US2111466A - Fluid operated relay mechanism - Google Patents

Description

5 March 15, 1938. a. WUNSC H 'FLUID OPERATED RELAY MECHANISM Filed Sept. 17, 1936 Av Av a 5 m% x \CzuBEE QEEE S 3mm Guido Wibwa/ Patented Mar. 15, 1938 UNITED STATES PATENT OFFICE FLUID orzaa'mo RELAY nmcnmsm Application Septemherli, 1936',"Serial No. 101,329

. In Germany December 11, 1935 4 Claims. (01. 137-111) Tl'iis invention relates to fluid pressure operated relays such as are employed in regulators -for controlling physical conditions and, among other objects, aims to provide important improvements in fluid jet relays such as those of the well known Askania typ whereby to increase the efliciency and reduce the power required to supply the pressure fluid. The main idea is to produce the most efficient ratios be:

tween the sizes of the jet nozzle and the orifice or orifices into which the jet discharges, so that both the pressure regain or efiective pressure in and the volume of fluid delivered to the control conduits for actuating the servo motor or control device may be increased to a maximum for any ordinary operating fluid medium.

Other aims and advantages of the invention will appear in the specification, when considered in connection 'with the accompanying drawing, wherein:

Fig. 1 is a sectional view showing jet pipe relay mechanism embodying the invention; Fig. 2 is a sectional view taken at right angles to Fig. 1;

Fig. 3 is a fragmentary sectional view of a 1 tube and conduit to illustrate the relative sizes of the nozzle and a receivingoriflce; and

Figs. 4 and 5 are charts illustrating the efllciency of 'jet pipe relay systems embodying the m invention.

In relay mechanisms of the type illustrated,

the pressure fluid is usually supplied by a pump and the velocity of the fluid is transformed into I a pressure head which is delivered through either one of two small orifices of a pair of control conduits to actuate a servo motor or control device (not shown). The pressure and volume of the fluid delivered to the control device through the conduits, in conjunction with other factors, deter- 40 mine the energy delivered to the control device.

It is therefore highly desirable to regain a high percentage of the pump pressure in and to deliver a maximum volume of the fluid to the control conduits. That is to say. both the pressure emciency and the volumetric efliclency are very important factors. Heretofore, the sizes of the jet nozzle and the orifices have been practically the same. An appreciable percentage of pressure loss 50 and low volumetric efliciency, ,with consequent power waste, increase in size. capacity and cost of pumping equipment, have been tolerated. In some installations, considerable power is required to operate heavy control equipment and the losses 55 involve heavy expense. The present invention,

therefore, aims to reduce such losses and greatly increase the efflciency of such relay systems.

Referringfparticularly to the drawing, Figs. 1 and 2 disclose an Askania" jet pipe relay system embodying the invention. This particular 5 type of pivoted-jet pipe is the subject of a copending application, Ser. No. 93,306, flied July 29, 1936. However, it is to be understood that the invention is equally applicable to all relay systems wherein fluid jets are delivered to ori- 10 does of controlling conduits. .The illustrated system discloses a jet pipe Ill carried by a bar ll having trunnion pins l2 and mounted for pivotal movementin a vertical plane. Pressure fluid is adapted to be supplied to thejet pipe by an ordi- 15 nary pump (not shown) through a stationary conduit l3 having a nozzle ll projecting into the upper open 'end of the jet pipe. The jet pipe is adapted to deliver the fluid to one or the other or to both of a pair of orifices of the control conduits l5 and It in a distributor blockv I! to operate a control device (not shown), it being understood that the jet pipe moves relative to the orlflces in response to changes in the condition to be controlled. In case liquid, such as oil, is used, the jet pipe nozzle is surrounded by an oil catcher l8 which is usually kept full of oil returning through one or the other 0! the control-conduits from the control device or by the oil not used or not delivered to one of the conduits.

From the above explanation of the illustrated example, it will be understood that the efiective fluid pressure for actuating 'a control device has to be built up or regained in the respective control conduits l5 and i6 and the rate of flow, as

well as the pressure therein are the important factors with which this invention is concerned. The ratio of the sizes of the nozzle and each orifice in terms of their diameters d/D, is less 40 than one to one. That is to say, the cross sectional area of the nozzle bore is less than that of the respective reception orifices, the areas oi round nozzles and orifices being proportional to the squares. of the diameters. For most suitable fluids, a long series of experiments has demonstrated that best results are obtained when the ratio of the'diameters ranges between one to two "and one to one, depending upon some variable i'actors, such as the kind of oil used, the characa ter of the jet, the distance between the nozzle and the receiving orifices and other factors.

Referring now to Fig. 3, there is shown an illustrative jet .pip'e nozzle 20 discharging into a conduit 2| having an orifice of larger'diameter,

' jet pipe delivery;

.for a rangeof ratios oi. vnozzle and orifice diameters between 1 to 2 or .5 'and 1 to 1 or unity. This curve happens to represent the fiow efilciency' of an oil which is an excellentexample for illustrative purposes. It shows that the volumetric efiiciency all! for any ratio d/D between .5 and 1.0 is greater than the efiiciency when the ratio is 1.0, the maximum efiiciency being obtained when the ratio is .8, Expressed in terms of the areas, thisratio' would .be .64'

to 1 and the critical range ofv areas wouid be 1 .to 4. Incidentally, V'represents the volume deliveredby the pumpthrough the jet pipe and v the volume regained'or delivered through the conduit 2|.

Fig. 51s a graph or chart in which the curve is drawn to illustrate the pressure regain or efiiciency under the same conditions as those explained in connection with Fig. 4. The curve also happens to show that the pressure regain or efiiciency p/P for any ratio d/D between .5 and unity isgr'eater than the emciency when the ratio is unity. This curve very closely coincides.

with the volumetric curve and also shows that a maximum pressure efiiciency is obtained when the ratio 'd/D is approximately .8.

From the foregoing explanation of the charts, it will'be seen that the ratio d/D should'be within the range .5 to 1 to produce the best results.

An'area ratio of approximately two .to three or .64 to 1 (diameter about .8 to 1) has been chosen merely for illustration in Fig. 3. However. the

critical ratio will be-diilerent depending upon the characteristics of the operating fluid, the, jet

. nozzle di'stance orz clearance, fluid pressure and other variable factors. Satisfactory results have been obtained using'regulator oils having vis cosities from about 1000 to 20 Bayboit seconds. with apressu're range or 20 to 130 pounds per square inch, and jet nozzle clearances up to about one-fourth of an inch. However, this is not intended to-deflne particular limits.

Having thus explained the nature of the invention, with the understanding thtt it is not limited to the illustrative embodiment thereof, what I claim and desire to secure by Letters Patent is:

1.'Jet relay'mechanism comprising, in com- .bination', a reception orifice; and a nozzle movable relatively to said orifice and arranged to discharge a Jet of pressure fluid into said orifice to build up a pressure in the same depending upon the degree in which the nozzle and the orifice-- register, the cross sectional area of the nozzle bore being smaller than that of the orifice bore and greater than one fourth the cross sectional area of the orifice bore, whereby the loss of fluidpressure and fluid volume becomes a minimum, and even a gain in pressure fluid volume may be attained. 1

2. Jet relay mechanism comprising, in combination, a reception orifice; and a nozzle movable relatively to said orifice and arranged to discharge a Jet 01 pressure ,fluid into said orifice to build up a pressure in the same depending upon the degree in which the nozzle and the orifice register, the cross sectional area of the nozzle bore being approximately .64 of the cross sectional area of the orifice bore,

3. Jet relay mechanism comprising, in combination, a plurality of reception orifices; and a jet-pipe mounted for movement relatively there to and arranged to discharge a jet or pressure fluidinto said orifices to create a pressure in the samedepending'upon the degree in which the jet-pipe'nozzle and the orifices register, the cross sectional area of the jet-pipe nozzle being smaller than the bore of the orifices and greater than one fourth of the cross sectionalarea of the respective orifices. v

4. Jet relay; mechanism comprising, in com bination, two reception orifices positioned adia- -cen t to each other; and a' jet-pipe pivotally mounted for movement relatively to said orifices and arranged to discharge a jet of pressure fiuid into said orifices to create a pressure in the same depending upon the degree in which the cross sectional area of the Jet-pipe nozzle being smaller than'the bore ot the orifices and greater 'jthan one fourth of the cross sectional areaoi' the orifices.

iet-pipefnozzle and the orificesmegister; the v

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