US3623497A

US3623497A - Fluidic switch

Info

Publication number: US3623497A
Authority: US
Inventors: Donald L Kaske
Original assignee: Johnson Service Co
Current assignee: Johnson Controls International Inc
Priority date: 1969-12-08
Filing date: 1969-12-08
Publication date: 1971-11-30
Anticipated expiration: 1988-11-30
Also published as: GB1336573A; FR2070770B1; DE2060370C3; CA928221A; FR2070770A1; DE2060370B2; DE2060370A1

Abstract

A fluidic differential switch includes a pair of summing impact modulators each having opposed nozzles referred to as independent and dependent nozzles for reference purposes. The summing impact modulators are reversely connected with respect to a signal input and a reference input. Thus, the outputs of the modulators are connected to a pair of fluidic ''''Nor'''' gates, each of which has a pair of input signal means controlling a main signal stream. The one input for each of the fluidic ''''Nor'''' gates is interconnected to a modulator and the other input is interconnected to the output of the opposite ''''Nor'''' gate. The switch output is taken from one of the ''''Nor'''' gates.

Description

United States Patent [72] lnventor Donald L. Kaske Waukesha, Wis.

[21 Appl. No. 882,964

[22] Filed Dec. 8, 1969 [45] Patented Nov. 30, 197 l [73] Assignee Johnson Service Company Milwaukee, Wis.

[54] FLUIDIC SWITCH Primary Examiner-Samuel Scott Attorney-Andrus, Sceales, Starke & Sawall ABSTRACT: A fluidic differential switch includes a pair of lo clamsznnwmg Flgs' summing impact modulators each having opposed nozzles [52] U.S. Cl 137/8l.5 referred to as independent and dependent nozzles for [51] Int. Cl FlSc 1/12 reference purposes. The summing impact modulators are [50] FieldofSearch 137/815 reversely connected with respect to a signal input and a reference input. Thus, the outputs of the modulators are con- 156] References Cited nected to a pair of fluidic Nor" gates, each of which has a UNITED STATES PATENTS pair of input signal means controlling a main signal stream. 3 323 532 19 7 campagnuolo |37/3| 5 The one input for each of the fluidic "Nor gates is intercon- 3 33 3g 7 9 7 ouigley' t 137/815 nected to a modulator and the other input is interconnected to 3,340,885 9/1967 Bauer l37/8l.5 the Output of the Opposite gate- The Switch Output is 3,388,713 6/1968 Bjornsen 137 81.s take" from one Ofthe s 3,443,575 5/1969 Hughes l37/81.5

1 Valve mm a 4 Z/ 30 22 g f Remote pressur signal m k u v J 7 1/ zay za 1 i T V Z6 U y I J cl n 1 Al F Remote Supply F'lter pressure slgnol PATENTEU 30 I97! 3,623 ,497

7 Valve I A 3" 27 Remote pressur signal ,2? Am a @113 l i9 g 1y & ivi /v\ m m \E F 2 Ez/ U Air Remote Supply pressure sIgnQI to ddh A I r j pp y 1 Line 7 I' f /f INVENTOR DONALD L KASKE pflgw Attorneys BACKGROUND OF INVENTION This invention relates to a fluidic switch, and particularly to a differential fluidic signal switch employing fluidic devices between the input fluid signal and an output fluid control signal.

Differential pressure switches are employed to efiect switching of a controlled device at relatively high and low pressures. Generally, prior art devices have employed diaphragms, mechanical components and the like to introduce a differential action. The switch thus places load means in one position at a first selected pressure. The switch remains in such stable state until the pressure changes in a preselected direction and amount. At the second distinctly different pressure selected, the switch moves to the second stable state. Mechanical and diaphragm-type units provide the desired differential action. They generally have encountered life and repeatability problems inherent in mechanical type devices.

SUMMARY OF INVENTION The present invention is particularly directed to a differential switching device employing pure fluid devices, and thus provides the difi'erential pressure response without moving elements, such as diaphragms, mechanical members and the like.

Generally, in accordance with the present invention, a fluid signal input is applied to the input signal means of a pure fluid or fluidic amplifying or comparing means having a high-pressure reference input means and a low-pressure input means. The several reference input means establish corresponding fluidic streams which are directly compared with the signal input stream through appropriate stream strength comparator means, The signals resulting from the comparison are interconnected to a fluidic flip-flop means of a set and reset variety with the one compared signal output connected to the set input and the opposite compared signal output applied to the reset input. The fluid control or output signal is taken from one side of the flip-flop means and provides a differential pressure response. The output signal may be applied to a valve to establish a high-pressure and high-flow output, if deemed necessary.

The flip-flop means could, for example, be a pair of fluidic Nor" gates, each of which has a pair of input signal means controlling a main signal stream. The one input for each of the fluidic Nor" gates is interconnected to the amplifier means, and the other input is interconnected to the output of the opposite Nor gate. The output is taken from one of the Nor" gates. In a particularly novel and important construction of the present invention, the fluidic comparing means includes a pair of summing impact modulators each having opposed nozzles, referred to as independent and dependent nozzles for reference purposes, connected respectively to the signal input and to the corresponding reference signals. The summing impact modulators are reversely connected with respect to the signal input, thus the independent nozzle of the one modulator is connected to the signal input, and the dependent nozzle of the opposite summing modulator is correspondingly connected to the signal input. The opposite nozzles or inputs of the two summing impact modulators are connected respectively to the highand low-pressure reference inputs. Independent reference signals are provided to the summing impact modulators, and thereby permit separate adjustment for the highand low-switching pressure settings. This permits resetting of the respective levels independently of all other level settings, either internally or with remote input signals through the use of suitable fluidic steering diodes and the like.

Applicant has found that the present invention provides a pure fluid differential switch having reliable and repeatable operation with essentially no wear, lost motion and the like.

DESCRIPTION OF THE DRAWING The drawing furnished herewith illustrates the preferred embodiment of the invention presently contemplated by the inventor for carrying out the subject invention in which the above advantages and features are clearly disclosed, as well as others, which will be readily understood from the following description.

In the drawing:

FIG. 1 is a schematic fluidic diagram illustrating a differential switch constructed in accordance with the present invention; and

FIG. 2 is a diagrammatic illustration Nor" gate unit shown in FIG. 1.

of preferred fluidic DESCRIPTION OF PREFERRED EMBODIMENT OF INVENTION Referring to the drawing, the present invention is plied to a differential switching assembly, signal line 1 adapted to be shown apincluding an input terconnected to a logic switching section 11 of a set-reset flipembodiment of the invention, the switching section 11 includes a pair of fluidic Nor"-gate 13 into a high-pressure and a high-flow signal for power operation of a load or the like, not shown.

In the illustrated embodiment of the invention, fluidic comparators 4 and 5 is shown as a summing impact modulator. The high-pressure reference fluidic comparator 4 The summing impact modulator 4 is shown similar to that described in US. Pat. Nos. 3,272,215 and 3,388,713, issued to Bjornsen et al., and includes an independent noule 21, which is connected to the input signal line 1 through a filter 22. An opposed dependent nozzle 23 is connected to the supply 7 in series with a fluidic diode 24, regulator 8 and a series dropping fluidic resistor 25. The regulator 8 permits adjustment of the pressure input signal to permit setting or adjustment of the setting of the high-pressure operating signal level. The resistor provides a linear dropping resistance, and the diode 24 restricts the fluid flow to the summing impact modulator 4 from the supply line 7.

The fluidic diode 24 may be any suitable one-way element, such as a check valve unit connected in series to the nozzle. This permits connection of a remote set signal line 27 to increase the pressure level signal level without introducing feedback through the regulator 8.

The

noules

21 and 23 provide a pair of opposed impacting streams with the position of impact dependent upon the strength of the input signal and the reference signal as set by regulator 8 and/or the remote high-pressure setline 27. The illustrated impact modulator 4, as more fully disclosed in the above patents, includes an intermediate or central wall 26 with orifice 27a aligned with the impacting streams created by

nozzles

21 and 23. Wall 26 defines a reference chamber 28 to one side thereof and an output chamber 29 to the opposite side thereof. The output chamber 29 is provided with an output signal line 30 connected to the input line or terminal 14 of the corresponding gate 12. The relative strength of the impacting streams movesthe impact position with respect to the orifice 270. If the signal pressure applied to the independent noule 21 is higher than the reference pressure appearing at the dependent nozzle 23, the impact point is shifted into or toward the output chamber and establishes a relatively highoutput pressure signal. When the reference pressure is higher than the independent pressure, the impact point moves into the reference chamber 28, and the output pressure decreases to the reference level. As in the illustrated embodiment of the invention, a positive logic is established for operating of the Nor gates.

The summing impact modulator 5 corresponds to the impact modulator 4. The impact modulator 5, however, is reversely connected with the dependent nozzle 23' connected to the filter 22 and input signal line 1 in series with a fluidic diode 31 to prevent feedback flow from the output chamber 29'. The summing impact modulator 5 functions in exactly the same manner as the modulator 4, but produces a high-pressure output at its output line 30' when the signal level drops below the level of the reference pressure signal. The signal from the summing impact modulators 4 and 5 are connected to the fluidic logic gates, as previously described.

The illustrated fluidic logic gates 12 and 13 are also similar members, and consequently, the gate 12 is diagrammatically shown in FIG. 2 and described in detail. The gates are preferably constructed in accordance with the teaching of the copending application entitled Multiple Purpose Fluidic Device," which was filed on Mar. 3, 1969, with Ser. No. 803,588, and which is assigned to the same assignee as the present application.

More particularly, the illustrated logic gate 12 is an impacting stream construction, including a pair of opposed

main stream nozzles

32 and 33 interconnected to the fluid supply line 7 through a flow reducing restrictor 33a and defining an impact position with respect to an orifice 34 in an output chamber 35 mounted concentrically of nozzle 33.

A pair of

control nozzles

36 and 37 are mounted, one to each side of the stream 38 emitted from the one nozzle 32. The

nozzles

36 and 37 are mounted to the opposite side of the stream 38 and angularly related to establish

control streams

39 and 40 directed toward orifice of the main stream nozzle 32. The signal is applied to the nozzle 36, deflects the main stream 38 with respect to the opposed impacting stream 39 to reduce the relative strength and cause the impact point to move away from the orifice 34 and output chamber 35, and

thereby decrease the output of the Nor"-gate 12 to a reference or zero level. The signal at the control nozzle 37 operates in a similar manner. 1f signals are applied to both of the

control nozzles

36 and 37, they effectively pinch off the emitted main stream 38, reducing its strength and resulting in a similar reference or level output of the Nor"-gate 12. The fluidic device thus establishes a logic function which may be defined in binary logic with a binary 1, corresponding to a positive output pressure signal of a selected amplitude, established only when the cutofi signal is not applied to either of the

control nozzles

36 and 37.

The nozzle 36 is interconnected to input line 14, and the nozzle 37 is connected to the line 15 in the illustrated embodiment of the invention. Similarly, the Nor"-gate 13 has its related control nozzles, not shown, connected to lines 17 and 18.

The fluidic system is described in binary logic terminology, as follows. If a binary signal is applied to either or both of the inputs 14 and 15, the output signal of the gate 12 is a binary 0. When and only when binary 0 signals are applied to both of the inputs l4 and 15 does the output change to a binary 1 signal. Gate 13 similarly responds to signals at lines 17 and 18.

As the input pressure is increased to the low-level set point or reference pressure as established by the regulator 10, the fluidic amplifier or modulator S will go to zero. This removes the signal from the input 18 of the Nor"-gate 13. The Nor"- gate 13, however, remains off or at binary 0 output level, as a result of the signal applied to the second input 17 from the first high-pressure Nor-gate 12.

When the pressure reaches the level established by the highpressure set point established by the positioning of regulator 8, the signal of the independent side of the fluidic modulator 4 rises above the dependent side, and consequently, results in an essentially step turn on of the modulator 4 and establishes a bi nary 1 output signal at line 30. This applies a positive fluid signal to the input 14 of Nor-gate 12. As previously noted, the binary 1 input at either of the inputs results in binary 0 output. As a result, a binary 0 is now applied via the line 16 to the input 17 of gate 13. The modulator 5 is at binary 0, and consequently, the Nor"-gate l3 sees a pair of binary 0 signals and produces a binary 1 output corresponding to an on signal.

As the pressure decreases, a reverse sequence occurs with respect to the gates 12 and 13, with the gate 13 being maintained on with a binary 1 output, even though the pressure drops below the high-pressure setting and the fluidic amplifier or modulator 4 reverts to a binary 0 output. When the pressure drops to the low pressure setting, the second binary 1 signal is applied to the low-pressure gate 13 establishing an output which turns off the gate 13, resets the circuit with a binary O or off output appearing at the output line 19. Thus, the system provides a pure fluid differential switching action.

As a result, a positive pressure or binary 1 appears at the output line 19 only when the pressure level rises above the selected level. The positive output pressure signal is maintained, however, as long as the signal pressure level is maintained above the setting of a low-pressure regulator 10, with a corresponding energization or operation of the valve 20.

The valve 20, as previously noted, may be employed to establish a high-pressure and high-flow characteristic. Thus, it may be a diaphragm-type valve or the like, which is connected directly to the main fluid supply line 17 via a line 41 and biased to a closed position. An output signal at line 19 opens the valve 20 to establish the high-pressure and high-flow characteristic.

Thus, the operation of the illustrated embodiment of the invention may be briefly summarized as follows.

The regulators 8 and 10 are set to turn on the switch or valve 20 at a selected high pressure and to turn off the device at a desired low pressure. In the absence or at a very low level of an input signal, the impact modulator 4 establishes a binary 0 and modulator 5 establishes a binary l. The binary 1 from modulator 5 is applied to turnoff gate 13 and establish a binary 0 output signal. The inputs to the high-pressure gate 12 are thereby effectively removed or at binary 0. Gate 12 is therefore, on and provides a hold off low-pressure gate 13. As the pressure increases to the low-pressure setting, summing impact modulator 5 will operate with the impact position moving into the exhaust region and establish a binary 0 to the Norgate 13. This removes the signal from the one side of the gate 13. It is held in its previous set condition, however, by the output of the first Nor-gate 12. Consequently, the signal input pressure can continue to increase until such time as the signal pressure establishes a level to turn on the impact modulator 4 and establish a binary 1 signal to the related logic gate 12. This will turn off the logic gate 12 removing the binary 1 signal from the input of the gate 13, which now turns on to actuate valve 20 and simultaneously supplies a binary 1 signal at the input of gate 12 to hold it off, even though the pressure drops below the high-pressure setting. Thus, as the pressure decreases, the summing impact modulator 4 will operate to remove the binary l signal from the related Nor"-gate 12. However, the gate 12 is held off by the binary 1 output from gate 13 at this time. As the input continues to decrease, however, and the pressure drops to the low-pressure setting of the regulator 10, the impact modulator 5 establishes a binary l or tumoff signal to the gate 13 and establishes a binary 0 output. The absence of a signal at the line 19 allows the logic gate 12 to turn on to thereby establish a binary 1 applied to the gate 13 to hold gate 13 off until the pressure moves above both the low-pressure level and the high-pressure level.

The highand low-pressure setting can be separately adjusted by regulations of the independent pressure regulators. Conversely, the remote control or setting can be established through the remote input pressure line which will correspondingly effect the strength of the reference streams. The use of the impact modulators for both the amplification and logic provides high-input impedance, and thereby maintains a minimum flow consumption. The present invention thus provides a pure fluidic differential switching control.

lclaim:

l. A differential fluidic switch responsive to at least two different fluid signal levels, comprising a fluidic amplifier means having streams established by a signal input means, a highpressure reference input means, and a low-pressure reference input means; said amplifier means having first comparator means to compare the fluidic streams of the signal input means and stream of the high-reference input means and establishing a first operative output signal at a high-pressure output line with the input signal at a predetermined level relative to said high-pressure reference level; said amplifier means having second comparator means to compare the fluidic streams of the signal input means and the low-pressure reference input means and establishing a second operative output signal at a low-pressure output line with the input signal at a predetermined level relative to said low-pressure reference level, and a fluidic set-reset flip-flop means having a switching output means and a pair of inputs defining set and reset inputs connected respectively to the highand -low pressure outputs and having hold inputs connected to the switching output means to establish and maintain an output signal at said switching output means in accordance with the last operative signal at said set and reset inputs in response to movement of the input signal between said high and low levels.

2. The fluidic switch of claim 1 having a valve means couples to one of said output lines to establish a high pressure and large flow output signal.

3. The fluid switch of claim 1 wherein said reference input means includes a fluid supply regulator and a fluid diode between the regulator and the amplifier means. and a remote reference signal source means connected directly to the amplifier means. 4

4. The fluidic switch of claim 1 wherein said first and second comparator means are individual summing impact modulators each having dependent and independent inputs, the inputs of the pair of modulators being oppositecle connected to the signal input means and the correspon mg reference input means, and said flip-flop means includes a first dual input fluidic Nor" gate and a second dual input fluidic Nor" gate, said first gate having a first input connected to the high-pressure output line of the first modulator and a second input connected to the output of the second gate, said second gate having a first input connected to the low-pressure output line of the second modulator and a second input connected to the output of the first gate.

5. The fluidic switch of claim 1 wherein said first and second comparator means are summing impact modulators each having dependent and independent inputs, the inputs of the pair of modulators being oppositely connected to the signal input means and the corresponding reference input means.

6. The fluid switch of claim 5 wherein each of said reference input means includes a fluid supply regulator and a fluid diode between the regulator and the corresponding reference connected input to the modulator, and a remote reference signal source means connected directly to the said corresponding reference connected input.

7. The fluidic switch of claim 1 wherein said flip-flop means includes a first dual input fluidic Nor" gate and a second dual input fluidic Nor gate, said first gate having a first input connected to the high-pressure output line and a second input connected to the output of the second gate, said second gate having a first input connected to the low-pressure output line and a second input connected to the output of the first gate.

8. The fluidic switch of claim 7 wherein each of said gates being an impacting stream comparator having a pair of impacting streams and a pair of control nozzles defining the first and second inputs connected to similarly control one of said impacting streams.

9. The differential fluidic switch of claim 8 wherein said pair of control nozzles are angularly and oppositely mounted to the opposite sides of the controlled impacting stream whereby either of said control nozzles establishes a control stream reducing the effective strength of the controlled impacting stream.

10. The fluidic switch of claim 9 having a valve means coupled to one of said output lines to establish a high pressure and large flow output signal.

Claims

1. A differential fluidic switch responsive to at least two different fluid signal levels, comprising a fluidic amplifier means having streams established by a signal input means, a highpressure reference input means, and a low-pressure reference input means; said amplifier means having first comparator means to compare the fluidic streams of the signal input means and stream of the high-reference input means and establishing a first operative output signal at a high-pressure output line with the input signal at a predetermined level relative to said highpressure reference level; said amplifier means having second comparator means to compare the fluidic streams of the signal input means and the low-pressure reference input means and establishing a second operative output signal at a low-pressure output line with the input signal at a predetermined level relative to said low-pressure reference level, and a fluidic setreset flip-flop means having a switching output means and a pair of inputs defining set and reset inputs connected respectively to the high-and-low pressure outputs and having hold inputs connected to the switching output means to establish and maintain an output signal at said switching output means in accordance with the last operative signal at said set and reset inputs in response to movement of the input signal between said high and low levels.

3. The fluid switch of claim 1 wherein said reference input means includes a fluid supply regulator and a fluid diode between the regulator and the amplifier means, and a remote reference signal source means connected directly to the amplifier means.

4. The fluidic switch of claim 1 wherein said first and second comparator means are individual summing impact modulators each having dependent and independent inputs, the inputs of the pair of modulators being oppositely connected to the signal input means and the corresponding reference input means, and said flip-flop means includes a first dual input fluidic ''''Nor'''' gate and a second dual input fluidic ''''Nor'''' gate, said first gate having a first input connected to the high-pressure output line of the first modulator and a second input connected to the output of the second gate, said second gate having a first input connected to the low-pressure output line of the second modulator and a second input connected to the output of the first gate.

7. The fluidic switch of claim 1 wherein said flip-flop means includes a first dual input fluidic ''''Nor'''' gate and a second dual input fluidic ''''Nor'''' gate, said first gate having a first input connected to the high-pressure output line and a second input connected to the output of the second gate, said second gate having a first input connected to the low-pressure output line and a second input connected to the output of the first gate.