US2304782A - Pressure-responsive device - Google Patents

Description

Dec. 15, 1942. R. R. DONALDSON 2,304,732

PRESSURE RESPONSIYE DEVICE Filed June 10, 1940 ATTORNEY.

PBESSURE-RESPONSIVE DEVICE Robert B. Donaldson, Pittsburgh, Pa, assignor to John lVL Hopwood, Mount Lebanon, Pa.

Application June 10, 1940. Serial No. 339,691

30mins;

This invention relates to pressure-actuated devices and more particularly to pressure-actuated relay devices oi the type adapted to respond to a primary pressure or impulse and to send out a sending pressure or impulse that is proportional to the primary pressure and at the same time maintain the sending pressure constant at the particular value called for by the primary presdevice embodying a form of the invention;

Figure 2 is an end .view 01' the device as seen in looking in the direction of arrows 11-11 on P18. 1; and

Figure 3 is a view in transverse section taken on line HIHI of Fig. l. I

Throughout the drawing and the specification like reference characters indicate like parts.

The device embodying the invention in the form illustrated in Fig. 1, comprises a hollow body i, the interior oi which is subdivided into chambers A and B by means of spaced flexible pressure-sensitive diaphragms 2 and 3. Chamber A is disposed to receive a primary or actuating impulse irom a pipe 4, and chamber B is arranged to receive a sending pressure impulse from a supply pipe I which is transmitted from chamber B to a sending line I to be utilized for operating a device (not shown) which may be located at either a remote or relatively short distance from the device. The supp y pressure received by chamber B from supply line I is maintained substantially constant by any suitable mechanism (not shown). The value of the pressure in chamber B is established and maintained by means of a valve mechanism 1 that is operated by movement oi. diaphragms 2 and 3 and is, of course, determined and dependent upon the degree oi force exerted against diaphragms 2 and 3 within chamber A whether eflected by means 01 The valve mechanism is so constructed that air or other suitable pressure medium is admitted from pipe 5 to chamberB to increase the pressure therein in response to movement of diaphragms 2 and 3 in one direction, 1. e., to the right as seen in Fig. 1, and to shut oi! the admission of such medium and exhaust, the same from chamber B through an exhaust passage to reduce the pressure therein in response to movement of the diaphragm in the opposite direction.

Diaphragms 2 and 3 are urged in one direction by means of an adjustable compression spring 8 located in chamber A and a compression spring I located in chamber B. Spring 8 may be adjusted less than the pressure received by chamber A from pipe 4.

Body i comprises a bonnet or housing II which is closed at one end and open at the other with the open end terminating in'an annular flange ll, an annular spacer ring it, and a bonnet or housing l3 in which chamber B is formed. Bonnet It likewise is closed at one end and open at the other, the open and terminating in a iiange l4. Flange ii,spacer I2, and flange ll asshown in Fig. 1 have substantially the same diameter so that they may be placed one on the other in abutting relationship and bolted together by means of bolts or cap screws ll.

Diaphragms 2 and 3 are mounted in spaced relationship as an assembly or unit. This assembly comprises a tubular-threaded member I, having at one end a head II. The outer face of this head is machined to form a flange II to receive one end oi spring 9. The under side of head I! is machined to provide a shoulder ll that extends through an aperture in diaphragm 3 and serves to position the diaphragm. Diaphragm 3 is clamped tightly against flange I. by means of annular ring 20 which passes over ll. The inner face of member 2| is provided with a groove ii that terminates in an opening 22 leading into the space 23 between diaphragms 2 and 3 and this space communicates with the atmosphere through a passageway 24 that is drilled in spacing ring I2.

Passageway 24 and space 23 have communication with the interior of chamber B through a port 25 drilled transversely through member apressure medium orapurely mechanical means. 55 I6 and a longitudinal pasage 26 in member It and a valve port 21 formed in head l8. Valve port 21 is controlled by valve 1 as will be described later on in connection with the description of the valve assembly.

The central portion of diaphragm 2 rests against spacer 28 which is provided with-a shoulder 28 located in the central aperture of the diaphragm. The inner portion of diaphragm 2 is clamped tightly against spacer 28 with a cap nut 28 threaded on the end of member l8.

The outer edge of diaphragm 2v is clamped between flange II which is recessed at 8| to receive the diaphragm, and spacer l2, and the outer edge of diaphragm I is clamped tightly between spacer i2 and flange l4. Spacer I2 is recessed as 'at 8| to receive the outer edge of diaphragm 3.

The means provided for adjusting the tension of spring 8 comprises a traveling nut 82 which has screw thread engagement with a rotatable but stationary screw 33 disposed within bonnet 18. The traveling nut is provided with a shank 34 that extends into spring 8 so that the end of the spring in contact with the nut will be maintained in a fixed position with reference to the axis of screw 33. In order to prevent tuming of the nut as it is advanced or retracted along the screw, a dowel pin II is provided. One end of pin 38 extends into an edge of the travelinl nut while its outer end is disposed to slide in a guide-way or groove 38 formed on the interior of bonnet It. The dowel pin and guide-way hold nut 32 so that it cannot rotate on screw 28. The screw is formed with a shaft 61 that extends through the closed end of bonnet l0 and is provided at its outer end with a handwheel 38 whereby the traveling nut may be moved along the screw to adjust the tension of sprin 8 as required. A collar or flange 88 is formed on the shaft and this flange is iournaled in a recessed bearing and packing gland. 40, packing 4| being interposed between flange 38 and the bottom of the recessed bearing and gland 40 to prevent the escape of air or pressure medium along shaft to the atmosphere.

Valve 1 comprises a valve body 42 which is threaded through a threaded opening in the closed end of bonnet It. This valve body is hollow and is provided with a valve seat 43 at its outer end through which pressure from pipe 6 is admitted into chamber B. Valve 1 also includes a valve rod 44 which is disposed within the valve body and formed at its outer end with a valve element 45 which is mounted on a reduced end portion 46 of the rod. The valve rod is urged in a direction to seat valve element 45 on seat 43 by means of a relatively light compression spring 41. One end of spring 41 bears against the inner end opposite forces on the diaphragm assembly and a pressure medium is introduced into chamber A from pipe 4 then the valve-assembly will move towards the right as seen in Fig. 1, whereby valve element is lifted off its valve seat, and allow pressure from pipe 5 to flow into chamber B and into sending pipe 6. As soon as the pressure in chamber B exerts a force on diaphragm 3 equal to the force exerted on diaphragm 2 by the pressure in chamber A, valve element 48 will be moved "1 to the left until it seats on valve 48 and shuts of! further introduction of pressure from pipe 8 into chamber B. At this point an equilibrium is reached and the device is in balance.

As has already been stated, if springs 8 and 8 exert equal and opposite forces on the diaphragm assembly, then, as the pressure in pipe 4 and chamber A increases or decreases, the valve mechanism will be actuated to establish a pressure in chamber B that is equal to the pressure in chamber A. If the pressure in chamber A remains steady but the pressure in line 5 varies because of leakage in line 8 or in the device (not shown) being operated by the pressure in pipe 4,the diaphragms 2 and 3 will flex in such a direction that pressure frompipe 5 will be introduced into chamber B to build up the pressure therein to the required value. If the pressure tends to fall in chamber A, the diaphragms will flex in a direction to close the inlet to chamber B and open the exhaust port 21, allowing pressure in chamber B to escape through the exhaust passages to the atmosphere. Therefore the pressures in chamber B and in pipe 8 will always be equal to the value of pressure transmitted to chamber A by pipe 4, and under steady pressure conditions in chamber A the diaphragms and of valve body 42 and the other end is supported on a flanged collar 48 disposed over the middle portion of the valve rod and resting on a shoulder 50 formed on the valve rod. The inner end portion 5| of the valve rod extends into port 21 of head 11 and serves to open or close the port. Port 21 is preferably conical in form so that it will keep valve rod 44 in line and make positive seating of portion 81 in the valve port when it is positioned to close the port.

When the tension of spring 8 is adjusted so that it exerts a force equal and opposite to that exerted by spring 8, valve element 45 will be seated on valve seat 43 and the inner end of the valve rod will be seated to close port 21, whereby pressure may neither be exhausted from chamber B nor introduced into it from the supply pipe 5.

Whenever the springs 8 and 8 exert equal and valve 1 will operate to regulate the pressurein chamber B and pipe I to a constant steady value.

If the compression of spring 8 is increased by turning the handwheel 38 in a direction to move traveling nut 32 towards cap nut 28, the excess of force exerted by spring 8 in opposition to that exerted by spring 9 will represent the equivalent of a loading pressure in chamber A. This will mean that even though no pressure is transmitted from pipe 4 to chamber-A, the inlet port to value when the force of pressure exerted on diaphragm 3 balances the force exerted by spring 8 over and above that exerted in opposition thereto by spring 9.

With an adjustment such as above described, it follows that as the pressure in chamber A is increased the pressure in chamber B will likewise be increased, but the pressure in chamber B will exceed that in ichamber A by the amount of the loading imposed on the diaphragm assembly by spring 8. If the pressure in chamber A decreases then diaphragms 2 and 3 will flex to the left as seen in Fig. 1 and uncover the exhaust valve port 21, allowing pressure to escape to the atmosphere until the pressure in chamber B has been reduced to a value that will balance the force of the 'pressure in chamber A and the loading of spring 8.

The device shown may also be used as a manually-operated sending device. Thus, if no pressure is transmitted to chamber A from pipe 4,

ece ved pressures may be sent out throu h p pe t bi? il'- justine the compression of spring 0. through adjustment of spring t, it is possible to have send ing pressure sent out through pipe 3 that will vary from zero gauge pressure to tho mommum of the pressure in pipe 6.

No matter what loading is imposed by spring b when the device is mnnually operated, dia= phmgm 3 will act to regulate the pressure in chamber B and maintain it at e, value called for by the olndinz'oi spring 8. v-While only a single form of my improved preosure-sensitive relay device has been shown and described-and while only o single form of the improved valve mechanism has been disclosed, it wilibeapporenttothoseekiliedintheertthct various modifications and changes may be mdc without either from the miter from the scope of he; invention Thereiore, what i cluim and desire to secure by Letters Patent is:

i. A relay for sending and maintaining presa hollow member located between them nt their middle portions, o clamping member extending through said spacer and diaphremo and rigidly secured thereto but movnble thercwit said spacer hcvinu o posceeeway opening into the space between the diflDWi ii acid body having an exhaust cpeninc providing H 11 mm; cation between the space between the diophrogms end the atmosphere, said clumping membm' mt ing a, passageway formed therein extending from the chamber side thereof to the suid hollow mem ber, thereby providing at 's i rowdy from the interior of said chamber to the atmosphere, a valve body mounted on said relay body and hav ing an inlet port adapted for connection to as source of pressure medium, a valve stem within said valve body and bovine e valve element adopted to seat on said inlet port, the other end of said valve stem extending into said climber and seating in the chamber end oi the way in said clamping member, whereby in response to on actuating force being applied to cold diophregms in one direction, the valve stem is cure in the member on the oienhrcema are in ectuotcd to odmit hnnouro to void chommre, said inlet end cold 9mm in when the force exertedbythepmsiueonaaid diaphragm '11:; the octuetins force and the inlet being closed and the exhaust is uncovered when the force of pressure excwdc the actuating force.

2.Arele.yioreendincpreesurectoaeendine line and such pwrea at values that are proportional plied to tln relay, comprising a housing, a die phraem assembly forming a cloned chamber at one side thereof in sold housing, actuating means on the other side of said diaphragm assembly yieldingly urging the diaphragm assembly in one direction, vulvc moons associated withand actudied by said diophrcgm assembly fordelivering pressure medium to the chamber and tending line until the premure therein is of a value suiucicnt to the actuating force, said die.- phragm assembly comprising spaced dlaphragms, means for holding said diaphragms in spaced relotion at the edges and the middle portions thereof, the holding means at the middle portioncoi the diaphragm being provided with a passage way establishing communication between the chamber and the atmosphere, there being on er heust valve sent formed at the chomber end of sold passageway, the valve assembly having a valve stem one end of which is positioned to cover or uncover the exhaust valve sent, the other end of the vulve stem controlling the inlet of said balance, end to open the exhaust passase valve sent and close the inlet of the valve when the force exerted by the pressure on the diaphramns exceeds the opposing octuotine force.

3. A device according to claim 2 characterized by the fact that the valve means comprises a body adjustebly mounted on the housing and extending into the pressure chemben'a valve stem extending through mid'body and provided with e "valve element at one end odcpted to open or close the inlet port of the vulve body and havihc its opposite end udeptcd to be rwcived in the on haust volve cent associated with the diaphragm assembly, and means yicldineiy urging the valve stem in a. direction to close the inlet port.

nonm'r R. DONALDSON.

to an actuating force sp

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