US3107693A

US3107693A - Pneumatic relay

Info

Publication number: US3107693A
Application number: US112387A
Authority: US
Inventors: Louis M Puster; Joseph P Wagner
Original assignee: Robertshaw Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 1961-05-24
Filing date: 1961-05-24
Publication date: 1963-10-22
Anticipated expiration: 1980-10-22

Description

ct. 22, 1963 1.. M. PUSTER ETAL 3,107,693

PNEUMATIC RELAY Filed May 24. 1961 2 Sheets-Sheet 2 AIR SUPPLY ENGINE U L ENGINE AIR SUPPLY.

ENGINE FUEL ENGINE 3,167,693 Patented Get. 22, 1953 3,107,693 PNEUMATIC RELAY Louis 1V. Puster and Joseph P. Wagner, Knoxville, Tenn,

assignors to Robertshaw Controls Company, a corporation of Delaware Filed May 24, 1%1, Ser. No. 112,387 1 Claim. (Cl. 137-625.66)

The present invention relates to control valves and more particularly to a condition responsive diaphragm operated pneumatic relay.

An object of this invention is to control the flow of fluid under pressure into and out of a pneumatic relay in accordance with a variable condition.

Another object of this invention is to connect a source of pressurized fluid to a pneumatically operated device in accordance with a condition.

Another object of the invention is to prevent the flow of fluid under pressure from a source through the relay in accordance with a condition.

These and other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings in which:

FIG. 1 is a front elevation of the relay of the invention;

FIG. 2 is a section taken substantially along the line II--II of FIG. 1 but staggered to include oflcenter details;

FIG. 3 is a front elevation of a modification of the relay of the invention;

FIG. 4 is a section taken substantially along the line IVIV of FIG. 3 but staggered to include ollcenter details; and

FIGS. 5 and 6 are schematic diagrams of systems embodying the devices of FIGS. 1-4.

The device of this invention may briefly be described as a relay provided with a supply port, an outlet port, a vent port, a diaphragm pressure port, and a valving element movable between positions for controlling the flow of pressurized fluid into and out of the relay in accordance with a pressure condition at the diaphragm pressure port.

Referring now more particularly to the drawings, FIGS. 1 and 2 show a relay 10 comprised of a body 12, a cover 14, and a bottom cap 16. A supply port 18, an outlet port 20, and a vent port 22 are respectively formed in the body 12 and communicate with a plurality of chambers within the relay to be more fully described hereinafter. A signal pressure port 24 is formed in the cover 14 and likewise communicates with an interior chamber.

The supply port 18 communicates by means of a lateral passage 26 with a substantially cylindrical supply chamber 28 formed in the lower portion of the body 12. An outlet chamber 32 is formed by a reduced passage which extends axially of the supply chamber 28 and defines a shoulder 30 therebetween. An annular valve seat 34 is formed on the shoulder 36*.

A guide bushing 36, comprising an enlarged base portion 38 and a tubular neck portion 40 of reduced diameter, is positioned within a recess 42 in the wall of the supply chamber 28 and extends therein in coaxial alignment with the chamber 32. A circular valve poppet 44, including a stern portion 46 and an enlarged head portion 48, is provided with a circular recess in the upper surface thereof adapted to receive a relatively soft valve insert 56 therein. The stem portion 46 is reciprocable within the tubular portion 40 and the insert 50 is adapted to cooperate with the annular valve seat 34 for controlling flow of fluid therethrough. A light poppet spring 52 encircles the tubular guide portion 40 and is compressed between the base portion 33 and the underside of the valve poppet head portion 43. Communication between the outlet chamber 32 and the outlet port 21} is afforded by means of a laterally extending passage 54.

The vent port 22 communicates with an enlarged vent chamber 56 formed in the upper portion of the body 12 coaxial with the chamber 32. The vent chamber 56 receives a valve element 58 comprising a tubular stem portion 66 which extends into chamber 32 and is formed with a valve seat 62 on the end thereof and an actuating plate 64 on the opposite end thereof. A cross-drilled orifice 66 in the hollow stem portion 611 provides communication between the vent chamber 56 and the control chamber 32.

A valve spring 68 encompasses the valve element 58 within the vent chamber 56 and is compressed between a shouldered spring seat Washer 719, seated on the bottom of the vent chamber 56, and the underside of the actuating plate 64. The spring seat washer 70 is annular and the stern portion 611 extends therethrough. An O-ring seal 71 is positioned around the stem 69 between the spring seat washer 76 and the body 12 to effect a seal between the vent chamber 56 and the control chamber 32.

A diaphragm element 72 extends across the upper surface of the relay body 12 forming a flexible wall for the vent chamber 56 and also a sealing means between the relay body 12 and the cover portion 14. The central portion of the diaphragm 72 overlies the upper surface of the actuator plate 64 but it is to be understood that no connection between these elements is necessary or desired.

A shallow recess, formed in the lower face of the cover 14, provides a signal pressure chamber 74 overlying the diaphragm 72. The chamber 74 communicates with the diaphragm pressure port 24 by means of a lateral passage 76 and a perpendicular port 77.

A gasket 78, positioned between the lower face of the relay body 12 and the bottom cap 16, forms a pressure seal therebetween and appropriate assembly screws 80 are used to retain the several elements of the relay 10 in the assembled relation. Suitable mounting brackets 82 are secured to the cover 14 and bottom cap 16, respectively, and provide for panel mounting of the device.

Referring to FIGS. 3 and 4, a modification of the relay lil is shown. In the modified embodiment, the passage 154, between the control port and the control chamber 132, is extended laterally into the body 112 beyond the control chamber 132 a sufiicient distance to intersect the vertically extending passage 184 which has a smaller diameter than passage 154. This passage 184, formed is the relay body 112, connects the control chamber 132 with the diaphragm pressure chamber 174. The passage 184 extends through the relay body 112 and connects with an appropriate opening 192 in the diaphragm 172 and is in alignment with a corresponding passage 194 in the cover 114.

A substantially hollow orifice screw 186, positioned in the fluid passage 176 connecting the signal pressure port 124 and the fluid passage 184, is provided with a restricting orifice 188 in the sidewall thereof. A tapered shoulder 198, formed adjacent the head portion of the orifice screw, is adapted to engage a complemental tapered seat on the cover portion 114 to form a pressure seal therebetween. An 0 ring seal 191 is fitted within an annular recess 193 adjacent the innermost end of the orifice screw 186 forming a seal between the orifice screw and the wall of the fluid passage 176.

Operation In operation, the relay 141 will be utilized to control the flow of fluid under pressure from :a source through the supply port 18 to the outlet port 20' in accordance with the pressure condition above the diaphragm, or to dead end the supply without permitting passage of fluid under pressure to the outlet port 211. The path open to the pressurized fluid will be determined by the pressure condition existing in the pressure chamber 74. If a fluid under sufficient pressure is present within the diaphragm pressure port 24, passage 76, and chamber 7- the diaphragm '72 will be flexed downwardly, thus forcing the actuating plate 64 downwardly against the bias of the spring As the valve element 58 moves downwardly as a result of increased pressure within the chamber 74, the valve seat 62 engages the insert 5a) of the valve poppet 44, effecting a seal therebet-ween and forcing the valve poppet 44 downwardly against the bias of the poppet spring 52. The downward movement of the poppet 44 moves the insert Sll away from engagement with the annular valve seat 34, thus permitting fluid under pressure to pass from the supply port 18 to the outlet port Zilby way of the passage 26, supply chamber 23, control chamber 32, and passage 54 to the outlet port 2%.

Simultaneously, the passage of fluid under pressure from outlet chamber 32 to the vent chamber 5a? is prevented since the insert 56' has been engaged by the valve seat 62, thus effectively preventing fluid from passing through the orifice d6 of the stem so and out into the vent chamber 56. Leakageof pressurized fluid between the outlet chamber 32 and the vent chamber 56 around the stem at is precluded by the stem seal '71.

Thus, it may be seen that an increase of signal pressure of a predetermined value on the top of the diaphragm 72 results in opening of the normally closed valve poppet &4 connecting the supply chamber 28 to the outlet chamber 32, while closing the connection between the outlet chamber 32 and the vent chamber 56. Under these conditions, fluid under pressure is permitted to pass from the supply port 18 to the outlet port 29.

If for any reason the pressure existing in the chamber 74- should be reduced or dissipated, the spring will urge the valve element 38 upwardly, thus unseating the stern from the insert 50 and allowing the poppet 44 to move upwardly in response to the spring 52 thus contacting the annular seat and eifecting a seal between the supply chamber 28 and the outlet chamber 32. As the valve stem 61') moves away from the insert 5%, the control chamber 32 becomes connected to the vent chamber 56 through the orifice 66 of the stem 6% to vent to atmosphere any pressure remaining in the outlet chamber 32. Under these conditions, the supply port 18 and chamber 28 are isolated from the remainder of the relay it and remain pressurized.

in the modification shown in FIGS. 3 and 4, existence of a pressure condition of suflicient magnitude on the top of the diaphragm 172 will result in actuation of the relay llllll in the same manner as previously described; however, if the pressure within the recess 174 becomes partially reduced, the valve element 158 will remain in the downward position, thus retaining the communication'between the supply chamber 128 and the outlet chamber 132 by supply pressure on the top of the diaphragm 172 through the passage 18 iand the restricting orifice 188. It is important to note, however, that if the signal pressure existing on the top of the diaphragm 1'72 should become completely lost, the quantity of fluid passing through the restricting orifice 188 will be insufficient to retain the valve element 158 in the downward position, thus allowing the diaphragm 172 and valve element to be moved upwardly by the spring 168, seating the valve poppet 148 on the annular seat 134 and sealing the passage 13b between the supply chamber 123 and the outlet chamber 132.

While the pneumatic relays here described may have many and varied applications, their operation will be further understood with reference to a description of FIGS. 5 and 6 wherein simplified pneumatic control systems are utilized to indicate monitored variables of an engine and to shut down the fuel supply to the engine in response to predetermined changes in the variables.

Referring now to the system disclosed in FIG. 5, the system here shown requires the use of the relay ill shown in FIGS. 1 and 2. A source of fluid under pressure, in

ounces this example an air supply is connected through suitable conduits to the normally closed supply port 18 of the relay I'll. Simultaneously fluid under pressure is introduced to the norm-ally closed port 312 of a push button type three way valve 332. It will be understood that at this point no pressure will have been admitted to the system.

in order to actuate the automatic fuel supply valve fil 0*! hereby connecting port 512 with port 311 and allowing itll under pressure to flow through the restricting orifice ill to the transmitter valve 310, the diaphragm port 24 and the normally closed push button valve 326. Pressure being exerted on the diaphragm of the relay it will cause the relay to transfer connecting the supply port to the outlet 2r? and thus permit fluid under pressure from the supply to enter the system. At this time pressure will be conducted through suitable conduits to the diaphragm of the normally closed automatic fuel supply valve 394 causing the valve to transfer and connecting the fuel supply to the engine. A manually operable fuel supply valve 3% is also positioned in the fuel supply line for manually controlling the supply of fuel to engine.

In operation once the system is pressurized as described above the push button 303 of the valve 302 is released returning the port 312 to its normally closed position and pressure is maintained throughout the system through the relay Ill.

As shown in FIG. 5 the engine protected by thissystem may be shut down by any of three methods. First the transmitter 315 may sense a variation in the monitored variable condition which exceeds the present limit thus opening the transmitter valve and allowing fluid under pressure to escape from the system in general and the top of the diaphragm of the relay It) in particular. Upon a loss of pressure or the diaphragm of relay 10, the relay will transfer, closing its supply port 18 and connecting the outlet port 26 to the vent port 22. With the outlet port connected to the vent port 22 pressure previously existing on the diaphragm of the automatic fuel supply valve 39 will be released to atmosphere and the fuel supply valve Sti will transfer thus shutting off the supply of fuel to the engine.

A second method for effecting shutdown of the engine is vent the system to atmosphere by depressing the push button of valve 326. Such action will also serve to vent the diaphragm of relay 1t) and the system will shut the engine down as previously described.

A third method for effecting shutdown of the engine would be to manually actuate the manual fuel supply valve 3% to the closed position.

Referring now particularly to FIG. 6- a supply of fluid under pressure, such as compressed air or the like, furnishes the pneumatic pressure for the system and is introduced through suitable conduits to the normally closed supply port 118 of the relay 1%. Simultaneously, air is introduced to the normally closed push button type valve 29-2.

A supply of fuel to the engine is controlled by a diaphragm actuated fuel valve 204 which is shown in its normally closed position and a manually operated fuel valve 2%. A pneumatic transmitter valve 210 is employed to respond to some predetermined engine variable such as temperature, pressure, vibration, etc. When the variable is within a safe limit, the transmitter valve 210 is closed. If the variable exceeds the safe limit, the valve 210 opens and pressure within the system is vented to atmosphere through the open valve.

The entire system may be rendered operative upon actuation of the push button type valve 2432. Upon opening of the push button valve 2tl2, fluid under pressure is supplied to the transmitter 210 and the system by way of the diaphragm port 124 of the relay 1% and the passage 184 through the restricting orifice 1823. Upon the resulting increase in pressure in the recess 174 (FIG. 4), the

no push button 363 of valve 302 will be depressed :2 J diaphragm 172 is deflected downwardly causing the relay 1% to transfer, connecting supply port 118 to the outlet port 129 and blocking the vent port 122. Fluid under pressure may now flow directly from the air supply through the relay 1% to the remainder of the system. The push button valve 292- may be released to assume its normally closed position and pressure will be maintained on top of the diaphragm 172 by an automatic reversal of the flow of air through the passage 184 and restricting orifice 188.

Fluid under pressure is conducted through an appropriate conduit from the relay b to the normally closed automatic fuel valve 204 pressurizing the diaphragm of the normally closed fuel valve 204 causing it to transfer. The automatic fuel valve being a normally closed valve, is now transferred to allow fuel to pass therethrough to supply the requirements of the engine.

Assume now that transmitter valve 210 senses a change in the variable condition it is monitoring, which changed condition now exceeds the predetermined safe limit. The sequence of operation to shut down the engine to prevent damage thereto begins immediately and automatically; The transmitter valve 210 senses the unsafe condition and responds thereto by transferring to connect the transmitter supply to the transmitter vent. Pressure entrapped in the system is now allowed to escape through the open transmitter vent.

Pressure is thus allowed to escape from the diaphragm of the automatic fuel valve 204 causing it to transfer to its normally closed positions. With the closure of the valve 204 controlling the supply of engine fuel, the engine is shut down.

The system of FIG. 6 will remain in the condition described until the push button valve 292 is opened to allow a new pulse of air to pressurize the system once again. If upon introduction of new air, the transmitter valve 21% sensing the unsafe condition previously described continues to sense an unsafe condition, the new air will merely escape to atmosphere and the system will remain unpressurized and the engine inoperative.

If, on the other hand, the transmitter valve 219 has reverted to the closed position and sensed a safe condition, the system will become pressurized again as originally described. .If it is desired to shut down the engine and render the system inoperative, this may be accomplished quickly and easily by venting the pressure from the system. To accomplish this end, an additional normally closed push button type valve 226 is provided. Actuation of this valve, will result in a drop in pressure on the diaphragm of the relay 1% and a subsequent transfer of the relay 1% to close its supply port 118 to the air supply and automatically connecting the vent port 122 to the outlet 12% whereby the pressure in the remainder of the system may be vented to atmosphere.

With further reference to FIG. 6, it will be understood that the transmitter 210 may be deleted and the relay 186 in conjunction with valves 202, 226 may be used to remotely or locally control the supply of air to a valve such as the automatic fuel supply valve 204 with the advantage that if the supply of air to the relay were lost, the relay would transfer to close its supply port 118 and when the air supply was restored the relay 100 would remain closed until it was reopened by depressing push button valve 202. This feature would be particularly important in a system requiring attendance of an operator during start procedures.

It is to be understood that the invention is not limited to the details of construction and arrangement of parts disclosed except within the scope of the appended claim.

What is claimed is:

in a pneumatic relay including a relay body having an inlet port for connection to a source of pressurized fluid, an outlet port, and a vent port, the combination comprising an inlet chamber within said body connected to said inlet port, an outlet chamber within said body connected to saidoutlet port, a vent chamber Within said body connected to said vent port, a passage connecting said inlet chamber and said outlet chamber,a valve seat at the end of said passage within said inlet chamber, first valve means supported within said inlet chamber for movement between open and closed positions, a resilient valve element carried by said first valve for engaging said seat when said valve is in its closed position, a spring means normally urging said valve to its closed position, a second valve having a hollow stem slidable in a bore between said outlet chamber and said vent chamber and extending into said passage, said stem having an opening adjacent the end in said passage arranged to engage and be closed by said resilient valve element, second resilient means normally urging said second valve means to an open position away from said valve element to connect said vent chamber to said outlet chamber through said hollow stem, a signal pressure chamber having an inlet for connection with a variable signal pressure, a

iaphragm responsive to the variable signal pressure for moving said second valve against the force of said resilient means from its normally open position to engage and close said opening with said valve element and move said first valve against the force of said spring to disengage said valve element from said seat, and a restricted passage connecting the outlet port with the signal pressure port for augmenting the variable signal pressure with the supply pressure to delay the closing of said control valve upon a subsequent reduction in the signal pressure.

References Cited in the file of this patent UNITED STATES PATENTS 1,687,047 Trail i Oct. 9, 1928 2,013,665 Messier Sept. 10, 1935 2,237,930 Dewandre Apr. 8, 1941 2,514,747 Daniels July 11, 1950 2,674,266 Gardner Apr. 6, 1954 2,925,804 Hanson et al Feb. 23, 1960 2,966,927 Peters Jan. 3, 1961 2,970,612 Lornitzo Feb. 7, 1961