US2907336A

US2907336A - Pneumatic relay

Info

Publication number: US2907336A
Authority: US
Inventors: Edmund D Haigler; William D Huston; Jr Frederick E Lombard
Original assignee: American Machine and Metals Inc
Current assignee: American Machine and Metals Inc
Priority date: 1954-10-08
Filing date: 1954-10-08
Publication date: 1959-10-06
Anticipated expiration: 1976-10-06

Description

1959 v E. D. HAIGLER ETAL 2,907,336

- PNEUMATIC RELAY Filed Oct. 8, 1954 2 Sheets-Sheet 1 INVENTORS E'aww/va 0- Hnzcu-u.

MAL/4M a #0571) Fesoavcx Eilunraneo, JR.

BY FMM rm ATT RNEYS 0 L 195 E. D. HAIGLER EI'AL 2,907,336 PNEUMATIC RELAY Filed Oct. 8, 1954 2 Sheets-Sheet 2 BY Q r United States Patent F 2,907,336 PNEUMATIC RELAY Edmund D. Haigler, Hatboro, William D. Huston, Sellersville, and Frederick E. Lombard, Jr., Doylestown, Pa., assignors to American Machine and Metals, Inc., New York, N.Y., a corporation of Delaware Application October 8, 1954, Serial No. 461,276 1 Claim. (Cl. 137-82) This invention relates to pneumatically operated instruments and particularly to a pressure relay for use therein.

A variable condition can be used, such as temperature.

pressure, flow or the like, 'to position a valve or flapper and nozzle relative to each other so as to vary the air pressure in the nozzle in accordance with the variable condition. The nozzle can be connected to a supply of air through a restriction so that, for example, as the valve or flapper is moved to closed position relative to the nozzle by change of the variable condition, air pressure in the nozzle will rise and vice versa. In order to utilize the nozzle air pressure and produce a pressure proportional thereto, a device known as a pressure relay normally is employed, the relay being used to amplify nozzle air pressure. One of the objects of the invention is to provide an improved pressure relay organization which can be readily assembled and disassembled with respect to an instrument.

A further object of the invention is to provide a relay which can be economically made.

A still further object of the invention is to provide a pressure relay base which is rigid and will properly support the various air connections.

Another object of the invention is to provide an improved method of producing bases for pressure relays. In a preferred aspect of the invention, the relay base is formedfrom bar stock having a uniform transverse crosss'ection throughout its length. The selected bar stock is cut off to the desired length and longitudinally extendingapertures drilled or suitably formed through the base to serve as the supply pressure passage and output pressure passage, these passages intersecting a valve,

chamber located in the block between its ends. The supply and output pressure passages may be joined to a threaded connection passage to which the air lines can be connected.

A pressure responsive device may be mounted between a plate or abutment means carried on the block and a face of the block itself. In one form, the pressure responsivemeans may be a capsule means responsive to pressure for operating a valve arrangement in the valve chamber. Also it may be in the form of a pair of capsules in anon-bleedtype of relay as will be described. The supply pressure passage may have an interconnectingnozzlepressure. passage with a restriction therein for feeding airto the nozzle. The restriction may be in the form of aremovable assembly having an orifice ofthe desired size, together with a cleaning means forcleaning th'eor'ifice. .In some instances, the base and connections can,be used'witliouFthepressure responsive means. The

'r'elay of'the present invention has been found to be particularly useful in conjunction with a control instrument, but is not limited thereto, having a differential carriage, the flapper being moved by a lever and spring also mounted on the differential carriage, the carriage being rotatable about the axis of the flapper. In one arranger 2,907,336 c Patented Oct. 6, 1 959,

ment, the differential carriage also is connected through an adjustable linkage proportional band arrangement to a feedback mechanism. The nozzle is mounted on a carrier preferably composed of a pair of plates straddling the differential carriage, the carrier also being rotatable about an axis. 'The set point adjustment can be achieved by rotating the carrier, such serving to move the flapper and nozzle relative to each other.

The base of the pressure relay involved herein is rigid and can be removably mounted in the casing in which the various measuring and control elements are mounted, suitable connections being made to the supply and output lines and to the various elements of the instrument.

These and other objects, advantages and features of the invention will become apparent from the following description and drawings, which are merely exemplary.

In the drawings:

Fig. 1 is a front elevation of an instrument having a pressure relay of the present invention mounted therein;

, Fig. 2 is an enlarged sectional view of one form of the pressure relay assembly;

Fig. 3 is a section along the line 33 of Fig. 2; and

Fig. 4 is a schematic view of a relay having a different arrangement of parts as compared with 'Fig. 2 and having a different arrangement of connections thereto, the view being of reduced size. a

A general description will be given of the instrument of Fig. l, the instrument shown therein being described in detail and claimed in copending application Serial No. 456,261, filed September 15, 1954, now Patent Number 2,770,247.

Casing 20 serves as the frame to which the various elements are secured,including the measuring assembly mounting plate 21. The mechanism mounted on said plate includes the measuring, indicating and pneumatic control portions.

Bourdon tube 22 or other measuring element can be connected to the measured variable, said tube being connected through link 23 With the differential carriage 24, there being a lever 25 mounted at 25A on said differential carriage for rotating flapper 26. Nozzle 27 is mounted on carrier plate 28. The carrier is pivoted about an axis so as to permit movement of the nozzle and flapper relative to each other, said carrier being adjustable by means of set point adjusting knob, and arrangement 29. j

The carrier is connected by link 30 through suitable gauge mechanism with the set point hand 31. 'Bourdon tube 22 also is Connected through suitable gauge mechanism with indicating pointer 32. The feedback capsule or mechanism 33 is connected through the adjustable proportional band arrangement 34 to the differential carriage through link 35, this structure being described in detail in said aforementioned pending application.

Nozzle 27 is connected through pipe 36 with the nozzle passage in the pressure relay generally indicated at 37. Air is fed to the nozzle through a restriction from the supply pressure passage which also is connected to the pressure responsive means 37.

As the flapper 26 and nozzle 27 are moved relative to each other by change in the variable condition or measured variable, there will be change in pressure in the nozzle passage, which also is fed to the pressure responsive means of the pressure relay in a manner about to be described. As the pressure changes in the pressure responsive means of the relay, the output pressure passage will be connected to the supply pressure or to atmosphere as determined by nozzle pressure.

The relay is mounted on a rigid base 50 (Figs. 2, 3), said base preferably being formed from bar stock which has a uniform transverse cross section. The bar stock may be formed by rolling or other suitable metal forming operations, it being selected and cut to the desired length as needed. The rigid base also could be of formed plastic, although it is preferable that metal be employed.

Air passages can be formed in the base by suitable cutting machines. For example, the supply pressure aperture or passage 51 and output pressure aperture or passage 52 can be drilled in a suitable machine. In the form shown, these are drilled or cut from opposite ends of the base and are angularly disposed or skewed relative to each other so as to permit use of a minimum thickness of bar stock for the base. The outer ends of

passages

51 and 52 may be closed by

suitable plugs

66 and 67. The threaded connecting

apertures

68 and 69 must be of a predetermined length to provide a suitable connection.

Valve chamber 53 can be formed in the base intermediate its ends by using suitable drills or milling cutters. Valve seat 54 may be formed in the base, the other valve seat 55 being in plug 56, which is screw-threadedly adjustably mounted at 57 in aperture 58 of the valve chamber. Aperture 59 of the valve chamber can be closed by suitable screw plug means 60 having a well 62 therein carrying valve spring 61, said valve spring bearing against the valve 63. Valve 63 may be composed of two spherical elements 64A and 64B carried by spacer pin 65. Aperturcs 68 and 69 are transversely drilled so as to interconnect with supply pressure passage 51 and output pressure passage 52, the

apertures

68 and 69 thereafter being suitably treated so as to receive the external supply and output pressure connections to the relay. It should be apparent that in place of having

apertures

68 and 69 accessible from the longitudinal face 50A of the base of the relay. plugs 66 or 67 can be omitted and threads cut into the walls of one or both of the passages Sland 52 so as to receive end connection means. In Fig. 4, an end connection is illustrated at one end of the relay.

In order to provide for the nozzle supply air and a connection to the pressure responsive means, an aperture 70 (Figs. 2, 3) may be suitably formed crosswise of the base to receive the restriction or orifice assembly 71. The restriction may comprise a body 72 having a cleaning plunger 73 mounted therein, said cleaning plunger having cleaning needle 74 adapted to be passed through the orifice 75. Spring 76 normally holds the cleaning plunger in retracted position. Aperture 77 is connected to fitting 78 (Figs. 1 and 2) for receiving connecting pipe 79 to the pressure responsive means and also for receiving connection 36 to the nozzle or the source of control pressure to the relay.

The pressure responsive means can have its outer end connected to pressure responsive mounting plate 81, said mounting plate being spaced from the upper longitudinal face 82 of base 50 by means of spacer posts 83. Diaphragm stud 80 can be adjustably mounted on plate 81 by means of

nuts

84, 85. Capsule or wafer 86 has its interior connected through pipe 79 With the nozzle passage or with the control air source. Button or plate 87 is in abutting relationship with valve 64, spring 61 holding valve 6413 in contact therewith.

When there is no pressure exerted on the diaphragm, valve 64A will be in contact with valve seat 54 so as to close the connection between pressure passage 51 and the output pressure passage 52. At the same time, valve 64B will be unseated relative to valve seat 56 to permit output passage 52 to be in communication with the atmosphere and thus vent the pressure therein. As pressure increases in nozzle passage 79, valve elements 64A and 64B will reverse position so as to connect the supply pressure with the output pressure.

Supply pressure gauge 88 may be screw-threadedly engaged in the passage 89 which is formed transversely of base 50 so as to intersect and be in communicating relation with the supply pressure passage 51. If desired, a second gauge 89 (Fig. 4) may be mounted directly on the block and carried in a passage cut so as to intersect supply pressure passage 52. Connection 96 may be provided for a remote output pressure gauge 97 (Fig. 1).

The base 50 with all of its assembled parts suitably adjusted can be mounted upon casing 20, as illustrated in Fig. 2,. said casing having suitable apertures 90, 9'1 and 92 for receiving the various connections and for giving access to the clean out and adjusting plug 60. It should be evident that the assembly presents a rigid organization which can be mounted in the casing without the problem of interconnecting various parts with pipe connections which might strain the same. The relay can be adjusted exteriorally of the casing as needed. The piping stresses will be transmitted primarily to the heavy block. The principles of the base also can be employed as a connecting base for a control instrument of the type described.

In addition to the bleed type relay illustrated in Fig. 2, a non-bleed type relay 93 seen in Fig. 4 can be used. In this instance a second diaphragm 94 is employed carrying a valve seat 95 for the purpose of exhausting air from output pressure passage 98, valve 99 cooperating therewith and being movable in the same manner as valve assembly 63 of Fig. 2.

It should be apparent that details of the invention can be varied without departing from the spirit of the invention except as set forth in the appended claim.

What is claimed is:

In a pneumatic control instrument relay, the combination including a formed metal bar stock block of selected length and having uniform cross section, said block having a supply pressure aperture extending 1ongitudinally therein to a valve chamber located between the ends of the block, valve means in said chamber, an output pressure aperture extending longitudinally therein to said valve chamber, supply and output pressure connections intersecting said apertures respectively. a nozzle pressure passage intersecting said supply pressure aperture, gauge connection means with at least one of said apertures, plate means mounted on the exterior of said block, spacer post means holding said plate means spaced from said block, and pressure responsive means mounted between said plate means and block and connected to said valve means in said valve chamber, said plate means overlying said pressure responsive means so as to protect the same from damage and to maintain the elements in the desired relative positions, said pressure responsive means being adjustable relative to said plate rreans.

References Cited in the file of this patent Williams Jan. 17, 1956