Patent Description:
The present invention is especially related to an arm actuator assembly for a crane, which can contribute to electrification and replace solutions of cranes where there are used hydraulic cylinders today.

At present there is great interest within the marine industry to develop environmentally friendly propulsion systems for marine vessels, where the main goal is to achieve zero emissions or close to zero emissions from the marine vessel. Electric and hybrid electric (electric and fuel) propulsion systems are increasingly being used. Such systems enable the marine vessel to be driven entirely or in part by electrical energy stored in energy storage devices. With this also follows the interest of developing equipment on the marine vessels that can utilize electrical energy stored in such energy storage devices. An example of such equipment is offshore cranes which mainly use hydraulic cylinders for operation of the arms thereof. There however exist solutions which utilize electrical motors for rotation of the crane structure.

In <CIT> (EMS-Tech Inc. ) is described a slewing actuator system for horizontally rotating a boom structure by means of engagement with gearing means. The slewing actuator system comprises a rotatable cylindrical disc with exterior teeth that are in engagement with one or more fixed motor-driven (electrical) fearing means that impart rotational movement to cylindrical disc and thus the boom structure arranged thereto.

<CIT>describes a similar solution to <CIT> where a crane boom is arranged to a rotatable disc.

The operation of the crane arms in <CIT> and <CIT> are however based on the use of hydraulic cylinders.

Use of hydraulic cylinders introduce a need for both hydraulic and electric technology. It is well known for a skilled person that a hydraulic solution is less efficient than an electric solution.

Further, contact with hydraulic oil is not healthy for personnel and leakage of hydraulic oil to the environment may give unwanted effects (especially for fish farmers).

From <CIT> is known a front end mechanism for an excavating machine making use of cogwheels for operation of the boom and arms of the excavating machine.

There is accordingly a need for an arm actuator assembly enabling electrification and replacing hydraulic cylinders used for operating the arms of the crane.

It is further a need for an arm actuator assembly enabling an electrical solution that will improve issues regarding efficiency, health and environment.

The main object of the present invention is to provide an arm actuator assembly for a crane partly or entirely solving the above-mentioned drawbacks of prior art.

It is further an object of the present invention to provide an arm actuator assembly for a crane enabling arms of the crane to be operated by electrical actuators, removing the need for hydraulic cylinders for operation of arms of the crane.

An object of the present invention is to provide an arm actuator assembly for a crane comprising at least one fixed cogwheel arranged in a parallel vertical plane of an arm of the crane and at least one arm drive pinion gear arranged to the arm and in engagement with the fixed cogwheel enabling elevation and lowering of the arm in the vertical plane by operation of the at least one arm drive pinion gear.

It is further an object of the present invention to provide an arm actuator assembly for a crane further comprising an upper elbow arm drive unit arranged for operating an upper elbow arm of the crane.

It is further an object of the present invention to provide an arm actuator assembly for a crane, which has low maintenance costs compared to prior art solution.

An object of the present invention is to provide an arm actuator assembly for a crane which provides an environmentally friendly solution by that it does not use polluting fluids, such as hydraulic oil or similar, which can constitute a risk for the environment or personnel at breakdown or leakage.

Further objects of the present invention will appear from the following description, claims and attached drawings.

An arm actuator assembly for a crane according to the present invention is defined by the technical features of claim <NUM>. Preferable features of the arm actuator assembly are disclosed in the dependent claims.

Cranes comprise at least one main arm pivotally arranged to a support structure at a lower end thereof by means of a pivoting connection. Cranes further may comprise at least one elbow arm pivotally arranged to the upper end of the main arm, possibly via a connection link. Further, the support structure of the crane is typically formed by a tower (pedestal) and a base platform, where the base platform, which the main arm of the crane are connected to, typically is arranged to the tower by means of a rotational interface (slew bearing), enabling the crane to rotate about the tower.

The present invention provides an arm actuator assembly for a crane where the main components are at least one fixed cogwheel and at least one arm drive pinion gear.

According to a first embodiment of the arm actuator assembly for a crane according to the present invention, the arm actuator assembly comprises at least one cogwheel arranged in a parallel vertical plane of the main arm and fixed to the support structure with its horizontal center axis corresponding with horizontal center axis of the pivoting connection between the main arm and support structure. According to the first embodiment of the arm actuator assembly further comprises at least one main arm drive pinion gear arranged to the main arm and in engagement with the at least one fixed cogwheel. Accordingly, in the first embodiment of the arm actuator assembly for a crane according to the present invention operation of the at least one main arm drive pinion gear in engagement with the at least one fixed cogwheel enable elevation or lowering of the main arm of the crane in the vertical plane. The at least one main arm drive pinion gear is preferably driven by at least one electric power source (motor). If desired or necessary there can be arranged a gear exchange between the electric power source and the main arm drive pinion gear. According to the arm actuator assembly for a crane according to the present invention the at least one cogwheel exhibits a (considerably) larger diameter than the at least one main arm drive pinion gear. According to the present invention is preferably at least one main arm drive pinion gear arranged at lower side of the main arm.

Accordingly, the arm actuator assembly for a crane according to the first embodiment of the present invention works by that operation of the at least one electrical power source results in that the at least one main arm drive pinion gear travels along the exterior circumference of the fixed cogwheel and in engagement therewith, resulting in that the main arm is elevated or lowered in the vertical plane according to the rotational direction of the main arm drive pinion gear.

According to a second embodiment of the arm actuator assembly for a crane according to the present invention the arm actuator assembly further comprises an upper elbow arm drive unit for an elbow arm arranged for operating an upper elbow arm of the crane. According to the second embodiment of the arm actuator assembly for a crane according to the present invention the elbow arm drive unit is arranged to the lower part of the main arm or the support structure for the crane.

According to the second embodiment of the arm actuator assembly for a crane according to the present invention, the elbow arm drive unit is formed by a torque arm pivotally arranged to lower part of the main arm and further comprising a tension arm extending between the upper elbow arm and torque arm, wherein the tension arm is pivotally arranged to the upper elbow arm and main arm, respectively. According to the second embodiment of the arm actuator assembly for a crane, the torque arm is a single or double torque arm.

In an alternative embodiment of the second embodiment of the arm actuator assembly for a crane according to the present invention the torque arm is arranged with to pivot about a horizontal centre axis of a main arm drive pinion gear arranged at rear part of the main arm.

Accordingly, the arm actuator assembly for a crane according to the second embodiment of the present invention works by that, as the main arm is elevated or lowered in the vertical plane as described above, the elbow arm will correspondingly move in the vertical plane due to the interaction of the tension arm.

In a further alternative embodiment of the arm actuator assembly for a crane, which is not a part of the present invention, the elbow arm drive unit is formed by a tension winch, preferably an electrically driven winch, arranged to the support structure of the crane and a tension wire extending between the tension winch and rear part of the elbow arm, alternatively rear part of a connection link connecting the main arm and elbow arm. By controlling the winch, the elbow arm can be controlled both in correspondence with the movement of the main arm and separately.

Accordingly, the arm actuator assembly for a crane according to the present invention provides a solution, which enables the crane to be driven by electrical power. Accordingly, there is no need for hydraulic cylinders for operation of the arms of the crane.

Further, sufficient power/moment of the arm actuator assembly for a crane according to the present invention can be achieved by utilizing several main arm drive pinion gears in engagement with the at least one fixed cogwheel. Further, the diameter of the cogwheel can also be designed to achieve sufficient power/moment of the arm actuator assembly according to the present invention.

Further advantages with the present invention over prior art is that the arm actuator assembly according to the present invention removes the need for hydraulic reservoir, hydraulic pipes and hoses, as well as hydraulic pumps, which would provide free space at the deck of a marine vessel.

The present invention would further provide a more rapid/force/power effective controlling of the crane, as the there are no intermediate means transferring the power/force to the crane arm, as the main arm drive pinion gears are directly connected to the main arm via the cogwheel.

A great advantage with the present invention is that there are low requirements for maintenance due to few moveable and force transferring parts.

Further, the present invention further provides a solution which is less exposed to wear, compared to prior art, due to few parts for transferring forces and that there is no requirement for a sealed system as hydraulic systems.

Even though the present invention is mainly related to operation of the main arm by means of the fixed cogwheel and the main arm drive pinion gears, the same principle can also be used for operation of the elbow arm in relation to the main arm by arranging a fixed cogwheel to upper end portion of the main arm, with its center in the pivoting connection between the main arm and the elbow arm, and further arrange at least one elbow arm drive pinion gear to the elbow arm.

Further preferable features and advantageous details of the present invention will appear from the following example description, claims and attached drawings.

The present invention will below be described in further detail with references to the attached drawing where:.

Reference is now made to <FIG> which is a principle drawing of a crane <NUM>, in the form of a deck crane, according to prior art. The crane <NUM> has a support structure <NUM> formed by a base platform <NUM> rotatably arranged on upper end of a tower <NUM> (pedestal) via a rotational interface <NUM> (slew bearing), which is well known in prior art and needs no further description herein.

The crane <NUM> further comprises a main arm <NUM> having a lower end pivotally mounted on the base platform <NUM> by means of a pivoting connection <NUM>, e.g. formed by a shaft <NUM> and attachment lugs <NUM>. The main arm <NUM> can be raised and lowered by actuation of at least one hydraulic cylinder <NUM> having its lower end arranged to the base platform <NUM> and upper end arranged to an intermediate location along the length of the main arm <NUM>.

The crane <NUM> also comprises an upper elbow arm <NUM> having a lower end pivotally arranged to the upper end portion of the main arm <NUM>. The upper elbow arm <NUM> is pivotally connected relative to the main arm <NUM> by at least one hydraulic cylinder <NUM> having lower end portion pivotally arranged to an intermediate location along the main arm <NUM> and upper end portion pivotally arranged an intermediate location along the length of the upper elbow arm <NUM>.

Operation of the hydraulic cylinders <NUM> and <NUM> enables the crane <NUM> to be raised and lowered as well as to be extended and retracted, and the rotational interface <NUM> enables the crane <NUM> to be rotated about the tower <NUM>.

The crane <NUM> further includes a main load winch <NUM> mounted on the lower end portion of the main arm <NUM> or the base platform <NUM> to pay out or reel in a main load wire <NUM> which is wound about a spool <NUM>. A hook <NUM> is attached to the distal end of the wire <NUM>. Between the spool <NUM> and hook <NUM>, the wire <NUM> extends over a guide sheave <NUM> mounted on the distal end of the main arm <NUM>, a further guide sheave <NUM> mounted on the lower or proximal end of elbow arm <NUM>, and a distal sheave <NUM> mounted on the distal end portion of the elbow arm <NUM>.

Accordingly, above is described a typical crane <NUM> which are used for offshore applications. The same principle as described above also applies for larger offshore cranes.

The present invention is related to an arm actuator assembly enabling such cranes, especially offshore/maritime cranes, to be operated without the use of hydraulic cylinders, at least minimizing the use of hydraulic cylinders for operation thereof.

Reference is now made to <FIG> which is a principle drawing of a crane <NUM> provided with an arm actuator assembly <NUM> for a crane according to a first embodiment of the present invention. The crane <NUM> comprises as described above a support structure <NUM> comprising a base platform <NUM> rotatably arranged to a tower <NUM> by means of a rotational interface <NUM>. The main arm <NUM> is pivotably arranged to the base platform <NUM> by that the base platform <NUM> is provided with a pivoting connection <NUM>. The pivoting connection <NUM> can e.g. be formed by two attachment lugs <NUM> adapted to receive and accommodate the lower end of the main arm <NUM>, and wherein the attachment lugs <NUM> and the main arm <NUM> at lower part thereof is provided with corresponding through holes for receiving and accommodating a shaft <NUM> arranging the lower end of the main arm <NUM> pivotally to the attachment lugs <NUM>/base platform <NUM>. Accordingly, the longitudinal centre axis of the shaft <NUM> forms a pivoting centre axis which the main arm <NUM> pivots about.

The present invention provides, as mentioned, an arm actuator assembly <NUM> which removes the need for hydraulic cylinders <NUM> and <NUM> for operation of the main arm <NUM> and/or elbow arm <NUM>. The main component of the arm actuator assembly <NUM> according to the present invention is at least one cogwheel <NUM>, wherein the at least one cogwheel <NUM>, with its circumference, is arranged in a parallel vertical plane with the main arm <NUM> and fixed to the support structure <NUM>, i.e. the base platform <NUM> with its horizontal center axis corresponding with the pivoting centre axis of the main arm <NUM>, i.e. the horizontal center axis of the pivoting connection <NUM>/shaft <NUM>.

The arm actuator assembly <NUM> according to the present invention further comprises at least one main arm drive pinion gear 220a-b arranged to the main arm <NUM> and in engagement with the fixed cogwheel <NUM>. According to the arm actuator assembly <NUM> for a crane <NUM> according to the present invention the at least one cogwheel <NUM> exhibits a (considerably) larger diameter than the at least one main arm drive pinion gear 220a-b.

In the shown example, the arm actuator assembly <NUM> according to the present invention comprises a main arm drive pinion gear 220a, arranged to the main arm <NUM> at a distance from the lower end of the main arm <NUM> corresponding to the exterior circumference of and in engagement with the cogwheel <NUM> by means of an attachment device <NUM>, wherein the main arm drive pinion gear 220a is arranged at a lower side of the main arm <NUM>. The arm actuator assembly <NUM> in the shown example further comprises a main arm drive pinion gear 220b arranged to the main arm <NUM> at rear part thereof and in engagement with the fixed cogwheel <NUM> by means of an attachment device <NUM>, wherein the main arm drive pinion gear 220b is arranged at an upper side of the main arm <NUM>.

The at least one main arm drive pinion gear 220a-b is arranged to at least one electrical power source <NUM>, such as an electric motor, capable of providing the necessary driving torque for the at least one main arm drive pinion gear 220a-b to operate the main arm <NUM> in the vertical plane directly or via a gear exchange.

Accordingly, as the at least one main arm drive pinion gear 220a-b travels along the exterior circumference of the fixed cogwheel <NUM> and in engagement therewith, being powered by the at least one electrical power source <NUM>, the main arm <NUM> is elevated or lowered in the vertical plane.

In the example shown in <FIG>, the upper elbow arm <NUM> is pivotally connected to the main arm <NUM> via a connection link <NUM>, wherein the connection link <NUM> connects the upper elbow arm <NUM> and main arm <NUM> at one end and provides a connection point <NUM> at the other end for a tension arm <NUM>. The upper elbow arm <NUM> can alternatively be pivotally connected to the main arm <NUM>, as shown in <FIG>.

According to the arm actuator assembly <NUM> of the first embodiment, the arm actuator assembly <NUM> further comprises an elbow drive unit <NUM> arranged at lower part of the main arm <NUM> and which is arranged for connection to the tension arm <NUM>, such that the tension arm <NUM> is arranged extending between the elbow drive unit <NUM> and the connection link <NUM>. In an alternative embodiment, the tension arm <NUM> is connected to a rear end of the elbow arm <NUM> as shown for a tension wire <NUM> in <FIG>.

In the shown example the elbow drive unit <NUM> is formed by a single or double torque arm <NUM>, as shown in <FIG>, respectively. In the shown example the single or double torque arm <NUM> is rotatably connected at a center axis of the main arm drive pinion gear 220b, wherein the torque arm <NUM> has a longitudinal extension longer than the exterior circumference of the main arm drive pinion gear 220b allowing it to pivot freely about the main arm drive pinion gear 220b. Accordingly, as the main arm <NUM> is elevated or lowered in the vertical plane as described above, the elbow arm <NUM> will correspondingly move in the vertical plane due to the interaction of the tension arm <NUM> which is pivotally connected to the elbow drive unit <NUM> at one end and to the connection link <NUM> or rear part of the elbow arm <NUM> at the other end.

This is only an example, and the elbow drive unit <NUM> can e.g. be arranged to a separate attachment lug arranged to the lower part of the main arm <NUM>.

Reference is now made to <FIG> which are principle drawings of an alternative embodiment of the arm actuator assembly <NUM>, which is not a part of the present invention, arranged to a knuckle jib crane <NUM>. In this example, the elbow arm <NUM> is pivotally connected to the main arm <NUM> at a distance from the end of the elbow arm <NUM>, such that the elbow arm <NUM> exhibits overhang <NUM> at rear end thereof. The arm actuator assembly <NUM> according to the alternative embodiment comprises three main arm drive pinion gears 220a-c providing a higher moment which is required for a larger crane, compared to the first embodiment, arranged to the main arm <NUM> by means of separate attachment devices or where two or more pinion gears 220a-c are arranged to a common attachment device, as described in the first embodiment. In the embodiment shown in <FIG> the main arm drive pinion gears 220a-c are arranged at lower part and lower end of the main arm <NUM>, and the main arm drive pinion gears 220a-c are distributed along the circumference of the cogwheel <NUM>.

In this embodiment the arm actuator assembly <NUM> for operation of the elbow arm <NUM> comprises a controllable tension winch <NUM> arranged to the base platform <NUM> for controlling a tension wire <NUM> arranged fixed to the overhang <NUM> at one end, alternatively rear end of a connection link <NUM> connecting the main arm <NUM> and elbow arm <NUM>, and running over a pulley <NUM> and is arranged to the tension winch <NUM> at the other end. In this way, the arm actuator assembly <NUM> in the alternative embodiment is capable of operation of both the main arm <NUM> and elbow arm <NUM>. The tension winch <NUM> can be controlled to move the elbow arm <NUM> both in correspondence with the movement of the main arm <NUM> and separately.

Even though in the examples there are shown cranes <NUM> which comprise both main arm <NUM> and elbow arm <NUM> it is obvious for a skilled person that the main principle of the present invention can be used on cranes comprising only one arm or more than two arms. Any crane <NUM> which would require elevation or lowering movement in the vertical plane of an arm <NUM> pivotally arranged to a base platform <NUM> at one end can utilize the fixed cogwheel <NUM> and drive pinion gear(s) 220a-c for operation thereof.

Further, the arm actuator assembly <NUM> according to the present invention can comprise only one drive pinion gear 220a-c or several drive pinion gears 220a-c depending on the size/requirements of the crane <NUM>. Further, gear exchanges can be used in connection with the arm drive pinion gear 220a-c if required or desired.

It will further be preferable that the arm actuator assembly <NUM> according to the present invention is provided with safety devices, which will lock the arm drive pinion gear(s) 220a-c at loss of power or fail function. Alternatively that the main arm <NUM> is provided with a safety mechanism that locks the main arm <NUM> to the fixed cogwheel <NUM>.

Further, the features of the above described example embodiments can be combined to form further embodiments within the scope of the attached claims.

A crane provided with the arm actuator assembly according to the present invention will have a more horizontal load path than conventional cranes and due to that it can be electrically controlled.

Further, a crane provided with the arm actuator system according to the present invention will be easier and safer to use within automatic operations. A crane provided with the arm actuator assembly according to the present invention will provide enhanced monitoring and improved precise control compared to hydraulically operated cranes.

By enabling a crane to be operated electrically, features as remote, automatic, robotic operations can easily be added.

Claim 1:
Arm actuator assembly (<NUM>) for a crane (<NUM>) comprising at least a main arm (<NUM>) pivotally arranged to a support structure (<NUM>) at a lower end thereof by means of a pivoting connection (<NUM>), wherein the arm actuator assembly (<NUM>) comprising:
- at least one cogwheel (<NUM>) arranged with its circumference in a parallel vertical plane of the main arm (<NUM>) and fixed with its horizontal center axis corresponding with horizontal center axis of the pivoting connection (<NUM>) between the main arm (<NUM>) and support structure (<NUM>),
- at least one main arm drive pinion gear (220a-c) arranged to the main arm (<NUM>) in engagement with the at least one fixed cogwheel (<NUM>),
- an upper elbow arm drive unit (<NUM>) for an elbow arm (<NUM>) arranged for operating an upper elbow arm (<NUM>) of the crane (<NUM>), wherein the elbow arm drive unit (<NUM>) is formed by a torque arm (<NUM>) pivotally arranged to a horizontal center axis of a main arm drive pinion gear (220b) arranged at rear part of the main arm (<NUM>) and further comprising a tension arm (<NUM>) extending between the upper elbow arm (<NUM>) and torque arm (<NUM>), wherein the tension arm (<NUM>) is pivotally arranged to the upper elbow arm (<NUM>) and main arm (<NUM>), respectively,
wherein operation of the at least one drive pinion gear (220a-c) in engagement with the at least one fixed cogwheel (<NUM>) elevate or lower the main arm (<NUM>) of the crane (<NUM>) in the vertical plane.