplifier where this signal is amplifieed producing alternating OR
and NOR signals. An inhibit signal generated by the Step Selector
14, communicated to the alternate gate of the Amplifier 54, will
lock Amplifier 54 in the OR signal generating state and termiante
the response of this amplifier to the signals generated by
Amplifier 51.
The frequency of the oscillator comprising Amplifier 51,
Constriction 52, and Capacitor 53 may be made variable by providing
a bias signal at the input gate of Amplifier 51. This bias signal
is controlled by Valve 55 bleeding a measured quantity of fluid
from the Pressure Source 50 to the input of the Amplifier 51
establishing a bias pressure at the input gate. Increasing the bias
signal reduces the feedback signal required to make the amplifier
switch states, therefore, the Amplifier 51 will oscillate at a
faster rate. Decreasing the bias signal increases the signal
required to make the amplifier switch states and causes the
amplifier to oscillate at a slower rate.
The OR and NOR signals from Amplifier 54 are transmitted to the
Phase Generator 20 illustrated in FIG. 6. The illustrated
embodiment of the phase generator comprises six fluidic amplifiers
designated as 61 through 66 and six bistable fluidic elements
designated as 71 through 76, in a cyclic feedback arrangement to
form a repetitive shift register. The illustrated embodiment uses
NOR fluidic amplifier and bistable fluidic amplifiers, however, it
is recognized that other types of active fluidic elements may be
used to perform comparable functions. A typical bistable element
illustrated in FIG. 7 has a set gate C.sub.1, a clear gate C.sub.2,
and a reset gate R. It also has a set output 01 and clear output
02. A fluid signal at the set gate C.sub.1, causes the bistable
element to generate a signal at the set output 01, and terminates a
signal at the clear output 02. A signal at the clear gate C.sub.2
causes the bistable element to change state generating a signal at
the clear output 02 and terminating the signal at the set output
01. A reset R input places the bistable element in either the set
or clear state according to whether reset is operable to function
as a set or clear input gate.
In operation, the OR signal from the Clock 19 is transmitted to the
Amplifiers 61, 63 and 65, and the NOR signals are transmitted to
Amplifiers 62, 64 and 66. The output signal of Amplifier 61 is
transmitted to the set gate of Bistable Element 72 and the clear
gate of Bistable Element 71. The clear output of Bistable Element
71 is transmitted back to the alternate input gate of Amplifier 61.
In a similar manner the output of Amplifier 62 is transmitted to
the set gate of Bistable Element 73 and the clear gate of Bistable
Element 72 and the clear output of Bistable Element 72 is
transmitted to the alternate input gate of Amplifier 62. The
remaining amplifier and bistable elements are connected in a like
manner, with the output of Amplifier 66 transmitting signals to the
clear gate of Bistable Element 76 and the set gate of Bistable
Element 71 making the fluidic circuit cyclic so that the output
signals will be repetitive.
The states of the Bistable Elements 71 through 76 may initially set
by a reset signal from the Reset Control 25 so that the clear
outputs from all the bistable elements are in the ONE state except
the clear output of Bistable Element 71 which is in the ZERO state.
In this description, the ONE state represents a positive fluidic
signal and the ZERO state represents a signal of lesser amplitude
or no fluidic signal. The feedback signals from the bistable
elements to the inputs of their associated amplifiers are then ONE
for all amplifiers except Amplifier 61 which has a ZERO signal
feedback signal. The Clock 19 is normally stopped by an inhibit
signal from either the Direction Selector 17 or the Step Selector
14, therefore, the OR signals transmitted from the clock to
Amplifiers 61, 63 and 65 are ONE's and the NOR signal communicated
to Amplifiers 62, 64 and 66 are ZERO's. The clock signals in the
inhibited state do not cause any changes in the reset state of the
phase generator. The first clock signal inverts the signals to the
amplifiers so that Amplifiers 61, 63 and 65 now receive ZERO
signals, and Amplifiers 62, 64 and 66 now receive ONE signals.
Amplifier 61 is the only amplifier which has ZERO inputs at both of
its input gates and therefore the only amplifier which will
generate an output signal. The output signal of Amplifier 61 is
communicated to the clear gate of Bistable Element 71 and the set
gate of Bistable Element 72. Bistable Element 71 clears and feeds
back a ONE signal to the input gate of Amplifier 61. Bistable
Element 72 sets and transmits a ZERO signal to terminal designated
A and also feeds back a ZERO signal to the input of Amplifier 62.
The states of the remaining elements of the phase generator remain
unchanged. The next signal from the clock is inverted again, and
transmits ONE signals to Amplifiers 61, 63 and 65 which do not
cause these amplifiers to produce an output signal and ZERO signals
to Amplifiers 62, 64 and 66. Amplifier 62 is now capable of
generating an output signal because it has ZERO signals at both
inputs. The output signal of Amplifier 62 clears Bistable Element
72 which feeds back a ONE signal to the input of Amplifier 62 and
restores A to a ONE and sets Bistable Element 73 which feeds back a
ZERO signal to the input of Amplifier 63. The next signal from the
clock in a similar manner causes Amplifier 63 to generate an output
signal which clears Bistable Element 73 feeding back a ONE signal
to Amplifier 63 and sets Bistable Element 74 generating a ZERO
signal at Terminal B of the phase generator and also feeds back a
ZERO signal to the input of Amplifier 64. One skilled in the art
will readily see that for subsequent signals from the clock, the
ZERO output signal will shift to the next successive bistable
element. The output signal of the phase generator is taken from the
clear outputs of Bistable Elements 72, 74 and 76 designated as A, B
and C. The output signals generated by each successive clock cycle
is given in the code table of FIG. 8.
The coded output signals from the Phase Generator 20 are
transmitted to the Code Generator 21 illustrated in FIG. 9. The
illustrated embodiment of the code generator comprises nine (9) NOR
fluidic amplifiers designated as 101 through 109, for generating a
counter clockwise code, nine (9) NOR fluidic amplifiers designated
as 111 through 119 for generating a clockwise code and nine (9)
bistable fluidic elements designated as 121 through 129 cooperating
with both sets of fluidic amplifiers to produce the desired
sequential code. The Direction Selector 17 applies fluidic power to
one or the other set of amplifiers, rendering the alternate set
inoperative.
The coded output signal of the Code Generator 21 is generated at
the set output of the bistable elements designated as V.sub.1
through V.sub.9. Each bistable element has a reset input which upon
a reset command establishes the output code shown as Line 1 on the
Code Table illustrated in FIG. 10. The reset position is
illustrated as Position 1, however, it may be any other position
that has a more meaningful function when the stepper motor is used
in combination with another device.
In operation, the coded output signals from the phase generator are
transmitted to both sets of NOR Amplifiers 101 through 109 and 111
through 119 as illustrated in FIG. 9. The output signal designated
A from the Bistable Element 72 in the Phase Generator 20 is
transmitted to input of Amplifiers 101, 104 and 107 in the set of
amplifiers generating a counter clockwise sequential set of signals
and the inputs of Elements 111, 114 and 117 in the set of
amplifiers generating a clockwise sequential set of signals. In a
similar manner, the output signals designated as B and C from the
Bistable Elements 74 and 76 of the phase generator are transmitted
to the remaining amplifiers as shown. The amplifiers also receive a
feedback signal from the set output of their associated bistable
element. Bistable Element 121 feeds back a set signal to the
alternate inputs of Amplifiers 101 and 111, Bistable Element 122
feeds back a set signal to Amplifiers 102 and 112 respectively, and
so forth. In the reset state or Position 1, the clear outputs of
Bistable Elements 121 through 124 are ONE and the set outputs are
ZERO. As before, a ONE output is indicative of a fluidic signal and
a ZERO output is indicative of a lesser amplitude or the absence of
a fluidic signal. In the remainder of the bistable elements, the
set outputs are ONE and the clear outputs are ZERO. The feedback
signals to Amplifiers 101, 111, 102, 112, 103, 113, 104, and 114
are ZERO's and the feedback signals to the remainder amplifiers are
ONE's. In the following discussion, it is assumed that the
Direction Selector 17 is in the counter clockwise (CCW) position
and the fluidic power is applied only to the Amplifiers 101 through
109, therefore, Amplifiers 111 through 119 are inoperative and have
no effect on the state of the bistable elements.
Consider the generation of a coded signal by the Phase Generator
20, transmitting ZERO signals to Amplifiers 101, 104 and 109 and
ONE signals to the remainder of the amplifiers. The ONE signals
make the remainder of the amplifiers nonresponsive to the signals
at the alternate input gate. Of these three amplifiers receiving
ZERO signals from the code generator, only Amplifiers 101 and 104
have ZERO feedback signals from their associated bistable elements
and are the only amplifiers which generate output signals. The
output signal from Amplifier 101 is transmitted to the clear gate
of Bistable Element 122, generating a ONE signal at V.sub.2. The
output signal is also transmitted to the set gate of Bistable
Element 127 generating a ZERO signal at V.sub.7. The output of
Amplifier 101 therefore does not change the state of the output
signals of the Bistable Elements 122 or 127. The output signal from
Amplifier 104 is transmitted to the clear gate of Bistable
Amplifier 125 producing a ONE signal at V.sub.5 and is also
transmitted to the set gate of Amplifier 121 causing it to generate
a ZERO signal at V.sub.1. The remaining bistable elements receive
ZERO signals at both the set and clear gates, so they do not change
state. The ZERO A signal from the phase generator has therefore
caused the ONE signal at V.sub.1 to be terminated and caused a ONE
signal to be generated at V.sub.5 shifting the ONE signals of the
code, one step to the right shown as Position 2 in the Code Table,
FIG. 10. The next signal generated by the Phase Generator 20 is one
which transmits a ZERO B signal to Amplifiers 102, 105 and 108. Of
these amplifiers, Amplifiers 102 and 105 have ZERO feedback signals
and will generate output signals. These output signals are
transmitted to the clear gates of the Bistable Elements 123 and 126
and to the set gate of Elements 128 and 122 generating ZERO signals
at V.sub.2 and V.sub.8 and a ONE signal at V.sub.3 and V.sub.6. In
like manner, the C signal produces ONE signals at output of
Amplifiers 103 and 106 which clears Bistable Elements 124 and 127
and sets Bistable Elements 129 and 123 generating a ZERO signal at
V.sub.9 and V.sub.3 and a ONE signal at V.sub.4 and V.sub.7. The
coded signals from the phase generator repeat starting with a ZERO
A again causing the ONE output signals to step progressively to the
right as shown on the Code Table illustrated in FIG. 10. The
fluidic circuits of the code generator are cyclic, therefore, the 9
sequential sets of coded signals are repetitive starting over with
the first set after the generation of the 9th or last set. One
skilled in the art will quickly recognize that if the counter
clockwise set of Amplifiers 101 through 109 are de-energized and
fluid power is applied to the clockwise Amplifiers 111 through 119,
the sequence of the coded signals generated by the Code Generator
21 will be reversed, and the set of ONE's shown on the table of
FIG. 5 will step to the left with each successive input signal from
the phase generator.
Referring to FIG. 9, the coded signals from the respective set
outputs of the bistable elements in the Code Generator 21 are
designated as D1 through D9. The coded output signals D1 through D9
are transmitted to the Interface 22 which comprises nine (9) fluid
actuated relay valves 131 through 139 as illustrated in FIG. 11.
The relay valves are two position, three way valves controlling the
power input to the Fluid Actuator 12 from a Fluid Power Source 140.
The valves are normally open communicating fluid power from the
Source 140 to the Input Ports 40 of the Fluid Actuator 12. A
fluidic signal from the Code Generator 21 closes the valve and
vents the output side of the valve to air. The use of fluid
actuated valves in the interface buffers the code generator from
extraneous signals generated in the fluid actuator, so that these
extraneous signals cannot affect the signals generated in the code
generator. The illustrated embodiment shows four (4) valves, 131,
132, 133 and 134 in the unactuated state conducting fluid power to
the four adjacent chambers of the fluid actuator indicative of
Position 1 on the Code Table of FIG. 10. The activated Valves 135
through 139 are venting the five remaining chambers of the actuator
to air. One versed in the art will recognize that the illustrated
embodiment represents one way to amplify the coded output signal
from the code generator, and that other fluidic elements such as
fluidic amplifiers or other types of relay valves will function
equally well as an interface between the Code Generator 21 and the
Fluid Actuator 12.
The signals from the Code Generator 21 are also communicated to the
Decoder 23 as shown in FIG. 9. The Decoder 23 is illustrated as a
series of Fluidic Amplifiers 151 through 159 which function as OR
gates receiving signals from the set outputs of the associated
bistable element and the clear output of the preceding bistable
element. The amplifiers generate a ZERO output signal only when it
receives a ZERO or no signal from both the associated and preceding
bistable elements. This condition exists when the set output of the
preceding bistable element is a ZERO and the set output of the
associated bistable element is ONE and corresponds to the beginning
of each series of ONE's in the code illustrated in FIG. 10. The
singular ZERO outut signal from the OR amplifiers steps in the same
sequential pattern as the coded signals. Therefore, the OR
amplifier generating a ZERO signal in response to the signals
received from the bistable elements of the code generator
corresponds to the coded signal being generated by the code
generator.
The signals from the Decoder 23 are transmitted to the Step
Selector 14, illustrated in FIG. 9 as a 9 position fluid switch.
The function of the switch is to transmit the signal being
transmitted to the selected position of the switch to the Inverter
Amplifier 161 of FIG. 12 which inverts the signal and transmits the
inverted signal to the Clock 19. When the signal generated by the
Code Generator 21 does not correspond to the position selected on
the switch, the signal transmitted to the selected position from
the Decoder 23 is a ONE which is inverted by Amplifier 161 to a
ZERO signal. The ZERO signal communicated to the Clock 19 has no
effect on the operation of the clock and the clock runs. A ZERO
signal, generated by the decoder and transmitted to the selected
position of the Step Selector 14, is inverted by the inverter
amplifier and becomes a ONE signal. The ONE signal communicated to
the Clock 19 stops the clock.
The inverter amplifier illustrated in FIG. 12 as a Fluidic
Amplifier 161 functions as follows. Fluid power is supplied to
Amplifier 161 from a Fluid Power Source 162 through a two way
Switch 163 and a normally closed Momentary Switch 164. The control
signal from the Step Selector Switch 14 is communicated to the
control gate of the amplifier. The output from the Amplifier 161 is
a ZERO when the amplifier receives a ONE signal from the Position
Selector 14 switching the signal to the OR output, or when either
the Momentary Switch 164 or the Two Position Switch 163 are opened
terminating fluid power to the amplifier. The output signal of the
Amplifier 161 is ONE when the Momentary Switch 164 and Two Way
Switch 163 are closed and the signal from the Step Selector 14 is a
ZERO. The ONE output signal generated by the inverter amplifier is
the inhibit signal which stops the clock.
The normally closed Momentary Switch 164 and the Two-Position
Switch 163 are respectively the Cycle Selector 15 and the Mode
Selector 16 illustrated in the block diagram FIG. 1. In normal
operation, Switches 163 and 164 are closed applying power to the
Amplifier 161. When the signal from the Step Selector 14 is a ZERO
indicating the coded signal generated by the code generator
corresponds to the selected position of the Step Selector 14 the
output signal from the Amplifier 161 is a ONE. Movement of the step
selector to an alternate position causes the signal transmitted by
the step selector to change from a ZERO to a ONE. This terminates
the ONE output from the amplifier and terminates the inhibit signal
to the Clock 19 and the clock starts. The clock signals activate
the fluidic logic which generates sequential sets of coded signals
until the coded signal generated by the Code Generator 21 again
corresponds to the new position of the Step Selector 14.
Depressing the Momentary Switch 164 terminates the power to
Amplifier 161 causing it to generate a ZERO signal which starts the
Clock 19. The duration of the ZERO signal is sufficient to cause
the clock to oscillate at least one complete cycle which is
sufficient to permit the Code Generator 21 to generate the next
sequential coded signal. This removes the ZERO signal from the Step
Selector 14 and causes the output of the inverter amplifier to be a
ZERO until a complete set of coded signals has been generated by
the code generator, and the code generator again generates a signal
indicative of the selected position on the step selector. Before
the code generator generates a complete set of signals, the
momentary switch recloses applying power to the amplifier, so that
when the signal transmitted by the Step Selector 14 becomes ZERO
again, the amplifier will generate an inhibit signal. Activating
the Momentary Switch 164 causes the code generator to generate a
set of coded signals equivalent to one revolution of the ring gear
in the Fluid Actuator 12.
Activating the two-position Switch 163 to the open position removes
the fluid power from the Amplifier 161, causing the amplifier to
generate a continuous ZERO signal. The Clock 19 runs free in the
absence of an inhibit signal and the fluid logic continues to
generate repetitive sequential sets of coded signals as long as the
Switch 163 is in the open position. Closing Switch 163 reapplies
the fluid power to Amplifier 161 which will generate an inhibit
signal when the coded signal generated by the code generator
corresponds to the position selected on the Step Selector 14. The
ZERO signal transmitted by the step selector will again cause the
amplifier to generate an inhibit signal and stop the Clock 19.
The output signals from the code generator are also communicated to
the Position Indicator 24. The position indicator may be any type
of fluidic device giving a visual indication in response to an
input fluidic signal, such as the Bendix Piston Circuit Monitor
described in Brochure SL-247 or the Numerical Communicator
described in U.S. Pat. No. 3,561,676.
The Direction Selector 17 is illustrated as a three-position Switch
165 in FIG. 13. Power is transmitted to the Switch 165 from a Fluid
Power Source 166. The switch in the "CW" (clockwise) position
directs this power to Amplifiers 111 through 119 in the Code
Generator 21. Likewise, it directs the power to Amplifiers 101
through 109 in the code generator when the switch is in the "CCW"
(counter clockwise) position. In the central or "Hold" position, as
illustrated in FIG. 13, the power is terminated to both sets of
amplifiers and disables the Code Generator 21.
The Reset 25 is illustrated in FIG. 14 as a normally open Momentary
Switch 167 which when activated transmits a fluidic signal from a
Fluid Power Source 168 to the reset gates of Bistable Elements 71
through 76 in the Phase Generator 20 and the Bistable Elements 121
through 129 in the Code Generator 21. The reset signals are applied
to the terminals designated R on the respective bistable
elements.
While a specific embodiment has been described, the invention is
not to be so limited and many variations are, of course, possible
within the scope of the present invention.
* * * * *