GB2551402A

GB2551402A - Waterjet propulsion control systems

Info

Publication number: GB2551402A
Application number: GB1611521.4A
Authority: GB
Inventors: Curtis Timothy
Original assignee: Birdon (uk) Ltd
Current assignee: Birdon (uk) Ltd
Priority date: 2016-06-06
Filing date: 2016-06-30
Publication date: 2017-12-20
Anticipated expiration: 2036-06-30
Also published as: WO2017214008A1; GB201809228D0; GB2551402B; GB2560133B; GB201611521D0; GB2560133A; US20200317314A1

Abstract

A waterjet propulsion control system 10 comprises: an electric actuation system with at least one electric actuator 12 and 14; a motor controller system with at least one motor controller 16; at least one jet controller 18; a reverser 20; a fixed reverse scoop 22; a feedback system; a steering arm (30, Fig 3); and a power supply. The electric actuation system is driven by the motor controller system to power the steering arm and the reverser through operation of the at least one electric actuator. The feedback system is built into the electric actuation system as at least one encoder. The system may also allow a user to have direct actuator control and bypass the automatic settings for control system backup. A method of controlling a waterjet-powered watercraft that comprises a pair of electric actuators and associated motor controllers is also disclosed. In the method the electric actuators are connected to opposing ends of a steering arm but act in opposite directions to steer the watercraft. The use of electric actuators eliminates the need for the use of hydraulic actuators.

Description

WATERJET PROPULSION CONTROL SYSTEMS Field of the Invention

The invention generally relates to the field of waterjet propulsion control systems for watercraft. Background of the Invention

Current waterjet technology uses hydraulic actuators, which may comprise a hydraulic cylinder, linked to a hydraulic system aboard the vessel. A typical system will have a hydraulic reservoir complete with a level gauge, temperature alarm, and tank breather where hydraulic oil is stored. When the jet is commanded to actuate, a pump connected to the engine, an electric motor, or a power take off pulls oil from the tank and pressurises a hydraulic manifold. The manifold has valves inside that send the oil to the hydraulic cylinder causing the cylinder rod to extend or retract. As the rod extends or retracts, it applies a force to the jet to control the steering or reverse, and a feedback sensor closes the control loop providing an indication of the location of the steering nozzle or reverse system. The feedback sensor can be directly mounted, or remotely mounted through a push/pull cable or similar. The return oil passes through a cooling system (cooled by either raw water or air), and then passes through a filtration system and back into the reservoir.

Hydraulic systems are field proven and have been widely used in the industry for decades, but they have significant issues. These issues include the large size and weight of the overall hydraulic system, the large amount of power required to generate the required hydraulic oil flow and pressure, the number of connections and hoses, the excess heat generated, the slop in the feedback systems, the overshooting and seeking of the cylinders, limited ramping ability, significant maintenance, environmental concerns, and lag when interfacing with control systems. A more detailed description of each item is below. A typical hydraulic system consists of a reservoir, level gauge, temperature gauge, breather, pumps, valves, manifold, solenoid valves, solenoids, hydraulic cylinders, hydraulic coolers, hydraulic filter, a large number of hoses and fittings, and hydraulic oil. Creating a hydraulic system that can be easily serviced and maintained requires spreading this system out around the engine room which occupies significant space.

Hydraulic pumps require significant power to generate the required pressure and flow to operate actuators within an acceptable timeframe for the operator. Even a small system requires an 8-10 horsepower pump. Many of these pumps are fixed displacement and use that energy continuously, dumping the power into the system in the form of heat. Other variable displacement pumps run continuously but can meter the flow automatically. However, they still operate at 1-2 horsepower when idle with the excess heat going into the system. When more power is required, they increase power consumption with reduces power available from the engine to power the waterjets. A hydraulic system is a network of high pressure hoses and connections. These hoses operate in a hot environment, filled with hot abrasive fluid, and require periodic replacement. Each hose and fitting has at least two connections, which all need to handle high pressures, typically 1,500-3,000 psi (approximately 10.3 MN/m^to 20.6 MN/m^). These hoses and connectors are also subjected to near constant vibration and chafing. Any leak in the hydraulic system or failure of a hose or connection will render the hydraulic system ineffective and require system shutdown until it can be repaired or replaced.

Hydraulic systems generate significant heat, even when the system is at idle. The power consumed by the pump at idle in a small system is typically 2-8 horsepower per engine. This energy is dumped back into the system as heat. When the system is operating, the pressure differentials also generate large amounts of heat. This excess heat must be removed from the system or else the hydraulic oil will begin to break down and foam, which causes a spongy, unusable, and potentially dangerous system. The cooling system typically consists of a tube and shell heat exchanger which requires raw water pumping through, or a radiator based system with a fan. Cooling with a heat exchanger requires a raw water pump or tap off another flow, which also requires additional energy, and also piping, strainers, pumps, etc. Cooling using a radiator requires a fan and additional airflow, again requiring more power and developing heat.

To close a feedback loop in a hydraulic system accurately over a long term becomes very difficult as there are many parts working in unison with varying backlash. Slop builds up very quickly in hydraulic systems and increases rapidly with wear.

Due to uncontrollable backlash, system inertia, and slow internal leaks, hydraulic systems have a tendency to seek for position, which can cause unexpected motion even though no commands are given. In addition, the long feedback loop causes overshooting of position resulting in jittering to regain position. This all causes excess wear on components.

Due to the difficulties with feedback position sensing, and also controllability of proportional hydraulic valves, hydraulic cylinders have limited ramping ability. This means they have an abrupt start and an abrupt stop, which results in heavy system wear and shocks throughout the system.

Hydraulic systems require regular maintenance to ensure consistent operation. Hydraulic oil needs to be cleaned down to micron levels to use proportional valves. Any dirt in the system from initial manufacture, contaminated oil, or even wearing valves and pumps can cause valves to stick in place and result in inconsistent manoeuvrability. Filters require regular replacement. Seals in the valves and pumps also need replacing regularly. Hoses wear out from high temperatures, regular use, high vibration, and chafing. In addition, the oil needs to be replaced regularly and the entire system bled again for proper operation.

Hydraulic oil is a known environmental contaminant and any leaks are detrimental to marine life. Hydraulic oil leaks due to worn components or maintenance end up in the vessel’s bilge, and ultimately can end up in the water. In addition, used filters, hoses, oil, etc. must be disposed of correctly to prevent environmental seepage.

Hydraulic systems are difficult to interface with control systems due to the lag in the actuation and feedback loop. Control systems update at high rates, and must be slowed down and have slop intentionally added into them to adequately control a hydraulic system. These issues compound as hydraulic components wear.

SUMMARY OF THE INVENTION

The invention provides a waterjet propulsion control system as specified in claim 1.

The invention also includes a method for controlling jet-powered watercraft as specified in claim 12.

Brief Description of the Drawings

In order that the invention may be well understood, some embodiments thereof will now be described with reference to the drawings, in which:

Figure 1 is a perspective view of a waterjet and a waterjet propulsion control system;

Figure 2 shows pairs of electric actuators and motor controllers of the waterjet propulsion control system;

Figure 3 provides an alternative view of the pairs of electric actuators and motor controllers shown in Figure 2;

Figure 4 provides a closer view of the motor controllers that are integrated into the waterjet to minimise wiring, noise, and heat while improving reliability;

Figure 5 depicts a control panel for an emergency backup system of the waterjet propulsion control system; and

Figure 6 shows a fixed reverse scoop of the waterjet propulsion control system.

It is to be understood that in some instances, various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention. Therefore, drawings may not be to scale.

Detailed Description

Embodiments of waterjet propulsion control systems are described with specificity herein to meet statutory requirements. However, the description itself is not intended to necessarily limit the scope of the claims. Rather, the claimed subject matter may be embodied in other ways to include different steps or combinations of steps similar to the ones described herein, in conjunction with other present or future technologies. Furthermore, the described features, structures, or characteristics may be combined in any suitable manner into one or more embodiments.

Referring to Figure 1, a waterjet propulsion control system 10 comprises an electric actuation system comprising a plurality of electric actuators 12, 14, a motor controller system comprising a plurality of motor controllers 16, a steering nozzle 18 and a reverser 20. The waterjet propulsion control system 10 may further comprise a fixed reverse scoop 22. The reverser 20 may be a reverse bucket as shown in the drawings or a reverse gate. The motor controllers 16 and a jet controller (not shown) are mounted, or integrated, with a water) et 24. The water) et has a drive input 26. The jet controller may comprise an electronic system configured to provide commands to the motor controllers 16 to operate the electric actuators 12, 14.

As best seen in Figure 3, the electric actuators 12 are connected with a steering arm 30 by respective pivot connections 32. The steering arm 30 is connected by pivot connection 34 with a frame member 36 and to the steering nozzle 18. The arrangement is such that when the drive rods 38 of the electric actuators 12 retract or extend, the steering arm 30 pivots about the pivot connection 34 to turn the steering nozzle 18 relative to the water jet 24.

The electric actuators 14 are connected with respective link systems 42 that are supported by frame members 44. One of the link systems 42 and its frame member 44 can be seen in Figure 1. The other link system and its frame member 44 are disposed on the opposite side of the steering nozzle 18. The ends of the link systems 42 remote from the electric actuators 14 are pivot connected with the reverse bucket 20. The arrangement is such that when the drive rods 46 of the electric actuators 14 retract or extend, the reverse bucket 20 between its use position shown in Figures 1 and 6 and a non-use position in which it has rotated anticlockwise from the position shown in Figure 1 to a position at least partially above (as viewed in Figure 1) the steering nozzle 18.

The water) et propulsion control system 10 employs the novel incorporation of an electric actuation system comprising electric actuators 12, 14. The motor controllers 16 and a jet controller may be mounted on the waterjet 24 in close proximity to the electric actuators 12, 14 to minimise noise, heat, and cable lengths. Locating the electric actuators 12,14 and controls in a housing 50 helps improve reliability. The housing 50 extends over the electric actuators 12, 14 and motor controllers 16, but has been ‘cut back’ in the drawings to allow the electric actuators and motor controllers to be seen more clearly. The navigation system can use configured as a basic system to control engine throttles, transmission, jet bucket and steering. The system can also be configured to provide an intuitive user interface for navigation and full vessel control on a touch screen glass helm. This intuitive user interface control can also include station keeping and dynamic positioning capability, as well as multi-vessel positioning control from a single vessel. Those persons skilled in the art will recognise that known control logic schemes can be used to operate this configuration.

The illustrated waterjet propulsion control system 10 has an electric actuation system that uses redundant actuators 12, 14 for steering and reverse functions, so that one electric actuator 12, 14 of each pair acts as the master and the other as the slave. In addition to providing redundancy from failure, this configuration reduces the overall load on each electric actuator 12, 14 during normal operation. Reducing the load improves the lifespan of the disclosed system.

The electric actuation system may comprise linear actuators 12, 14 driven by motor controllers 16 to power the steering nozzle 16 and reverse bucket 18. The electric actuators 12, 14 and controllers 16 may be mounted inside the watercraft to a jet transom, and may protected in a secure enclosure. The motor controllers 16 and the electric actuators 12, 14 can be two separate components as shown in the drawings, or the motor controllers can be constructed as a part of the electric actuators themselves. As best seen in Figures 2 and 3, the electric actuators 12, 14 may be nose mounted to respective ball socket 52 to allow tilting as they are actuated. This may prevent binding of the electric actuators 12, 14 and eliminates the need for slotted holes on the steering arm 30 and reverse bucket 20. The electric actuators 12, 14 may be synchronised and use feedback from one actuator per pair. In one configuration, when the master actuator is commanded with a position, the slave actuator applies the same current as the master for the reverse bucket 20 and the same current in the opposite direction for the steering arm 30.

Power to the electric actuators 12, 14 is brought directly from the vessel’s main power supply into the breakers in a power box (not shown) on or near the water) et 26. Power surges can be handled by using capacitor banks, ultra capacitors, or similar.

Referring to Figure 5, the water) et propulsion system 10 may comprise an emergency backup system 60. This may comprise a backup panel 62 that the user can operate to override signals from the primary control system, or)et controller, to send signals and power directly to the electric actuators 12,14. The “Steering or Bucket/Auto” switches 64 are operable to send signals to the respective electric actuators to ignore commands from the associated motor controller 16. The respective toggle switches 66 are operable to send signals to the electric actuators 12, 14 to move in a positive or negative direction. The electric actuators 12, 14 will stop when they hit their respective hard stops or the toggle switch 66 is released. This emergency backup system 60 bypasses the main control system should an error ever arise. For example, if the main control system experiences an error and fails, the backup panel 62 can be used to safely bring the watercraft back to shore by manually actuating each electric actuator 12, 14. The backup panel 62 also allows manual testing of the waterjet propulsion control system 10 by manually operating the controllers, actuators, wiring, and other components without relying on the main control system.

Referring to Figure 5, the reverse for a waterjet in a standard hydraulic system is a bucket or scoop that drops down over the waterjet to direct water back towards the vessel. The use of a fixed reverse scoop 22 supplements the actuated reverse bucket 20, which is powered by the electric actuators 14 used for reverse propulsion, by becoming an extension to direct flow and thrust. The fixed scoop 22 is located such that it supplements the reverse bucket 18 to add additional reverse thrust. The fixed reverse scoop 22 is designed to stay out of the water stream and jet stream while the vessel is in forward motion.

As opposed to the feedback loop in hydraulic systems, the feedback in the waterjet propulsion system 10 may be built into the electric actuators 12, 14 as encoders for immediate high resolution feedback. Since the feedback is built into the electric actuation system, no additional feedback loop is required. The feedback can be homed by monitoring current and running the jets until they reach their mechanical limits and then centred geometrically and thrust balanced. A position sensor or contact switch could also be used. This high accuracy feedback, immediate response, and controllable power in the electric actuators 12, 14 allows for adjustable ramping to eliminate shock through the system and increase component lifespan. This ramping and speed can also be adjusted based on the specific operator or the vessel condition.

While the disclosed apparatus was designed for use in control systems for waterjet-powered watercraft, the features and advantages of this design described in this application can be utilised by a number of different industries.

The described features, advantages, and characteristics may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognise that the various components of this design may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognised in certain embodiments that may not be present in all embodiments.

Reference throughout this specification to “one embodiment”, “an embodiment”, or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus the appearance of the phrase “in one embodiment”, “in an embodiment”, and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

Claims

1. A waterjet propulsion control system comprising: (a) an electric actuation system comprising at least one electric actuator; (b) a motor controller system comprising at least one motor controller; (c) at least one jet controller; (d) a reverser; (e) a fixed reverse scoop; (f) a feedback system; (g) a steering arm to connect with a steering nozzle; and (h) a power supply, wherein the electric actuation system is driven by the motor controller system to power said steering arm and the reverser, the electric actuation system is directly powered by the power supply and the feedback system is built into the electric actuation as at least one encoder.

2. The system of claim 1, wherein the at least one motor controller is built into a respective electric actuator.

3. The system of claim 1 or 2, wherein the reverser comprises a reverse bucket or a reverse gate.

4. The system of claim 1, 2 or 3 wherein the power supply comprises at least one capacitor bank.

5. The system of any one of the preeeding elaims, wherein the power supply eomprises at least one ultra capacitor.

6. The system of any one of the preceding claims, wherein said electric actuation system and said motor controller system are mounted inside the watercraft to a jet transom.

7. The system of any one of the preceding claims, wherein the at least one electric actuator is nose mounted to a respective ball socket to allow tilting when actuated.

8. The system of claim 1, further comprising an emergency backup system comprising: (a) a backup panel; (b) a “steering or bucket/auto” switch; (c) a toggle switch; and (d) electrical wiring; wherein the “steering or bucket/auto” switch is wired to be capable of sending a signal to a said electric actuator to ignore commands from a said motor controller electrically coupled with said electric actuator and the toggle switch is wired to be capable of sending a signal to the said electric actuator to move the electric actuator in a positive or negative direction.

9. The system of any one of the preceding claims, wherein the feedback system further comprises a position sensor.

10. The system of any one of the preceding claims, wherein the feedback system further comprises a contact switch.

11. The system of any one of the preceding claims, comprising two said electric actuators and respective said motor controllers that are synchronised and use feedback from one of said actuator for the pair.

12. A method for controlling jet-powered watercraft wherein: (a) a pair of electric actuators and an associated pair of motor controllers are mounted inside the housing of the watercraft; (b) the motor controllers and electric actuators are powered using the watercraft’s main power supply; (c) a steering arm is used to steer the watercraft; (d) a reverse bucket is used to reverse the travel direction of the watercraft; (e) a positioning command from a user is sent to a first of said electric actuators; (i) once said first electric actuator receives the positioning command, the second electric actuator applies the same current to said steering as the first electric actuator but in the opposite direction.

13. The method of claim 12, wherein at least one capacitor bank is implemented with the power supply to prevent power surges.

14. The method of claim 12, wherein at least one ultra capacitor is implemented with the power supply to prevent power surges.

15. The method of claim 12, 13 or 14, wherein a fixed reverse scoop is used in conjunction with the reverse bucket to increase the reverse thrust of the watercraft.

16. The method of any one of claims 12 to 15, wherein a second pair of electric actuators and associated motor controllers are mounted inside the housing of the watercraft and powered using said main supply, said second pair of electric actuators are cormected with said reverse bucket, a forward/reversing command input by said user is sent to a first of said second pair of electric actuators and once the first of said second pair of electric actuators receives said forward/reversing command, the second electric actuator of said second pair of electric actuators applies the same current to the reverse bucket in the same direction as said first electric actuator of said second pair.

17. A watercraft comprising a waterjet and a waterjet propulsion system as claimed in any one of claims 1 to 11.

18. A waterjet propulsion control system substantially as herein described with reference to the drawings.