US3494371A - Fluidic phase monitor - Google Patents

Description

, `1970l l G. A.- THIRY FLUIDIC I VHASE MONITOR Feb. 10

2 Sheets-Sheet 1 Filed Nov. 24. r 196'? Feb. l0, 1970 G. A. THIRY FLUIDIC PHASE MON ITOR 2 sheds-sheet 2 Filed Nov. 24. 1967 INVENTOR.

@Y f il United States Patent O 3,494,371 FLUIDIC PHASE MGNITOR Geza A. Thiry, Lakewood, Ohio, assignor to Houdaille Industries, Inc., a corporation of Michigan Filed Nov. 24, 1967, Ser. No. 685,627 Int. Cl. FlSc 3/00; 606m 1/12; G06d 1/04 U.S. Cl. 137-815 8 Claims ABSTRACT 0F THE DISCLOSURE A fluidic switch applies bias to a fluidic diode to contain the charge of a iluidic capacitor, or of elements having capacitance. At a preset charge value, the bias of the diode is removed until discharge occurs. After substantial discharge, bias is automatically reestablished.

Such charge-value-responsive removal of bias may correspond to a timing-out operation indicating malfunction of a monitored element intended to have a higher operating frequency than the characteristic frequency of the charge-discharge cycle of a capacitor which is continuously fed from a pressure source. The recycling of the monitored element provides an alternative bias control that must repeatedly cause removal of the bias prior to attainment of the pre-set charge value in order to avoid a malfunction indication.

This invention relates to means for discharging a iluidic capacitor, or elements having iluidic capacitance, and to iluidic means for applying and removing diode bias and to a fluidic timer that may utilize the characteristic period of a charge-discharge cycle of a fluidic capacitor, or of elements having capacitance.

According to one application of the invention, a fluidic capacitor, or elements having capacitance, may be continuously charged from a pressure source and periodically both discharged and reset for charge at a characteristically regular frequency that may be adjusted by varying the rate of charge. The system can be employed so that such resetting corresponds to a timing-out operation indicating malfunction of a monitored element intended to have a higher frequency of operation than the characteristic charge-discharge frequency to which the capacitor is adjusted and that operates as an alternative resetting means.

An object of the invention is to provide, in a fluidic system, capacitor means and a uidic diode biased to contain the charge of the capacitor means together with means responsive to charging of the capacitor means to a pre-set value for removing the bias of the diode until the capacitor means discharges substantially, and for thereupon reestablishing the bias'.

Another object of the invention is the provision of a iluidic phase monitor for making a time comparison between the frequency of a standard charge-discharge cycle and the frequency of operation of a monitored element.

It will be understood that, as used herein, capacitor means includes either a capacitor, as such, or parts of fluidic system having the property of iluidic capacitance.

The foregoing and other objects and changes of the invention will be better understood from the following description which is given by way of example and not by way of limitation.

In the drawings, FIGURE 1 is a schematic representation of a fluidic system embodying the invention, and FIGURE 2 is a view of a system similar to FIGURE l but including certain refinements.

DESCRIPTION OF SYSTEM OF FIGURE 1 In FIGURE 1 is shown a fluidic control system which may have the well-known form of an integrated iluidic 3,494,371 Patented Feb. 10, 1970 circuit formed in laminar material, or may have the form of physically separate fiuidic elements joined by small tubes. Assuming that the system is integrated, the external ttings of such an integrated system can be at the locations marked x. Leading from a pressure source (not shown) is a pressure supply line 7 which leads into the main internal pressure header 8. This, through suitable pressure reducing restrictions R1, R2, R3, leads to various branch lines as illustrated.

The system shown may be employed to monitor the frequency of operation or cycling of a cyclic type lubricant distributor or any other periodically operating device indicated schematically at 9. The monitored device may have a rotating shaft or any other element adopted to periodically close otf a vent or port 13; for example, the illustrated cyclic type distributor has a reciprocating element 10 operated by the back and forth movement of a valve stem to close the vent or port 13 at the end of a 'short external line, although it will be understood that any other element adapted to intermittently close or 0bstruct a vent may be utilized, as, for example, a projecting ear or tab on a rotating shaft or the like.

In the system shown in FIGURE l, a capacitor 11 in the form of a simple tank is provided connected to the header 8 via an adjustable needle valve 12 which constitutes adjustable throttling means. A counter 42 may be provided of a known type adapted to tally the number of times that the capacitor is pressurized and dumped to above and below certain pressure valves (say respectively 6 p.s.i. and 1 p.s.i.). Also provided is a iluidic diode 18 which is adapted to allow How upwardly as viewed in FIGURE 1, but not in the reverse direction. This diode may be a ilapper valve or any other simple mechanical valve adapted to operate to allow flow in one direction if the pressure is higher on the input side than on the output side in such direction of ilow, but adapted to stop flow in the opposite direction.

In the illustrated system, uidic elements include a nor gate 17, a standard or non-biased flip-Hop switch 15, and a one-shot multivibrator 20. The nor switch or gate 17 is of standard design and provided with control inlets or ports 23, 25 and 31 and with conventional vents (not shown). In a well-known manner the control inlets or ports 23 and 25 are adapted, upon the reception of supplied pressure signals, to shift a signal received through the incoming power line 48 from a power outlet or power output port 19 to a power outlet or power output port 24 and are pressure signal control inlets. The outlet passage leading to each power output port is vented in the conventional `manner (see for example page 42 of Fluidic Systems Design Guide, First Edition, 1966, Fluidonics Division, Imperial-Eastman Corporation, 6300 W. Howard St., Chicago, lll. 60648). The switch 17 is also adapted, upon the reception of a vacuum signal at control inlet or port 31, as upon closing off a vent or port 32, to similarly shift power output from power outlet or port 19` to power outlet port 24, and the control inlet 31 will be understood to be a vacuum signal control inlet. The switch 17 is a nor switch in the sense that power output at port 19 indicates that there is a control pressure signal in neither port 23 nor port 25. Switches of the above type and general description are well known.

The vent or port 32 may simply be the Open end of a branch line 47. This vent or port 32 may be closed olf in response to the building of pressure in aline 46 leading from the capacitor 11 by interposition of an expansiblechamber motor means 14, which comprises bellows 45 adapted to close off the port 32 upon a suicient pressure rise (say 8 p.s.i.) within the bellows 45, and to open the port 32 when pressure within the line 46 and the bellows 45 drops below such value.

Although the vacuum-imposing control switch 14 involves mechanical movement incidental to expansion and contraction of the bellows 45, it involves no sliding rr1o tion. Since mechanical movement is involved, the period of operation and the inertial lag of the device may be substantial as compared to pure fluidic gate, but are adequate considering the required frequency of operation of the device.

The ip-ilop switch is of a well-known type in which control ports 28 and 33 are adapated to flip the power input via line 34 to one or the other of the output ports 35 and 36 depending upon what control signals are applied to the control ports 28 and 33. A pressure pulse at 28 or a vacuum pulse at 33 ilips output to port 36, while a pressure pulse at 33 or a vacuum pulse at 33 flips output to port 35. Thus, closing bleed or vent 37 may impose a vacuum pulse to act as a reset control, and such closing will flip the switch 15 to the output port 36 to activate the normal operation indicator 38. The normal operation indicator 38 and the malfunction or flow indicator 39 may comprise Visiwink controls of a known commercial type comprising colored discs adopted to be moved by line signal pressure into position where they become visible through a viewing glass..

The one-shot multivibrator is of a known type adapted to momentarily shift power output from port 40 to port 22 upon reception of a triggering signal or pulse via control port 41 and to thereupon automatically reestablish power output at port 40. In general, the rise time of the control pulse at the port 41 should be of shorter duration than the normal duration of the temporary output of port 22. This implies a positive abrupt closing of port 13. Where the closing of the port is likely to be of longer duration an additional nor switch 21 (FIGURE 2) may be employed, in a manner to be later described in connection with the description of the ernbodiment of FIGURE 2. Also, when it is desired to provide lthe flip-flop switch 15 in the form of a biased ipop, it is desirable to provide another nor switch 16 (FIGURE 2), in a manner to be later described in connection with the description of the embodiment of FIG- URE 2.

However, for the time being, it will be assumed that these refinements are not used, in order that the invention may be more readily described and understood.

OPERATION OF SYSTEM IN FIGURE l The capacitor 11 lls at a constant rate from the pressure supply source 7 via the needle valve 12. This valve may be adjusted to vary the rate of lling of the capacitor I11, and thus to vary, within limits, the period of operation of the system.

The capacitor 11 is dumped periodically, this dumping being caused by periodic reclosing of the port 13 in a manner to be described below. If this reclosing of the port 13 does not occur promptly enough, pressure builds to the point (say 7 p.s.i) where vacuum-imposing control switch 14 closes thereby, via line 30, switching llip-flop switch 15 to port 35 and causing a trouble signal to appear at 39. Also the signal via the output port 35 may go to a spool valve of any known type, for example a Miller valve (not shown), that comprises a large power amplifier for automatic shut-down or start up of 'a controlled system such as a centralized lubricating distributor system.

Periodic reclosing of the port 13 causes periodic dumping of the capacitor in the following manner. Prior to such reclosing, the nor switch 17 normally maintains a bias (say 8 p.s.i.) at the diode 18 via the power outlet port 19 of the nor switch. That is, during such time as outlet or port 19 is the operative power outlet or port, incoming power via line 48 is applied through nor power outlet or port v19 against diode 18. Characteristically there is a substantial pressure drop across the nor Switch 17 between the power input lead 48 and the power output port 19 (through-switch flow being exhausted via the vent associated with port 19), so that say 25 pounds input pressure becomes say 8 pounds 0n the immediately -upstream side of diode 18, thus maintaining the just mentioned bias.

With this bias established, capacitor 11 continues charging up toward the bias value of say 8 p.s.i. However, reclosing of the port 13 iires the one-shot multivibrator 20 by applying a pressure signal of short or long duration at control inlet or port 41 causing a temporary output signal via alternate power outlet or port 22 of the multivibrator 20. This signal, via the control port 23 of nor switch 17, shifts power incoming via line 32 to the or power outlet or port 24. This, in turn, establishes a feedback to the control inlet or port 25 via the loop 26, so that output to power outlet 24 is maintained after cessation of an incoming signal at control port 23. However, because of bleeding of the feedback loop 26 at vent 27, the flow incoming via line 48 is insuicient in itself to maintain the feedback signal without supplementation byl discharge of the capacitor as described immediately be ow.

With shifting of output to port 24, there occurs a background venting or dumping of the capacitor through the internal Vents of switch 17, through vent 27, and in part through the loop 26, because, with bias removed from the diode 18, the capacitor 11 discharges across this diode, into port 19, back around the internal power passaging of the nor switch 17, out of port 24, and out vent 27 and around the feedback loop 26. Vent 27 bleeds the feedback loop 26 which, in this described state of the system, is carrying a waning signal as discharge of the capacitor 11 nears completion. When the signal drops sutlciently, the nor switch 17 switches from the power outlet 24 to the power outlet 19, completing the dumping phase. Pressure then 4starts to climb again in capacitor 11, starting another filling cycle.

As previously stated, if reclosing of the port 13 does not occur promptly enough, the capacitor is not dumped soon enough to avoid pressure buildup in the vacuumimposing control switch 14, which, when it closes, switches flip-flop switch 15, causing a trouble signal, all as above described. Closing of the vacuum-imposing switch 14 also dumps the capacitor 11 by removing bias of the diode 18 because such element vacuum switches the nor switch 17 via the line 29 as well as vacuum switching via the line 30 as above described. The capacitor continues to recharge and be dumped by closing of element 14 until such time as the trouble is remedied, i.e., until the cycle time of the monitored system again becomes brief enough so that the capacitor is dumped by closing of 13 rather than by closing of 32.

After trouble has been indicated and eliminated, and it is desired to recommence normal operation of the monitor, the port 37 may be closed momentarily to reset power output in flip-flop switch 15 to port 36. Since flip-flop switch 15 is not biased in the FIGURE l system it is also necessary to close port 37 momentarily after each start-up of the system in order to be sure that flip-flop switch 15 is feeding power output port 36 rather than power output port 35 at start-up. Otherwise a false trouble signal will occur.

DESCRIPTION AND OPERATION OF SYSTEM OF FIGURE 2 FIGURE 2 is similar to FIGURE 1, and like elements have like reference numbers. However, the nor switches 16 and 21 have been added and the switch 15 has been converted to a biased Hip-flop switch, the favored outlet being indicated by a -l-. For proper relationship of the operating parts, indicators 38 and 39 have been reversed in position in FIGURE 2 from their position in FIGURE l, and of course the connections to a controlled spool valve would have been correspondingly reversed. Port 37 has been replaced by a spring-loaded push-button or plunger control 43 of a well-known type adapted to be momentarily lmanually depressed by finger pressure to generate a momentary pressure pulse for resetting.

Since flip-flop switch I5 is biased, it automatically feeds power to port 35 upon system start-up. The push-button 43 is not strictly necessary, but without it the system must be shut down and restarted after each malfunction indication in order to reset the flip-flop for no-rmal operation. With push-button 43, resetting can be accomplished without shutting down the system by providing momentary pressure pulse generated by push-button 43 and applied at control port 33.

Aberrations in the operation of one-shot multivibrator 20 may occur if the rise time of the triggering pulse at control port 41 is of longer duration than the characteristic period of the momentary output at port 22. To avoid this possibility, nor switch 21 is provided. An incoming pressure pulse caused by rapid or slow closing of orifice 13 will result in an abrupt pressure rise at control port 41 of the multivibrator 2f), thus assuring proper operation of the multivibrator.

Without limitation, and by way of example only, typical circuit values may be given. The incoming line pressure may be 25 p.s.i. The drop through resistor R1 may be to 1/2 p.s.i. The drop through resistors R2 may be to l2 p.s.i. The drop through resistor R3 may be to 6 p.s.i. With conventional commercially available circuit elements such as flip-flop 15, nor switches 16, 17, 21, and multivibrator 2li), and conventional interconnecting lines, typical cycle of charge and discharge of the capacitor may be varied from .2 second to 400 seconds, depending upon the adjustment of the needle valve 12. For the longer end of this time range, say from about l0 seconds to about 400 seconds, the petcock 44 may remain open to utilize the full capacity of the capacitor 11. For the shorter or briefer end of this time range, say from about .2 second to about 15 seconds, the petcock 44 may be closed to utilize the inherent capacitance of the lines interconnecting the diode 18 with the elements 12, 14, and 42.

Elements may be changed, eliminated and added without departing from the invention.

What is claimed is:

1. In a fluidic system, capacitor means, a fluidic diode biased by outlet back-pressure to contain the charge of said capacitor means, means responsive to charging of said capacitor means to a pre-set value for removing the outlet back-pressure bias of said diode until said capacitor means discharges substantially and for thereupon reestablishing said bias.

2. Apparatus as in claim 1 including charging means and adjustable throttling means for throttling said charging means to vary the characteristic period of the chargedischarge cycle.

3. Apparatus as in clai-m 1, said means responsive to charging for removing, then reestablishing, bias, including a fluidic nor switch having a vented vacuum signal control inlet and also including an expansible-chamber motor means adapted to close off said venting at a given pressure in said capacitor means.

4. In a fluidic system, capacitor means, means for continuously feeding said capacitor means from `a pressure source, a uidic diode capable of being biased to contain the charge of said capacitor means, fluidic switch means having a first power outlet means via which said bias is applied and second power outlet means via which power is directed to remove said bias, first and second control inlet means each of which is adapted to switch power from said first to said second power outlet means upon reception of its own signal, and indicating means responsive to a signal received by the first of said control inlet means but not to a signal received by the second of said control inlet means, whereby operation of said indicating means occurs when bias is removed solely via the first of said control inlet means and not when bias is removed solely via the second of said control inlet means.

5. In apparatus as in claim 4, means for generating signals for reception by the first of said control inlet means in response to charging of said capacitor 'means to a preset value, whereby when bias is removed via the said second control inlet means to allow discharge of said capacitor means, a signal for reception at the said first control inlet means cannot then occur.

6. In a fluidic system, a nor switch, capacitor means connected to a pressure source via the nor power outlet of the nor switch, a liuidic diode between the nor power outlet and the capacitor means and blocking flow into the capacitor means from the nor power outlet, a vacuum signal control inlet in the nor switch for shifting power from the nor power outlet to the or power outlet upon reception of a vacuum signal as by blocking of a vent port connected to the vacuum signal control inlet, at least one pressure signal control inlet, and feedback loop means from the or power outlet to the pressure signal control inlet.

7. Apparatus as in claim 6, said feedback loop means including Imeans for attenuating the power signal from said pressure source to such an extent that it alone is ineffective to impose a control signal without reinforcement from power transmitted by discharge of said capacitor means across said diode, into sand nor power outlet, back around the nor switch interior to said or power outlet, and thence around said loop.

8. In a iiuidic system, a iiuidic switch having first and second power outlets, capacitor means connected to a pressure source via said first power outlet, a fluidic diode between said first power outlet and the capacitor means and blocking flow into the capacitor means from said first power outlet, control inlet means for shifting power from Said first to said second power outlet upon reception of a control signal, and feedback loop means from said second power outlet to a control inlet of said control inlet means.

References Cited UNITED STATES PATENTS 2,248,363 7/ 1941 Kuenhold 13.7-206 3,144,309 8/1964 Sparrow 137-815 X 3,392,741 7/1968 Shinn 137-815 M. CARY NELSON, Primary Examiner WILLIAM R. CLINE, Assistant Examiner U.S. C1. X.R. 23S-201

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