US2717611A

US2717611A - Gaseous fluid relays

Info

Publication number: US2717611A
Authority: US
Inventors: Lerousseau Robert; Bourdeau Georges
Original assignee: REGULATEURS FRANCEL
Current assignee: REGULATEURS FRANCEL
Priority date: 1950-07-21
Filing date: 1951-07-12
Publication date: 1955-09-13
Anticipated expiration: 1972-09-13
Also published as: FR1022236A; CH302597A

Description

Sept. 13, 1955 Filed July 12, 1951 R. LEROUSSEAU ET AL GASEOUS FLUID RELAYS 5 Sheets-Sheet l pt 13, 19 R. LEROUSSEAU ET AL 2,717,611 I GASEOUS FLUID RELAYS Filed July 12, 1951 5 Sheets-Sheet 2 56 7 as "III/II 37 n/M v W p 13, 1955 R. LEROUSSEAU ETAL 2,717,611

GASEOUS FLUID RELAYS Filed July 12, 1951 5 Sheets-Shed s Err UIIIIIIIIIIIIA 5 55 J;

Sept 1 1 R. LEROUSSEAU ET AL 2,717,611

GA'sEous FLUID RELAYS Filed July 12, 1951 5 Sheets-Sheet 4 Sept. 13, 1955 Filed July 12, 1951 R. LEROUSSEAU ET AL GASEOUS FLUID RELAYS 5 Sheets-Sheet 5 gdw y United States Patent GASEOUS FLUID RELAYS Robert Lerousseau and Georges Bourdeau, Paris, France,

assignors to Regulateurs Francel, Paris, France, a corporation of France Application July 12, 1951, Serial No. 236,416

Claims priority, application France July 21, 1950 Claims. ((31. 137-85) The present invention relates to gaseous liuid relays of the type described in French Patent No. 954,055 filed September 25, 1947, which comprises, as a fundamental means, a nozzle through which a gaseous fluid jet is released, cooperating with a shutter, or movable screen located in the path of said jet, and with a movable surface the position of which, with reference to the nozzle, determines the air pressure in said nozzle, the variations of said pressure being amplifiable for various purposes.

According to the above-mentioned French patent, the shape of the nozzle is such that the contracted region of the fluid jet is located within the nozzle or, at least, in the plane of the output section of this member. Such an arrangement already gives interesting results, as far as the sensitiveness and accuracy of operation of said device are concerned. v

However, it was found possible to still increase this sensitiveness without lowering the fidelity and even increasing it, which resulted in providing a use for various purposes, by means of extremely reduced forces, of the variations of a phenomenon, even when said variations have a very small amplitude and a very weak self-power.

The object of the present invention is a modification of the above-mentioned fundamental means, which modification gives the results set forth, principally by giving said fundamental means an extremely increased sensitiveness, without lowering in any way its fidelity, the means thus modified being possibly cornbinable with an emplifying device, the variations of which are practically instantaneous and the multiplication factor of which is particularly increased.

The modification of the above-mentioned means fundamentally consists, on the one hand, in giving the gaseous fluid jet the shape of a jet contracted at the outside of the nozzle, for instance through shaping the outlet orifice of the nozzle as a thin walled orifice and, on the other, in simultaneously locating the shutter-screen in the contracted zone obtained, preferably at the place of maximum contraction, said shutter-screen, either at right angle or at a different angle to the fluid jet, being made movable and being moved depending upon conditions, either parallel or at an angle to itself, under the action of the variable phenomenon.

This arrangement does away with the necessity existing in the above-cited devices of adjusting the nozzle in a very precise manner relatively to the nozzle, which results in the suppression of a dead torque reducing the sensitiveness.

Moreover this arrangement allows a sensitive element to act directly on the nozzle, even if the respective displacements of the nozzle and screen, within certain relatively broad limits, are not parallel to one another.

On the other hand, since it is unnecessary to completely obturate the nozzle in order to submit the screen to the action of all partial jets of which the main jet is formed, said arrangement also allows to move, before the nozzle and in a frictionless manner, a screen driven by an element with reduced torque, to which will be opposed only 2,717,51 i Patented Sept. 13, 1955 the kinetic energy of the fluid jet, which energy is entirely under control, because of the low pressure which is sulficient for operating the relays intended to amplify the force displacing the screen which modulates the pressure within the nozzle.

Such a device may be combined, for example, with amplifying relays and/or servo-motors, with indicating, registering, repeating, or regulating devices.

Further features of the invention will appear from the following description, with reference to the appended drawings, diagrammatically illustrating various embodiments of the present invention, and in which:

Figs. 1, 2 and 3 are large scale diametrical sections of nozzles such as embodied in the device described in the above-mentioned patents;

Fig. 4 is a similar view of a nozzle according to the present invention;

Fig. 5 is a view, similar to Fig. 4, embodying an arrangement of the nozzle shown in Fig. 4 in cooperation with an orientable screen;

Fig. 6 is a perspective view, with parts broken away, a first embodiment of the invention;

Fig. 7 is a diagrammatic View of a second embodiment of the invention, with an associated servo-motor device;

Fig. 8 is a similar view of a further embodiment;

Fig. 9 is a view similar to that shown in Fig. 7, relating to a further application of the invention;

Fig. 10 is also a view similar to Fig. 7, relating to a fifth modification;

Fig. 11 shows diagrammatically a sixth embodiment;

Fig. 12 shows a seventh modification, relating to applications of the invention for indicating, registering and rejecting purposes, and

Fig. 13 is a plan view of a portion of the same.

In the embodiment shown in Fig. 1, a nozzle 1 cooperates with a screen 2 carried on a resilient blade 3 fixed on the same support 4 as said nozzle. If an air jet issued from a container (not shown) of relatively reduced effective capacity and low pressure uniformly fed with compressed air, is blown through nozzle 1 towards screen 2, a contraction of said air jet is produced, in plane A-A, upstream to orifice 5 of said nozzle. The latter, however, spreads downstream to orifice 5 and, in such a condition impinges on screen 2, on which it exerts a certain pressure. The latter is counteracted by spring 3 which is bent. The screen assumes a balance position and the pressure within and behind the nozzle takes a determined value. If, by any suitable means, the position of screen 2 with relation to orifice 5 of the nozzle is varied, for example by being shifted to the left of the drawing, by means of a stop 8, a key 7 carried on screen 2, the screen will be brought nearer to orifice 5 and the air pressure within nozzle 1 will increase. If, on the other hand, while stop 8 is left behind in its initial position shown in Fig.v 1, the air pressure within nozzle 1 is increased, screen 2 will be pushed away (against the action of spring 3 which is bent) and meets stop 8 in its new position, air will escape more easily through nozzle 1 and the pressure will decrease Within the latter, until a new balance condition is obtained, and so on, whenever stop 8 is moved forward or backward. From the relative position of stop 8 and orifice 5 thus depends the pressure within the nozzle and consequently within the tank located upstream to said nozzle. Variations of the distance from the stop to orifice 5 of the nozzle are obtained, for instance, by displacing stop 8 parallel to itself towards the nozzle, or by giving said stop an angle with reference to the direction of the air jet and displacing said stop parallel to itself and obliquely to the direction of the jet.

Similar effects are produced when using, instead of a nozzle with cylindrical inner bore such as shown at. 1 in Fig. 1, a converging nozzle such as shown in Fig. 2,

and the convergency angle a of which is larger than that b of the air jet within the nozzle. In such a case, the gaseous jet leaves the inner wall of the nozzle and the maximum concentration zone of the air jet is in plane A--A of outlet orifice of the nozzle.

If a bi-cylindrical nozzle is used, such as shown at 11, 12, in Fig. 3, with a wide angled separating shoulder 13 therebetween, maximum concentration zone AA will be located within cylindrical portion 12. In the three latter cases, the gaseous jet expands beyond the outlet orifice of the nozzle and the gaseous jets meeting a screen such as 2 in Fig. 5, impinge on it in a spreaded shape.

If however, according to the invention, the nozzle through which the air jet is projected, is formed in such a manner that outlet orifice 14 of said nozzle (Fig. 4) is formed in a thin end wall 16 substantially perpendicular to the axis of the nozzle, the orifice 14 being substantially smaller in diameter than the wall 16. With such construction the gaseous jet will leave internal wall 17 of the nozzle and the maximum contraction zone A-A of the air jet will be located downstream and at a certain distance of said orifice 14. Screen 2 is to be located within this maximum contraction zone of the air jet. In this position the gaseous jets are quite concentrated, contrarily to what happens in the case of the nozzle devices of Figs. 1, 2 and 3. The impact zone is more reduced and therefrom results at this point a concentration of energy which increase the sensitiveness and fidelity of the device. These qualities attain a maximum when the face of the screen receiving the air jet is located within the maximum contraction zone of the air jet, as shown in Fig. 5.

Such a nozzle with thin-walled orifice is well adapted to angular displacements which it may be necessary to give screen 2 (as, for instance, positions 2a, 2b) by rotating the latter about an axis of rotation 18, at right angle to the geometrical axis of the air jets.

On the other hand, the combination of screen 2, key 7 and stop 8, diagrammatically shown in Fig. 1 may be reduced, according to one feature of the invention, to a single screen, the face of which nearer to the nozzle is formed as a cam and is moved in such a manner that the distance between the nozzle and the point at which the air jet impinges on the latter is varied, thus varying the air pressure behind the nozzle. This particular embodiment is shown in Figs. 6 to 12.

There may thus be provided such a device providing a nozzle the outlet orifice 14 of which, forming a thin walled orifice, has a half-millimeter (0.5 mm.) diameter, and in which screen 2, located at 0.2 mm. distance from said U orifice 14, receives a thrust of two decigrarns per square centimeter (0.2 gr. per cm?) and consequently can be moved by means of an extremely reduced force. The variations of the air pressure behind the nozzle (herein called modulated pressure) may be amplified at will and may serve to obtain any desired slave or independent control, with or without using servo-motors.

For instance, by forming the screen as an end cam 19 (Fig. 6) mounted on the axis of a galvanometer 20 and opposite the upper section 21 of which is located a nozzle 22, fed with compressed air and the orifice of which, formed as a thin walled orifice, directs a thin air jet on cam 21, and by giving said cam a height decreasing from 24 to through 21 according to a predetermined law, the rotation of the cam will cause a variation, according to said law, of the distance between orifice 23 of the nozzle and cam 21, thus varying, according to the same law, the air pressure behind the nozzle. Since small variations of the distance between the cam and the nozzle provide large variations of said pressure, the maximum height variations of cam 21 from 24 to 25 may be small, thus remaining within the concentration zone of the air jet; With a 0.5 mm. nozzle orifice and an air pressure of 0.2 gram per square centimeter at the outlet of said orifice, a power of one quarter of a milliwatt is suificient to produce behind the nozzle pressure modulations which can be almost instantaneously amplified up to a desired number of tons.

The nozzle may be made movable, when it is desired to obtain an air pressure, determined at every instant, as a function of the position of an element indicating the condition of a phenomenon. Fig. 7 shows such a device in which 24 is a member fastened at one end 25 to a fixed support 26 and which is deformable as a function of an inner pressure varying according to temperature, and the variations of which are intended to modulate the air pressure within nozzle 31, submitted to the displace ments of an arm 35. Element 24 rotates, around a fixed shaft 23, by means of a connecting rod 29, a screen 30 located opposite the orifice of a nozzle 31, fed with air through fixed duct 27 and flexible hose 32, the distance from said screen to the nozzle orifice being chosen so that said screen remains in the contraction zone of the air jet issuing from nozzle 31 for all positions which end 33 of indicator 24- can assume. The nozzle is fixed to arm 34 of a

bell crank lever

34, 35 pivoted on a shaft 36, fixed on a support 37. One end of arm 35 leans on push rod 38 of bellows 39 connected to pipe 40 which itself is connected to hose 32. A throttling valve 41 is used to regulate the air pressure at nozzle 31 and bellows 39.

Air flowing through duct 27 under a pressure regulated by throttle valve 41 being admitted into pipe 40, an air jet flows out through nozzle 31 and a determined pressure is established in the

assembly

31, 32, 40, 39 as a function of the position of screen 30 corresponding to a determined condition of element 24. The air pressure within bellows 39 moves the nozzle away from the screen through the agency of bell crank

lever

35, 34, until a balance position is attained due to screen 30 reacting on the air jet flowing out of the nozzle. By adjusting the air feed pressure by means of valve 41, the nozzle is caused to assume such a position that the distance from its orifice to the active face of screen 30 be the position for which said face is located within the maximum contraction zone of the air jet from the nozzle.

If, due to a variation in the phenomenon determining the shape of element 24, end 33 of the latter drives screen 30 and the nozzle further apart from one another, the effect of the reaction thrust of the air jet on the screen decreasing due to this separation, results in a decrease of the pressure within

ducts

32 and 40 and in bellows 39 which collapse. Push rod 38 is lowered, arm 35 follows, and arm 34 drives nozzle 31 nearer to screen 30, until the reaction of the air jet on the screen increases the reaction thrust of the air jet on the nozzle and drives the latter to a new balance position corresponding to the deformation of the above-mentioned element and thus to a new condition of the temperature the variations of which are to be observed.

A variation in the opposite direction of the condition of said phenomenon producing, in another direction, modifications of the screen-nozzle assembly would drive back the bell-crank lever and bellows and a new balance would be established, corresponding to the new condition of the phenomenon.

It must be appreciated that the displacements of nozzle 31 and screen 30 may be non-parallel without the sensitiveness and operational accuracy of the device being affected, as the portions of both these elements which are concerned with the contracted zone of the air jet may describe large radius circumferences which are either tangent or slightly secant.

The visible or audible temperature indication is obtained by controlling through arm 35 any suitable apparatus adapted to give such indications under the effect of the displacements of arm 35. v

Fig. 8 relates to cases in which it is desired, as with relation to Fig. 7, to translate into indications a registering or regulation of quite small intensity variations of an electric current, which itself is very small. In Fig. 8, nozzle 42, with a thin Walled orifice, is solid with an arm 43 pivoted on a shaft 44 solid with a fixed support 45. At normal position, nozzle 42 is at such a distance from the end edge 46 of a cam 47 that said edge is within the contraction zone of the air jet flowing out of the nozzle. Said cam 47 is solid with the moving frame of a galvanometer 48. In order to insure said distance, arm 43 rests on push-rod 49 of the movable member 50 of a capsule 51. Nozzle 42 and capsule 51 are fed with air under pressure through

respective ducts

52 and 53, connected to an air feeder 54, in which is interposed a regulating valve 55.

The operation of the device shown in Fig. 8 is the same as that of the device shown in Fig. 7, obvious modifications being taken into account. If the system is supposed to be mechanically and aerodynamically balanced, for a given pressure of the feed air and for a given current flowing through the galvanometer, that is if cam 47 occupies an angular position corresponding to said current, if, moreover, nozzle 42 is supposed to be at such a distance from the cam that edge 46 and the cam are in the contraction zone of the air jet, and if, at the same time, the feed air pressure in capsule 51 is such that the membrane of said capsule drives the nozzle to the considered position, and if, in such conditions, the current flowing through the galvanometer increases and drives the cam in such a manner that the distance between said cam and the nozzle orifice is increased, the reaction of the cam on the air pressure in the system formed by nozzle 42 and capsule 51 will decrease; as the said pressure de- I creases, capsule 51 will grow thinner, lever 43 will be driven downwards and the nozzle will be brought nearer to cam 46, until the distance between both members is so small that the reaction of the cam on the air jet and consequently on the air pressure in the system again assumes its former value, the balance of the system being recovered. The displacements of lever 43 may be used, being suitably amplified, for transmitting every indication, registering, regulating correlated to the intensity changes of the current flowing through meter 48.

Fig. 9 shows the invention as applied to measuring variations in the length of a hair or a silk-worm thread 56, due to variations in the dampness of air. The hair is fastened at one end to a fixed point and at its other end to an unextensible thread 57 wound on a small diameter pulley 58 keyed on a shaft 59, pivoted on points to a fixed support 62. On shaft 59 is mounted a spiral recoil spring 63, holding hair 56 slightly taught, and an end cam 64 the edge of which cooperates with a nozzle 65 having a thin walled orifice and projecting an air jet on edge 64 of the cam. The nozzle is mounted on a

balance lever

66, 67 os'cillable on a shaft 68 in

bearings

69, 69. Nozzle 65 is connected through a flexible hose 70, to bellows 71 solid with a fixed support 72. A push-rod 73, carried on the lower face of the bellows, presses on arm 67 of the balance lever. Air under pressure is fed through duct 74, provided with regulating valve 75, to nozzle 65 and bellows 71.

If hair 56 is supposed to be balanced by the tension of spring 63 and the upper edge of cam 64 opposite nozzle 65 to be located within the contraction zone of the air jet flowing out of said nozzle, if moreover in such a position of the above-named members, the air pressure regulated by valve 75 is supposed to be such that the reaction against the cam of the air jet on nozzle 65 repulses the latter upwards due to an elongation of the air, by increasing the distance between the nozzle and the cam, the pressure will be made to decrease within and behind the nozzle and consequently the pressure will also decrease within the bellows. Arm 67 of the balance lever will move upwards and will thus lower the nozzle until the latter assumes a new balance position corresponding to the amount by which the hair was elongated.

There may be derived from

balance lever

66, 67, an actuating motion, with possible amplification, for an indicating or registering device which will reproduce on large scale the expansions or contractions of the hair.

In the case of the device shown in Fig. 10, a galvanom: eter 76 rotates an end cam 77, opposite to which is located a nozzle 78 the outlet orifice of which delivers an air jet under pressure, said nozzle being normally at such a distance from the cam that the upper face of the latter is in the contraction zone of an air jet escaping through said nozzle. The nozzle is mounted on an arm 79 rotatable about a shaft 80 on a fixed support 81. This support carries bellows 82 provided with a push-rod 83, pressing on lever 79. The latter carries, through an arm 84, another nozzle 78a, for instance with a thin walled orifice, cooperating with a shutter 85 mounted on a membrane 86 of a capsule 87 which is also supported on arm 79. A spring 88 strives to move membrane 86 aside from nozzle 78a. A compressed air duct 89 feeds, through regulating valve 90, partly flexible pipe 91 and constriction 92, nozzle 78 and capsule 87 and, through pipe 93, provided with a constriction 94, and pipe 95, bellows 82. It feeds also, through partly flexible pipe 96, nozzle 78a.

The device being balanced, if the edge of cam 77 being rotated by a rotation of the frame of galvanometer 76, is supposed to get nearer nozzle 78, the pressure will increase very slightly in capsule 87 (a few millimeters water height for instance). Membrane 86 is then repulsed and closes nozzle 78a, against the action of spring 88. The pressure increases in bellows 82 which expand and drive nozzle 78 away from cam 77 up to the point where, the leakage at the nozzle becoming sufficient, shutter 85 is driven away from nozzle 7 8a, whence there is recovered a leakage, the amount of which is equal to that of the compressed air brought in through constriction 94, whence a new balance of the device is attained. An opposite action of the edge of cam 77 would produce opposite actions and effects and the condition of balance would also be recovered.

The amplifying relay may either be fixed to arm 79 or be independent. Only the nozzle must in every case accompany arm 79.

In the latter case (Fig. 11) the pipe connecting nozzle 78 to capsule 87 is flexible. The parts which are common to both devices (Figs. 10 and 11) are designed by the same reference numbers. The operation is the same in either case.

Fig. 12 shows the invention as applied to indicating and registering the variations of a phenomenon resulting in a weak electric current, as well as to controlling a regulating mechanism. Fig. 13 is a plan view of a portion of such a device.

in this apparatus the component elements of the apparatus shown in the other figures are again to be found, viz.: a galvanometer 97, an end cam 98, a nozzle 99 with a thin walled orifice, a capsule 100 with a membrane 101 carrying a shutter 102 acting on a nozzle 103, possibly with thin walled orifice, and provided with a compression spring 104. Bellows 105 control an arm 106, pivoted on a shaft 1060. Moreover, in this apparatus there may be seen an index 107 solid with arm 106 and the tip of which moves before a graduated scale 108, as well as an arm 109 carrying a registering style which traces on a rotating cylinder 111 an amplified registering of the variations of the phenomenon corresponding to the intensity variations of the current flowing through meter 97. Capsule 100, nozzle 103 and bellows 105 are fed with compressed air through duct 112 and

branch pipes

113 and 114. A tension spring 115 strives to constantly bring nozzle 103 nearer to shutter 102. On arm 107 is hinged at 116 a connecting-rod 117 the other end of which is hinged at 118 on a lever 119 pivoted at 120 on a fixed support (not shown) and hinged at 121 on nozzle holder 122. Holes such as 123 in lever 119 make possible, by threading shaft 118 in any one of the said holes, to vary the ratio of the arms of lever 119.

On the other hand, there is hinged on shaft 106a a lever 124 through which extends a threaded rod 125, hinged at 126 on an arm 1-27 solid with an arm 128, pivoted on shaft 105a. A spring 128a presses on arm 127 and under a'rin 124. A milled knob 129 screwed on rod 125 allows to vary the relative angular position of

arms

124 and 128. The lower end of arm 123 carries a nozzle I30, possibly with thin walled orifice, cooperating with a shutter screen 131 mounted on a spring 132 fixed on a small arm 133 solid with index 107. A stop 134 limits the displacement of screen 131 towards nozzle 130.

Lever 124 carries an inclined vane 135 cooperating with a nozzle 13 6, possibly with thin walled orifice, through the agency of a key 137, mounted on a resilient arm 138 fixed to nozzle 136. The latter is carried on the bottom of bellows 140 fed with compressed air through a branch pipe 141 derived from duct 112 and comprising a constr'iction 141d. A spring 142 seated on a fixed support 143 opposes the displacements of the bottom 139 of said bellows 140.

On the other hand, bellows 144, fixed on support 14-3 are fed with compressed air through a branch pipe 146 derived from duct 112. The said bellows act by means of a push-rod 145, on lever 124. Branch pipe 146 feeds also, through a partially flexible duct 147, nozzle 130.

There is also shown on this figure a valve 148 located in a compressed fluid duct 149 and controlled by means of'a resilient membrane 150 with compression spring 151. This membrane 150 communicates through branch pipe 141 with main compressed air feed duct 112.

This device operates as follows:

The balance being assumed to be established for a certain value of the intensity of the current flowing through meter 97, and for this value of said current the portion of edge 98 opposite the orifice of nozzle 99 being supposed to lie in the contraction zone of the air jet issued from nozzle 99 and also, in such a condition, shutter screen 102 of capsule 100 being supposed to be located, under the etfect of the pressure prevailing within the capsule and of the force of spring 1194, within the contraction zone of the air jet issued from nozzle 103, in the case in which the orifice of the latter is thin walled, and in which index 107 is opposite to a certain mark on scale 108; if then the current flowing through the meter increases, cam 98 rotates on its shaft and its edge is brought nearer to nozzle 99. The reaction exerted by the air jet on the nozzle will vary and will push the latter to the left of the drawing, while the air pressure in capsule 11 5 will increase the shutter screen 102 will be consequently brought nearer to nozzle 103, up to the point where it will close it. There results a displacement of arm 106 to the left of the drawing and consequently arm 107 will be displaced to the right, thus tensioning spring 115; Index 16 7 moving to the right of the drawing, connecting rod 117 rotates lever 119 which separates nozzle 99 from the cam until, the reaction of the jet on nozzle 99 being thus decreased and the pressure decreasing behind said nozzle, the pressure within capsule is also decreased and a new state of balance is established in the system, due to the leak caused at nozzle 103. After this balance is attained, the device stops and index 107 gives, on scale 108 a new indication corresponding to the new intensity of the electric current through the meter, this intensity value corresponding to a new condition of the phenomenon determining the intensity of said current.

Through displacing hinge point 118 of connecting rod 117, the ratio of displacements of index 107 and nozzle 99 can be varied.

Arm 109 forming an extension of index 107 registers, as a diagram a, the variations of the considered phenomenon.

Supposing

regulator

148, 150, 151 to be at its middle position, and that for this middle position lever 124 is also at its middle position, and that nozzle 13-0 and cam 98 and

screens

131 and 137 are at respective positions such that said screens are in the middle contraction zone of the air jets issued from said nozzles and also that bellows 105, 140 and 144 are at their middle positions, and supposing also that a variation of the phenomenon to be re ulated increases the intensity of the current through meter 97; bellows 105 within which the pressure increases, pushes lever 106 to the left of the drawing and, displacing screen 131 to the right, releases nozzle and decreases the air pressure within capsule 100. This pressure decrease is transmitted to bellows 144 which lower lever 124 and bring nozzle 130 nearer to screen 131 until a new balance condition is established, corresponding to the new condition sought for, of the phenomenon to be regulated. The vane, which in this case is made inclinac-le, is brought to press on screen 135 and causes the shutting of nozzle 136,- and consequently an increase of pressure in capsule 140, said increase of pressure being converted into a displacement from right to left of wall 139, up to the point where, due to the inclination of edge 135, the leakage corresponding to the balance condition is reestablished,

device

136, 137, 138, 139, stops for an internal pressure higher than before, due to the opposed spring 142 contracting. This new pressure value is transmitted through duct 141 to valve 148 causing the partial or total formation of orifice 148.

if the variation of the phenomenon to be regulated occurs in the opposite direction, all actions in the device will also occur in the opposite direction.

Through acting on milled knob 129, it is possible to control the variation of the position of nozzle 130 with relation to arms 196, 107 and consequently of the medium regulating point.

instead of being shaped as an end cam, the screen may also be shaped as a cam the edge of which cooperating with the nozzle is parallel in each of its active portions to the axis of rotation of said cam.

in the case in which an end cam is used the skews which it comprises may be given such a shape that the generatrix of said skews always extends through the rotation pivot of the cam.

Though only a few embodiments of the present invention have been described and illustrated, it is to be understood that many modifications may be used within the scope of said invention as defined in the following claims.

What we claim is:

l. in a gaseous fluid relay, a nozzle having a thin end wall perpendicular to the axis of the nozzle and provided with a jet orifice axially thereof smaller than the diameter of said end wall whereby a fluid jet issuing from said nozzle will have a zone of maximum contraction spaced outwardly from said orifice, a conduit supplying gaseous fluid to said nozzle, and a movable screen adjacent to and in front of said nozzle.

2. A device constructed in accordance with claim 1 wherein said screen normally has a portion within the contracted zone of said fluid jet.

3. A gaseous fluid relay comprising a nozzle having a thin end wall perpendicular to the axis of said nozzle and provided axially thereof with a jet orifice smaller in diameter than said end wall whereby the issuing fluid jet from said orifice will have a zone of maximum contraction spaced outwardly from said orifice, a conduit supplying gaseous fluid to said nozzle, a movable screen adjacent to and in front of said nozzle, and screen-actuating means responsive to a variable behavior phenomenon, operatively connected to said screen for varying the distance of said screen from said nozzle. 7

4. A device constructed in accordance with claim 3 provided with control means responsive to variations in pressure in said conduit occurring incident to variations in the distance of said screen from said nozzle.

5. A device constructed in accordance with claim 3 wherein said screen normally has a portion within the contracted zone of said fluid jet.

6. A gaseous fluid relay comprising a nozzle having a thin end wall perpendicular to the axis of said nozzle and provided axially thereof with a jet orifice smaller in diameter than said end wall whereby the issuing fluid jet from said orifice will have a zone of maximum contraction spaced outwardly from said orifice, a conduit supplying gaseous fluid to said nozzle, a movable screen adjacent to and in front of said nozzle, screen-actuating means responsive to a variable behavior phenomenon, operatively connected to said screen for varying the distance of said screen from said nozzle, means for supporting said nozzle for movement toward and away from said screen, and means responsive to variations in pressure in said conduit occurring incident to variations in the distance of said screen from said nozzle for moving said support to move said nozzle toward and away from said screen.

7. A gaseous fiuid relay comprising a nozzle having a thin end wall perpendicular to the axis of said nozzle and provided axially thereof with a jet orifice smaller in diameter than said end wall whereby the issuing fiuitl jet from said orifice will have a zone of maximum contraction spaced outwardly from said orifice, a conduit supplying gaseous fluid to said nozzle, a movable screen adjacent to and in front of said nozzle, screen-actuating means responsive to a variable behavior phenomenon, operatively connected to said screen for varying the distance of said screen from said nozzle, a pivoted arm carrying said nozzle, an expansible chamber device communicating with said conduit to be expanded and contracted in accordance with variations in pressure in said conduit, and an arm rigid with said pivoted arm and engaging said expansible chamber device.

8. A gaseous fluid relay comprising a nozzle having a thin end wall perpendicular to the axis of said nozzle and provided axially thereof with a jet orifice smaller in diameter than said end wall whereby the issuing fluid jet from said orifice will have a zone of maximum contraction spaced outwardly from said orifice, a conduit supplying gaseous fluid to said nozzle, a movable screen adjacent to and in front of said nozzle, an arcuate member fixed at one end and connected at its other end to said screen and subject to deformations to move said screen toward and away from said nozzle, and means subject to variations in pressure in said conduit incident to variations in the distance of said screen from said nozzle for moving said nozzle toward and away from said screen.

9. A device constructed in accordance with claim 8 wherein the means for moving said nozzle comprises an expansible chamber device communicating with said conduit and having mechanical connection with said nozzle.

10. A device constructed in accordance with claim 8 wherein the means for moving said nozzle comprises a pivoted supporting arm for said nozzle, a bellows communicating with said conduit to be expanded or contracted in accordance with pressure variations in said conduit, one end of said bellows being fixed and the other end being movable, and an operating arm fixed to said pivoted arm and engaging the movable end of said bellows.

References Cited in the file of this patent UNITED STATES PATENTS 1,813,733 Freeman July 7, 1931 1,917,092 Bristol July 4, 1933 1,950,989 Mason Mar. 13, 1934 2,310,298 Kuhl et al. Feb. 9, 1943 2,310,415 Frymoyer Feb. 9, 1943 2,332,627 Erbguth Oct. 26, 1943 2,380,858 McMahon July 31, 1945 2,461,026 Bilyeu Feb. 8, 1949 2,635,465 White Apr. 21, 1953 FOREIGN PATENTS 2,988 Great Britain 1888 395,962 Germany 1922