US3516435A - Actuating mechanism of flap and slide valves,particularly for tankers - Google Patents

Description

June 23, 1970 H. SCHUMACHER ACTUATING MECHANISM OF FLAP AND SLIDE VALVES' PARTICULARLY FOR TANKERS Filed May 31, 1968 Fly. 7

8 Sheets-Sheet l sr 6.1', e M" June 23, 1970 H. scHuMAcHER 3,515,435

ACTUATING MECHANISM OF' FLAP AND SLIDE VALVES, PARTICULARLY FOR TANKERS Filed May 31, 19.68 8 Sheets-Sheet 24 \26 lo e Il Il I? JUL. E'; a#42 I i l frigid.' g i Jnrenor:

HBM; savannas/2 ar 6...;7 2 9M' June 23, 1970 H. scHuMAcHER 3,515,435

l ACTUATING MECHANISM 0F FLAP AND SLIDE VALVES, PARTICULARLY FOR TANKERS Filed May 31. 1968 8 Sheets-Sheet 5 June 23, 1970 H. scHuMAcHl-:R

ACTUATING MECHANISM OF FLAP AND SLIDE VALVES PARTICULARLY FOR TANKERS B Sheets-Sheet 4 Filed May 31, 1968 Jn Venzorf HMS' SCJUNCAIH .er D M- Fria/msn' June 23, 1970 H. scHuMAcHER 3,516,435

ACTUATING MECHANISM OF' FLA? AND SLIDE.

VALVES, PARTICULARLY FOR TANKERS Filed May 3l, 1968 8 Shefms--SheeiI Jnvenzor.-

June 23, 1970 H. scHuMAcHER 3,516,435

ACTUATI MECHANISM F P AND SLIDE.

VALV PARTICULA F TANKERS Filed May $51, 1968 8 Sheets-Sheet 6 Jn Vemar.- HH/vs Schuh/9:11512 r 6m', n Mula June 23, 1970 H. scHuMAcHER 3,516,435

ACTUATING MECHANISM OF' FLAP AND SLIDE VALVES, PARTICULARLY FOR TANKERS Filed May 3l. 1968 8 Sheets-Sheet '7 June 23,v 1970 Filed May 31, 1968 H. SCHUMACHER AGTUATING MECHANISM OF FLAP AND SLIDE VALVES, PARTICULARLY FOR TANKERS 8 Sheets-Sheet 3 United States Patent O 3,516,435 ACTUATING MECHANISM F FLAP AND SLIDE VALVES, PARTICULARLY FOR TANKERS Hans Schumacher, Werdohl, Westphalia, Germany, as-

signor to Kracht Pumpenund Motorenfabrik K.G., Werdohl, Westphalia, Germany Filed May 31, 1968, Ser. No. 733,589 Claims priority, application Germany, June 1, 1967, 1,600,835; Jan. 19, 1968, 1,675,439 Int. Cl. B63b 25/08; F16k 3/02, 1.7/10 U.S. Cl. 137-553 21 Claims ABSTRACT OF THE DISCLOSURE An improved actuating mechanism for flap and slide valves, more particularly for tankers, with a central oil delivery and return pipeline to which the actuating mechanism is connected by a hydraulically biased three-way valve with counter-pressure spring, biasing the control slide in the sense of connecting the delivery socket with the working socket, and with means indicating the position of the actuating mechanism, wherein the improvement comprises a construction in which less than two lines are required between the operating stand and each actuating mechanism, and wherein the position of the cutolf mechanism is reliably displayed on the operating stand.

The invention relates, as indicated, to the hydraulic actuation of the pipeline flap and slide valves in tankers.

The requirement of operating cutolf devices from a centrally positioned control stand and to monitor them from there, necessitates the provision of a connection between the control room and each of the units to be controlled. In view of the fact that with a View to achieving, particularly in ships, a sufficiently long useful life, these connections must be made from corrosion-resisting materials, the hydraulic network forms a substantial part of the costs of the whole hydraulic actuating equipment.

Another problem encountered in hydraulic actuating mechanisms of this kind is the fact that, in view of the length of the lines required, their volume is very great compared with the volume of the actuators for the ap and slide valves. The compression of the oil in these conduits is so great that the compressed oil volume amounts to 50 percent and more of the volume of the actuating mechanisms.

In a known actuating device of the kind hereinbefore described (German published specication No. 1,052,- 764) only a single oil pipe is provided between the threeway valve acting as control valve and the side of the actuating mechanism effective in the opening sense. The side of the actuating mechanism effective in the closing sense is biased by a compressed gas cushion. Thus, when the valve is opened, the oil pressure acts against the gas pressure which must be suficient to ensure the reliable closing of the cutoif mechanism. The servo chamber as here connected to the working socket of the three-way valve is given a variable bias by means of a cam which is connected to a lever, associated with a positional dial. After setting the lever at the desired opening position, the pressure in the oil line leading to the actuator is increased until the pressure in the servo chamber corresponds to the preset spring pressure. Where the cutoff mechanism is retained by substantial frictional forces, the preset pressure may also be reached without a movement of the cutoff member. A reliable indication that the cutoff member has, in fact, reached the preset position, can be obtained only by simultaneously observing a pressure increase in the gas cushion. Hence, in this case an additional line must be provided between the gas cushion and ICC the control valve so that always two lines are necessary between the operating stand and any cutoff mechanism. Apart from that, gases are much more strongly affected by changes of the Volume in consequence of changes in the temperature than oils so that the display is not always reliable.

It is, therefore, an object of the invention to provide an actuating mechanism for the flap and slide valves, particularly in tankers, in which less than two lines are necessary between the control stand and each actuating mechanism, and by means of which the position of the cutoff mechanism may be reliably displayed in the control stand.

It is a further object of the invention to provide an actuating mechanism of the kind hereinbefore mentioned, in which the working connection of the three-way valve is connected to the side of the actuator effective in the closing direction, wherein the side of the actuator eifective in the opening direction is directly connected to a servo valve, whilst the servo chamber of the threeway valve is directly connected to this connecting line, wherein the display means are located in or on this connecting line, and wherein the bias of the spring of the three-way valve is such that it balances the equalizing pressure in the servo chamber, which pressure is lower than the operating pressure, but sufficiently high for the normal actuation of the actuating device.

Preferably, the equalizing pressure is between about 40 to percent of the operating pressure.

It is a further object of the invention to provide an actuating mechanism of the kind hereinbefore mentioned, in which the closing force for an actuator for a cutoff slide, wherein the piston chamber remote from the piston rod is pressurized during actuation in the closing sense, is limited; to this end, the control piston of the three-way valve is preferably constructed in two parts, wherein one part, carrying the control edges, rests on the said spring and a second servo chamber is formed between these two parts and communicates with the working connection of the three-way valve, and the second part is located between this second servo chamber and the first servo chamber.

It is a further object of the invention to provide an actuating mechanism of the kind hereinbefore mentioned, wherein, with the servo valves provided in a central control room, actuation may be effected from the deck of the vessel in that the connecting pipeline is connected on the deck through a cutoff member to a central oil return line arranged on the deck of the vessel.

It is a further object of the invention to provide an actuating mechanism of the kind hereinbefore mentioned, in which the positional indicator is a volumeter, mounted preferably in the connecting line.

Preferably, a pressure gauge is additionally connected into the connecting line so that its indication appears on the scale of the volumeter.

It is another object of the invention to provide an actuating mechanism of the kind hereinbefore mentioned, in which the indicator of the volumeter has an adjustable scale for adapting it to the operational compression of the oil in the connecting line.

It is a further object of the invention to provide an actuating mechanism of the kind hereinbefore described, comprising a hydraulically releasable non-return valve between the control slide and the indicator.

It is a further object of the invention to provide an actuating mechanism of the kind hereinbefore described and comprising a single three-way valve for a plurality of `actuating devices, in which the closing sides of all actuators are connected to the working connection of the three-way valve, which has a second servo chamber mounted in series to the first servo chamber and communicating with the line leading to the closing sides of the actuators and adapted to be overridden by the action of the first servo chamber, wherein the first servo chamber is connected via non-return valves to the connecting pipeline between the servo valve and the releasable nonretum valve.

Preferably, the three-way valve, the servo 'valves and the indicators for the actuating devices connected to the three-way valve are combined to form one control unit, arranged on deck or in the control room.

Moreover, in this embodiment, the first servo chamber is preferably connected via a restriction with the oil return line. In addition, the control edge of the three-way valve, controlling the connection to the oil return pipe, is preferably equipped with a damping cone.

It is a further object of the invention to provide an actuating mechanism of the kind hereinbefore mentioned in which, for venting and scavenging the pipelines, the three-way valve has a third hydraulic bias effective in the direction of the spring and adapted to be connected at choice with the pressure line or with the oil return line, wherein a connecting line is provided connecting the two sides of the actuators and comprising a spring-loaded nonreturn valve, effective in the direction of the closing sides of the actuators, and the opening pressure of which is lower than the operating pressure, but higher than the closing pressure.

Further features and advantages of the invention will become apparent from the following exemplified description with reference to the accompanying drawings which illustrate the invention, `but in no restrictive manner. In the drawings:

FIG. 1 is a diagram of the pipelines and apparatus for locally operated actuating devices on board a tanker;

FIG. 2 is a diagram of the pipelines and apparatus for centrally operated actuating devices on board a tanker;

FIG. 3 is a circuit of the actuating mechanism according to the invention, showing a first embodiment thereof;

FIG. 4 is a circuit, showing a second embodiment of the actuating mechanism according to the invention;

FIG. 5 is a circuit diagram, showing a third embodiment of the actuating device according to the invention;

FIG. 6 shows the scale of a position indicator, used in the actuating mechanism according to the invention;

FIGS. 7-12 show the scale of FIG. 6 in different operating conditions;

FIG. 13 is a diagram of the pipelines and apparatus for a modified embodiment with locally operated actuating devices on board a tanker;

FIG. 14 is a diagram of the pipelines and apparatus for a modified embodiment with centrally operated actuating devices on board a tanker;

FIG. 15 shows the hydraulic circuit for operating the devices of FIGS. 13 and 14.

1n the drawings and in the description, the same reference numerals are used for identical parts, and the individual embodiments of the invention are indicated by the prefixes 1, 2 and 3, respectively.

FIG. 1 shows diagrammatically the pipelines and apparatus for an actuating mechanism for locally controlled actuating devices. A delivery pipeline extends from the pressure oil station 2 with one section 4 within the tank space of the ship conveniently at the level of the shutoff devices to be operated, and with another section 6 on the deck over the length of the tanker. A return pipeline 8 extends adjacently to the delivery pipe within the tank space. A return pipe 10 is also arranged on deck adjacent to the pipe 6.

Where control devices are combined to form groups, with connections to delivery and return oil within the group for the individual control devices, one connecting pipe 24 and 26 for the group of control devices is sufficient.

Each control device 22, 122, 222 is connected by a single pipe 28 with the associated actuating device 40, 140 and 240, respectively.

FIG. 2 Shows the pipelines and apparatus for a single pipeline system for a centrally controlled actuating system. Also here, the delivery pipeline extends with one section 4 from the pressure oil station 2 within the tank space of the ship. A second pipeline section 6 extends to the control apparatus 22, 122 and 222, arranged in a control room 21. A return pipeline 8 extends adjacently to the delivery line 4, whilst a further return pipe 30 connects the control devices with the hydraulic plant. The actuating devices 40, and 240 are connected to the pipes 4 and 8, as described in FIG. 1.

Each control device 22 is connected by a single line 28 with the associated actuating mechanism.

Closing from the deck may be effected by means of a valve 32 which is opened in Order to cause the closing, as described further below. A return pipe 34 is necessary for returning the oil, expelled from the cutoff valve during this process to the hydraulic plant; this return pipe may be connected with the return line 30 or may extend separately to the hydraulic station.

FIG. 3 shows diagrammatically the actuating equipment of a hydraulic cylinder 40 of the type used for operating so-called gate slide valves 42. The control mechanism 22, arranged on deck or in a control room comprises as control valve a four/three-way valve 23 with three positions O, I, II (i.e., Stop, Open and Close). Conveniently, these positions are constructed as stops or registers. If the slide valve 42 is to be operated only from one end position into the other, the centre position of the multi-way valve is unnecessary, and a four/two-way valve with two positions I and II is used. The connections between the control device 22 and the cylinder 40, and the delivery and return line are shown in FIGS. 1 and 2 and described in the associated text. A restriction 27 in the line 28 permits the control of the adjusting speed of the actuator; the pressure gauge 29 serves as operational control. The line 28 is protected against excessive pressure by a safety valve 31.

The pipe 28 connects the control device 22 with the cylinder 41 of the actuator unit 40. Immediately adjacently to the actuating cylinder, there is a three-way valve 48 with counterpressure spring 54, the servo chamber 46 of which communicates via a conduit 44 with the line 28. The three-way valve operates as control valve.

The working side of the three-way valve is connected with the side 43 of the actuating cylinder 40, acting in the closing direction, by means of the closing pressure pipe 50.

A control piston 52 is easily movably mounted in the three-way valve 48. The counterpressure spring 54 urges the piston in the direction of the servo chamber 46. The servo chamber 46 is Sealed by a seal 64 against the piston.

Conveniently, the force of the spring 54 is adjustable and is so dimensioned that, only when a certain pressure is reached in the servo chamber 46, for example amounting to about 60 to 8O percent of the operating pressure of the installation, will the control piston 52 assume a position in which the control edges 56 and 58 close the connecting ports 60 and 62 for the pressurized oil or for the return oil with minimum overlap, as shown in the drawing. In the following, this pressure will be referred to as the equilibrium pressure.

The equilibrium pressure is so chosen that at this pressure the actuating units develop the required adjusting forces. The difference between the equilibrium pressure and the operating pressure should be sufficient to cover the pressure requirements occurring on the one hand in the form of flow resistance of the oil flow during the opening movement, and on the other hand needed for overcoming the frictional forces in the pipeline, during the movement out of the closed position.

In the FIG. 3 embodiment, the positional control is very simple. It consists of the pressure display or indication in the line 28 and is suitable substantially for installations adapted to be moved only from one end position into the other.

The operation of the FIG. 3 arrangement will be described in the following:

The slide valve is closed. The multiway valve 23 of the control mechanism 22 is in the position 0 or Il. The pressure in the line 28 is below the equilibrium pressure and the control piston 52 is displaced relative to the servo chamber 46. In this position, the connection 60 of the delivery conduit 4 communicates with the rod chamber 43 of the cylinder so that the piston of the cylinder 40 keeps the slide valve 42 closed with a force corresponding to the operating pressure.

`In the position I of the multiway valve 23, pressurized oil is fed into the pipe 28, causing the pressure therein to rise. The control piston 52 of the three-way Valve 48 is displaced against the pressure of the spring 54 and reaches the position shown in the drawing when equilibrium pressure has been established. When this equilibrium pressure is slightly exceeded, the piston opens the discharge of return oil from the cylinder 43. Thus, the actuation takes place only when the equilibrium pressure, adjusted by means of the spring 54, has been exceeded.

Assuming, for example, that the equilibrium pressure has been set, by means of the spring 54, at 70 percent of the operating pressure, this pressure will not be required in the cylinder chamber over the whole opening stroke. However, since the three-way valve 48 requires, on the other hand, the equilibrium pressure in order to enable reiiux oil to escape from the cylinder chamber 43, this valve regulates the reflux oil outlet automatically in that way that the cylinder chamber 43 remains always under a yback pressure which compensates the part of the opening force, by which the same -would be too large owing to the equilbrium pressure acting upon the cylinder chamber 41 with normal or low load on the closing member of the fitting, without the back pressure in the cylinder chamber 43. Thus, in this state, the control slide 52 covers the outlet port 62 in a restricting manner.

If the full equilibrium pressure is needed for the movement, the back pressure reaches zero value. The outlet port is fully opened. If the opening force requirements rise yet further, the pressure in the cylinder chamber 41 and in the servo chamber 46 rises beyond the equilibrium pressure, possibly to the operating pressure.

Thus, the circuit just described achieves that the pressure in the cylinder chamber 41 is kept substantially constant over the entire travel of the actuating mechanism, excepting the case, where a pressure higher than the equilibrium pressure is needed.

This control, referred to in this description as constant pressure control, compensates automatically load changes occurring at the closing member of the connections and fittings.

When the multiway valve 23 is reset into the position O, the oil column in the line 28 is blocked.

In order to protect the pipe 28 against an excessively high pressure, particularly due to heating, a safety valve 31 is provided with a response pressure which is a certain amount above the operating pressure.

When the three-way valve 23 is actuated, there occurs first a pressure release in the oil column enclosed in the pipe 28. When the equilibrium pressure is slightly higher than this pressure, the spring 54 returns the control piston 52 so far into the servo chamber 46 that hydraulic oil can flow from the pressure conduit 4 into the cylinder chamber 43. The conduit 28 acts now as reflux conduit for the oil displaced from the cylinder chamber 41. The closing speed is determined by the restriction 27.

When the valve assembly reaches the nal closing position, or if the slide valve is prevented in continuing its closing movement by extraneous causes, the pressure in the line 28 will decline to zero.

If the slide valve 42 is to be closed from the deck, only the cutoff valve 32 need be opened. This connects the line 28 with the return conduit 34, causing the slide valve to close as described above. In this case, the restriction 21 determines the closing velocity.

In the FIG. 4 embodiment, the valve is a wedge-type slide valve, the closing member of which is mounted on the piston rod of the actuator 140. This would enable the actuator to develop a larger closing and opening effort, `but for reasons of safety, the closing should be effected with a reduced pressure in the piston chamber 143 of the actuator.

To this end, the control piston of the three-way valve 148 is divided into two parts, namely the actual piston 152, carrying the control edges, and an auxiliary piston 153; a second servo chamber 147 is formed between these two parts and communicates via bores in the piston 152 with the Working connection of the actuating device. In this arrangement, the piston 152 and the second servo chamber 147 act as a reducing valve between the delivery conduit 4 and the piston chamber 143. The spring 154 is so adjusted that the piston assumes the intermediate position shown in the drawing, when the reduced pressure in the piston chamber amounts to about 40 to 50 percent of the operating pressure.

A non-return valve 125 is mounted between the multiway valve 123 and the restriction 27 in the conduit 28; this valve is hydraulically released in the position II and retains the oil column in the conduit 68 in the position 0.

The circuit shown in FIG. 4 contains, in addition to a pressure gauge, a volumeter 126 located in the conduit 28 and serving to indicate the position in the control device 122, the arrangement being such that the pressure gauge and the volumeter have a common display device 126 (FIG. 6).

The driven spindle of the volumeter 126 drives through suitable means (eg, a clutch coupling with a permanent magnet) in the display device 128 a reduction gearing, the input spindle of which carries a display symbol 172 arranged over a fixed base scale 171 (FIG. 6) of the instrument so that the revolutions of the volumeter spindle are shown at a 1:1 ratio, and even small ows into or out of the conduit 28 can be observed. The output spindle of the reduction gearing carries the position indicator 172, connected with this spindle by a slipping clutch, not shown in the drawing.

The position indicator sweeps a scale arranged on an adjustable scale ring 174 with a calibration corresponding to the opening travel.

The indicating instrument 128 comprises further a pressure gauge with a pointer 177 which sweeps a scale 178, provided with specially marked panels for the equilibrium pressure 179, the operating pressure 180 and the response pressure 181 of the safety valve 231.

In the embodiment of FIG. 5, the cutoff Valve has a rotary flap 242, actuated by a piston 245 via a pivoting drive 240.

This arrangement corresponds substantially to that described with reference to FIG. 3. As in the FIG. 4 circuit, the positional display is effected by a volumeter 226 and a pressure gauge with a common indicating instrument 228.

The positional indication by means of a volumeter and pressure gauge will now be described generally for all constructions with reference to FIG. 5.

Up to the point at which the equilibrum pressure is achieved in the control chamber 246, the conduit 28 receives a certain volume of oil, referred to in the following as spoiler volume A. This spoiler volume A depends only on the length and on the diameter of the conduit 28 and may be regarded as constant.

If the pressure necessary for actuating the actuator exceeds the equilibrium pressure, the conduit 28 receives an additional spoiler volume B. The spoiler volume B depends on the pressure existing at the time between the equilibrium pressure and the operating pressure. The spoiler volumes A and B are static.

Since during the movement of the actuator, the conduit 28 has a ow resistance, a pressure drop occurs in this conduit. This pressure drop results in a further, dynamically determined spoiler volume X, which acts in a positive manner during the opening of the slide valve and in a negative manner during the closing of the slide valve in the positional display to be described. Hence, the -display of the pressure gauge is above or below the actual operating pressure in the actuator and in the control chamber 246, as a function of the direction of flow in the conduit 28, so long as oil flows in this conduit.

After these preliminary remarks, the operation of the arrangement of FIG. will now be described.

The flap valve is closed. The multiway valve 232 is in the position II. The conduit 28 is depressurized. The position indicator 173 rests on the limit stop 175. The pressure gauge 177 shows zero pressure (FIG. 6).

For opening the ap valve, the three-way valve 232 is placed into position I. The spoiler volume A enters into the conduit 28. The pointer 173 sweeps the range S of the scale, corresponding to the spoiler volume A. At r`the same time, the pressure rises to equilibrium pressure. After the spoiler volume A has entered, the pointer 173 has reached the zero mark on the scale 174 and the pressure in the servo chamber 246 is equal to the force of the spring 254 and balances the same (equilibrium pressure) (FIG. 7). In order to maintain this equilibrium pressure during the starting movement in the three-Way valve 148, the pressure on the volumeter must be above the equilibrium pressure by the now-dependent pressure drop in the conduit 28 between the control device 222 and the servo chamber 246. Hence, an additional spoiler volume X enters into the conduit 28 and is detected by the volumeter. The pointer 173 leads therefore the actual amount of oil fed into the position chamber 241 by this spoiler volume X. When the multiway valve 232 is returned into the position 0, in order to retain the liiap in an intermediate position, the spoiler volume X, trapped in the conduit 28 by the non-return valve 225, is displaced into the cylinder chamber 241 so that the flap assumes exactly the position indicated by the pointer `173 on the scale. The pressure in the oil column in the conduit 28 is relieved to the equilibrium pressure, which is displayed by the pointer 177 (FIG. 8).

If the actuator is moved into the fully open position, once this position is reached the spoiler volume X becomes zero, because the flow has ceased. The pointer 173 reaches the fully open mark on the scale at equilibrium pressure. (See FIG. 9.) If the -multiway valve 123 remains in the position I, the pressure rises to the operating pressure and the spoiler rvolume B is fed into the conduit 28. The pointer 173 runs beyond the fully open mark with simultaneous rise in the pressure display to the operating pressure. This indicates that the actuator has, in fact, reached its end position.

If an excessive torque is required during the start of the opening movement of the ap valve, the spoiler volume B enters into the conduit 28, in addition to the spoiler Volume A, whilst the pressure rises to the operating pressure value. The display indicates that the ap valve is still closed (FIG. 11).

For closing the ilap valve, the multiway valve 232 is moved into the position II, in which the non-return valve 225 is released. First the spoiler volume B ows from the conduit 28, relieving the pressure to the equilibrium pressure value. After removal of the spoiler volume B, the pointer reaches the fully open mark of the scale under equilibrium pressure (FIG. 9). At the same time, the three-way valve 248 starts to affect the hydraulic oil supply to the cylinder chamber 243 in such a way that the above-mentioned constant pressure control ensures that the oil is displaced from the cylinder chamber 241 at such a pressure that equilibrium pressure is maintained in the servo chamber 246 of the three-way valve. -In the conduit 28, the llow resistance is effective. The volumeter indicates therefore additionally the displacement of the spoiler volume X, by which amount the spoiler volume A is reduced during the closing movement.

If the three-way valve 123 is moved into the position 0 during the closing movement, the actuator continues to move with stationary pointer 173 until the spoiler volume X has been fed into the conduit 28. Thus, the actuator reaches accurately the position indicated by the pointer 173 under equilibrium pressure. At the end of the closing movement, the spoiler volume A is fully displaced and the pointer 173 returns to 0 under simultaneous decline of the pressure until it comes to rest against the stop 175 (FIG. 6).

If complete closure becomes impossible, owing to an obstruction, the pointer will not reach its end position. The simultaneous drop of the pressure to zero indicates that the flap valve has not been fully closed (FIG. 12).

Contrary to slide valves, ilap valves as subject to dynamic iniluences of the tlowing medium which bias the ilap preferably in the closing direction.

Normally, in an intermediate position, the piston 245 of the pivoting drive 240` is held because equal pressure is present in both cylinder chambers 241 and 243. If the liap is affected by a torque, oil is displaced from the cylinder chamber 241 into the conduit 28 and the pressure in the latter rises. The servo piston 252 of the three-way valve 248 is displaced against the pressure of the spring, causing the pressure in the cylinder chamber 243 to drop and a corresponding counter-moment to be created. If the load on the ap valve is removed, the pressure in the conduit 28 returns to equilibrium pressure value.

This dynamic loading of the ap valve is displayed on the indicating instrument as a deviation from the equilibrium pressure.

In the embodiment shown in FIG. 13, there are only a central hydraulic oil line 6 and a central oil return line 10 on the deck of the vessel, extending from the central hydraulic oil station 2. These lines extend over the length of the loading space of the ship. The tank sections, indicated diagramrnatically by vertical dividing lines and consisting, for example, of a centre tank and a wing tank each, contain each the connections between flap and slide Valves controlling the tanks, and not shown in the drawing, and actuated by the actuating units 40, 240, indicated merely schematically.

On deck, there is a control apparatus 13, connected by a conduit 26 with the return oil line 10, and a line 24 connected with the pressure line 6. The control apparatus contains the switching and indicating units 322 and a closing pressure control apparatus 349. The switching and indicating units 322 are connected by conduits 28 with the drive sides of the actuators 40, 240y biased in the opening direction. The sides effective in the closing direction of all actuating units arranged in one tank section are connected to each other and through a conduit 50 with the closing pressure control unit 349.

In the embodiment shown in IFIG. 14, the control unit 13, constructed in the same way as in the FIG. 1 embodiment, is housed in a central control room 21. The conduits 50 and 28 connect this control room with the actuating units of each tank section. On deck, there is only an additional oil return conduit 10 for the emergency shutdown.

The operation of the actuating equipment and also the positional display are, in principle, as described above with reference to FIG. 5. In the following, therefore, only the differences in the arrangement and operation of this embodiment will be described.

The control unit 13 contains an actuating and indicating apparatus 322 with a control valve 323 for each actuator 40, 240, as well as a hydraulically releasable nonreturn valve effective in the direction of the control valve, an indicating instrument 326 and a pressure relief valve 331. Between the non-return valve 325 and the control valve 323, there is a further non-return valve 330 with a parallel restriction 338, and effective in the direction of the control valve. The hydraulic oil connection of the control valves contains also a preferably variable restriction 337. The hydraulic oil connections of the individual actuating and indicating units 322l are connected to a common connecting conduit 24', connected to the hydraulic oil conduit 24. In a similar manner, the return oil connections are connected to an oil return conduit 26 which is in turn connected to the oil return line 26.

The closing pressure control unit 349 contains for all connected actuating units a three-way valve 348 with a biasing spring 354, a rst servo chamber 346 and a second servo chamber 347. The servo chamber 347 is connected with the closing pressure conduit 501, to which all actuators 40, 240 are connected at their sides effective in the closing direction. The construction of the threeway valve may be the same as that of the three-way valve 148 according to FIG. 4.

The servo chamber 346 is connected with a conduit 344, to which the individual actuating and indicating units 322 are connected. This connection is made between the non-return valve 330 and the control valve 323, that is to say in a section of the conduit 28 which is depressurized in the positions and II of the control valve 323. The connections are each secured by non-return valves 333, closing in the direction of the control valve 323. The servo chamber 346 communicates further -via an adjustable restriction 335 with the return oil connection of the closing pressure control unit 349, which is also connected to the conduit 26. The restriction 335 causes the depressurization of the conduit 344 and thus also of the servo chamber 345 after the termination of an opening movement. t

The return oil connection of the three-way valve 348 contains also a pressure relief valve 361, whereby, when one or more actuators are operated, a minimum closing pressure is maintained for the actuators remaining in the inoperative position.

The closing pressure adjusted at the three-way valve by the spring 354, is effective on the closing sides of all actuators 40, 240.

For opening a slide or ilap, the control valve 323 is moved into the position I. Conveniently, this position has a spring-biased return relative to the position 0. As already described, in the position I, hydraulic oil flows through the non-return valve 330 and the releasable nonreturn valve 335, as well as through the volumeter 326, into the conduit 2-8. As soon as the pressure in the conduit 28 becomes larger than the equilibrium pressure, the servo chamber 346i becomes effective via the conduit 344 and overrides the servo chamber 347. The three-way valve 323 starts to establish a connection between the conduit 5t) and the return conduit, causing the closing pressure to drop. The resulting diiterential pressure between the conduit 28 and the conduit 50 initiates the opening movement of the actuator.

The opening speed of the actuator is determined by the restriction 337 which also prevents an excessively sudden pressure rise in the servo chamber 346 and thus an excessively sudden pressure drop in the closing pressure line. Further restricting means can be incorporated in the closing pressure line 50, in order to effect the timing of the pressure drop. Thus, for example, a restriction or a volumetric flow controller may be mounted in the closing pressure line itself. In addition, the control edge of the three-way valve, controlling the connection to the return conduit, may be pro-vided with a damping cone, such as known in the art.

The non-return valves 333 associated with the non-operated actuating devices prevent hydraulic oil from passing from the conduit 344 into the conduits 28 to the other, not actuated, actuating devices.

When the actuating lever of the control valve is released after the desired opening position has been reached, the control valve is returned to the position 0 by the spring. The pressure in the conduit 344 is relieved via the restriction 335 so that the servo chamber 346 -becomes ineffective. Through the servo chamber 347, the full closing is again built up in the conduit 350, causing the actuator to be firmly locked between the oil column in the conduit 50, affected by the closing pressure and the oil column locked in the conduit 28 and subject to the same pressure.

For closing one of the shuto valves, the control valve 323 is moved into the position II. In this position, the non-return valve 325 is released. The conduit 344 remains depressurized so that the three-way valve 348 is controlled exclusively by the servo chamber 347. Oil may leave the conduit 28 through the released non-return valve 325 and the restriction 338, and may flow back into the return line. The restriction 338 determines the closing speed. When the actuator has reached its end position, the oil column in the conduit 28 is relieved to zero pressure.

The positional indication in the operational conditions just described takes into consideration the dierent spoiler volumes in the way described above with reference to FIG. 5.

For scavenging the conduits 50 and 28, and particularly for venting the pipelines and for correcting the positional indication after an emergency shutdown, the three-way valve 348 is equipped with a third servo chamber 353, effective in the direction of the spring and equipped with a control slide valve 345 connected via a conduit 355 to the hydraulic oil feed 24 and to the oil return conduit 26. The control slide 345 connects the conduit 355 normally with the oil return conduit, but when the control slide 345 is operated, the conduit 355 is connected to the hydraulic oil feed.

Moreover, each actuator 40, 240 has, between the two actuating sides, a connection 351, containing a springloaded non-return valve 339, opening in the direction towards the conduit 28, and set at a pressure higher than the closing pressure, but lower than the operating pressure.

For scavenging the pipeline, the slide valve 345 is operated and the servovalves 323 are placed into the position II. Using the pressure in the servo chamber 353, the slide valve of the three-way valve is placed into a position in which the closing pressure line and the hydraulic oil line communicate fully. Hydraulic oil then flows through the line 50, via the connection 351i and the non-return valve 339 into the conduit 28, and from there through the control valves 323 into the oil return conduit. In this manner, a quick and reliable venting is achieved. Naturally, a bypass conduit to the three-way valve 348 between the conduits 24 and 40 with a simple shutoff valve may be provided to this end.

I claim:

ll. An improved hydraulic actuating system for flap and slide valves, particularly on tankers, with a central pressure oil and return oil conduit, to which the actuating device is connected via a three-way valve with one-sided hydraulic bias and with a counter-pressure spring which biases the servo piston in the sense of establishing a connection between the pressure and working connections, and with means for displaying the position of the actuating mechanism, wherein the improvement comprises that the working connection of the three-way valve is connected to the side of the actuating mechanism effective in the closing direction, that the side of the actuating mechanisrn effective in the opening direction is connected directly to a control valve, that the servo chamber of the three-way valve is directly connected to this connecting conduit which also contains the indicating means, andthat the bias of the said spring of the three-way valve is such that it balances an equilibrium pressure in the servo chamber which pressure is lower than the operating pressure but is sufficiently high for the normal operation of the actuating mechanism.

2. An actuating system as set forth in claim 1, wherein the said equilibrium pressure amounts to about 40 to 90 percent of the operating pressure.

3. An actuating system as set forth in claim 1, for a slide valve in which the piston chamber remote from the piston rod is affected by a pressure during actuation in the closing direction, wherein the servo piston of the three-way valve is formed in two parts, of which one part, carrying the control edges, rests on the said spring and a second servo chamber is formed between the two parts which communicates with the working connection of the three-way valve, and wherein the second part of the piston is located between this second servo chamber and the rst servo chamber.

4. An actuating system as set forth in claim 1, with central actuation and means for actuating the system from the deck of the ship, wherein the said connecting conduit is connected on the deck by means of a shutoff member to a central, deck-mounted, oil return conduit.

5. An actuating system as set Vforth in claim 1, wherein a volumeter is provided for the positional display indication.

6. An actuating system as set forth in claim 5, comprising an additional pressure gage on or in the said connecting conduit, wherein the display means of this pressure gage are visible within the eld of the scale of the volumeter.

7. An actuating mechanism as set forth in claim 1, with a volumeter for the positional display, wherein the display means of the said volumeter have an adjustable scale.

`8. An actuating system as set forth in claim 1, comprising a hydraulically releasable non-return valve between the control slide and the display instrument.

9. An actuating system as set forth in yclaim |1, with a hydraulically releasable non-return valve between the control slide and the display instrument, wherein a single three-way valve is provided for a plurality of actuators, with the closing sides of all actuators being connected to the working connection of the said three-way valve, and comprising a second servo chamber arranged in series to the rst servo chamber and communicating with the conduit leading to the closing sides of all connected actuators and adapted to be overridden by the action of the first servo chamber, wherein the first servo chamber is connected via non-return valves to the said connecting conduit at a point between the servo valve and the releasable non-return valve.

10. An actuating system as set forth in claim 9, wherein the said three-way valve, the control slides and the display instruments are combined to form a unit, arranged on deck or in a control room.

11. An actuating system as set forth in claim 9, wherein the first servo chamber is connected via a restriction with the oil return conduit.

'12. An actuating system as set forth in claim 9, wherein the control edge of the three-way valve, controlling the communication with the oil return conduit, is provided with a damping cone.

13. An actuating system as set forth in claim 9, wherein the connection between the oil return socket of the threeway valve and the oil return conduit contains -a pressure relief valve.

14. An actuating system as set forth in claim 9, com prising an adjustable restriction in the oil pressure conduit upstream of the pressure oil connection of the servo control slide.

15. An actuating system as set forth in claim 9, comprising a non-return valve with parallel restriction, arranged between the servo control slide and the releasable non-return valve and effective in the direction of the said servo control slide.

16. An actuating system as set forth in claim 9, wherein the three-way valve has a third hydraulic servo charnber acting in the direction of the spring, adapted to be connected via a valve with the pressure conduit, and comprising a conduit connecting both sides of the actuating devices, arranged on or in the same, and containing a spring-loaded no-return valve, effective in the direction of the closing side, the opening pressure of which non-return valve is lower than the operating pressure, but higher than the closing pressure.

17. A hydraulic actuating system for flap and slide valves, particularly on tankers, with a central pressure oil and return oil conduit to which the actuating device is connected via a three-way valve with a one-sided hydraulic bias and with a counter pressure spring which biases the servo piston in the sense of establishing a connection between the pressure and working connections, and with means for displaying the position of the actuating mechanism, wherein the working connection of the three-way valve is connected to the side of the actuating mechanism effective in the closing direction, the side of the actuating mechanism e'ective in the opening direction is connected directly to a control valve, the servo chamber of the three-way valve is connected directly to this connection which also contains the indicating means, and the bias of the said spring of the three-way valve is such that it balances an equilibrium pressure in the servo chamber, which pressure is lower than the operating pressure but sufliciently high for the normal actuation of the actuating mechanism, and wherein a volumeter is provided for the positional display.

18. A hydraulic actuating system for ap and slide valves, particularly on tankers, with a central pressure oil and return oil conduit to which the actuating device is connected Via a three-way valve with a one-sided hydraulic bias and with a counter pressure spring which biases the servo piston in the sense of establishing a connection between the pressure and working connections, and with means for displaying the position of the actuating mechanism, wherein the working connection of the three-way valve is connected to the side of the actuating mechanism effective in the closing direction, the side of the actuating mechanism eifective in the opening direction is connected directly to a control valve, the servo chamber of the three-way valve is connected directly to this connection which also contains the indicating means, and the bias of the said spring of the three-way valve is such that it balances an equilibrium pressure in the servo chamber, which pressure is lower than the operating pressure but is sufficiently high for the normal operation of the actuating mechanism, and wherein a volumeter is provided for the positional display, and comprising further an additional pressure gage on or in the said connecting conduit, wherein the display means of the said pressure gage are visible within the field of the scale of the volumeter.

19. A hydraulic actuating system for flap and slide valves, particularly on tankers, with a central pressure oil and return oil conduit to which the actuating device is connected via a three-way valve with a one sided hydraulic bias, and with a counter pressure spring which biases the servo piston in the sense of establishing a connection between the pressure and working connections, and with means for displaying the position of the actuating mechanism, wherein the working connection of the three-way valve is connected to the side of the actuating mechanism effective in the closing direction, the side of the actuating mechanism elfective in the opening direction is connected directly to a control valve, the servo chamber of the three-way valve is connected directly to this connection, which also contains the indicating means, and the bias of the said spring of the three-way valve is such that it balances an equilibrium pressure in the servo chamber, which pressure is lower than the operating pressure but is sufficiently high for the normal operation of the actuating mechanism, and comprising a volume meter for the positional display and an additional pressure gage on or in the said connecting conduit, wherein the display means of the pressure gage are visible within the eld of the scale of the volume meter, and comprising further a hydraulically releasable non-return valve between the control slide and the display instrument.

20. A hydraulic actuating system for flap and slide valves, particularly on tankers, with a central pressure oil and return oil conduit to which the actuating device is connected via a three-way valve with a one sided hydraulic bias, and with a counter pressure spring which biases the servo piston in the sense of establishing a connection between the pressure and working connections, and with means for displaying the position of the actuating mechanism, wherein the working connection of the three-way valve is connected to the side of the actuating mechanism effective in the closing direction, the side of the actuating mechanism effective inthe opening direction is connected directly to a control valve, the servo chamber of the three-way valve is connected directly to this connection which also contains the indicating means, and the bias of the said spring of the three-way valve is such that it balances an equilibrium pressure in the servo chamber, which pressure is lower than the operating pressure but sufliciently high for the normal operation of the actuating mechanism, and comprising hydraulically releasable non-return valve between the control slide and the display instrument, wherein a single three-way valve is provided for a plurality of actuators, with the closing sides of all connected actuators being connected to the Working connection of the said three-way valve, and comprising a second servo chamber arranged in series to the first servo chamber and communicating with the conduit leading to the closing sides of all connected actuators, and adapted to be overridden by the action of the first servo chamber, wherein the iirst servo chamber is connected via non-return valves to the said connecting conduit at a point between the servo valve and the releasable non-return valve.

21. A hydraulic actuating system for ap and slide valves, particularly on tankers, with a central pressure oil and return oil conduit to which the actuating device is connected via a three-way valve with a one-sided hydraulic bias and with a counter pressure spring which biases the servo piston in the sense of establishing a connection between the pressure and working connections, and with means for displaying the position of the actuating mechanism, wherein the working connection of the three-way valve is connected to the side of the actuating mechanism effective in the closing direction, the side of the actuating mechanism effective in the opening direction is connected directly to a control valve, the servo chamber of the three-way valve is connected directly to this connection which also contains the indicating means, and the bias of the said spring of the three-way valve is such that it balances an equilibrium pressure in the servo chamber, which is lower than the operating pressure but suiciently high for the normal operation of the actuating mechanism, comprising a volume meter for displaying the position, and comprising further a hydraulically releasable non-return valve between the control slide and the display instrument, wherein a single three-way valve is provided for a plurality of actuators, with the closing sides of all connected actuators being connected to the working connection of the said three-way valve, and comprising a second servo chamber arranged in series to the rst servo chamber and communicating with the conduit leading to the closing sides of all connected actuators, and adapted to be overridden by the action of the first servo chamber, wherein the first servo chamber is connected via non-return valves to the said connecting circuit at a point between the servo valve and the releasable non-return valve.

References Cited UNITED STATES PATENTS 2,888,029 5/1959 Govan et al. 137-344 3,009,474 ll/ 1961 Crichton 137-344 3,156,255 11/1964 Gasquet et al. 137-344 3,191,621 6/1965 McKinnon et al 137-553 3,439,706 4/ 1969 Barrett 137-554 HENRY T. KLINKSIEK, Primary Examiner U.S. C1. X.R.

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