The invention relates to a marine shell door, in particular a marine ship shell door. The shell door comprises a framework including a door plate. The framework provides a skeleton structure to the shell door. The door plate is movable connected to a door casing.

All shell doors in the hull of a ship are subjected to special safety requirements. In particular when the shell door is positioned at a lower region of the ship under the waterline. The strength and securing and locking arrangements of shell doors on Ro-Ro passenger ships are defined in the SOLAS regulations. The SOLAS regulations have been redrafted after a serious accident with a ferry ship, the Ms Estonia. An official report about that accident indicated that the locks on the bow door had failed from the strain of the waves and the door had separated from the rest of the vessel. It is very important that the latches do not fail and keep on working under all circumstances. A hydraulic operation of the latches has proven to provide a reliable solution and decrease a risk on malfunction of the shell door.

DE 202006020570U1 discloses a shell door which is provided with a plurality of hydraulically acted latches. The latch is axially movable and operated by a hydraulic cylinder. A plurality of latches is provided at the shell door outer circumference. A central pump is provided for operating the hydraulic cylinders. Fluid conduits are provided to connect the central pump in fluid communication with the hydraulic cylinders.

One drawback in this context is that the fluid conduits extend along a long path. The fluid conduits extend through several compartments of the framework to reach the cylinders at the circumference of the shell door. The fluid conduits are vulnerable for damages. During a lifetime of a ship, oxidation of the fluid conduits may cause leakages. Occasionally, the fluid conduits may get at least partially obstructed when the fluid conduits are accidentally hit. In case of a leakage, the whole content of the central pump may leak into the environment which may be a volume of 30liters of hydraulic fluid. Such a leakage on board of a ship generally results in environmental pollution.

DE1.281.292 discloses a hatch cover for a ship comprising a pair of a first and a second hatch cover part which cover parts are pivotable positioned and actuable by a hydraulic force. The first hatch cover part comprises a drive unit including a reservoir for hydraulic fluid, an electric motor and a pump. The drive unit is arranged for driving a hydraulic cylinder in the second cover part. The drive unit is positioned in a first closed box in the first hatch cover part. The closed box is provided to prevent any leakages of oil from the cover part to a tonnage of the ship. The hydraulic cylinder is arranged in a separate second closed box in the second hydraulic cover part. A fluid conduit is provided to connect both boxes to connect the drive unit in fluid communication with the cylinder. The fluid conduit in between the two separate boxes extends through a protective guidance which is welded to the boxes to prevent damaging of the fluid conduit. Such damage might cause a leakage of oil.

Although the closed boxes may reduce a risk on oil leakage to a tonnage of the ship, the presented solution is still not satisfying.

The general object of the present invention to at least partially eliminate the above mentioned drawbacks and/or to provide a useable alternative. More specific, it is an object of the invention to provide a reliable hydraulically operated marine shell door which complies to the SOLAS regulations.

According to the invention, this object is achieved by a marine shell door according to claim 1.

The marine shell door, also called a ship shell door, according to the invention comprises a framework including a door plate. The framework provides a skeleton structure to reinforce the shell door. Typically, the framework includes a plurality of compartments.

The marine shell door is improved in that it further comprises at least one hydraulic actuator unit for operating said shell door itself and/or at least one shell door component, said at least one hydraulic actuator unit comprises a hydraulic actuator and an actuator pump which is dedicated to said hydraulic actuator for operating said hydraulic actuator, wherein said actuator pump has an electrical motor and a pump housing for supplying hydraulic fluid to the hydraulic actuator.

The marine shell door according to the invention has several advantages.

The wording 'unit' means that corresponding hydraulic components of the hydraulic actuator unit are assembled together at a single location. A first advantage is that the operation of the marine shell door is decentralised. The shell door has no central main actuator pump to act all installed actuators to operate e.g. all latches of the shell door. In contrast, the shell door has for each individual movement an individual actuator pump.

Advantageously, the installation of the shell door on board of a ship is simplified. No relatively long fluid conduits are necessary anymore to connect a plurality of shell door components to one central pump. The fluid conduit is generally a stainless steel piping. In practise, those fluid conduits are difficult to install. The stainless steel fluid conduits have to be bended and mounted to the shell door and walls around the shell door which is labour intensive. The long stainless steel fluid conduits would have to pass from the central pump through all compartments of the framework towards the hydraulic actuator. It takes sometimes a week to get a proper installation of all fluid conduits. Now, according to the invention it is no longer necessary to install those long stainless steel fluid conduits which makes the installation of the shell door much easier. It suffices to install just an electric cable to connect the hydraulic actuator unit with a control unit of the ships control centre. Due to its flexibility, it is relatively easy in comparison with a steel fluid conduit to install the electric cable.

Another drawback of long fluid conduits is that they may get damaged due to all kind of occasions e.g. due to corrosion or a collision with a passing object. The damages to the fluid conduits may cause fluid leakages which can cause an environmental pollution or an obstruction in a conduit which may result to a failure of the shell door or operatable components. It needs no further explanation, that in emergency situations onboard of a ship, it may be very dangerous when shell doors get blocked or latches fail. Advantageously, by eliminating the need of long fluid conduits, the marine shell door according to the invention provides an increased safety.

A further advantage of the shell door according to the invention, is that a suitable pump for operating the only hydraulic actuator in stead of a plurality of hydraulic actuators may have small dimensions. As a result, the hydraulic actuator unit may have a more compact configuration. The hydraulic actuator unit may be a build-in actuator unit. The hydraulic actuator unit may be sufficient small to position the hydraulic actuator unit at every desired position e.g. within a small compartment of the framework at an interior of the shell door.

With respect to the disclosed hatch cover of DE1.281.292, the marine shell door according to the invention is further advantageous in that the hydraulic actuator unit of the marine shell door which includes the hydraulic actuator is very compact in comparison with the hatch cover in which the cylinder is arranged separately from the drive unit. Due to the compactness of the hydraulic actuator unit, the hydraulic actuator unit can be integrated at several places in a shell door of a ship. Only an electrical connection may be necessary to operate the at least one hydraulic unit. The compact configuration of the hydraulic unit allows a decentralised implementation of the operational parts of the marine shell door. Each hydraulic actuator is operated by a corresponding individual hydraulic pump. No central hydraulic pump with a large oil reservoir is required to operate several hydraulic actuators. In the marine shell door according to the invention, the hydraulic pump is configured and in its capacity adapted to one single hydraulic actuator which allows a compact configuration of the hydraulic pump.

In an embodiment of the marine shell door according to the invention, the hydraulic actuator unit further comprises a unit manifold. The unit manifold provides a fluid connection of the actuator pump with the hydraulic actuator. The unit manifold comprises at least one fluid channel which forms a fluid connection between the actuator pump and the hydraulic actuator. The actuator pump is in fluid communication connected with the hydraulic actuator. Advantageously, the unit manifold provides a solid connection of the actuator pump and the hydraulic actuator. No external fluid conduits are necessary, the at least one fluid channel in the internal of the unit manifold suffice to supply hydraulic fluid from the actuator pump to the hydraulic actuator. The internal fluid channel of the unit manifold is less vulnerable to damages from outside the hydraulic actuator unit. In contrast to hydraulic conduits, the unit manifold may provide a more reliable configuration which is less vulnerable to damages by oxidation or accidental hits. Further, the unit manifold contributes to a compact configuration of the hydraulic actuator unit. With respect to the disclosed hatch cover of DE1.281.292, the embodiment of the marine shell door according to the invention has the advantage in that the marine shell door is arranged free of external fluid conduits. External positioned fluid conduits are vulnerable to corrosion and may provide an obstacle which may get damaged due to collisions. Corroded or otherwise damaged fluid conduits will leak and cause a failure of connected actuators. In the embodiment no fluid conduits are necessary. The presence of the unit manifold has eliminated any external fluid conduit. Instead of an external fluid, the unit manifold has an internal fluid channel for transferring hydraulic fluid from the actuator pump to the hydraulic actuator. The internal fluid channels of the unit manifold increase the reliability and durability of the marine shell door according to the invention.

In an embodiment of the marine shell door according to the invention, the hydraulic actuator is a double acting cylinder. The hydraulic actuator includes a movable actuator member which is positioned in an actuator housing. The actuator member subdivides the actuator housing in a push and pull fluid chamber which can be pressurised with hydraulic fluid to move the actuator member. Advantageously, the double acting cylinder provides an active controlled operation of a shell door component in both forward and backward direction.

In an embodiment of the marine shell door according to the invention, the unit manifold comprises a first and second fluid channel for conducting hydraulic fluid from the pump housing to respectively the push and pull chamber in the actuator housing.

Advantageously, both the first and second fluid channel are provided inside the unit manifold which provides an improved protected positioning.

In an embodiment of the marine shell door according to the invention, the actuator housing has a cylindrical body. The cylindrical body of the actuator housing is mounted to the unit manifold by at least one tie rod. The at least one tie rod is a hollow tie rod and in fluid communication with the second fluid channel of the unit manifold, such that the pull fluid chamber of the hydraulic actuator can be pressurized via the hollow rod.

Advantageously, the hollow rod provides a passageway for a hydraulic fluid to supply the hydraulic fluid from the actuator pump via the fluid channel of the unit manifold to the pull chamber of the hydraulic actuator. Additional hydraulic fluid conduits may become redundant which may decrease a risk on damages. The configuration of the hydraulic actuator unit is simplified which advantageously reduces an assembly time.

In an embodiment of the marine shell door according to the invention, the hydraulic actuator unit has a pump housing which is positioned aside the housing of the actuator member. The actuator pump may have a cylindrical pump housing and the actuator member may have a cylindrical actuator housing. The actuator housing is connected at a proximal end face to the unit manifold. The pump housing is also connected at an end face to the unit manifold. The pump housing is positioned in parallel with the actuator member. The actuator housing and pump housing are mounted to the unit manifold at a mounting surface at one side of the unit manifold, wherein the pump housing and the actuator housing are positioned side-by-side.

Advantageously, the pump housing and the cylindrical actuator housing are positioned side-by-side to obtain a compact configuration of the hydraulic actuator unit. Advantageously, the compact configuration of the hydraulic actuator unit allows an easy built-in of the hydraulic actuator unit in the framework of the marine shell door.

In an embodiment of the marine shell door according to the invention, the unit manifold is an assembly of a pump end cover and an hydraulic actuator end cover.

Avantageously, the assembly provides a modular configuration. The modular configuration allows an easy adjustment to different circumstances. By replacing one of the end covers, it is possible to implement a larger or smaller hydraulic actuator.

In an embodiment of the marine shell door according to the invention, wherein a pair of reed sensors is provided at the actuator housing for detecting a position of the actuator member. The reed sensors are provided to magnetically detect an inward or outward position of the actuator member. The reed sensors are electrically connected to the control unit. In operation, one of the reed sensors provide a remaining signal to the control unit, such that it is always apparent in what position the hydraulic actuator unit is. It is for example always clear at the control unit whether a shell door is locked or unlocked, or whether a shell door is open or closed. Herewith, the presence of the reed sensors increase the safety of the marine shell door.

In an embodiment of the marine shell door according to the invention, the actuator pump comprises a gear pump which is positioned inside the pump housing. Preferably, the pump element is a gear pump, because the gear pump provides a high efficiency and provides a relative silent operation which is desirable on board of a ship, in particular a luxurious yacht.

In an embodiment of the marine shell door according to the invention, the shell door is a watertight ship shell door. In an embodiment of the marine shell door, the marine shell door comprises at least one latch. The door plate has an outer circumference. The door plate is movable connected to the door casing. The shell door comprises at least one latch adjacent the outer circumference.

In an embodiment, the door plate has an outer circumference, in which at least one hydraulic unit, including in particular a latch, is positioned adjacent the outer circumference for latching the shell door to a door casing. The at least one latch is connected to the doorplate.

In another embodiment, at least one hydraulic unit, including in particular a latch, is positioned adjacent the door casing for latching the shell door to the door casing. The at least one hydraulic unit is connected to the door casing. The at least one latch is associated with a corresponding hydraulic actuator unit, wherein said hydraulic actuator unit comprises a hydraulic actuator for moving the latch and a corresponding actuator pump which is dedicated to said hydraulic actuator for operating said hydraulic actuator.

Advantageously, the at least one latch is associated with a corresponding hydraulic actuator unit. Said hydraulic actuator unit comprises a hydraulic actuator for moving the latch and a corresponding actuator pump. The hydraulic actuator and the actuator pump form a set. The actuator pump is dedicated to the hydraulic actuator for operating said hydraulic actuator. Each single latch is provided with an own hydraulic actuator unit which includes a for each latch an own actuator pump. The application of smaller pumps for each individual hydraulic actuator in stead of a central large hydraulic pump reduces a risk in which a large volume of hydraulic fluid leaks flows into the environment.

In an embodiment of the shell door according to the invention, the shell door comprises at least two hydraulic actuator units. The shell door comprises at least a first hydraulic actuator unit and a second hydraulic actuator unit. The first and second hydraulic actuator unit may be connected to the movable part or fixed part of the shell door. The movable part comprises the doorplate and framework. The fixed part of the shell door comprises the door casing. The first hydraulic actuator unit has a first hydraulic actuator and a first actuator pump. The second hydraulic actuator unit has a second hydraulic actuator and a second actuator pump. Each of the hydraulic actuator units comprises a single hydraulic actuator which is provided with its own actuator pump. The hydraulic actuator unit has only one single hydraulic actuator and one single actuator pump, in which the single actuator pump is in fluid communication connected to the single hydraulic actuator. No hydraulic circuit is present to connect the first and second hydraulic actuator unit to each other. Advantageously, the decentralised arrangement of the first and second hydraulic actuator unit without interconnecting hydraulic conduits reduces a risk on damage to the hydraulic system. In an embodiment of the shell door according to the invention, the at least one latch comprises an movable latch pinion, wherein the latch pinion is connected to an associated hydraulic actuator unit for moving the latch pinion. The latch pinion has an elongated cylindrical body.

In an embodiment of the marine shell door according to the invention, the latch pinion is axially movable. The actuator member of the hydraulic actuator unit is axially movable in the actuator housing for operating the latch pinion. The axial movement of the latch pinion requires relatively less built-in space which results in a more compact configuration of the hydraulic actuator unit. The more compact configuration allows a positioning of the hydraulic actuator unit close to the outer circumference of the marine shell door.

In an embodiment of the marine shell door according to the invention, the actuator housing is integral with the unit manifold. The unit manifold and the actuator housing may be one-piece.

In an embodiment of the marine shell door according to the invention, the actuator housing is integral with a journal bearing of the latch. Advantageously, a more compact configuration may be achieved.

In an embodiment of the marine shell door according to the invention, the actuator member is integral with a hatch pinion of the latch.

In an embodiment of the marine shell door according to the invention, the shell door comprises at least one shell door operating mechanism for opening and closing the shell door. The at least one shell door operating mechanism is associated with a corresponding hydraulic actuator unit, wherein said hydraulic actuator unit comprises a hydraulic actuator for operating the shell door operating mechanism and a corresponding actuator pump which is dedicated to said hydraulic actuator for operating said hydraulic actuator.

In an embodiment of the marine shell door according to the invention, the hydraulic actuator unit is electrically connected to a control unit which is electrically connected to a ship control centre.

Further, the invention relates to a hydraulic power kit, in particular a marine shell door power kit, comprising a hydraulic actuator unit including a hydraulic actuator and a corresponding actuator pump which is dedicated to said hydraulic actuator for operating said hydraulic actuator, wherein the hydraulic actuator includes a movable actuator member which is positioned in an actuator housing, wherein the actuator pump includes a pump housing and an electric motor.

In an embodiment of the hydraulic power kit according to the invention, the hydraulic actuator unit corresponds to the hydraulic actuator unit as described above in relation to the marine shell door according to the invention. In an embodiment of the hydraulic power kit for a marine shell door, in particular for a shell door latch or for driving the shell door to and fro a closed or open position, wherein the power kit comprises a hydraulic actuator, an actuator pump and a unit manifold. The hydraulic actuator comprises an actuator member which is housed in an actuator housing. The actuator member is movable, in particular axially movable, with respect to the actuator housing. The pump has a pump housing. The actuator housing and the pump housing are connected to the unit manifold. The unit manifold provides a connection between the actuator housing and the pump housing. The hydraulic actuator is in fluid communication connected with the pump by the unit manifold. The unit manifold comprises at least one channel for a fluid supply from the pump to the hydraulic actuator.

In an embodiment of the hydraulic power kit according to the invention, the actuator pump has a pump housing which is positioned at the same side of the unit manifold as the actuator housing of the hydraulic actuator. In particular, the unit manifold comprises a channel block which is block-shaped including at least one fluid channel for conducting a fluid from the actuator pump to the actuator member. In particular, the actuator housing is integral with the unit manifold.

In an embodiment of the marine shell door, the hydraulic actuator unit is electrically connectable to a control unit which is electrically connectable to a ship control centre.

Advantageously, the marine shell door power kit only requires an electrical connection which simplifies the implementation. Further, the marine shell door power kit enables a more reliable configuration which is less vulnerable to damages, leakages etc.

In an embodiment the marine shell door power kit, the marine shell door power kit is a marine shell door latching system comprising at least one latch, the at least one latch being positioned adjacent an outer circumference of the door plate for latching the shell door to a door casing, wherein the at least one latch is associated with a corresponding hydraulic actuator unit, wherein said hydraulic actuator unit comprises a hydraulic actuator for moving the latch and a corresponding actuator pump which is dedicated to said hydraulic actuator for operating said hydraulic actuator.

Advantageously, the at least one latch is associated with a corresponding hydraulic actuator unit. Said hydraulic actuator unit comprises a hydraulic actuator for moving the latch and a corresponding actuator pump. The hydraulic actuator and the actuator pump form a set. The actuator pump is dedicated to the hydraulic actuator for operating said hydraulic actuator. Each single latch is provided with an own hydraulic actuator unit which includes a for each latch an own actuator pump. The application of smaller pumps for each individual hydraulic actuator in stead of a central large hydraulic pump reduces a risk in which a large volume of hydraulic fluid leaks flows into the environment. Further, the invention relates to a shell door latching system. The shell door latching system according to the invention comprises a shell door latch, a hydraulic actuator, a pump and a unit manifold. The shell door latch comprises a movable, in particular axially movable, latch pinion. The shell door latch is actable by the hydraulic actuator. The hydraulic actuator comprises an actuator member which is housed in an actuator housing. The pump has a pump housing. The actuator housing and the pump housing are connected to the unit manifold, wherein the unit manifold provides a direct connection between the actuator housing and pump housing. The hydraulic actuator is in fluid communication with the pump by the unit manifold. The unit manifold comprises at least one channel for a fluid supply from the pump to the hydraulic actuator.

In an embodiment of the shell door latching system according to the invention, the hydraulic actuator unit corresponds to the hydraulic actuator unit as described above in relation to the marine shell door according to the invention.

In an embodiment of the shell door latching system according to the invention, the actuator pump has a pump housing which is positioned at the same side of the unit manifold as the actuator housing of the hydraulic actuator. In particular, the unit manifold comprises a channel block which is block-shaped including a channel for conducting a fluid from the actuator pump to the actuator member. In particular, the actuator housing is integral with the unit manifold. In particular, the actuator housing is integral with a journal bearing of the latch. In particular, the actuator member is integral with a hitch pinion of the latch.

Further, the invention relates to a use of a marine shell door power kit for operating a marine shell door or a marine shell door component.

The invention will be explained in more detail with reference to the appended drawings. The drawings show a practical embodiment according to the invention, which may not be interpreted as limiting the scope of the invention. Specific features may also be considered apart from the shown embodiment and may be taken into account in a broader context as a delimiting feature, not only for the shown embodiment but as a common feature for all embodiments falling within the scope of the appended claims, in which:

Fig. 1A shows a front view of a preferred embodiment of a hydraulic actuator unit for a marine shell door according to the invention;

Fig. 1 B shows a side view of the hydraulic actuator unit as shown in Fig. 1 A;

Fig. 2 shows in a schematic view a hydraulic scheme representing an operation of the hydraulic actuator unit;

Fig. 3 shows a hydraulic scheme of a hydraulic actuator unit according to the invention; and Fig. 4 shows a side view of a shell door latching system.

Figure 1A shows in a front view a marine shell door hydraulic actuator unit 10 for operating a marine shell door according to the invention. The hydraulic actuator unit 10 is a hydraulically self containing unit which means that the hydraulic actuator unit only needs a connection to an electrical power source and a control unit for implementation. No external hydraulic connections for example to an external pump or reservoir are necessary for a proper operation of the hydraulic actuator unit 10. Preferably, according to the invention a shell door is provided which is fully electrically operated from a remote control unit. The hydraulic actuator unit 10 can be used to open or close the marine shell door and/or to operate movable marine shell door components. A shell door component is for example a latch being positioned adjacent an outer circumference of the shell door. The hydraulic actuator unit 10 can be used to drive a sliding shell door or a hinged shell door.

The hydraulic actuator unit 10 comprises an hydraulic actuator 1 1 , an actuator pump 15 for driving the hydraulic actuator 1 1 and a unit manifold 19. The unit manifold 19 includes at least one fluid channel and connects the actuator pump 15 in fluid communication to the hydraulic actuator 1 1.

The hydraulic actuator 11 is a hydraulic double acting cylinder. The hydraulic actuator 1 1 comprises an actuator housing 1 13. The actuator housing 1 13 is a cylinder body and is cylindrically shaped and has a cylindrical outer wall. The actuator housing 1 13 has a central axis in a longitudinal direction.

The hydraulic actuator 11 comprises a movable actuator member 1 12. The actuator member 1 12 is axially movable in the actuator housing 1 13 of the hydraulic actuator 1 1. The actuator member 1 12 includes a piston head and a piston rod. The piston head subdivides the actuator housing 1 13 in a first and second fluid chamber (1 12A, 1 12B, see fig. 3). The actuator member 1 12 is axially movable within the actuator housing 1 13 by supplying or discharging hydraulic fluid to the first or second fluid chamber which makes the hydraulic actuator 1 1 a double acting cylinder. The first and second fluid chamber can be pressurised to move the actuator remember 1 12 in or out the actuator housing 1 13. The first chamber is also called a push chamber 1 12A which can be pressurised to push the actuator member out of the actuator housing. Analogous, the second chamber opposite the piston head is called a pull chamber 1 12B which can be pressurized to move the actuator member 1 12 into the actuator housing 1 13.

At least two reed sensors (not shown) are provided at the cylindrical outer wall of the actuator housing 13. The reed sensors are provided to magnetically detect an inward or outward position of the actuator member 1 12. The reed sensors are electrically connected to the control unit. In operation, one of the reed sensors provide a remaining signal to the control unit, such that it is always apparent that the hydraulic actuator unit is in a

predetermined position. It is for example always clear at the control unit whether a shell door is locked or unlocked, or whether a shell door is open or closed. No signal of the reed sensors means that the shell door is in operation or that the hydraulic actuator unit fails and needs an inspection or servicing. Herewith, the presence of the reed sensors increase the safety of the marine shell door.

As shown in Fig. 1A and 1 B, the actuator pump 15 comprises a pump housing 152 and an electrical motor 151 for driving a pump element. The electrical motor 151 is electrically connectable to a control unit. The pump housing 152 has a cylindrical body and is mounted to a pump end cover 19A by at least one pump tie rod 154, in particular by at least two pump tie rods. The pump housing 152 houses the pump element which can be activated to pressurise the first or second fluid chamber of the hydraulic actuator. Preferably, the pump element is a gear pump, because the gear pump provides a high efficiency and provides a relative silent operation which is desirable on board of a ship, in particular in board of a luxurious yacht. The gear pump is driveable by the electrical motor 151 to move the actuator member of the hydraulic actuator. Further, the pump housing 152 houses a reservoir for storing hydraulic fluid.

The hydraulic actuator 1 1 comprises at the proximal and distal end face of the actuator housing 1 13 respectively a proximal and distal end cover 19B.1 19. The end covers delimit the push and pull chambers of the hydraulic actuator. The first and second fluid chamber have respectively a first and second fluid port to connect the first and second fluid chamber in fluid communication with the actuator pump 15. The first and second fluid port are positioned at the end covers 19B, 1 19. The end covers 19B, 1 19 comprise at least one fluid channel for conducting fluid to the push or pull chamber.

The end covers 19B, 1 19 are connected to each other by tie rods 1 14A, 1 14B, 1 14C,

1 14D. The tie rods extend external from the actuator housing 1 13 in longitudinal direction. The distal end cover 1 19 at the distal end face comprises one fluid channel for supplying hydraulic fluid to the pull chamber of the hydraulic actuator.

The hydraulic actuator end cover 19B at the proximal end face of the actuator housing is connected to the pump end cover 19A which assembly of end covers form the unit manifold 19. Alternatively, the unit manifold may be one piece. The unit manifold comprises at least one fluid channel 198, 199 for supplying hydraulic fluid from the actuator pump to the push or pull chamber of the hydraulic actuator. In the illustrated embodiment, the hydraulic actuator 1 1 is connected in fluid communication with the actuator pump 15 by the unit manifold 19 including the at least one fluid channel 198. The unit manifold 19 comprises a first fluid channel 198 to connect the first fluid chamber of the hydraulic actuator 1 1 in fluid communication with the actuator pump. The unit manifold 19 comprises a second fluid channel 199 to connect the second fluid chamber of the hydraulic actuator 1 1 in fluid communication with the actuator pump. Fig. 2 shows the unit manifold in further detail. The unit manifold 19 has a block shape. The unit manifold comprises two block shaped segments 19A, 19B, which serves as respectively the pump and actuator end cover. The block shaped segments 19A.19B are connectable to each other by a bold. Here a single bold and a centre pinion provides an assembly of the two end covers. The unit manifold 19 has a one sided mounting surface for mounting both the actuator housing 13 and the pump housing 152 at one side of the unit manifold 19. In the hydraulic actuator unit 10, the actuator housing 13 is positioned beside the pump housing 152. The actuator housing 13 and actuator pump 15 are positioned side-by-side. The hydraulic actuator unit 10 has an actuator pump 15 which is positioned aside the hydraulic actuator 1 1.

As shown in Fig. 1A and 1 B, the hydraulic actuator 1 1 is connected to the unit manifold 19 by at least one tie rod. As shown, four tie rods 1 14A, 1 14B, 1 14C, 1 14D are provided to mount the actuator housing 1 13 to the unit manifold 19 and end cover 1 19. The at least one tie rod clamps the actuator housing 1 13 to the unit manifold 19.

At least one tie rod is a hollow tie rod 114A. The hollow tie rod 114A provides a fluid passageway for conducting a hydraulic fluid to one of the fluid chambers of the hydraulic actuator. The hollow tie rod extends from the unit manifold 19 to the distal end cover 1 19 of the actuator housing 13 and is in fluid communication connected via a fluid channel in the end cover with a fluid port of a fluid chamber. As illustrated, the hollow tie rod is in fluid communication connected with the pull chamber of the hydraulic actuator 1 1.

The unit manifold 19 comprises at least one non return valve 192. The non return valve is positioned in the at least one fluid channel 198, 199 of the unit manifold 19.

The unit manifold 19 comprises at least one tool connector 191 for connecting a tool to the unit manifold in fluid communication with the at least one fluid channel. A connectable tool may for example be a measurement tool or an external pump which may be used as an emergency pump in an emergency case to operate the hydraulic actuator unit by hand.

The hydraulic actuator unit 10 has a simple modular configuration. The modular configuration is determined by i.e. the end covers and tie rod assembly. The configuration of the hydraulic actuator unit 10 is such that it allows an easy design adjustment to obtain a hydraulic actuator unit 10 for another application which requires another stroke or another working force. Due to the simple configuration, the hydraulic actuator unit 10 can be fit to such an application by adjusting the length or diameter of the pump housing, hydraulic actuator housing 13 and the actuator member 1 12. In an application which requires a larger working force, the design of the hydraulic actuator unit 10 can be adjusted by up scaling the diameter of the actuator housing. By increasing the diameter of the actuator housing 13, the hydraulic actuator may exert a working force of e.g. 120kN instead of 30kN. Fig. 3 shows a hydraulic scheme for operating the hydraulic actuator unit 10 according to the invention. The hydraulic scheme illustrates an actuator pump 15, a unit manifold 19 and a hydraulic actuator 11. The actuator pump 15 comprises an electrical motor 151 which is connected to a pump element. The electrical motor 151 is electrically connectable to a control unit. The pump element is driveable in two directions by the electrical motor. Further, the actuator pump 15 comprises a pump reservoir.

The actuator pump 15 is connected to the hydraulic actuator 1 1 via the unit manifold 19. The unit manifold 19 comprises a first fluid channel 198 and a second fluid channel 199. The first fluid channel 198 connects the actuator pump 15 in fluid communication with a first fluid chamber 112A of the hydraulic actuator 11. The second fluid channel 199 connects the actuator pump 15 in fluid complication with the second fluid chamber 1 12B of the hydraulic actuator 1 1. The first and second fluid channel 198, 199 include each a non return valve 192 and at least one pressure control valve 193. As illustrated, the first and second fluid channel have at both sides of the non return valve 192 a first and second pressure control valve 193A, 193B. The first pressure valve 193A is situated in a pump circuit. The first pressure valve 193A is provided to prevent leakages due to overpressure by the pump. The second pressure valve 193A is situated in a hold circuit for holding the actuator in a determined position. The second pressure valve 193B is provided to prevent overpressure in the hold circuit due to a rising temperature. The second pressure valve 193B is normally closed and adjusted to open at a higher pressure than the first pressure valve 193A. The first pressure valve 193A determines the system safety.

The first and second fluid channel 198, 199 are further provided with a tool connector 191. The tool connector 191 is provided for connecting a tool like a manual pump or measurement tool.

Fig. 4 shows a shell door latching system, wherein the hydraulic actuator unit 10 is connected to a latch 20. The latch comprises a latch pinion 21 which is positioned in a journal bearing 22. The journal bearing has a mounting flange including mounting holes for fastening the journal bearing 22 to a marine shell door, in particular to a framework at an interior of a marine shell door. The journal bearing has a central through hole for guiding the latch pinion 21. The latch pinion 21 is axially movable with respect to the journal bearing 22. The latch pinion 21 is cylindrical and has a distal end face and a proximal end face. To latch the marine shell door in a door casing, the distal end face of the latch pinion 21 is received in a latch hole of the door casing. The proximal end face of the latch pinion 21 is connected to the actuator member 1 12 of the hydraulic actuator 1 1. The hydraulic actuator unit is arranged as shown in Fig. 1-3.

Although the invention has been disclosed with reference to particular embodiments, from reading this description those of skilled in the art may appreciate a change or modification that may be possible from a technical point of view but which do not depart from the scope of the invention as described above and claimed hereafter. Modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. It will be understood by those of skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. Therefore, it is intended that the invention is not limited to the particular embodiments disclosed in the above detailed description, but that the invention will include all embodiments falling within the scope of the appended claims.