LIFTING/SKIDDING DEVICE WITH A PERMANENT MAGNET SYNCHRONOUS MOTOR

Abstract

A lifting/skidding device includes an electric motor, a gear coupled to the motor and a lifting/skidding mechanism coupled to the gear, wherein the motor is embodied as a permanent magnet synchronous machine. The lifting/skidding device is adapted for lifting/skidding an offshore construction.

Claims

1.-8. (canceled)

9. A lifting device or skidding device, comprising an electric motor, a gear coupled to said motor, and a lifting or skidding mechanism coupled to said gear, wherein the lifting or skidding mechanism comprises a pinion coupled to said gear and a gear rack engaged with said pinion; wherein said motor is embodied as a permanent magnet synchronous machine, said motor and an output of said gear are arranged co-axially and said motor and said gear are arranged in a single housing or said motor or gear is arranged in the housing of said gear or motor, such that the motor is integrated as part of the construction of the gearbox.

10. The lifting device or skidding device as claimed in claim 9, wherein said gear is embodied as a planetary gear.

11. The lifting device or skidding device as claimed in claim 10, wherein said planetary gear is the only gear between said motor and said lifting or skidding mechanism.

12. The lifting device or skidding device as claimed in claim 9, wherein said motor and said gear comprise a common lubrication circuit.

13. The lifting device or skidding device as claimed in claim 12, further comprising: a heater in the lubrication circuit.

14. The lifting device or skidding device as claimed in claim 9, wherein the lifting device or skidding device is adapted for lifting or skidding an offshore construction.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0021] FIG. 1 shows a schematic oblique view of an exemplary lifting/skidding device with a rack and pinion gear;

[0022] FIG. 2 shows an exploded view of the inner workings of the motor gear unit and

[0023] FIG. 3 shows a schematic oblique view of an exemplary lifting/skidding device with a hoist drum.

DETAILED DESCRIPTION

[0024] The illustration in the drawing is schematically. It is noted that in different figures, similar or identical elements or features are provided with the same reference signs or with reference signs, which are different from the corresponding reference signs only within the first digit. In order to avoid unnecessary repetitions elements or features which have already been elucidated with respect to a previously described embodiment are not elucidated again at a later position of the description.

[0025] FIG. 1 shows a schematic oblique view of an exemplary lifting/skidding device 1, comprising a motor gear unit 2 with a housing 3 and a gear output 4. The housing 3 is cylindrical. The gear output 4 protrudes axially from the housing 3 of the motor gear unit 2. Furthermore the lifting/skidding device 1 comprises a pinion 5 coupled to the motor gear unit 2 by means of the gear output 4 and a gear rack 6 engaged with said pinion 5. The pinion 5 and the gear rack 6 are part of a lifting/skidding mechanism 7. For example, a platform (not shown) may be connected to the gear racks 6 of several lifting/skidding devices 1 and moved upwards and downwards respectively horizontally by activating the motor gear unit 2. In FIG. 1, the pinion 5 is taken off the gear output 4. However, in the operating state of the lifting/skidding device 1 the pinion 5 is mounted on the gear output 4 of course.

[0026] FIG. 2 now shows an exploded view of the inner workings of the motor gear unit 2. Concretely, FIG. 2 shows an electric motor 8, comprising a bearing 9 on the non driven end, a motor stator core 10, a motor rotor 11, a bearing 12 and a sun gear 13. Furthermore, FIG. 2 shows a gear 14, comprising planetary gears 15, bearings 16, a combined planet carrier and bearing 17, and the gear output 4 fixed to the planet carrier 17. In the above listing, the bearing 12 and the sun gear 13 are associated with the motor 8. However, the bearing 12 and the sun gear 13 may also associated with the gear 14 or both the motor 8 and the gear 14. Furthermore, the bearing 9 on the non driven end may also be omitted. The arrangement of FIG. 2 is built into the housing 3 of the motor gear unit 2 shown in FIG. 1 in its operational state.

[0027] Accordingly, FIGS. 1 and 2 show a lifting/skidding device 1, comprising, the electric motor 8, the gear 14 coupled to said motor 8 and the lifting/skidding mechanism 7 coupled to said gear 14. The motor 8 is embodied as a permanent magnet synchronous machine, which delivers high torque at comparably low speeds, thereby reducing the required gearbox ratio significantly with respect to known arrangements comprising a standard induction machine. Moreover, the permanent magnet synchronous motor 8 is superior to induction machines with respect to efficiency.

[0028] In the example shown in FIGS. 1 and 2, the motor 8 and the output 4 of said gear 14 are arranged co-axially. This is accomplished by using the planetary gear 14. In this example, the planetary gear 14 is the only gear between said motor 8 and said lifting/skidding mechanism 7. The planetary gear may also have additional reduction stages. Finally, other additional gears may be used as the case may be, for example spur gears.

[0029] The permanent magnet synchronous motor 8 allows for a compact construction of the lifting/skidding device 1. It consists of comparably few parts and can be integrated as part of the construction of the gearbox itself. Hence, said motor 8 and said gear 14 are arranged in a single housing 3 in the example shown in FIGS. 1 and 2. However a motor 8 having a dedicated housing may also be arranged in the housing of said gear 14 or vice versa. Generally, the housing of the gear 14 acts as a heat transfer body for the motor 8 in the presented compact design.

[0030] In an advantageous embodiment, the lifting/skidding device 1 comprises a common lubrication circuit for said motor 8 and said gear 14. In this way, the lubrication oil of the gearbox acts as heat transfer medium for the motor 8. In this context, it is of particular advantage, if the lifting/skidding device 1 comprises a heater in said lubrication circuit. In this way, the lubrication oil heater functions as indirect standstill heater of the motor 8.

[0031] In the example disclosed above, the lifting/skidding mechanism 7 comprises the pinion 5 coupled to the gear 14 and the gear rack 6 engaged with said pinion 5. However, this is not the only possibility for a lifting/skidding mechanism 7. The lifting/skidding mechanism 7 may also comprise a hoist drum coupled to said gear 14 for example as shown in FIG. 3. A hoist rope 19, wound around the hoist drum 18 may then be used to move objects.

[0032] In applications including but not limited to the lifting/skidding device 1 can be used for lifting/skidding an offshore construction (for example: drilling rig, windmill installation vessel, hoist ship etc.). The reduced size and weight of the presented lifting/skidding device 1 as well as its beneficial shape makes it particularly usable in offshore environments.

[0033] Advantageously, the lifting/skidding device 1 is torque controlled, which results in smoother operation and longer lifetime of mechanical parts.

[0034] Generally, the usage of the permanent magnet synchronous motor 8 provides:reduced size and weighta beneficial shapereduced mechanical losses and in turn improved efficiencyreduced number of partsreduced rotating masses, in particular if additional spur gears may be omitted.

[0035] Finally, it should be noted that the term comprising does not exclude other elements or steps and the use of articles a or an does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.