US2319907A - Blow-off valve - Google Patents

Description

May 25, 1943. E D 'STIRLING I 2,319,907

BLOW-OFF VALVE Filed Jan. 30, 1942 2 Sheets-Sheet l INVENTOB FREDERICZKnSTIRUNG ATTOR'NES May 25, 1943. F. D. sTlRLlNG 2,319,907

BLOW-OFF VALVE Filed Jan. 30, 1942 2 Sheets-Sheet 2 FIG. 3

l NvEN'ron FREDERICKDSTIRU NG Wma@ ATToR Patented May 25, 1943 BLOW-OFF VALVE Frederick D. Stirling, Montreal, Quebec, Canada, assigner to T. McAvity & Sons Ltd., Montreal,

Quebec, Canada Application January 30, 1942, Serial No. 428,928

1 Claim.

This invention relates to improvements in blow-nii apparatus for locomotives and other boilers.

The main object of this invention is to provide a more satisfactory and efficient blow-01T apparatus of the type in which the stem of the blow-off valve is connected to an operating piston working in a cylinder to which steam is supplied to open the valve against the resistance of a valve closing spring. In such apparatus various methods of packing the valve stem guide have been resorted to in order to prevent the action of the valve stern and the piston being interfered with by the clogging action of sludge accumulating within the valve stem guide and within the piston cylinder. None of these packing methods has proven entirely satisfactory and considerable difficulty is still experienced in connection with sticking of the valve and/or the valve operating piston due to the clogging action of the sludge which is blown through the valve guide and into the piston cylinder.

According to the present invention the packing usually interposed between the valve stem and the valve stem guide is omitted and means, preferably operating on the ejector principle, is provided for removing from the valve stem guide and the cylinder the sludge which passes into these parts during the open period of the blowoff valve.

A further feature of the invention resides in the provision of a blow-oi apparatus consisting of two units including an emergency shutdown unit and a blow-off unit combined in a novel manner to provide for relative angular adjustment thereof, the shut-down unit comprising a screw-down valve contained in a valve body 'which is fastened in place over the sludge discharge opening of the boiler and the blow-off unit comprising a piston actuated blow-off valve contained in a separate valve body which is bolted or otherwise fastened to the rst mentioned valve body so that the angular relation between the two units may be changed to vary the angular relation between the inlet and outlet ends of a valve-controlled blow-off passage conjointly provided by said units.

Another feature of the invention resides in the provision of an improved control unit for controlling the flow of steam or other pressure fluid to and from the operating cylinder of the blowoff valve.

The foregoing and other objects, advantages and characteristic features of the invention. will be` more readily understood from the following detailed description taken in connection with the accompanying drawings,` in which- Figure 1 is a side elevation of a blow-nii apparatus embodying my invention.

Figure 2 is a longitudinal sectional view taken substantially along the line 2-2 of Figure 1.

Figure 3 is an elevational view of a portion of a control valve assembly forming part of the apparatus appearing in Fig. 1.

Figure 4 is a top plan view of the assembly shown in Figure 3.

Figure 5 is a vertical sectional View of the valve assembly shown in Figs. 3 and 4 with the addition of an operating handle.

As shown in these drawings, my improved blow-off apparatus comprises three main units including an emergency shut-oi" unit A, a blow-o unit B and a control unit C.

Unit A comprises a valve body 4 provided with a blow-off passage 5 consisting of two intersecting bores 6 and 'I arranged at right angles to each other, the end 8 of bore 6 constituting the entrance end of said passage and the end 9 of bore 'I constituting the exit or discharge end of said passage. A valve seat I0 is provided adjacent the discharge end 9 of said passage and is adapted to be engaged, at times, by an emergency shut-off valve I I, the latter being provided with an operating stem` I2 in threaded engagement I3 with a valve-stem guide and packing gland I4 fitted in the end of bore 'I remote from discharge end 9. The outer end of valve stem I2 is formed so that a hand wheel or other turning device may be applied thereto for turning the stem in either a valve opening or a valve closing direction. Normally the shut-off valve Il is positioned in a retracted or open position with reference to the seat I and is closed against the seat only in case of emergency to shut off the discharge of sludge from the boiler through the passage 5.

Unit B comprises a valve body I5 provided with a substantially L-shaped blow-off passage Ilia formed by two intersecting bores I6 and I'l arranged at right angles to each other, the inlet end of said passage being formed by the end I8 of bore I6 and the outlet end of said passage being formed by the end I9 of bore I1. The bore I6 is provided, intermediate its length, with an inwardly projecting rib 20 dividing said bore into two chambers designated 2l and 22. The end of bore I6 remote from the entrance forming end I8 is closed by a wall 23 provided with a centrally disposed, tubular, valve-stem guide 24 which projects into chamber 22 and across the adjacent gagement with the piston 29.

end of bore A valve stem is sildably arranged in guide 24 and is provided, at one end, with a, Valve 26 which is normally closed against a Valve seat member 2l, the latter having screw threaded engagement with a wall portion of chamber 2| and being butted against the rib 20. A piston 29 is secured to Valve stem 25 at the end remote from valve 26. This piston works in a cylinder 30 formed by a casing 3| which is fastened by stud bolts 32 to valve body l5 so that the inner end of the cylinder is formed by the aforesaid wall 23. Valve 26 is normally held closed by a spring 33 encircling the valve stem 25 between the cylinder end of valve-stem guide 24 and an abutment 34 carried by said stem adjacent its point of connection to piston 29. A bent sludge ejector tube 35 is arranged in bore with the upper end of the Ytube fitted in an opening 36 provided in the previously mentioned wall 23. Tube 35 is thus in open communication with cylinder 36 and with the cylinder end of valve-stem guide 24.

As shown more particularly in Fig. 1, piston 29 is provided with drain openings 40 which register with similar openings 4| of cylinder casing 3| when the piston is in the valve closing position shown in the drawings. The outer ends of the drain openings 4| are normally closed by removable drain plugs 42.

The end wall of cylinder casing 3| is also provided with three openings designated 44, and 46. Opening 44 constitutes a steam inlet opening through which steam is supplied to the outer end of cylinder 30 to move piston 29 to a valve opening position against the resistance of valve closing spring 33. Opening 45 is a drain opening for the outer end of cylinder 30 and is intended to be connected to a suitable form of normally closed automatic drain valve (not shown) which opens when pressure in cylinder 36 drops below a predetermined value due to condensation of steam which occurs in the supply line connected to steam inlet 44 when said inlet is connected to drain to permit the piston 26 to return to a valve closing position after being actuated to a valve opening position. Opening 46 is a threaded opening through which is threaded a manually operaible valve actuating plunger 49 provided at its inner end with a head 50 for en- When it is desirable or necessary to effect manual opening of the "blow-oil valve 26, this may be accomplished by screwing the plunger 46 inwardly so that the vhead 56 will engage and force the piston 29 to a valve opening position against the resistance of spring 33. To facilitate operation thereof the plunger 49 is provided with handle means 5| at its outer end and is also threaded through a nut 52 which bears against the cylinder casing 3| and is provided with a suitable handle extension 53.

Unit C comprises a valve casing 55 provided with an upper steam inlet port 56, a lower drain port 5l and an intermediate port 58. Ports 56 and 5'! open, respectively, into upper and lower chambers 59 and 66. Port 58 opens into a Vertical passage 6| which connects the chambers 59 and 66, the upper end of passage 6| being provided with a Valve seat 62 and the lower end of passage 6I being provided with a valve seat 63. Communication between chamber 59 and passage 6| is normally disrupted by a valve 65 which is closed against the valve seat 62 by a Valve closing spring 66. Chamber 60 contadns a. normally open valve 61 which, at times, is closed against the seat 63 by moving a valve opening plunger or stem 68.

plunger 66 in a valve closing direction against the resistance of a spring 69 which is conned between the lower end of casing 55 and an enlargement 10 provided at the lower end of the The plunger 68 is moved to a valve closing position against the resistance of spring 69 by means of an operating handle which is pivoted to casing 55 as indicated at 12 and is provided with a valve operating nger or projection |3 engaging the enlargement 10 at the lower end of stem or plunger 68.

A stem 12a is interposed between the valves and 61 so that, through the agency of said stem, the valve 65 is raised from its seat 62 when the valve 6l is closed against its seat 63. Stearninlet port 56 of control unit C is connected to receive steam from the locomotive boiler or any other suitable source while the intermediate port 58 of said unit is connected by pipe 'I5 to the steam inlet opening 44 of cylinder casing 3|. When the component parts of control unit C are arranged as shown in Fig. 5, the steam inlet port 44 of cylinder casing 3| is connected to drain through pipe 'I5 and port 58, passage 6|, and chamber 60 of control unit C. In these circumstances there is no steam pressure in the right hand end of cylinder 30 and the blow-off valve 26 is held closed by the spring 33. When it is desired to open the blow-01T valve the handle of control unit C is operated to close valve 6l and to open valve 65. This permits steam supplied to the inlet port 56 of unit C to flow through chamber 59, passage 6|, and port 58 of unit IC and through pipe 15 to the right hand end of cylinder 36 so that the steam pressure thus developed in the right hand end of said cylinder causes piston 29 to be moved'to the left to open the blow-off valve 26.

In the use of this apparatus the units A and B are secured together by bolts '|8 so that the blow-off passage |5a of unit B constitutes a continuation of the blow-off passage 5 of unit A. Unit A is provided at the entrance end 8 of blow-off passage 5 with a ange 80 which is adapted to be bolted to the locomotive boiler 'so that the entrance end of blow-off passage 5 registers with the boiler sludge discharge opening. Unit A is also provided with an atta-ching flange 86a which surrounds the discharge end 9 of passage 5 and is fastened by the bolts 18 to a flange 8| which surrounds the entrance end I8 of the blow-off passage |5a of unit B. The number and arrangement of the fastening bolts 'I8 and the bolt receiving openings provided in coupling ilanges 86a and 8| of units A and B is preferably such that these units may be bolted together so that the axis of bore of unit B extends in the same direction as the axis of bore 6 of unit A or in such manner that the axis of bore I1 extends in a direction at right angles to the direction of the axis of bore 6. The last mentioned arrangement is sometimes resorted to when it is necessary or desired that the discharge end of the complete blow-OIT passage conjointly provided by units A and B be directed at right angles to the inlet end of said passage. Assuming that shut-down valve v|| is in its normally open position and that blow-ofi valve 26 has been operated to open position either by the admission of steam 'to the right hand end of cylinder 36 or by operation of the emergency screw plunger 49, the direction of ilo-w of sludge through the complete blow-off passageconjointly provided by units A and B v`will be 'substantially as represented bythe arrows in Fig. 2. ySince there is no packing in the valve-stem guide 24, a portion of the sludge will pass through this guide and into cylinder 3,0. However, as the blow-off steam from the boiler passes through chamber 22 and bore l1 it ex `panels and increases in velocity so that as this high velocity steam passes the discharge end of the ejector tube 35 it creates suillcient suction in the tube to withdraw therethrough the sludge which has entered cylinder 30 through valvestem guide 24. In practice it has been found that, with this arrangement, the valve-stem guide and the cylinder are kept suiliciently clear of accumulated sludge to prevent interference with the action of the valve 26 and the piston 29.`

When the valve 26 is in closed position the boiler pressure acting through the passage 5 of valve body A assists the spring 33 in holding the valve tightly against its seat 21. It will be noted, however, the area of valve 26 is less than the area of piston 29. Consequently, the boiler pressure acting to hold valve 26 in its closed p0- sition will not prevent the opening of this valve by the boiler pressure steam ywhich is supplied to cylinder 30 to move piston 29 in a valve opening direction.

Any suitable packing may be arranged between the flanges 80a and 8| of the units A and B and, if desired, between flange 80 of unit A and the portion of the boiler to which said flange is secured.

Having thus described what I now consider to be the preferredembodiment of this invention it will be understood that various modifications may be resorted to within the scope and spirit of the appended claim.

Having thus described my invention, what I claim is:

Blowi apparatus comprising a valve body provided with a bore having one end open and the other end closed by an end wall provided with a valve-stem guide which extends from one side of said lwall toward the open end of said bore, a valve seat arranged in said bore between said Valve stem guide and the open end of the bore, a second bore provided in said valve body and arranged to extend at an angle to said rst mentioned bore, said second mentioned bore being open at both ends and having one end communicating with the iirst mentioned Ibore adjacent said end wall, an ejector tube arranged in said second mentioned bore with one end of the tube itted in an opening in said end wall and the other end of the tube directed away from said first -mentioned bore, a casing'secured to said end Wall to form a cylinder located at the side of said end wall remote from the valve-stem guide, the interior of said cylinder being in communi cation with said second mentioned bore through said tube, a piston working in said cylinder, a valve stem working in said valve-stem guide and having one end secured to said piston, a valve secured to the opposite end of said valve stem, biasing means normally holding said valve in a closed position against said seat and means for supplying steam to said cylinder to move said piston to a valve opening position against tne resistance of said biasing means.

FREDERICK D. STIRLING.

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