US2385151A - Automatic blow-off valve apparatus - Google Patents

Description

AUTOMATIC BLOW-OFF VALVE APPARATUS Filed Feb. 27, 1943 D k v Q R) m K) i N :r i. N

I INVENTOR RAYMOND E, MILLER ZYZZMJZ,

ATTORNEY Patented Sept. 1 8, 1945 UNITED STATES PATENT OFFICE AUTOMATIC BLOW-OFF VALVE APPARATUS Raymond E. Miller, Wilkinsburg, Pa, assignor to The Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Application February 27, 1943, Serial No. 477,404

4 Claims.

This invention relates to apparatus for eifecting the removal of mud or sludge from steam boilers or for effecting the removal of collected liquid condensate from an air storage reservoir and the like.

It is well known by those skilled in the art that as feed water added to a locomotive steam boiler is changed to steam, the solids in the water are deposited in the form of mud or sludge in the mud-drum of the boiler or in the water space between the inner and outer plates of the boiler above the foundation or mud-ring. In order to prevent damage to the boiler and to effect safe and efficient operation of steam locomotives it is therefore necessary to prevent an excessive amount of such mud or sludge from accumulating in the boiler.

In locomotive construction it is common practice to provide a communication leading from some low point interiorly of the boiler, such as the mud-drum or the water space between the inner and outer plates of the boiler just above the mud-ring, to the exterior of the boiler through which the mud or sludge collected in the boiler may be discharged to the road bed. Heretofore it has been common practice to interpose in this communication a blow-off Valve which normally closes the communication and which must be operated manually by the engineman at intervals of from to minutes to discharge the collected mud. The timing of such operation is left to the enginemans judgment and since his most important consideration is to attend to operating duties and in view of the fast operating schedules which must be maintained and the heavy trafiic conditions which are met he cannot be relied upon to eiiect anything but haphazard control f the blow-off valve.

From the foregoing it will be understood that manual control of the blow-off valve is very often unsatisfactory, for the reason that too frequently boiler water is either blown off when there is no necessity for doing so, or it is not blown off until after trouble has occurred. Either practice results in costly wastes.

The principal bject of the invention is to provide means which is automatically operative, at predetermined regular intervals, to discharge accumulated foreign matter from air storage reservoirs or to discharge accumulated mud or sludge from a locomotive steam boiler.

According to the invention this object is accomplished by means of a blow-off valve which in the case of a locomotive is interposed in the usual boiler sludge or mud discharge communication which is automatically controlled by means of a fluid pressure responsive mechanism.

Other objects and advantages will appear in the following more detailed description of the invention.

In th accompanying drawing; Fig. 1 is a diagrammatic view, partly in section, of steam boiler blow-01f apparatus embodying the invention; Fig. 2 is a fragmentary diagrammatic elevational view,on a reduced scale, illustrating the blow-ofi apparatus in connection with a locomotive steam boiler. I

As shown in Fig. l the apparatus comprises a combined blow-offvalve and fluid pressure control mechanism I, two volume reservoirs, 3 and 4, which as shown, may be combined in a two compartment casing structure. The apparatus also comprises a cut-out cock device 5 which may be located in the cab of' a locomotive and is manually operative to cutoff the supply of fluid under pressure to the fluid pressure control mechanism.

The combined blow-off valve and fluid pressure control mechanism I may comprise a pipe bracket portion 1, a blow-off valve portion 8 comprising a valve body section 9 and a cylinder section II), a fluid pressure vent valve portion II and a control portion 12, which portions are secured together in any suitable manner. For insuring leak tight joints, suitable gaskets may be interposed between the adjacent sealing faces of the various casing portions, such as gasket l3 which is interposed between the pipe bracket portion 1 and the blow-off portion 8, and a gasket 14 similarly clamped between the pipe bracket portion and the control portion I2.

The valve body section 9 of the blow-off valve portion 8 has formed thereinan inlet chamber 15 which, as shown in Fig. 2, is connected through a pipe 18 to the mud-drum or water space between the inner and outer plates 16 and I1, respectively, of the boiler, just above the mud-ring. In this valve body there is also formed an outlet chamber l9 which, as shown in Fig. 2, may be connected to a pipe 20 leading to the road bed or if desired may be connected to a blow-ofi mufiier r blow-off separator of the usual well known type.

The inlet and outlet chambers l5 and I9, respectively, are separated by an apertured baffle wall 2| having formed therein an annular valve seat 22. A blow-cit valve 23 disposed in chamber [5 is adapted to engage the valve seat 22, and is provided with a vertically disposed stem 24 which is slidably mounted for vertical movement in a suitable bore provided in the cylinder section 10.

Th stem 24 is operatively connected at its upper end to a piston 25, the upper face of which is subject to the pressure of fluid in a chamber 26. A coil spring 21 is preferably interposed between the piston 25 and a shoulder 28 formed on the cylinder section H), which spring, at all times, tends to urge the piston and associated blow-off valve upwardly into the position in whichthey are shown in Fig. 1 of the drawing.

The control portion I2 may comprise a casing in which there is mounted a piston 23. At one side of the piston there is a chamber 30 which is constantly connected to a passage 3| which extends through the pipe bracket portion I and leads to the vent valve portion II and which is also connected to a branch passage 32 in the pipe bracket, which latter passage is connected to a pipe 33 leading to the volume reservoir 4. At the opposite side of the piston there is a valve chamber 35 which is constantly connected to a passage 36 which leads to the pipe bracket portion I. This chamber is also constantly open to a passage 3'! which extends through the pipe bracket portion 1 and which is connected to a pipe 38 leading to the volume reservoir 3.

Contained in valve chamber 35 is a slide valve 39 which is adapted to be operated by a piston stem 40 carried by the piston 29, Contained in chamber 38 is a spring 4| which, at all times, acts on the piston and tends to urge the piston, piston stem and slide valve toward the position in which they are shown in Fig. 1 of the drawmg.

The vent valve portion I I may comprise a casing having a chamber Ila, which is in constant open communication with the atmosphere by way of an atmospheric passage ll'b. Contained in this chamber is a valve Me which is subject to the pressure of an adjustable spring Nd and is adapted upon a predetermined increase in the pressure of fluid in passage 3| to unseat and establish communication between passage 3| and chamber I la and upon a predetermined decrease in the pressure of fluid in passage 3| to seat and cut off communication between the passage and chamber IIa. As shown the vent valve portion may be similar in construction and operation to the usual known safety valve device.

The pipe bracket portion 1 has formed therein a chamber 44 open at one end containing a strainer unit 45, which is inserted through the open end of the chamber and which is secured in the bracket portion by means of a screw plug 46 having screw-threaded connection with the bracket. suitable type but as shown may comprise outer and inner cylindrical members 41 and 48 made of wire mesh or similar material having packed therebetween a quantity of straining material 49. The inner surface of the cylindrical member 48 defines a passage 50, which is open to the passage 35 leading to chamber 35 in the control portion I2. Interposed in passage 50 is choke plug 5| having a restricted passage .55 therethrough which controls the rate of flow of fluid from passage 50 to passage 35 for a purpose hereinafter described. The chamber 44, exteriorly of the strainer unit is in constant open .com munication with a passage and pipe 52 leading to any suitable fluid pressure supply source.

The cut-out cock device 5 is interposed in the pipe 52 and may be of any suitable, well known construction having a cut-in position for opening communication therethrough and a cut-out po- The strainer unit 45 may be of any,

sition for cutting off communication therethrough.

Operation Assuming a locomotive, embodying the invention, is to be conditioned for service, the fluid pressure source (not shown) is charged to the pressure normally carried in the fluid pressure system. The cut-out cock device 5, may be in its cut-out position so that the several parts of the blow-off apparatus will be in the position illustrated in Fig. 1 of the drawing.

Now when it is desired to eflect operation of the blow-off apparatus, the cut-out cock device 5 is moved to its cut-in position. With the cutout cock in its cut-in position, fluid under pressure flows from the source of fluid under pressure through the cut-out cock 5 and pipe and passage 52 to the chamber 44 in the pipe bracket portion 1 of the combined blow-off valve and control mechanism I. Fluid under pressure thus supplied to chamber 44 flows through the strainer unit 45 to passage 50 from whence it flows through the restricted passsage 55 in choke'plug 5| and passage 36 to chamber 35 in the control portion I2.

Fluid under pressure flows from chamber 35 to volume reservoir 3 by way of passage 31 and connected pipe 38, the spring 4| maintaining the piston 29 and attached slide valve 39 in the position shown for a reason presently described. With the piston 29 in the position shown, fluid under pressure supplied to chamber 35, flows therefrom through a feed groove 60, having a predetermined flow area, to chamber 3!) and thence through passage 3| to the vent valve Fluid under pressure thus supplied to passage 3| also flows to volume reservoir 4 by way of passage 32 and pipe 33.

It will be understood that the restricted passage 55 in the choke plug 5| and the flow area of the feed groove 60 around the piston 39 are so proportioned that the spring 4| will maintain the piston and attached slide valve 39 in the position shown during the initial charging operation, so that the volume reservoirs 3 and 4 will be initially charged to substantially the same pressure.

Now when the pressure of fluid in the volume reservoirs 3 and 4 and acting against the valve ||c within the seated area of the valve has been increased to a degree suflicient to overcome the opposing pressure of spring IId, the valve will be cracked open. When this occurs the entire area of the valve will be subjected to the pressure of fluid in passage 3|, and as a result the valve will quickly snap to its unseated position. With valve He thus unseated, fluid under pressure in passage 3| is vented to the atmosphere by way of chamber Ha and atmospheric passage llb. As a result of this venting, the pressure of fluid in the connected chamber 30 and volume reservoir 4 will be reduced to that of the atmosphere.

It should here be mentioned that the vent valve II has a relatively great pressure range between its Opening and closing values, and that its capacity is such that when open or in its venting position it can, in a relatively short time, reduce the pressure in the chamber 30 and volume reservoir 4 to some predetermined low value, i. e. the closing value of the vent valve. It will be understood that the vent valve operates to reduce the pressure in chamber 30 and volume reservoir 4, at amuch faster rate than fluid under pressure can flow from chamber 35 to chamber 30 by way of feed grooves 60. Under these conditions the higher pressure of fluid in chamber 35 causes the piston 29 and attached slide valve 39 to move in a, direction toward the left hand against the opposing force of the spring 4I until brought to a stop by the piston engaging a sealing gasket 62, thus cutting off further flow of fluid through the feed groove 60 to chamber 30.

With the piston 29 in this position the slide valve 39 will be positioned so as to uncover a passage 63, in the seat for the slide valve, to the valve chamber 35, which leads to the chamber 26 in the cylinder section I of the blow-ofl valve portion 8 and also through a connected restricted passage 65 to the atmosphere. With the passage 63 thus uncovered, fluid under pressure flows therethrough from the slide valve chamber 35 and connected Volume reservoir 3 to the chamber 25 in the cylinder section I0 and also to the atmosphere by way of passage 63 and connected restricted passage 65. When, due to this flow, the pressure in chamber 26 has been increased to a degree slightly exceeding the opposing pressure of the spring 28, the piston and attached stem 24 will be caused to move downwardly from the position in which they are viewed in the drawing. This downward movement of the piston and attached stem causes the blow-off valve 23 to move in the same direction and out of sealing engagement with its seat 22. With the valve 23 thus unseated the water space between the inner and outer plates I5 and I6 of the boiler or the muddrum of the locomotive boiler is connected to the atmosphere by way of pipe I8, inlet chamber I5 in the valve section 9 of the blow-off portion 8, past the unseated blow-off valve 23, outlet'chamber I9 and pipe 20. With this communication thus established, the mud or sludge deposited in the mud-drum will be discharged.

When the pressure of fluid in chamber 30 and connected volume reservoir 4 is reduced to a predetermined value, i. e., to the closing value of the vent valve I I the vent valve will operate to close and cut-oiT further venting of fluid from the chamber and connected volume reservoir thus trapping a predetermined degree of fluid under pressure in the chamber and connected volume reservoir 4. Now, when the pressure of fluid in chamber 35 and connected volume reservoir 3 has been reduced, due to the venting of fluid by way of restricted passage 65, to a degree slightly below the combined opposing pressures of the trapped fluid and the spring 4|, in chamber 30, the piston 29 and attached slide valve 39 will be caused to move in a direction towardthe right hand into the position in which they are shown in the drawing.

It will be understood'that the restricted passage '65 controls the rate at which fluid under pressure is vented from chamber 35 and connected volume 3 and thus controls the length of time the blowoff valve is maintained unseated. It will also be understood that this time interval can be changed by changing the flow area of such passage to meet various requirements.

With the slide valve 39 thus positioned, com- 'munication between chamber 35 and passage 63 is cut-off and a cavity 68 in the slide valve establishes a communication between chamber 26 in the cylinder section II] of the blow-off valve portion 8 and the atmosphere 'by way of passage 63, cavity 68 in the slide valve and an atmospheric passage 69 through which fluid under pressure in chamber 26 will be quickly vented. When,

due to such venting, the pressure of fluid in chamber 26 is reduced to a degree slightly below the opposing pressure of the spring 21, the piston 25, stem 24 and blow-off valve 23 will be returned to the position in which they are shown in the drawing. With the blow-ofi valve 23 in this position, communication between inlet chamber I5 and outlet chamber I9 in the body section 9 will be cut oil, thus cutting off communication between the boiler and the atmosphere.

As soon as the piston 29 and slide valve 39 are returned to the position in which they are shown, the feed groove 60 again establishes communication between chambers 35 and 30, so that fluid under pressure is again supplied from chamber 44 to volume reservoirs 3 and 4 and the vent valve II in the same manner as hereinbeforedescribed. When the pressure of fluid in the volume reservoirs 3 and 4 and connected chambers have again been increased to the opening value of the vent valve, the vent valve will open and vent fluid from passage 3I and thereby from piston chamber 30, to again the control piston 29 to operate to effect the unseating of the blow-oft valve 23.

The interval of time elapsing between the successive openings of the blow-off valve 23 is determined according to relation between the flow area of the restricted portion of the passage in the screw plug 5I and the volume of the reservoir 3, all of which may be determined in accordance with railroad requirements.

From the foregoing description it will be understood that so long as the cut-out cock device 5 is maintained in its open position, the blow-off apparatus will operate at regular predetermined intervals of time, without attention from the engineman, to open the communication from the boiler to the atmosphere through which mud or sludge may be discharged from the boiler, In this way the inherent difliculties encountered with usual intermittent manually operable blow-off valve arrangements are eliminated and the discharge of mud or sludge from the boiler is controlled automatically, simply and systematically.

Although, the description of the apparatus has been more or less limited to the use of the invention in connection with the discharge of mud or sludge from a steam boiler, it will be understood that if desired this apparatus could be employed to drain collected liquid condensate from air storage reservoirs. To accomplish this it is only necessary to connect the inlet pipe I8 to the lower portion of a reservoir to be drained. With the inlet chamber I5 of the body portion 9 of the blow-off portion IIJ connected to a reservoir instead of to a steam boiler it will be apparent that the apparatus will operate in the same manner as previously described in connection with the discharge of mud or sludge from a boiler, to discharge collected condensate from the reservoir.

Having now described my invention, What I claim as new and desire to secure by Letterse Patent,i's:

l. A fluid pressure responsive control device comprising, in combination, a piston motor device having a fluid pressure chamber, a casin having a control passage through which fluid under pressure may be supplied to said pressure chamber to operate said motor device, an always open restricted exhaust communication leading from said passage to the atmosphere, a second chamber which may be charged with fluid under pressure constantly supplied from a fluid pressure supply source at a certain rate, a third chamber supplied with fluid under pressure from the secend mentioned chamber, a valve movable to one position to admit fluidunder pressure from the second mentioned chamber to said passage, and operative to another position tor isolating said second chamber from said passage a movable abutment subject tothe opposing fluid pressures in the second and third chambers and operative in response to a reduction in the pressure of fluid in said third -'chamber for actuating said valve to admit fluid under pressure from the charged second chamber to said passage, valve means operative in response to a certain increase in the pressure of fluid in said third chamber for reducing the'press-ure' of fluid in the third chamber to a certain degree; and zineans operative upon a re duction in --the pressure of fluid in the second mention-ed chamber to a certain degree by the flow of fluid therefrom by way of saidrestricted exhaust passage for effecting the operation of said abutment to move said valve to its second mentioned position, the exhaust flow of fluid from thesecond mentioned chamber by way'oi said passageandsaid communication being at a rate in excess of that o'f the supply thereto from the'fluid pressure supply source.

' 2. A fluid pressure operated control valve device comprising, in combination, a fluid pressure responsive device, a casing having therein a control passage through which fluid under pressure may flow to said fluid pressure responsive device for the operation thereof, a'first chamber charged with fluid under pressure, a second chamber charged with fluid under pressure from saidfirst chamber, a valve having one position for admitting fluid under pressure from said first chamber to said passage to operate said fluid pressure responsive device and having another position for isolating the first chamber from said passage and for connecting the passage to the atmosphere, a movable abutment subject to the opposing pressures of fluid in said first and said second chambers and operative in response'to a preselected reduction in the pressure of fluid in said second chamber for shifting said valve to said one position and for closing the charging communication between said first and second chambers and operative in response to a subsequent pro-selected reduction in the pressure of fluid in said first chamber for shifting the valve vice comprising, in combination, a motor device having'a piston cylinder, a casing having therein a control passage through which fluid under pressure may flow to said cylinder to effect the operation of said'device, a first chamber charged with fluid under pressure, a second chamber charged with fluid under pressure from said first chamber, valve means subject to the opposing pressures of fluid in said first and second chambers and having a position in which charging fiuid flows from said first chamber to said second chamber and in which said passage is connected to the atmosphere, said valve means being responsive to a pre-selected reduction in the presence of fluid in said second chamber to cut ofi the charging flow of fluid from said first chamber to said second chamber and to admit fluid under pressure from said first chamber to said passage, an always open exhaust communication through which fluid under pressure may flow to the atmosphere to effect a reduction in the pressure of fluid in said. first chamber at a preselected slow rate, said valve means being responsive when the pressure of fluid in said first chamber has been reduced to a pre-selected low degree to isolate the passage from said first chamber to said passage, to additionally connect the passage to the atmosphere and to admit charging fluid from said first chamber to said second chamber.

4. A fluid pressure responsive control device comprising, in combination, a fluid pressure motor device having a pressure chamber, a casing having a control passage through which fluid under pressure may be supplied to said pressure chamber to operate said motor device, an always open exhaust communication for venting fluid under pressure from said passage to the atmosphere at a certain restricted rate, a valve chamber supplied with fluid under pressure at a certain rate slower than the first mentioned rate, a valve in said chamber having a normal position in which said passage is connected to atmosphere and an operative position in which said passage is connected to said valve chamber, a third chamber, a movable abutment having a normal position in which fluid under pressure is supplied from said valve chamber to said third chamber and another position in which the chambers are disconnected, said movable abutment being subject to the opposing fluid pressures in said valve chamber and said third chamber and operative upon movement of said abutment to its other position in response t a reduction in fluid pressure in said third chamber to move said valve to its operative position, valve means operative in response to a certain increase in fluid pressure in said third chamber for reducing the pressure of fluid therein to a, certain degree, and means for biasing said movable abutment toward its normal position.

RAYMOND E. MILLER.

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