DK176054B1 - Steering mechanism for a ship - Google Patents

Description

t DK 176054 B1

FIELD OF THE INVENTION

The present invention relates to a steering mechanism for a ship, wherein said mechanism includes a rotatable shaft and a driven wheel coaxially attached to the rotatable shaft, said driven wheel being a whole wheel or wheel segment.

BACKGROUND OF THE INVENTION 10

The steering forces in ships can be quite significant. Therefore, power steering systems have become the norm for vessels of a size ranging from fishing trawlers to supertankers. Current power steering systems for ships are typically based on hydraulic cylinders.

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Description of the prior art DE 476125 discloses a steering mechanism in the form of a helm with helm for ships. The main rudder is moved via a swivel shaft 20 which is coaxially attached to a quadrant of a tooth drive.

DE 101 15 110 A1 provides a good example of a hydraulic power steering system for a ship. Hydraulic systems such as that described in DE 101 15 110 A1 have a number of disadvantages. The first disadvantage is that a hydraulic power supply is required to provide pressure and flow to the hydraulic cylinders. Since hydraulic power supplies are typically not standard equipment on ships, a purpose-built hydraulic power supply is usually required. This increases the cost, complexity and size of the operating system. Another disadvantage of hydraulic systems is that the hydraulic oil must be kept clean. If the oil becomes contaminated, the system may be damaged. Further disadvantages of hydraulic systems include that they typically noise and tend to leak 35 oil.

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In addition to the problems caused by the nature of the hydraulic systems, the use of linear actuators is also a problem.

In order to convert the linear movement of the hydraulic cylinders to rotational movement of the rudder, the linear cylinders are attached to the rudder bar via a rocker bar. Because of this geometry, the rocker rod also rotates as the rudder rotates, and the angle between the rocker rod and the linear cylinder is therefore reduced.

As the angle is reduced, a smaller part of the force exerted by the hydraulic cylinder is converted to torque. This 10 means that the torque applied by the hydraulic cylinders to the rudder is reduced as the rudder is guided away from its neutral position. Unfortunately, the force exerted by the water on the rudder increases as the rudder is turned away from its neutral position.

This means that the available torque is reduced, while increasing the need for torque. Since the control system has to be dimensioned for the greatest possible load case, the control system is oversized when the rudder is close to its neutral position. Since most of the time the helm is near its neutral position, the system is mostly oversized. The fact that the system is oversized makes control systems based on linear actuators heavier and more expensive than necessary.

In addition to the torque constraints of the current geometry, the geometry of the 25 current systems also has a limited range of rotation. In an ordinary system, the rudder will have an angular range of not more than ± 90 °. In some applications, such as a bow screw arrangement, free rotation without any obstructions is desirable. It could also be useful to rotate in a 30 direction for more than one full rotation. Systems based on the tilting principle will not be applicable in these situations.

Due to the emergence of cheaper, stronger and more 35 commonly available electric motors, there have been a number of 3 DK 176054 B1 applications where electric motors have replaced hydraulic cylinders in ship steering mechanisms.

A good example is GB 2,012,387 A. This patent discloses a 5 operating system based on an electric motor connected to a planetary gearbox. As the motor shaft rotates, the gearbox rotates at a speed determined by the gear ratio of the planetary gearbox. The gearbox is firmly connected to a rudder unit and rotates the rudder as the engine rotates.

10 The tiller is connected to the rudder via a hinge connection. The rudder therefore also rotates when the rudder stick turns.

This system has a problem similar to the hydraulic systems in that the torque used changes as the rudder turns. As with the hydraulic system, the steering forces are the least when the need is greatest. This means that this system must also be oversized. Another problem with this system is that it is difficult to add reserve control if the main engine should drop out. Even with this system it is possible to get free rotation.

EP 1 209 074 A1 is another good example of a control system based on an electric motor. This system was designed for use on ships with a control system based on a 25 turn screw assembly. However, the principle can also be applied to a rudder-based ship. A number of electric motors are connected to each other via a gearbox. The gearbox effect is applied to a small gear wheel. The small gear wheel engages with a large gear wheel axially mounted on the rotary shaft of the screw assembly. The gearbox is designed so that the engine rpm is added or subtracted to drive the small gear wheel. The problem with using this system to control ships is that the gearbox makes the system complex and expensive. If something goes wrong in the 35 gearbox, the boat would lose control.

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Summary of the present invention

A first aspect of the present invention is to provide a steering mechanism for a ship of the kind initially mentioned which is safer than hitherto known.

Another aspect of the present invention is to provide a rigid mechanism for a ship of the type mentioned initially, which is more extensible and adaptable than previously known.

A third aspect of the present invention is to provide a steering mechanism for a ship of the type mentioned initially, which is more energy efficient than hitherto known.

A fourth aspect of the present invention is to provide a steering mechanism for a ship of the type mentioned initially, which is cheaper, simpler and more robust than previously known.

The new and distinctive aspect of achieving the above-mentioned aspects of the present invention consists in providing a steering mechanism for a ship according to the preamble, which further includes at least two independent torque transfer mechanisms which can engage with said driven wheels, and an actuator for driving each of said torque transmission mechanisms. 1 35

This device exhibits a control system which provides a high degree of security. Because there are at least two actuators integrated into the control system, the other actuator will be able to take over the control of the ship should one of the actuators fail.

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The projected control mechanism can also be expanded. Since the actuators apply torque to a driven wheel via torque transfer mechanisms, multiple actuators can be easily added to the system by adding additional torque transfer mechanisms which are placed around the driven wheel.

The control mechanism can be designed with additional actuators during construction, or additional actuators can be added after commissioning.

10 Because the system can be expanded, the system can also be tailored. A manufacturer of control mechanisms could produce a base unit, including the driven wheel, at least two torque transmission mechanisms and the two actuators, and add the system additional actuators at the customer's request.

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The system also has the potential to be energy efficient, since the number of smaller, less powerful, parallel connected actuators can be used instead of one large and powerful actuator. When the power and speed requirements are low, such as during normal sailing, a single smaller actuator can be used. As the power and speed requirements increase, the other actuators could be activated one by one.

In a preferred embodiment of the steering mechanism, the 25 driven wheel may be a driven gear wheel and each torque transmission mechanism may be a drive gear which engages the driven gear wheel. The radius of the driven gear wheel is preferably greater than the radius of the drive gear.

With this device, the control mechanism becomes very simple. Due to the simple arrangement of the gears and the low number of moving parts, the system is also robust with little risk of failure. Furthermore, because of the reduced number of parts, the mechanism becomes cheaper, both from a manufacturing perspective and from a assembly perspective.

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For ships with a single rudder, the swivel shaft may be coaxially attached to the rudder bar of the ship. This device will provide a compact, independent controller.

5 For ships with more than one helm or space-limited ships around the helm, the pivot shaft can be connected to one or more helm of the ship via a gear, cable, belt or chain system.

In a preferred embodiment of the control mechanism, at least one actuator may include an electric motor controlled by an electronic feedback regulator of the rudder position, the feedback coming from one or more rudder motion sensors and the rudder reference signal being an electronic signal coming from a rudder through a man. machine interface or autopilot. Using an electric motor as an actuator allows the control system to be powered by an electric generator on board. Most ships today already have built-in generators, so system costs are kept low.

20 Electric motors also have positive torque versus speed ratios.

An electric motor has high torque at zero speed. This is beneficial since during normal operation the engine is stopped and used only to hold the rudder in position. Feedback control using such an engine and a rudder motion signal as feedback provides a very accurate control of the rudder's position.

Preferably, at least one actuator may be a spare motor with a manual control interface of the rudder position. Using a spare engine allows emergency operation of the steering mechanism from the 30 ship's bridge, instead of forcing manual activation of the steering mechanism. However, a manually operated actuator can also be used to safeguard against a power loss situation.

In systems with very strong control forces, the electric motors can drive the torque transmission mechanisms via a transmission. The transmission can increase the torque applied by the engines to the driven 7 DK 176054 B1 wheel. The transmission can also reduce the torque transmission mechanism, allowing the use of higher speed motors.

In a further embodiment of the steering mechanism, the torque transfer mechanisms may comprise a clutch mechanism which can decouple the torque applying actuator from the driven wheel. The clutch mechanism is useful for disconnecting the actuators when not in use. This increases the energy efficiency of the system, since the inertia of the actuators not used does not affect the system.

A brake that can stop the rudder movement may also be incorporated into the steering mechanism. A brake is useful when it is desirable to lock the rudder's position for a certain period of time.

Brief description of the drawing

The invention will be explained in more detail below, wherein further advantageous features and exemplary embodiments are described with reference to the drawing, in which

FIG. 1 is a schematic side view of the control mechanism according to the invention,

FIG. Figure 2 is a schematic view of a portion of the same,

FIG. 3 is a schematic top view of another exemplary embodiment of the control mechanism,

FIG. 4 is a schematic side view of a third exemplary embodiment of the control mechanism, FIG. 5 schematically shows a fourth exemplary embodiment of the control mechanism, seen from above, DK 176054 B1

FIG. 6 is a schematic side view of a fifth exemplary embodiment of the control mechanism; and FIG. 7 is a schematic side view of a sixth exemplary embodiment of the control mechanism.

Description of a Preferred Embodiment of the Invention 10 FIG. 1 is a schematic representation of an exemplary embodiment of the ship control mechanism of the present invention applied to a ship with a rotatable rudder 1.

The steering mechanism turns the rudder 1 via a rudder rod 2. A gear wheel 15 3 is coaxially attached to the rudder rod 2. The gear wheel 3, which from now on is referred to as the driven gear wheel 3, is driven by two independent drive gears 4 ', 4' '. The diameter of the drive gears 4 ', 4' 'is smaller than that of the driven gear wheel 3. In this way, there is a speed reduction and torque increase from the 20 drive gears 4', 4 '' to the driven gear wheel 3.

In this exemplary embodiment, the drive gears 4 ', 4' 'are cylindrical gears, but if further torque increase or speed reduction is desired, worm gears 25 (not shown) could be used instead of cylindrical gears. In addition to providing increased torque, worm gears are also self-locking, which may be desirable in some cases. A good example would be for ships where the helm is held in the same position for extended periods. When a worm gear is used, the rudder 30 locks itself as soon as the actuator releases the torque. If cylindrical gears are used instead, the actuator would constantly have to apply torque to keep the rudder in position.

The worm gear solution would therefore be more energy efficient.

In this exemplary embodiment, each drive gear 4 ', 4' 'is driven by an electric motor 5', 5 ''.

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In typical use, the first motor 5 'is not used and therefore uses no power. In case the second motor 5 '' fails, the first motor 5 'can be controlled by applying the voltage 6' of the first motor 5 'via a manual switching unit 7 which is connected to a battery 8. In another embodiment (not shown), the first engine could be replaced by a manually operated arm mechanism which turns the drive gear 4 'using manpower. This would be useful in the case of the ship losing power.

The second motor 5 '' is controlled via an automatic regulator 9. An electronic rudder angle reference signal 10 is input, either in digital or analog form, via a joystick 11. In this example, the joystick 11 is operated by a rudder. However, the electronic rudder angle reference signal 10 could also come from an autopilot system (not shown). The automatic regulator 9 receives a rudder angle signal 12 from a rudder angle sensor 13. The automatic regulator 9 attempts to force the difference between the rudder angle signal 12 and the rudder angle reference signal 10 to zero. This can be achieved with one of many different control algorithms, where a popular example is a PID controller. The controller can be digital or analog. To improve the performance of the controller 9, the sensor 13 could also return additional parameters such as speed, acceleration or strength to the controller 9.

The output signal 14 of the controller 9 is input to a motor driver 15. The motor driver 15 is attached to the ship's power supply 30 (not shown) via cables 16. The motor driver 15 applies power to the second motor 5 '' according to the output signal 14. The motor driver 15 depends on the type of motor, the other motor 5 '' is. In a preferred embodiment, the second motor 5 '' is an asynchronous motor and the motor driver 15 is a frequency converter.

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FIG. 2 schematically shows part of the same control mechanism shown in FIG. 1 when viewed from above. The rudder 1 is coaxially attached to the driven gear 3 via the rudder rod 2. The driven gear 3 is driven by the drive gears 4 ', 4' '.

5 The embodiment of FIG. 1 and 2, exemplary embodiment shows the use of cylindrical gears for transferring torque from the drive wheels 4 ', 4' 'to the driven wheel 3. However, it would also be possible to transfer torque via a belt, chain or cable system {not shown ). A belt, chain or cable system has the advantage that the motors can be located further away from the driven wheel 3. This is useful in cases where there is a lack of space around the driven wheel 3.

FIG. 3 shows another embodiment of the control system when viewed from above. In this embodiment, the driven gear wheel 17 is a wheel segment. The driven gear wheel 17 is coaxially secured to the rudder 1 via the rudder rod 2.

The drive gears 4 ', 4' 'drive the driven gear 17. This embodiment is used in cases where the angular motion of the rudder 2 is limited.

FIG. 4 shows a third embodiment of the control system when viewed from the side. In this case, the motors 5 ', 5' 'are secured to the drive gears 4', 4 '' via gear gears 25 18 ', 18' '. The gears 18 ', 18' 'further reduce the rpm of the drive gears 4', 4 '' relative to the rpm of the motors 5 ', 5' '. Therefore, due to the reduction in rpm, the torque increases. Smaller and faster motors can therefore be used to apply the same 30 torque.

FIG. 5 is a top view of a fourth embodiment of the control mechanism. This embodiment is used on a ship which has a double rudder (21 ', 21' ') assembly. As in the previous examples 35, the drive gears 4 ', 4' 'drive a driven gear 3. The driven gear 3 is attached to a sprocket 18 via a rotatable shaft 19. The two rudders 21', 21 '' are each coaxially connected to a sprocket 22 ', 22' 'via a rudder rod 23', 23 ''.

The three sprockets 19, 22 ', 22' 'are connected to each other via a chain 24. As the drive wheels 4', 4 '' rotate the driven wheel 3, 5 the two rudders 21 ', 21' 'in this way synchronously. The chain 24 could be replaced by another type of drive such as a gear system, belt system or cable system without changing the scope of the invention.

FIG. 6 shows a fifth embodiment of the control mechanism when viewed from the side. In this embodiment, a brake mechanism 25 is attached to the driven gear wheel 3. In this exemplary embodiment, the brake consists of a washer 26 coaxially attached to the driven gear wheel 3. A 15 brake shaft 27 presses on the disk 26 as the rotation of the driven gear wheel 3 wish to be stopped.

FIG. 7 shows a sixth embodiment of the control mechanism when viewed from the side. In this embodiment, 20 clutch mechanisms 28 ', 28' 'connect motors 5', 5 '' to drive gears 4 ', 4' '. When the clutch mechanisms 28 ', 28' 'are not engaged, the motors 5', 5 '' are decoupled from the drive wheels 4 ', 4' ', and therefore have no influence on the system. This is particularly useful when one motor 5 '' is operating and the other motor 25 5 'is being held in reserve. If the spare motor 5 'is connected directly to the system, the motor 5' which is in operation must rotate the inertia of the spare motor 5 ', thereby wasting energy. By decoupling the spare motor 5 'when not in use via a clutch mechanism 28', the load on the working motor 30 5 "is reduced.

If you want to save on operating costs, the control system could include several drive units operating in parallel to operate the helm (not shown). Since the rudder during typical operation is close to being centered, the steering forces are rather weak. Most of the time, therefore, only weak DK 176054 B1 steering forces are required. When only weak steering forces are required, a single motor could drive the steering mechanism. Accordingly, the auxiliary motors could be decoupled using a clutch mechanism 28 ', 28' 'similar to that shown in FIG. 7. As the need for steering forces increased, additional motors could be connected to the system one by one. This means that only a single small engine is used during normal operation. This will reduce power consumption and consequently operating costs.

10 Although electric motors have a number of positive features compared to hydraulic systems, in some cases hydraulic energy supply systems are already mounted in the ship. In these cases, it could be advantageous to operate the steering mechanism with hydraulic motors instead of electric motors. Hydraulic motors 15 have a very large power / size ratio, which makes them very advantageous in confined environments.

Claims (9)

13 DK 176054 B1 1. Steering mechanism for a ship including a pivot shaft (2), and 5. a driven wheel (3) coaxially attached to the pivot shaft (2), said driven wheel (3) being • an entire wheel or wheel segment. , characterized in that said mechanism further includes: 10. at least two torque transmission mechanisms (4 ', 4' ') which can engage with said driven wheels (3) and an actuator (5', 5 '') for driving each of said torque transmission mechanisms (4 ', 4' '). Steering mechanism according to claim 1, characterized in that the driven wheel (3) is a driven gear wheel (3) and each torque transmission mechanism (4 ', 4' ') is a driving gear (4', 4 '') which engages with the driven gear wheel (3). Steering mechanism according to claim 2, characterized in that the radius of the driven gear wheel (3) is greater than the radius of the drive wheels (4 ', 4' '). Steering mechanism according to claim 1, 2 or 3, characterized in that the rotatable shaft (2) is coaxially attached to the rudder rod (2) of the ship. Steering mechanism according to claim 1, 2 or 3, characterized in that the pivot shaft (2) is connected to the ship's rudder 30 (1) or rudder (21 ', 21' ') via a gear, cable, belt or chain system. Control mechanism according to any of the preceding claims, 2 characterized in that at least one actuator (5 '') includes an electric motor (5 '') which is controlled by an electronic 4 feedback regulator of the rudder position (9), wherein The feedback DK 176054 B1 comes from one or more rudder motion sensors (13) and wherein the rudder motion reference signal (10) is an electronic signal coming from a helm via a man-machine interface (11) or from an autopilot. 5 Control mechanism according to any one of the preceding claims, characterized in that at least one actuator (5 ') is a spare motor (5') with a manual control interface of the rudder position (7). 10 Control mechanism according to any one of the preceding claims, characterized in that said actuators (5 ', 5' ') drive torque transmission mechanisms (4', 4 '') via a transmission (18 ', 18' '). 15 Steering mechanism according to any one of the preceding claims, characterized in that each torque transmission mechanism (4 ', 4' ') comprises a clutch mechanism (28', 28 '') capable of decoupling the torque applying actuator (5 ', 5' '). from the 20 driven wheel (3). Control mechanism according to any one of the preceding claims, characterized in that a brake (25) is incorporated in the system, said brake (25) being able to stop the movement of the rudder (1).