US2309889A - Liquid pressure remote control system, more particularly for operating soot blowers of boilers and the like - Google Patents

Description

/F. s. EvEs 2,309,889

PARTICULARLY FOR Feb. 2, 1943.

LIQUID PRESSURE REMOTE CONTROL SYSTEM, MORE n OPERATING SOOT BLOWERS OF BOILERS AND THE LIKE 4 Sheets-Sheet l Filed Dec..` 7, 1940 T .wliwmllw NNWQ MENEN wf E W T sA th v/ Feb. 2, 1943. F. s. EvEs I 2,309,889 LIQUID PRESSURE REMQTE CONTROL SYSTEM, 'MORE PARTICULRLY FOR OPERATING SOOT BLOWERS OF BOILERS AND THE LIKE Filed Dec. 7, 1940 4 SheetsSheet 2 m9 )yf my ffy/ Jia

F. s. r-:vEs- 2,309,889 LIQUID PRESSURE REMOTE CONTROL SYSTEM, MORE PARTICULARLY FOR OPERATING SOOT BLOWERS OF BOILERSiAND THE LIKE Filed ne@ 7. 1940 4 sheets-sheet s Feb. 2, 1943.

Feb. 2, 1943. F. s'. EvEs 2,309,839

LIQUID PRESSURE REMOTE CONTROL SYSTEM, MORE -PARTICULARLY FOR OPERATING SOOT BLOWERS 0F BOILERS AND THE LIKE 4 Sheets-Sheet 4 Filed Dec. -7, 1940 Patented Feb. 2, 1943 LIQUID PRESSURE RElviOTE CONTROL SYS- TEM, MORE PARTICULAR/LY FOR, OPERAT- ING SOT BLOWEBS 0F BGELERS AND THE LIKE Frederick Sydney Eves, London, England, assignor to Automotive Products #Company Limited,

London, England Application December '7, 1940, Serial No. 369,104 In Great Britain February i6, 194i) 8 Claims.

This invention relates to liquid pressure remote control systems, more particularly for operating soot blowers of boilers and the like.

It is the primary object oi the present invention to provide an improved form and construction of liquid pressure remote control system of the form in which a double-acting piston and cylinder unit is arranged in conjunction with trip valves for the purpose of securing automatic reversal of the direction of movement and thus enabling the unit to operate with a reciprccatory motion when fed with pressure liquid. In particular the invention seeks to provide an improved arrangement for the trip valves whereby the latter are adapted to operate, at a distance, the means which are used for making the necessary reversals in the supply of pressure liquid. The invention is thus especially suitable for hydraulically actuated soot blowers of boilers and the like, as it enables the more intricate reversing valve mechanism and its associated parts to be positioned well away from the heat of the boiler or equivalent.

In a liquid pressure remote control system in which a, double-acting piston and cylinderunit is connected with a reversing valve device by a pair of interchangeable supply and return pipe lines, the present invention is characterised by the fact that said reversing valve device is actuated by pressure liquid fed thereto through a shunt pipe line under the control oi the unit.

Further, in a liquid pressure remote control system in which a double-acting piston and cylinder unit is fed with pressure liquid from a source through the medium of a reversing valve device connected with said unit by a pair of interchangeable flow and return pipe lines, according to the invention the piston and cylinder unit is adapted to operate a trip valve at the end of each stroke, thereby diverting its own feed lof pressure liquid into a shunt pipe line and thence to an auxiliary motor device winch changes over the reversing valve device.

Thus there is provided according to the invention a liquid pressure remote control system having in combination with a double-acting piston and cylinder unit, a reversing valve device operated by a double-acting auxiliary motor, which latter is fed with pressure liquid through the medium of a trip valve device actuated by the said double-acting unit as the end oi' each stroke is reached, so that the piston and cylinder unit is caused to oscillate continuously so long as the supply of pressure liquid to the unit is maintained.

Further, there is provided in conjunction with a liquid pressure remote control system, a reversing valve device which is connected with a source ci pressure liquid and a reservoir, connected with a double-acting piston and cylinder unit by a pair oi interchangeable flow and return pipe lines and is also connected by a shunt pipe line with a trip valve device actuated by the piston and cylinder unit, said reversing valve device comprising a double-acting motor, an auxiliary reversing valve interposed between the shunt pipe line and said auxiliary motor, and a main reversing valve arranged to change over the main ow and return pipe lines to the piston and cylinder unit, the arrangement being such that when the piston and cylinder unit reaches the end ci its stroke it operates the trip valve device which diverts the supply of pressure liquid into the shunt pipe line and thence to the auxiliary motor unit, thus changing over the main reversingvalve and at the same time changing over` the auxiliary reversing valve so that the auxiliary motor is actuated in the opposite direction the nexttime pressure liquid is diverted to the shunt pipe line.

Preferably the reversing valve device comprises a body formed with a pair of bores, one of which contains a piston constituting the movable element of the auxiliary motor, while the other contains a piston valve member acting as two individual reversing valves, one being interposed between the pressure supply and the flow and return pipe lines or the piston and cylinder unit, which is double acting, and the other being interposed between the shunt pipe ,line and the working spaces of the auxiliary motor. The piston valve member may be mechanically interconnected with the auxiliary motor by a snap-over mechanism adapted to move th'e piston valve member rapidly from one extreme position to the other as the piston of the auxiliary motor executes its stroke, said snap-over mechanism conveniently comprising an arm provided with a spring arranged to pass a dead centre position, the said member being coupled with the piston valve member and the motor piston individually by lost motion connections.

In the piston and cylinder unit each of the trip valves may be urged towards its closed position by the pressure liquid which is being fed to the unit, and th'e opening force which is exerted upon said valve by the movable member oi the piston .and cylinder unit at the end of the stroke oi the latter, may be transmitted through a resilient member adapted to store energy, which latter is utilised to open the trip valve rapidly immediately the fluid supply pressure is overcome. In cases where the unit comprises a cylinder and movable piston the trip valves may be tted into the ends of said cylinder so as to be opened directly by the piston as th'e latter reaches the end of each stroke. Thus in one arrangement the unit comprises a cylinder, a hollow double-acting piston slidable therein, and a tubular stem xed to one cylinder end and arranged to extend in a liquid-tight manner into the open end of the piston, the arrangement being such that the piston is retracted at a relatively rapid rate by feeding pressure liquid into the piston through the tubular stem, the forward or power stroke of the piston being effected by feeding pressure liquid into the opposite end of the cylinder.

During the retracting stroke of the piston a part of the liquid rejected from the said opposite end of the cylinder may be permitted to flow into the annular space surrounding the tubular stem within the cylinder, the trip valve at the stem end of the cylinder conveniently being opened by an annular member which surrounds the stem and is mounted upon the piston but urged away therefrom by means of a coiled com-- pression spring, while the trip valve at the said opposite end of the cylinder is actuated by a spring-pressed plunger member mounted cen-- trally in the corresponding end of the piston.

If desired a pair of trip valves corresponding respectively to the opposite ends of the stroke of the unit may be connected with a single shunt pipe line, each through the medium of a nonreturn valve adapted to prevent the pressure liquid flowing directly from one trip valve to the other, although, of course, said liquid can flow from either trip valve into the shunt pipe line.

YA pair of trip valves, each arranged to terminate movement of the unit in one direction, may be interconnected with the movable member thereof through mechanism adapted to modifythe length of stroke executed by the said movable member, the unit conveniently being arranged to operate a cam device by which the trip valves are actuated and which moves with a reversing motion corresponding to the strokes of the unit, while a follower device is caused to follow a continuous circuit uni-directionally. The cam device may thus comprise a drum formed in its outer curved surface with a groove including a continuous circuit which is traversed unidirectionally by a follower member, said circuit having terminal portions, the end parts of which bring about the operation of one or other of the trip valves, thus reversing the motion of the movable member of the piston and cylinder unit and also of the cam.

As a further aspect of the invention a soot blower installation for a boiler furnace or the like is provided having a blower nozzle operated by a liquid pressure remote control system as above defined. Thus there may be interposed between the unit and the blower nozzle a driving connection comprising a pair of members which normally transmit, from one to the other, the force generated by the piston and cylinder unit, and which are arranged so that, when the transmitted force exceeds a predetermined value, re1- ative movement of the members takes place and actuates a valve to stop the flow of pressure liquid into the piston and cylinder unit, one of the force transmitting members conveniently having a longitudinally extending push rod which is actuated by the other member to operate a valve for stopping the flow of pressure liquid to the piston and cylinder, unit, said pushA rod, or a member serving to actuate it, being engaged with a recess in the said other member when the device is in its normal, force-transmitting state.

The invention is illustrated by Way of example in the accompanying drawings, in which:

Figure 1 is a diagram showing the arrangement of a simple form of remote control system, the reversing valve device being drawn as a sectional elevation and the piston and cylinder unit being of elementary form;

Figure 2 is a sectional elevation of a piston and cylinder unit incorporating trip valves and arranged to provide a quick return motion;

Figure 3 is a fragmentary sectional elevation of a soot blower device of the retractable type and including an automatic cut-out device;

Figure l is a fragmentary sectional elevation drawn to an enlarged scale and taken mainly on the line l-f of Figure 3, although the left-hand trip valve is shown as a section taken on the line lia-4a;

Figure 5 is a diagram representing a development of the outer curved surface of the control cam shown in Figures 3 and 4; and

Figure 6 is a fragmentary perspective view of a part of the control cam.

The remote control system which is partly indicated in diagrammatic form in Figure 1 comprises a continuously running pump I0, which is replenished by a reservoir II and normally delivers pressure liquid into a pressure supply pipe I2 leading to a reversing valve device indicated generally at I 3. From the latter a return pipe I4 leads back to the reservoir II and pump I0 From the reversing valve device I 3 a pair of interchangeable ow and return pipe lines I5 and I6 lead respectively to the working spaces I1 and I8 of a double-acting piston and cylinder unit indicated generally at I9. This unit has a pair of cylinders 2t and 2I tted with end caps 22 and 23 respectively, and they contain a pair of pistons 24 and 25 connected together by a rack bar 26. The teeth of the latter are in permanent mesh with a pinion 21 carried upon a transverse shaft 28, said shaft thus being caused to rotate rst in one direction and then in the other as the piston assembly 24, 25, 26 reciprocates. The cylinder caps 22 and 23 are fitted with spherical trip valve members 29 and 30, each of which is urged on to its seat by a coiled compression spring 3l, while it is adapted to be pushed olf its seat by a longitudinally slidable pin 32 or 33. These pins 32 and 33 are arranged to be operated by the corresponding pistons 24 and 25 as each of said pistons reaches the end of its retracting stroke. The trip valve member 29 is also normally urged on to its seating by any pressure existing in the Vfloworreturnpipe line I6, to which it is connected by a pipe Ia, while the trip valve member 30 is similarly connected by a pipe IEa with the flow or return pipe line I5. When either of the trip valve members 29 or 38 is open, liquid is able to flow past the corresponding one of ya pair of nonreturn valves 34 and 35, which are joined by connections 3S and 31 with a shunt pipe line 38 leading back to the reversing valve device I3. The non-return valves 34 and 35, of course, prevent pressure liquid from one of the trip valves 29 and Sil from flowing back into the other trip valve.

The reversing valve device as shown in Figure 1 comprises a body 39, which is formed with a pair of mutually parallel bores 40 and 4 I the former of which is arranged to act as the cylinder of an auxiliary double-acting hydraulic motor. A piston 42 tted securely to a piston rod 43 has packing cups 44 and |45 and is slidably mounted in the bore 4|, the end portions of said piston rod 43 being arranged to pass slidably through bushes 56 and 41 fitted with packing cups 58 and 49 respectively. Thus the interior of the bore 5| is divided into two working spaces 55 and 5| communicating with passages 52 and 53 through whichworking liquid passes to .and from the auxiliary motor. At one end the piston rod 43 is fitted with an adjustable forked member 54 carrying the pivot 55 of a link 56, the opposite end of said link being formed with a slot 51 engaged by a pin 5S mounted upon an arm 59, which latter is pivotally mounted at 6l] upon a fixed support. A coiled tension spring 6I, having its lower end fastened pivotally at 62 to a fixed support, is arranged to extend upwardly and is fastened at -its opposite end to the upper extremity of the arm 59, the spring 5| thus being arranged to pass a dead centre position as the arm 59 moves in a counter-clockwise direction, as seen in Figure 1. This causes the arm 59 to have a snap-over action, for as the piston 42 moves towards the left the pin 58 is rst engaged by the right-hand end oi the slot 51 and thereafter the arm 59 is propelled forwardly, said arm eventually reaching and passing its vertical dead centre position, after which the spring 6| takes charge, thus drawing the arm 59 rapidly towards the left as far as is permitted by the lost motion device comprising the slot 51 and pin 58. This motion is utilised to change over a piston valve member '63, which fits slidably within the bore 4) and has its end parts 54 and '65 passing slidably through bushes 55 and 61, packing cups 68 and 59 being provided to prevent leakage of liquid. The piston valve member 63 is formed with a longitudinal bore 15, which is sealed at its ends by screw-threaded members 1| and 12. The screw-threaded member 1I is biiurcated at 13 to receive a link 14 which is pivoted at 15 and which has its opposite end formed with a slot 15 constituting a lost motion connection in conjunction with a pin 1" carried by the arm 59. The length of the slot 16 is arranged so that the pin 11 moves freely along it until the arm 59 is just about to reach the end of its angular movement, the pin 11 at this instant engaging with the end of the slot 15 so that the nal movement of the arm 5Fl, which is a rapid movement on account of the spring 6I, causes the piston valve member 63 to be swiftly slid along to its opposite position.

The bore 1I) within the piston valve member 63 is at all times in communication with the reservoir II on account of a port 18, to which the return pipe line Ill is connected, and which leads into an annular groove 19 connected with the bore by radial passages 80. In a similar way the main supply pipe I2 is in permanent communication with an annular groove y3| in the piston valve member 63 by way of a port 82, and said groove 8| is adapted to place this port into communication either with a port 83 leading to the pipe line I5, as shown in Figure l, or else with a port 84 leading to the pipe line It, this last connection occurring, of course, when the piston valve member 63 is moved to the left. When the piston valve member 63 is in the pcsition shown, the port B4k communicates with the reservoir so that the pipe i5 acts as a return, whereas when the valve member is moved to the left, a relatively narrow annular groove communicating with the bore 15 Iby radial passages comes into register with the port 83, thus placing the pipe line I5 into communication with the reservoir II. The annular grooves 19, 8| and 85, acting in conjunction with the ports 18, 84, 82 and 83, thus constitute a reversing valve adapted to control the direction in which the piston and cylinder unit I9 is operated by the pressure liquid delivered by the pump I9.

The piston valve member 53 also acts as a reversing valve interposed between the shunt pipe line 38 and the passages 5!) and 53 leading t0 the auxiliary motor 4|, 52. Thus a port v3b connected with the shunt pipe line 38 communicates with an annular groove 81 .adapted to place said port 85 either into communication with the passage 53, as shown, or into communication with the passage 52. The piston valve member 63 is also formed with a pair of narrow annular grooves 88 and 85, each of which has radial holes leading into the bore 15 and thence to the reservoir Il, the arrangement being such that when the piston valve member 53 is in the position shown, the passage 52 4communicates with the reservoir H, whereas when the valve member 53 is moved to the left, said passage 52 is in connection with the shunt pipe line 38, and the passage 53 then leads back to the reservoir by Way of the annular groove B5.

The reversing valve device I3, as shown in Figure l, is arranged to enable the pistons 24 and 25 of the piston and cylinder unit I9 to reciprocate continuously so long as pressure liquid is being delivered by the pump Ill. With the parts in the positions shown, pressure liquid passes vlrom the supply pipe line I?. into the pipe line |55, and upon entering the working space I8 forces the piston 25 to the left, at the same time moving the rack bar 25 and the piston 24 so that the latter expels liquid from the working space .Il back to the reservoir by way of the pipe lines I5 and I5. As the piston le reaches the end of this retracting stroke it engages With the pin 32 thus forces the trip valve 2t off its seating,

so permitting pressure liquid from the pipe line i5 to flow through the non-return valve 34 and into the shunt pipe line 38. It will be seen that this pressure liquid l'lows through the passage 53 and, entering the working space 5|, urges the piston 122 oi the auxiliary motor to the left. As previously described, the piston valve member E3 remains unmoved until the arm 59 snaps over, at which instant the valve member 53 moves quickly to the left, thus cutting ofi the supply of pressure liquid to the pipe ine i5 and transferring it to the pipe line l5. At the same time the Valve member 53 changes over the shunt pipe line 38 to the passage 52 of the auxiliary motor. Pressure liquid is then fed from the pipe line I5 to the working space |1, thus moving the pistons 24 and 25 in the opposite direction until the trip valve Sil is opened by the engagement of the piston 25 with the pin 33. This action actuates the reversing Valve device i3 so as to return the parts to their original positions and then movement of the pistons 264 and 25 towards the left begins once again. It will thus be seen that the reversing valve device I3, which enables the piston and cylinder unit Iii to reciprocate continuously, is not mechanically connected with the unit but is merely coupled thereto by the pipe lines I5, I6 and 33. These, of course, can be of any reasonable length and it is thus possible for the reversing valve device I3 to be placed well away from the unit, this being an important advantage for soot blower installations, as the parts associated with the blower nozzles are liable to become rather hot.

A modified construction of piston and cylinder unit |9 is shown in Figure 2, and is particularly adapted for use in cases where the unit is intended to drive mechanism through the medium of a ratchet device, thus producing an intermittent uni-directional rotating movement, such as is desirable for driving a soot blower nozzle of the known non-retractable type. It is desirable in these circumstances for the return stroke of the unit to take place quickly and with a relatively small volume of pressure liquid, whereas the forward stroke has to develop 4the requisite power and can take place moie slowly.

The unit comprises a central casting 90 formed with sleeves 9| and 92, into which the cylinders 20 and 2| are fitted. The central casting 90 contains a transverse shaft 28 carrying the pinion 21, which latter meshes as before with gear teeth 93 formed upon a rack bar 26. A roller |3| mounted upon a pivot pin |32 secured to the central casting 90 is adapted to engage with the under surface |33 of the rack bar 2S so as to prevent the latter from bending on account of the load transmitted to the pinion 21. The piston 24 at one end of the rack bar 23 has an annular packing cup 94, while the piston 25 at the opposite end has a packing ring 95, which need only be capable of withstanding low fluid pressure. Secured firmly to the cylinder cap 23 is an axial tubular stem 96, which passes through an annular packing cup 91 tted within the piston 25 by means of an annular nut 98. The stem 9S extends into a bore 99 formed in the rack bar 2S and thus produces an auxiliary working space which is adapted to be fed with pressure liquid through the interior of the stem 96. The latter accommodates with clearance a metal tube |0| which is connected with a bleed plug |02 and is used merely for extracting air from the auxiliary working space |00 when the device is being charged with liquid.

The end cap 23 carries a pair of ttngs |51) and |012 for connection to the pipe lines I5 and I5 respectively shown in Figure 1, said pipe lines, of course, leading to the reversing valve device I3. The fitting Ib has a passage |03, which passes direct to the interior of the stem 96 and thus leads into the auxiliary working space |00. A branch pipe connection |04 also connects the fitting |619 with a space within the other end cap 22', which space contains the trip valve member 29 and its spring 3|, said trip valve member having, as before, a pin 32 by which it is adapted to be opened by the piston 24'. The fitting |5b has a pipe connection |05, by which pressure liquid is delivered through the opposite end cap 2 2 into the working space I1, while a branch connection |08 leads to the trip valve 30, which latter has a pin 33 adapted to open it against the closing force exerted by the corresponding spring 3|. From the space containing the trip valve 30 a passageway |01, shown dotted, leads upward past a lightly loaded non-return valve member |06 and thence by a passage |09 into a chamber ||0 containing a ball valve member the latter being urged on to its seating by a spring H2. From below the seating of the ball valve member a passage ||3 leads into an annular Working space ||4 surrounding that part of the stem 96 which is exposed within the cylinder 2|, while the passage ||3 leads also to a lightly loaded non-return valve ||5 adapted to allow liquid from the space ||4 to pass out to the tting |6b and thus to the pipe line I6. The ball valve member is capable of being opened against the spring ||2 by a plunger member ||6 adapted to slide in a liquid-tight manner Within a bore formed in the end cap 23', said plunger member 6 having its lower surface acted upon by pressure liquid from the passage |03, i. e. the pressure liquid passing into the auxiliary working space |00. When the plunger member ||6 is thus lifted a spigot ||1 formed upon its upper part acts to raise the ball valve member 01T its seating. v

The trip valves 29 and 30 are connected by pipes H8 and ||9 respectively with a fitting |20 containing a pair of non-return ball valve members |2| and |22, which are urged apart as shown by a coiled compression spring |23. The space between said ball valve members |2| and |22 is connected by a tting 38a with the shunt pipe line 30, as seen in Figure l. v

in order to ensure that the trip valves 29 and 30 are opened rapidly at the end of the stroke, a. resilient buffer device is incorporated in each of the pistons 24 and 25. In the case of the piston 24 a hollow plunger member |24 having an air release hole |25 is mounted slidably within a bore formed in the piston and is urged outwardly by a coiled compression spring |26 so as to engage with an abutment ring |21. The plunger member |24 is arranged to press upon the pin 32 as the piston 24 nears the end of its stroke, but the trip valve 29 does not open immediately, as it is held closed lby the spring 3|l and by the supply pressure acting upon the said trip valve 29. As a consequence the plunger member |24 slides within the piston 24 and stores energy in the spring |26 until the force exerted by the latter is able to push the trip valve 29 off its seating. The pressure liquid from the pipe |04 immediately surrounds the member 29, with the result that said member rapidly assumes its fully opened position,

as the spring |26` is easily able to overcome the' spring 3|. The trip valve 30 is arranged eccentrically on account of the stem 96 and thereforev an annular plate |28 is provided upon the piston 25' for the purpose of actuating Vthe pin 33. TheI plate |28 is mounted on headed pins |29 and is urged away from the piston 25 by a coiled compression spring |30. The plate |28 acts, of course, in a manner exactly similar to that of the plunger member |24.

The power stroke of the pistons 24' and 25- takes place in a direction towards the right and is eiected by admitting pressure liquid into the tt'ing |517 so that said liquid flows vthrough the pipe |05 and enters the working space I1. During this movement liquid is rejected from the auxiliary working space |00 and passes through vthe passageway |03 back to the prevailing return pipe line I6, while liquid filling the annular working space I4 is also able to return to the pipe line I6 by opening the non-return valve ||5. It will be seen that pressure liquid is unable to flow up the passageway |01 during this stage of the operation, as the ball valve is closed.. As the piston 25 nears the end of its stroke the plate |29 coacts with the pin 33 and eventually opens the trip valve 30, thus permitting the pressure liquid from the fitting |5b to flow through the pipe I8 and into the shunt pipe line 38 by opening the non-return valve |22. This, of course, causes the reversing valve device |3 to change over,- thus transposing the pressure liquid supply and return pipe lines so that they become connected with the fittings |612 and |519 respectively. Pressure liquid then flows through the passage |83 and into the auxiliary working space |66 so as to effect the return stroke of the pistons 24 and 25. The effective cross-sectional area of the auxiliary working space |68 is equal to that of a circle having the same outside diameter as the stem 96, and it will be seen, therefore, that with pressure liquid supplied at a given rate the pistons 24 and 25 will move towards the left at a relatively rapid speed. During this movement liquid is rejected from the Working space |1 and part of this liquid is accommodated Within the enlarging annular space ||4 at the opposite 'end of the unit. it is for this purpose that the plunger member ||6 is provided, the incoming pressure liquid acting beneath said plunger member so that it raises the ball valve member I|| off its seating, thus permitting the rejected liquid from the pipe |05 to flow through the passage i6?, open the ball valve |66, and gain access to the annular space I4 by way of the ball valve and the passage H3. The ball valve |86 may be omitted if desired, but its use is found to be beneficial, as it tends. to steady the action of the ball valve member and prevent the latter from hunting. As the end of this return stroke is reached, the trip valve 26 is` opened by the plunger member |24, thus permitting pressure liquid to iiow from the pipe |64 into the pipe I I6 and the shunt pipe line 86 by way of the nonreturn valve 12| and once again changing over the reversing Valve device I3 so as to cause the next power stroke to commence.

Figures 3, 4, 5 and 6 show the general arrangement and construction of a soot blower device incorporating the invention, the blower nozzle being of the retractable type adapted to be 'projected into the boiler furnace or the like during one stroke of the piston and cylinder unit and to be retracted back into its housing during the next stroke of said unit. The soot blower nozzle, which is not shown in the drawings but which can be of the usual construction, is attached to a nozzle shaft indicated at |46, the latter being caused to advance axially as it is rotated in one direction and to be retracted when it is rotated in the opposite direction. For this purpose a sleeve |4| having a screw thread |42 of coarse pitch formed on its exterior is securely attached to the tail portion |43 of the nozzle shaft |48 by means of a nut |44 and key |45. The sleeve |4| is protected by a cylindrical casing |46 forming part of a main casing indicated generally at |41, which latter is formed with a bearing bush |48 for the reception of a tubular spindle |45 formed integrally with a gear wheel |58. The spindle |48 is splined, as indicated at |5|, these splines being slidable within longitudinal grooves |52 formed in the upstanding parts of the screw thread |42. Thus the sleeve |'l| is capable of being rotated by the gear wheel |56, but is at the same time free to move in an axial direction. The main casing |41 carries a xed nut member |53, which mates with the screw thread |42 and thus brings about the axial movement of the sleeve |4| and nozzle shaft |48 as these parts are rotated, thus of course advancing the blower nozzle into the boiler furnace during rotation of the shaft |46 in one direction and retracting it bv rotation in the other direction.

The gear wheel |58 is in mesh with a larger j gear wheel |54 formed integrally with a shaft |55 housed in bearings |56 and |51 upon the main casing |41. If necessary the gear wheel |54 can be rotated by hand through the medium of a shaft |58 having a pinion |59 in permanent mesh with said gear wheel |54. During normal operation, however, the soot blower is worked by a double-acting liquid pressure unit which is indicated generally at I6 and which is shown diagrammatically in Figure 4 to indicate its relation to the cut-off and trip valve devices which will be hereinafter described. The unit I8 comprises briefly a cylinder assembly |6| which is closed at its two ends |62 and |63 and has pistons |64 and |65 slidable in its end parts. These pistons are connected together by a bar |66, which is formed upon its surface with rack teeth |61' to engage with corresponding pinion teeth |66 formed upon a transverse shaft |68. Thus the pistons |64 and |65 are caused to reciprocate by pressure liquid the transverse shaft |68 correspondingly rotates flrst in one direction and then in the opposite direction. This reciprocation of the pistons is controlled by trip valve means which will be hereinafter described. The bar |66 is supported against deflection by engagement with a roller |16 (see Figure 3) mount.. ed upon a pivot pin |1| which is carried rmly by the cylinder assembly |6|. The transverse shaft |66 is mounted in bearings |12 and |13 formed in the centre part of the cylinder assembly 6|, which latter has a frusto-conical iiange portion |14 secured to the main casing |41 through the medium of a ring |15 composed of heat insulating material, thus to a large extent preventing the conduction of heat from the nozzle shaft |40 to the unit |68.

The transverse shaft |68 is drilled axially at |16 for the slidable reception of a push rod |11 adapted at one end to bear against a thrust member |18 tted, also slidably, within an oblique bore |19 formed in the end part of the transverse shaft |68. The ends of the thrust member are rounded and an normal operation the outer of these ends, indicated at |80, projects beyond the corresponding end surface |82 of the transverse shaft |66 and engages with a recess |8| formed eccentrically in the adjacent end surface |83 of the shaft |55. These adjacent parts of the two shafts |68 and |55 are also formed off centre with coaxial bores respectively for the accommodation of a dowel |86 serving to transmit torque from the shaft |68 to the shaft |55. The dowel |86 is so designed with regard to its material, its cross section, and its distance from the axis of the shafts |55 and |68 that it is just capable of transmitting the maximum torque that it is desired to impart to the gear wheel |54, so that if this torque is exceeded the dowel |86 will shear. It will be realised, of course, that it may be desirable, or even necessary in some cases, to provide two or more dowels such as |86 in order to carry the predetermined load.

The unit |60 is fed with pressure liquid through the pair of pipe lines I5 and i6, and connections |61 and |88 (see Figure 4), either one of which can supply the pressure liquid, while the other takes the rejected liquid, depending upon the direction in which the pistons |64 and |65 are being moved. The pipe line |88 does not lead directly to the unit |9, however, but is connected with a cut-off valve device indicated generally at |86, while a pipe |86a leads from the outer connection |68 of the valve device to the appropriate end of the unit I6. The cutoif valve device is shown more fully in Figure 3 and comprises a body |9| having a longitudinal bore |92 formed with a seating |93 for engagement by a spherical valve member |99. A plunger member |95 is slidable within the bore |92 and is urged by a strong spring |93 so as to hold the valve member |99 in its closed position, the spring |93 being of such strength that liquid within the pipe |880; and at 'a maximum pressure that is likely to be present in the remote control system as a whole is unable to force the valve member |94 olf its seating. The plunger |95 is formed with holes |91, which enable the liquid to ow through said plunger When the valve device is open.

The cut-off valve device |89 is normally held in this open position, as shown in Figure 3, by a tappet |98 formed at its lower end with a pin |99 around which the liquid can flow in passing to and from the connection |93, a packing washer 299 being provided to prevent leakage of said liquid. At its upper end the tappet |93 is engaged by a roller mounted pivotally upon a pin 292 extending between a pair of parallel twin link members 293 and 299. These are connected together by a bridge piece 295 and, at their upper ends, are mounted upon a pivot 298 carried by a casing 291. A lateral projection 298 formed upon the link 293, 294 engages an adjustable stop 299, and is maintained in this position by a spring 2m which acts upon a thrust member 2| extending between the link members 203 and 294 and pivoted thereto. The end of the thrust member 2H is d'mposed adjacent an adjustable screw 2M tted in the end ofthe push rod |11. during normal operation of the s-oot blower the shaft |55 rotates as one with the transverse spindle |68, with the result that the push rod ITI remains in its retracted position, as shown in Figure 3.

If the soot blower becomes jammed for any reason, however, the driving force produced by the unit I9 is suicient to shear the dowel |83 and the subsequent angular movement of the transverse spindle |38 relative to the shaft |55 causes the push rod |'VI' to deflect the link 293, 283, thus enabling the spring |93 to close the valve member |94. The cut-off valve device |39 is thus closed and it immediately prevents further operation of the unit 9; it will be seen that if pressure liquid happened at th'e time to be being fed through the pipe line |88 the flow would automatically be stopped by the ball |93 acting in the capacity of a non-return valve member. On the other hand, if the unit I9 were being driven in the opposite direction by pressure liquid passing through the pipe line |87 the closed valve ball member |93 would act to prevent the rejected'liquid from escaping through the pipe |88a, and thus no further pressure liquid would be able to enter the unit |9. The fact that the cut-off Valve device is brought into action usually means that the blower device needs dismantling and overhauling, and in these circumstances it is of course easy to renew the dowel or dowels |83 and to re-set the cut-olf valve device to its operative position. Means may, however, be provided if desired whereby th'e cut-off valve device |89 may be restored without the necessity of dismantling it. For example, a push button might be tted in the casing 29?.

The trip valve devices for the soot blower shown in Figures 3 to 6 are arranged so that When the feed of pressure liquid to the soot blower commences the nozzle shaft |49 is projectedto the full extent into th'e boiler or like furnace, rotation It will thus be seen that of said nozzle shaft in one direction taking place in the meantime. The following retracting stroke then commences, but terminates prematurely, the direction of movement ofthe nozzle shaft being reversed, while the nozzle itself is still disposed within the furnace space. The nozzle shaft, upon reaching its fully projected position, is once again reversed and executes a short stroke, and when it once again reaches its fully projected position a complete return stroke takes place, th'us bringing the nozzle shaft back to its fully retracted position.

The mechanism to produce this effect is disposed within a casing 2|5, which contains a cam drum 2|3 mounted upon pivots 2H and 2|8 and formed in one with a gear wheel 2|9, which meshes with a pinion 229 fastened to the transverse shaft |33. The cam drum 2|3 is formed in its curved outer surface with a cam groove, which is indicated generally at 22| in Figure 3 and is arranged to be in permanent engagement with a follower pin 222 carried at the extremity of a follower arm 223, as will be seen in Figure 4. The arm 223 at its lower end is pivotally mounted upon a pin 223 carried by a block 225, which is itself mounted pivotally between a pair of arms 226 by means of a pin 227, the two pins 224 and 22? being disposed mutually at right angles so as to allow the arm 223 to have a universal movement. The arm 223 is urged towards the cam drum 2|6 by a pivoted leaf spring 228 and is arranged so that whenever the follower pin 222 is engaged by an end wall of the cam groove 22| said arm 223 is either lifted or depressed, depending upon the direction in which the cam drum 2 6 happens to be rotating. Such lifting or depressing movement is imparted to the arms 223, which are formed in one with a tubular member 229 mounted between pivots 239 and 23| (see Figure 3). The tubular member 229 is also formed with a pair of upwardly extending arms 232 carrying between them a roller 233, which is adapted to open either the trip valve member 29 or the trip valve member 39, depending upon whether the follower arm 223 is depressed or lifted respectively.

The mechanism for operating the trip valves 29 and 39 is the same in each instance, and only that corresponding to the trip valve 39 has been shown in detail in Figure 4. It comprises a slider 234 which moves Within a tubular fitting 235 and is fitted with an adjustable screw 236 adapted to be engaged by the roller 233. A plunger member |23 is urged towards an abutment ring |21 by means of a coiled compression spring |26 and is adapted to engage the end of a pin 32 when the slider 234 is urged towards the left. When suicient force has been built up in the spring |26 the trip valve is operated in a manner exactly similar to that of the trip valve 29 shown in Figure 2. Wh'en the trip valve 39 opens, pressure liquid from the pipe line I5 is able to flow past a springloaded non-return valve 35 and thus enter the shunt pipe line 38 by way of a pipe connection 3l. In a similar way a non-return valve 33 is associated with the trip valve 23 and leads by a passage 33 into the shunt pipe line 38.

Figure 5 is a nat development of the curved surface of the camdrum 2|6, and it will be seen that the cam groove 22| follows a tortuous path in order to produce the above-mentioned sequence in the movements of the nozzle shaft |40. When Vthe nozzle shaft |40 is in its completely retracted K position, the Vdrum 2 6 is so disposed that the follower pin 222 occupies the position shown in dotted lines at the extremity of a terminal portion 231 of the groove 22| It will be appreciated that in practice the drum rotates while the pin 222 remains substantially xed, but in order to simplify this description the pin 222 will be regarded as moving along the groove 22|. Where junctions occur in the groove 22| the latter is shaped specially in order that the pin 222 may follow a uni-directional course, and an example is shown in perspective in Figure 6, which corresponds tothe junction 23B occurring at the lower part of the terminal portion 231. The pin 222, in moving downwards, is required to pass into the oblique portion 239, and therefore the branch groove 240 has its bottom arranged to slope upwards as indicated at 24|, a triangular flat portion 242 being provided so as to produce a relatively low wall 243 for the groove 231 where the latter is met by the branch groove 245. This, of course, efciently guides the follower pin 222 past the branch groove 245, but later in the cycle of operations enables said pin, in travelling along the branch groove 249, to rise up the sloping bottom 24| and subsequently move back into the terminal portion 231. Other sloping portions similar to 24| are provided at various positions in the groove 22| and are indicated at 244, 245, 246, 241 and 248.

When pressure liquid is first fed to the soot blower the extending movement of the nozzle shaft |45 is accompanied by downward movement of the pin 222 relative to the surface of the drum 2|6, said pin passing along the oblique portion 239 of the groove, riding up the sloping portion 244, and then dropping into a terminal portion 249 along which the pin travels until it reaches the end 255. 2|6 causes the pin 222 to be raised, thus opening the trip valve 39 and reversing the direction of the nozzle shaft |40 and also said drum 2|6. The pin 222 therefore returns along the terminal portion 249, but is diverted by the low wall of the groove at 25| and thus rides up the sloping bottom 245, said pin 222 shortly' reaching another terminal portion at 252. This, of course, reverses the movement of the nozzle shaft |45 before the nozzle itself has been withdrawn from the boiler or like furnace and causes said nozzle shaft |45] to move forward once again, the in 222 travelling along a portion 253 of the cam groove and eventually riding up a sloping bottom at 246. The pin 222 soon reaches the next terminal portion indicated at 254, which brings about `another short retracting stroke, said pin 222 travelling along a portion 255 of the groove and eventually reaching a terminal portion 255. Reversal occurs once again and the pin 222 returns along the portion 255 until it is deiiected sideways by the low wall of the groove at 251, said pin subsequently rising up the sloping bottom 248 and bringing about another reversal as it reaches a terminal portion 258. This begins the final retracting stroke of the nozzle shaft |40 and the pin 222 passes along a portion 259 of the groove until it rides up the sloping bottom 24|, thus re-entering the terminal portion 231 and reaching the end position indicated at 265. If the supply of pressure liquid is maintained another reversal occurs and the cycle recolnmences.

It will, of course, be appreciated that various other forms of trip valve device may be arranged in accordance with the invention and that the construction of the reversing valve device may be modiiied as desired. The invention is, of course, not restricted to soot blowers, as it is ap- The rotation of the drum K plicable to many forms of liquid pressure remote control systems.

What I claim is:

l. A liquid pressure remote control system comprising, a double acting piston and cylinder unit consisting of a hollow piston open at one end, the closed end of said piston and the cylinder together dening a major working space, a tubular stem iixed to one end of the cylinder and adapted to extend into the open end of the piston, packing for effecting a liquid-tight seal between the stem and the interior of the piston, means for bypassing a portion of the liquid ejected from the major working space into the annular space defined by the tube and the walls of the cylinder during reduction of the cubic area of said major working space, a source of liquid under pressure, a reversing valve, supply and return conduits connecting said reversing valve and said source of liquid under pressure, said valve including two ports, means connecting one of said ports to the tubular member of the piston and cylinder unit, means connecting the other of said ports to the major working space of said piston and cylinder unit, said reversing valve also including a movable portion adapted in one position to discharge liquid under pressure through one of the ports and to receive it through the other and in the other position to reverse the direction of flow through each port, and means responsive to a predetermined relative movement of the piston and cylinder unit in either direction for changing the position of the movable portion of sai-d reversing valve to cause reversal of iiow through the ports thereof, whereby alternate sides of the piston and cylinder unit will be alternately supplied with liquid under pressure causing reversal of direction at the completion of each stroke.

2. A liquid pressure remote control system comprising, a double acting piston and cylinder unit consisting of a hollow piston open at one end, the closed end of said piston and the cylinder together defining a major working space, a tubular stem fixe-d to one end of the cylinder and adapted to extend into the open end of the piston, packing for effecting a liquid-tight seal between the stem and the interior of the piston, said interior constituting a minor working space, a source of liquid under pressure, a reversing valve, supply and return conduits connecting said reversing valve and said source of liquid under pressure, said reversing valve including two ports, a conduit connecting one of said ports with the minor working space of said piston and cylinder unit, another conduit connecting the other port to the major working space of said piston and cylinder unit, said valve including a movable portion adapted in one position to discharge liquid under pressure through one of the ports and to receive it through the other, and in the other position to reverse the direction of iiow through each port, a valve normally spring closed located at either end of said piston and cylinder unit, each valve including a pin extending into the respective working space, a member carried at each end of said piston to engage the respective valve pin to open the respective valve, said members being spaced from the respective ends of the piston by springs capable of storing energy, one of said valves being adapted to be opened by a member carried at the end of a piston engaging a pin upon completion of its stroke in either direction, an auxiliary hydraulic motor for changing the position of the movable portion of said reversing valve to cause reversal of flow through the ports thereof, and a conduit connecting said auxiliary motor with each of the conduits connecting said ports and the working spaces of said piston and cylinder unit, the conduit connecting the auxiliary motor with the conduit serving one working space leading through the valve contiguous to the other working space, whereby the opening of a valve at the completion of the stroke of the piston will divert the pressure liquid being fed to the opposite side thereof to the auxiliary motor to eiect reversal of ow through the ports.

3. A liquid pressure remote control system comprising, a double acting piston and cylinder unit consisting of relatively movable elements, a source of liquid under pressure, a double acting hydraulic motor, means including a single movable valve element for selectively connecting said source of liquid under pressure and one of the opposite sides of said piston and cylinder unit and for simultaneously selectively connecting one of the opposite sides of said motor, valves normally closing both of the connections established by said means between said source of liquid under pressure and said motor, means responsive to relative movement or predetermined magnitude on the part of the elements of said piston and cylinder unit for opening one of said valves to open the connection between said pressure liquid and said motor to cause operation of the latter, and a mechanical linkage operatively connecting said motor to the movable valve element to move the latter to another position to connect the other side of the piston and cylinder unit and the other side of the motor with said source of liquid under pressure, whereby upon predetermined relative movement of the elements of the piston and cylinder unit in one direction a normally closed valve will be opened to actuate the motor to move the movable valve element to a position causing reversal of the direction of relative movement of the elements of the piston and cylinder unit,

4. A liquid pressure remote control system comprising, a double acting piston and cylinder unit, a source of liquid under pressure, a reversing valve including a portion movable into either of two positions, supply and return conduits connecting said reversing valve and said source of liquid under pressure, a liquid pressure piston and cylinder motor, a mechanical linkage connecting a moving portion of said motor with the movable portion of said reversing valve, said reversing valve including four ports, conduits connecting two of the ports with opposite sides of the piston and cylinder unit, conduits connecting the other two ports with opposite sides of the motor unit, branch conduits leading from each of the conduits connecting the reversing valve with opposite sides oi the piston and cylinder unit, a normally closed check valve in each of the branch conduits, a common conduit connecting each of said branch conduits on the normally closed side of the check valve with the reversing valve, said reversing valve in one position of its movable portion establishing connections between said source of liquid pressure and one side v of the piston and cylinder unit and between said common conduit and one of the conduits connecting the reversing valve and one side of the motor and in the other position of its movable portion establishing connections between said source of liquid under pressure and the other side of said piston and cylinder unit and between said common conduit and the other conduit connecting the reversing valve and the motor, and means responsive to a predetermined relative movement ofthe elements of said piston and cylinder unit in either direction for selectively opening one of said normally closed valves to establish a connection between said source of liquid under pressure and one side of said motor to actuate the same to cause movement of the movable portion of the reversing valve to its other position thereby to cause reversal of the movable portion of the piston and cylinder unit.

5. A liquid pressure remote control system as claimed in claim 4 further comprising, a spring coacting with the linkage connecting the movable portion of the valve and a movable portion of the motor to shift both of said movable portions rapidly from one extreme position to the other upon completion of a portion of the stroke of the auxiliary motor, whereby a time lag is eliminated.

6. A liquid pressure remote control system as claimed in claim 4 in which the mechanical linkage connecting the movable portion of the reversing valve and the movable portion of the auxiliary piston and cylinder unit comprises, a pivoted arm connected to the movable portion of said reversing valve and to the movable portion of said auxiliary motor, each of said connections being of the lost motion type, said arm being providedv with a spring arranged to pass a dead center position and thereby to rapidly shift the movable portion of said reversing valve from one position to the other as the movable portion of the auxiliary motor executes its stroke.

7. A liquid pressure remote control system as claimed in claim 4 in which the mechanical linkage connecting the movable portion of the reversing valve and the movable portion of the auxiliary piston and cylinder unit comprises, a pivoted arm connected to the movable portion of said reversing valve and to the movable portion of said auxiliary motor, each of said connections being of the lost motion type, said arm being provided with a spring arranged to pass a dead center position and thereby to rapidly shift the movable portion of said reversing valve from one position to the other as the movable portion of the auxiliary motor executes its stroke, the free angular movement of said arm to take up the lost motion in the connection to the movable portion of the reversing valve being greater than the free angular movement of said arm to take up the lost motion in the connection to the movable portion of said auxiliary motor.

8. A liquid pressure remote control system comprising, a double acting piston and cylinder unit, a reversing valve controlling the working space of the unit to which liquid is supplied, a double acting auxiliary hydraulic motor for actuating said reversing valve, trip valves controlling the ilow of liquid to said auxiliary motor, cam means driven by the movable portion of the piston and cylinder unit, and means driven by said cam for actuating said trip valves, said cam being provided with grooves for the reception of a portion of the cam operated means, said grooves being arranged in a circuit, the line of development of said cam being a function of the time of actuation of said trip valves, whereby the amplitude of the stroke of the piston and cylinder unit may be automatically varied under the control of a cam driven thereby.

FREDERICK SYDNEY EVES,

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