Control method for a ship with a controllable pitch propeller
The control system with multiple cruising curves and a self-learning capability addresses the inflexibility of existing systems by optimizing ship operation for diverse mission requirements, enhancing flexibility and effectiveness in military vessels.
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Patents
- Current Assignee / Owner
- TKMS GMBH
- Filing Date
- 2023-03-28
- Publication Date
- 2026-07-01
Smart Images
Figure IMGF0001 
Figure IMGF0002
Abstract
Description
[0001] The invention relates to a method for operating a ship with a controllable pitch propeller, i.e. a propeller in which the blades of the propeller can be rotated.
[0002] A variable-pitch propeller is a propeller in which the individual blades are rotatably mounted on the hub. This allows the pitch of the blades to be changed. This enables, for example, the achievement of very different sustained speeds. Maneuverability can also be increased. However, variable-pitch propellers are naturally more complex than fixed-pitch propellers, which are usually made from a single piece. The pitch ratio indicates the angle at which the blades are positioned relative to a surface passing through the propeller shaft. This angle often depends on the distance from the shaft, as propellers often have a pitch, for example, to minimize cavitation.
[0003] While a fixed-pitch propeller only has one engine speed that, in steady state (without acceleration), results in a specific speed, a ship with a controllable-pitch propeller can achieve the same speed, especially in the mid-speed range, through various combinations of engine speed and propeller pitch. To manage this, the ship's control system stores a speed curve that assigns a specific value pair of engine speed and propeller pitch to each current throttle position. This speed curve is optimized according to the typical requirements in the different speed ranges. At full speed, i.e., the highest throttle position, the speed is optimized for maximum speed.For low speeds, for example around 10% of the maximum speed, and the resulting throttle position, it is more likely that optimization is carried out to reduce noise, since such slow driving generally occurs in operation and a reduction of the acoustic signature can then be helpful.
[0004] However, it has become apparent that while these optimizations of the driving curve generally lead to good results, they can exhibit weaknesses in certain situations. For example, in some situations it may be necessary to be slow and quiet, yet still have as much power reserve as possible in order to quickly execute an evasive maneuver.
[0005] JP S60-25 883 A relates to a method for controlling a variable-pitch propeller in which the blade angle (pinch) can be changed by rotating the propeller blades around the propeller axis. WO 2020 / 025745 A1 discloses an improvement in the travel efficiency of a vehicle.
[0006] A control procedure for a variable pitch propeller is known from US 2007 / 134092 A1.
[0007] Further prior art is VAN BEEK, Teus. Technology guidelines for efficient design and operation of ship propulsors. Marine News, Wärtsilä Propulsion Netherlands BV, 1-2004, pp. 14-19 and 2021 Guidelines on the shaft / engine power limitation system to comply with the EEXI requirements and use of a power reserve, MEPC 76 / 15 / Add.2, Annex 9.
[0008] The purpose of the invention is to provide a control system that can respond more flexibly to specific mission requirements.
[0009] This problem is solved by the method with the features specified in claim 1. Advantageous further developments are described in the dependent claims, the following description, and the drawings.
[0010] The method according to the invention serves to operate a ship equipped with a propulsion motor, a controllable pitch propeller, a ship's control station, and a guidance system. The ship is preferably a military vessel, for example, a corvette, a frigate, a destroyer, a cruiser, a supply ship, a minesweeper, a minehunter, a torpedo boat, a carrier (e.g., an aircraft carrier or a helicopter carrier), a landing craft, a submarine, or the like. While for civilian ships, usually only one requirement is consistently paramount (efficiency for cargo ships, performance for recreational boats, etc.), military ships often have a wide range of requirements, depending on the mission currently being carried out. Therefore, the invention can achieve a greater effect with military ships. A speed target is set via the ship's control station and transmitted to the guidance system.The ship's control station is the input station where a user controls the vessel, specifying, for example, speed, direction (possibly via rudder position), and optionally, draft (also possibly via rudder position). The ship's control station can therefore be designed, in particular, as a computer console with suitable input devices. For example, the speed is set by an operator using a throttle lever. The control system is a computer system that receives the commands entered at the ship's control station and controls the corresponding ship systems, such as the propulsion motor for speed or a steering motor for adjusting the rudder position. The control system can be, or partially, integrated into the ship's control station.The control system determines the rotational speed of the propulsion motor and the pitch ratio of the controllable pitch propeller and controls the propulsion motor and propeller with these values. In practice, the pitch ratio of the controllable pitch propeller is adjusted by rotating the blades. This rotation, to set the angle specified by the control system according to the pitch ratio, can preferably be hydraulically or electrically controlled. Conventionally, this is done using the speed curve stored in the control system. The speed achievable in steady state is derived from the rotational speed and pitch ratio. The ship may initially be faster or slower, and the speed will only stabilize again once a new steady state is reached. For each ship, the speed resulting from the rotational speed and pitch ratio in steady state is unique and known.The speed requirement can either consist of a concrete specification or, as historically, be relative (for example, "half speed ahead" and "full speed ahead").
[0011] Furthermore, it must be considered that a certain engine speed can only be achieved if the engine can generate and thus provide sufficient power. However, the power output of an engine, especially in the case of internal combustion engines, is usually dependent on its torque.
[0012] According to the invention, the guidance system has at least one first and one second speed curve. A speed curve is the relationship between rotational speed and power. For a fixed-pitch propeller, this is a simple, direct relationship in a steady state, resulting in a straight line. If a change is required to deviate from the steady state, the engine can, for example, utilize its power reserve (the area above the speed curve up to the system's power limit), thereby increasing the rotational speed and consequently the airspeed. The upper end of the speed curve is the point of maximum power and thus the highest constant achievable airspeed. In the case of a variable-pitch propeller, the pitch of the blades is an additional variable.By rotating the blades at the hub, the pitch ratio of the propeller, and thus the flight path, is specifically influenced. In conventional operation, a precise pitch ratio of the variable-pitch propeller is defined for each rotational speed, resulting in exactly one flight path being predetermined according to the prior art. Therefore, the guidance system according to the invention has at least one more flight path than is usual according to the prior art. The first flight path is optimized for one of the requirements selected from the list, including efficiency, power reserve, and acoustic signature. The second flight path is optimized for a different requirement selected from the list, including efficiency, power reserve, and acoustic signature. Additionally, a mission requirement is specified, which is selected from the list, including efficiency, power reserve, and acoustic signature.This differs from the state of the art, where, for example, the low-speed range (low engine speed) is optimized for acoustic signature, the medium range for efficiency, and the high-speed range (high engine speed) for performance. The mission requirement thus defines the selection of the driving profile to be used based on the characteristics for which the corresponding driving profile has been optimized. For example, if the mission is a reconnaissance mission, the primary objective is to avoid detection. Therefore, the mission requirement for such a mission would be acoustic signature, in order to minimize noise emissions and thereby avoid detection as much as possible. Consequently, by specifying acoustic signature as the mission requirement, the driving profile optimized for acoustic signature is used.In another example, if the mission were a transfer trip, the resulting mission requirement would be efficiency, meaning the most economical driving style possible. By specifying this mission requirement, the driving profile optimized for efficiency is selected. The mission requirement can be specified, for example, by entering it into the system. Alternatively, a mission can be predefined for the system, with the system containing mission requirements for the various missions (as shown in the two examples above).
[0013] For example, the first flight path is optimized for the acoustic signature. Accordingly, the value pairs of rotational speed and pitch ratio of the variable-pitch propeller taken from this first flight path result in a particularly low acoustic signature. This makes it possible to operate very quietly, thus minimizing the risk of being detected by sonar. Furthermore, the second flight path, for example, is optimized for power reserve. During a normal mission, the mission requirement during slow-speed operation would likely be set to the acoustic signature, and the guidance system would adjust accordingly based on the first flight path. However, if, for example, the weather deteriorates dramatically, it may be advisable to switch the mission requirement to power reserve while maintaining the same low speed, in order to have sufficient power reserve available, for example, in heavy seas.A deterioration of the acoustic signature is accepted as a consequence of selecting the modified mission requirement, which is no longer relevant in heavy seas.
[0014] Typically, a ship has only one cruising profile. For a cargo ship, this will be optimized entirely for efficiency. For a submarine, it might be optimized entirely for acoustic signature. However, there are also cruising profiles that are not optimized for a single requirement, but rather divide the speed or power range into several sections, which are then optimized according to different criteria. Thus, a cruising profile is created that, for example, is optimized for acoustic signature at slow speeds, for efficiency at medium speeds, and for power reserve at high speeds, which, to a first approximation, corresponds to different operational scenarios (stealth cruising, transit cruising, combat cruising). This, however, limits the speed selectable for certain missions to the predefined ranges.Only through the use of two cruising curves on a ship, as described in the invention, and thus the targeted selection of the appropriate cruising curve, can this limitation be overcome. It is therefore essential to the invention that, according to the invention, not just one, but at least two cruising curves are available on a ship, which was not previously the case. Only through the availability of two different cruising curves is it possible to select the speed independently of the mission requirements. This results in a greater range of cruising modes for the ship.
[0015] In a further embodiment of the invention, the guidance system has a third driving curve. The third driving curve is optimized for requirements that differ from those of the first and second driving curves, selected from a list including efficiency, power reserve, and acoustic signature.
[0016] To complement the example described above, the third cruising profile could, for instance, be optimized for efficiency. If the ship is now on a mission, also at low speed, where the acoustic signature or power reserve is not as relevant—for example, during a patrol—then efficiency, and thus the time spent at sea via fuel consumption, can be specified as the mission requirement. Since the presence of such a ship is usually known and should be known anyway, the acoustic signature is irrelevant in this case.
[0017] Thus, the novel specification of a mission requirement allows for a much better optimization of the driving trajectory to the mission requirement, even for very different missions but with otherwise the same speed.
[0018] In a further embodiment of the invention, the mission requirement is specified in the form of a mission. The mission comprises a task, described in terms of time and location, that the ship and its crew must complete. Technical mission requirements for the ship are derived from the mission, which in turn provide a selection of requirements for the guidance system. This can be done automatically by entering a mission or mission requirements into the ship's control center, which then forwards a suitable requirement to the control station. The guidance system then sets a course according to the requirement. In particular, a mission can also have temporally or spatially sequential parts, each with different mission requirements.It can also be configured that the ship's control center automatically transmits or modifies requirements to the guidance system at a specific time or upon reaching a particular location. For example, a person might specify "transit" as a mission. The guidance system then directly links the "transit" requirement with the mission requirement of efficiency. This primarily concerns fuel conservation and selects the appropriate course. In another scenario, the person might specify "submarine hunting" as a mission. The guidance system then automatically links "submarine hunting" with the mission requirement of optimizing the acoustic signature and selects the appropriate course. By reducing the ship's own noise emissions, the probability of detecting submarines is increased. Furthermore, a "combat" mission might be specified.The control system then directly links the combat requirement with the mission requirement for power reserve and selects the appropriate driving profile. For this purpose, the control system can either use a predefined list that assigns mission requirements to missions or mission components, and can also specify a weighting of mission requirements (for example, 80% efficiency and 20% power reserve). The weighting of mission requirements results in an operating point being interpolated between two driving profiles. The relative mission requirement can be particularly useful when transitioning from one mission requirement to a second, different one, thus enabling a smooth transition and simultaneously facilitating the transition from one driving profile to another.Alternatively, the guidance system can be equipped with a self-learning program that is based on past assignments made by the crew. This makes it possible to automatically switch between the ship's navigation paths, either geographically or temporally, according to a predefined profile of mission requirements.
[0019] In a further embodiment of the invention, a relative mission requirement is specified. In contrast to the previous absolute specifications, where optimization is performed solely according to a mission requirement, a relative specification can also be used, for example, 70% optimized for acoustic signature and 30% for power reserve. This allows for an even more balanced driving style. Here, for example, optimization is performed separately according to the two relevant driving curves, and then the values extracted from these separate driving curves are weighted according to their relative importance, resulting in a new operating point that cannot be derived from any specific driving curve.
[0020] In a further embodiment of the invention, the guidance system is designed to be self-learning. This enables the guidance system to independently define the mission requirement. For this purpose, the guidance system can preferably access other ship systems to obtain further information. For example, the guidance system can detect a deployed towed sonar and then define the mission requirement based on an acoustic signature, since the ship is recognizably engaged in anti-submarine warfare. The self-learning embodiment is particularly preferred for defining a relative mission requirement. For example, the weighting between the acoustic signature and power reserve can be adjusted based on relevant weather forecasts. In particular, the guidance system can subsequently determine whether the provided power reserve was needed, too small, or too high, which in turn means that the acoustic signature was not optimal.Thus, the self-learning execution can learn from past mistakes. Alternatively, the self-learning execution can also learn, for example, from the crew's assignment of mission requirements during previous missions.
[0021] Preferably, the control system is first provided with a list specifying the mission requirements for various missions or mission components. Furthermore, the control system is given information about the relationship between propeller speed and pitch for a specific mission requirement, based on the ship's trajectory. From this point, the control system can then, for example, make variations, such as changing the propeller pitch ratio by rotating the propeller blades, and then use the ship's sensors, such as the sonar sensors, to determine if and how this affects, for example, the acoustic signature. A similar approach can be used for mission requirements such as efficiency, which is particularly easy with an electric propulsion motor, as its power consumption can be determined simply and precisely.
[0022] The ship according to the invention is explained in more detail below with reference to an embodiment shown in the drawings. Fig. 1 Ship Fig. 2 Sequence Fig. 3 Course of travel Part 1 Fig. 4 Course of travel Part 2
[0023] In Fig. 1Figure 10 depicts a ship. It has a propulsion motor 20 and a controllable pitch propeller 30 connected to the propulsion motor 20 via a shaft. The propulsion motor can be either an internal combustion engine, such as a diesel engine or a gas turbine, or an electric motor, which is powered, for example, by a diesel generator and / or a battery. The ship 10 also has a ship's control station 40. The crew sets a speed target, such as full speed or slow speed, via the ship's control station 40. This speed target is transmitted to the control system 50, which then determines the target speed f of the propulsion motor 20 and the pitch ratio of the controllable pitch propeller 30 from at least two driving curves 120 and controls these accordingly, so that the speed is achieved by varying the parameters along the driving curve. There are two options for this.If a mission requirement is specified, such as efficiency, the efficiency-based speed curve is used to determine the engine speed and gradient. The ship then accelerates particularly efficiently according to the speed curve until the specified operating point is reached. This would be the case, for example, for a transit voyage (mission transit) with the mission requirement of efficiency.
[0024] However, the control system 50 also stores a second mission requirement, which determines a second driving curve for setting the speed f of the drive motor and the pitch ratio of the variable-pitch propeller 30. If the second mission requirement is selected, the operating point is determined and controlled according to the second driving curve, assuming the same speed requirement. If this second mission requirement is, for example, an acoustic signature, acceleration occurs along the corresponding driving curve, for instance, more slowly than with the mission requirement "efficiency". It is also possible that with a relative requirement, such as "full speed", the achievable maximum speed will differ from that of "efficiency".
[0025] The mission requirements specified in the guidance system 50 can also be stored in terms of location and time, so that when a specified location is reached or a specified time has elapsed, the mission requirements are automatically changed, thus eliminating the need for manual selection of the mission requirements.
[0026] However, a mission requirement might also exist that, for example, weights the acoustic signature at 80% and the power reserve at 20%, such as when the weather is about to deteriorate dramatically during a submarine chase. In this case, a first pair of values, consisting of engine speed and gradient ratio, would be determined from the acoustic signature curve, and a second pair of values, also consisting of engine speed and gradient ratio, would be determined from the power reserve curve. The first pair of values would then be weighted at 80%, and the second pair at 20%, thus determining and aligning the optimal driving point for the current requirements.
[0027] The process is in Fig. 2The ship's control station 40 has two input options. Firstly, a speed such as 2 knots, 12 knots, or "full speed" is specified via speed setting 41. Additionally, the ship's control station 40 has a mission requirement setting 42. For example, "Acoustic Signature" is specified as a mission requirement along with the setting 2 knots, "Efficiency" is specified as a mission requirement at 12 knots, and "Power Reserve" is specified as a mission requirement at "full speed." For the mission requirement "Acoustic Signature," a first speed curve 61, optimized for the acoustic signature, is selected; for the mission requirement "Efficiency," a second speed curve 62, optimized for efficiency, is selected; and for the mission requirement "Power Reserve," a third speed curve 63, optimized for efficiency, is selected. The propulsion motor 20 is then controlled according to the selected speed curve 61, 62, or 63.
[0028] To achieve greater flexibility, the system shown features an adaptation element 70. In this case, the mission requirement is not simply selected, but rather weighted relatively among the available options and specified via mission requirement setting 42. For example, during surveillance at low speed, the possibility of a quick escape should be maintained, perhaps due to a higher probability of detection. In this case, a speed of 3 knots can be specified via speed setting 41, with a weighting of 70% for acoustic signature and 30% for power reserve. The operating points for 3 knots can then be determined from the first speed curve 61 (acoustic signature) and the third speed curve 63 (power reserve).In the adaptation element 70, the operating point of the first driving curve 61 is weighted with 70% and the operating point of the third driving curve 63 with 30%, thus determining a new averaged operating point consisting of rotational speed D and gradient ratio S, and transferring this to the drive motor 20.
[0029] Fig. 3 and Fig. 4 The figures show a purely schematic representation of a driving curve 120, simplified as two two-dimensional curves. In reality, it is a curve in three-dimensional space, so that in Fig. 3 and Fig. 4 In each case, the image shows this curve represented on a two-dimensional surface. The abscissa represents the position of the throttle lever f (f = 0 standstill, f Max = full speed). The ordinate represents... Fig. 3 the rotational speed D is specified in Fig. 4 the pitch ratio S. The pitch ratio S of the adjustable propeller 30 (shown in Fig. 4 Can the driving curve 120 now be in Fig. 3Both driving curves 120 are directly related and influence each other. Each position of the driving lever f is associated with a value for the rotational speed D (according to Fig. 3 ) and a slope ratio S (according to Fig. 4) connected. For each requirement, a driving curve 120 is created, where each driving curve is linked to two values, rotational speed D and gradient S (y-values), for each position of the drive lever f (x-value). The maximum load 110 represents an absolute limit. Operation is not possible to the left and above this line; this represents the maximum power P that the drive motor is capable of delivering depending on the rotational speed f. Consequently, the area above driving curve 120 up to the maximum load 110 is the power reserve 130, i.e., the power P that is still available, for example, for accelerating the ship. At the same time, the consumption must be taken into account, which is maximized at very low load and high rotational speed (here, bottom right).In a very simplified way, efficiency 140 thus runs in the indicated direction; efficiency 140 increases as the maximum load 110 is approached, with a corresponding increase typically occurring shortly before reaching the maximum load 110. It should be noted that the propeller also has an efficiency dependent on the pitch. Therefore, it is roughly possible to see how the driving curve 120 can be optimized with respect to efficiency 140, power reserve 130, or acoustic signature. The driving curve 120 can thus also be represented in a diagram with three orthogonal axes as a line in space, of which the depicted... Fig. 3 and Fig. 4 Each shows the projection of this line in space onto a two-dimensional representation. Reference sign
[0030] 10 Ship 20 Propulsion motor 30 Controllable pitch propeller 40 Ship's control station 41 Speed setting 42 Mission requirement setting 50 Guidance system 61 First speed curve 62 Second speed curve 63 Third speed curve 70 Adaptation element 100 Maximum speed 110 Maximum load 120 Speed curve 130 Power reserve 140 Efficiency
Claims
1. Method for operating a vessel (10) comprising a propulsion motor (20), a controllable-pitch propeller (30), a vessel control station (40) and a control system (50), wherein a speed target is set via the vessel control console (40) and transmitted to the control system (50), wherein the control system (50) determines and controls the rotational speed of the propulsion motor (20) and the pitch ratio of the controllable-pitch propeller (30), wherein the control system (50) comprises at least a first speed curve (61, 120) and a second speed curve (62, 120), wherein the first speed curve (61, 120) is optimised for one of the requirements selected from the list comprising efficiency (140), power reserve (130) and acoustic signature, wherein the second driving curve (62, 120) is optimised for a requirement differing from the first driving curve (61, 120) and selected from the list comprising efficiency (140), power reserve (130) and acoustic signature, wherein a mission requirement is additionally specified, selected from the list comprising efficiency (140), power reserve (130), acoustic signature, wherein the driving curve to be used is selected on the basis of the mission requirement, which driving curve corresponds to the mission requirement on the basis of the characteristics for which the respective driving curve has been optimised.
2. A method according to claim 1, characterised in that the control system (50) comprises a third driving curve (63, 120), wherein the third driving curve (63, 120) is optimised for requirements differing from those of the first driving curve (61, 120) and the second driving curve (62, 120), selected from the list comprising efficiency (140), power reserve (130) and acoustic signature.
3. A method according to any of the preceding claims, characterised in that the mission requirement is specified in the form of a mission.
4. A method according to any of the preceding claims, characterised in that a relative mission requirement is specified, wherein the relative mission requirement is not optimised solely on the basis of a mission requirement , but rather a relative specification of the mission requirements is provided, to which the driving curves are optimised.