FRESH WATER MARINE FLUSHING SYSTEM AND METHOD

Abstract

A system and method for controllably connecting a marine vessel's native fresh water network to its raw water network in order to flush the raw water network. The controllable connection is provided by a hydrostatic lockwhich ensures that water can only flow in the direction from the fresh water network to the raw water network and never in the opposite direction. A system controller directs the fresh water flush cycle and other operations.

Claims

1. A system for selectively reducing the salinity of water contained within a raw water network of a vessel, comprising: (a) a raw water inlet in a hull of said vessel, said raw water inlet connected to said raw water network; (b) an engine, having a raw water pump connected to said raw water network, said raw water pump having a raw water pump inlet and a raw water pump outlet; (c) said raw water pump inlet applying suction to said raw water network in order to draw raw water in through said raw water inlet, through said raw water network, and into said raw water pump; (d) said raw water pump pressurizing said raw water and propelling said raw water out said raw water pump outlet; (e) a fresh water tank; (f) a fresh water pump having an inlet connected to said fresh water tank and an outlet connected to a hydrostatic lock feed line; (g) a raw water network connection connecting to a hydrostatic lock outlet line; (h) a hydrostatic lock including, (i) a fresh water flush valve connected to said hydrostatic lock feed line, said fresh water flush valve being normally closed but being openable in response to an electrical signal, (ii) a check valve located between said fresh water flush valve and said hydrostatic lock outlet line, said check valve allowing flow from said fresh water flush valve to said hydrostatic lock outlet line but preventing flow in an opposite direction; (i) a swing gate valve in said raw water network and proximate said raw water inlet, said swing gate valve being configured to close when a first pressure within said raw water network exceeds a second pressure in said raw water inlet; and (j) said fresh water pump delivering a pressure sufficient so that when said fresh water flush valve is open and said raw water pump is operating said first pressure within said raw water network is above said second pressure in said raw water inlet.

2. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 1, further comprising: (a) a system controller, operable to selectively open said fresh water flush valve; (b) a salinity sensor located in said raw water network; and (c) said salinity sensor being connected to said system controller.

3. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 2, further comprising said system controller being operable to energize said pump and hold said fresh water flush valve open until a salinity measured by said salinity sensor drops below a defined threshold.

4. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 1 wherein said fresh water tank is a native fresh water tank used as a source for a sink in said vessel.

5. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 1, further comprising: (a) a second engine having a second raw water pump connected to said raw water network, said second raw water pump having a second raw water pump inlet and a second raw water pump outlet; (b) said second raw water pump also applying suction to said raw water network; and (c) said swing gate valve being located between said raw water pump and said raw water inlet.

6. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 5, wherein said connection between said hydrostatic lock outlet line and said raw water network lies between said raw water pump and said second raw water pump.

7. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 5, wherein said connection between said hydrostatic lock outlet line and said raw water network is a tee.

8. A system for selectively reducing the salinity of water contained within a raw water network of a vessel, comprising: (a) a first engine having a first raw water pump; (b) a second engine having a second raw water pump, (c) a raw water inlet in a hull of said vessel; (d) a raw water network connecting said raw water inlet to said first raw water pump and said second raw water pump; (e) a fresh water tank; (f) a fresh water pump having an inlet connected to said fresh water tank and an outlet connected to a fresh water flush valve, said fresh water flush valve being normally closed but being openable in response to an electrical signal; (g) a raw water network connection between said fresh water flush valve and said raw water network; (h) a swing gate valve in said raw water network, said swing gate valve being located between said first raw water pump and said raw water inlet, between said second raw water pump and said raw water inlet, and between said raw water network connection and said raw water inlet; (i) said swing gate valve being configured to close when a first pressure within said raw water network exceeds a second pressure in said raw water inlet; and (j) said fresh water pump delivering a pressure sufficient so that when said fresh water flush valve is open and said first and second raw water pumps are operating said first pressure within said raw water network is above said second pressure in said raw water inlet.

9. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 8, further comprising: (a) a first heat exchanger receiving raw water from said first raw water pump; and (b) a second heat exchanger receiving raw water from said second raw water pump.

10. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 9, further comprising: (a) a first raw water exit downstream of said first heat exchanger; (b) a second raw water exit downstream of said second heat exchanger; (c) a first salinity sensor proximate said first raw water exit; (d) a second salinity sensor proximate said second raw water exit; and (e) a system controller monitoring said first and second salinity sensors, said system controller being operable to selectively open said fresh water flush valve.

11. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 10, said system controller being configured to hold open said fresh water flush valve until a first salinity measured by said first salinity sensor and a second salinity measured by said second salinity sensor both fall below a defined threshold.

12. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 11, said system controller being configured to energize said fresh water pump until said first salinity and said second salinity fall below said threshold.

13. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 8, further comprising a check valve located between said fresh water flush valve and said connection between said fresh water flush valve and said raw water network, said check valve said check valve allowing flow from said fresh water flush valve to said raw water network but preventing flow in an opposite direction.

14. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 8, wherein said swing gate valve includes a reverse flow aperture permitting a small reverse flow even when said swing gate valve is closed.

15. A system for flushing raw water contained within a raw water network of a vessel with fresh water, comprising: (a) a raw water inlet in a hull of said vessel, said raw water inlet connected to said raw water network; (b) an engine, having a raw water pump connected to said raw water network, said raw water pump having a raw water pump inlet and a raw water pump outlet; (c) said raw water pump inlet applying suction to said raw water network in order to draw raw water in through said raw water inlet, through said raw water network, and into said raw water pump; (d) said raw water pump pressurizing said raw water and propelling said raw water out said raw water pump outlet; (e) a fresh water tank; (f) a fresh water pump having an inlet connected to said fresh water tank and an outlet connected to a fresh water flush valve; (g) said fresh water flush valve selectively connecting said fresh water pump outlet to a raw water network connection; (h) said fresh water flush valve being normally closed but being openable in response to an electrical signal; (i) a swing gate valve in said raw water network and proximate said raw water inlet, said swing gate valve being configured to close when a first pressure within said raw water network exceeds a second pressure in said raw water inlet; and (j) said fresh water pump delivering a pressure sufficient so that when said fresh water flush valve is open and said raw water pump is operating said first pressure within said raw water network is above said second pressure in said raw water inlet.

16. The system for flushing raw water contained within a raw water network of a vessel as recited in claim 15, further comprising: (a) a first heat exchanger receiving raw water from said first raw water pump; and (b) a second heat exchanger receiving raw water from said second raw water pump.

17. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 16, further comprising: (a) a first raw water exit downstream of said first heat exchanger; (b) a second raw water exit downstream of said second heat exchanger; (c) a first salinity sensor proximate said first raw water exit; (d) a second salinity sensor proximate said second raw water exit; and (e) a system controller monitoring said first and second salinity sensors, said system controller being operable to selectively open said fresh water flush valve.

18. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 17, said system controller being configured to hold open said fresh water flush valve until a first salinity measured by said first salinity sensor and a second salinity measured by said second salinity sensor both fall below a defined threshold.

19. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 18, said system controller being configured to energize said fresh water pump until said first salinity and said second salinity fall below said threshold.

20. The system for selectively reducing the salinity of water contained within a raw water network of a vessel as recited in claim 15, further comprising a check valve located between said fresh water flush valve and said connection between said fresh water flush valve and said raw water network, said check valve said check valve allowing flow from said fresh water flush valve to said raw water network but preventing flow in an opposite direction.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0033] FIG. 1 is an elevation view, showing the placement of the engines and freshwater tank in an exemplary marine vessel.

[0034] FIG. 2 is a perspective view, showing an exemplary prior art raw water system in a marine vessel.

[0035] FIG. 3 is a perspective view, showing an exemplary prior art fresh water system in a marine vessel.

[0036] FIG. 4 is a perspective view, showing exemplary prior art raw water and fresh water systems in a marine vessel.

[0037] FIG. 5 is a perspective view, showing the routing of raw water through a marine engine.

[0038] FIG. 6 is a perspective view, showing the routing of raw water through a marine engine.

[0039] FIG. 7 is a perspective view, showing the routing of raw water through a marine engine and a wet exhaust system.

[0040] FIG. 8 is an elevation view, showing the impeller in a prior art raw water pump.

[0041] FIG. 9 is a perspective view, showing an embodiment of the present invention.

[0042] FIG. 10 is a schematic view, showing the integration of mechanical components and electrical components in an embodiment of the present invention.

[0043] FIG. 11 is a sectional elevation view, showing a swing gate valve as used in the present invention.

[0044] FIG. 12 is a sectional elevation view, showing a linear check valve as used in the present invention.

[0045] FIG. 13 is a perspective view, showing two hydrostatic lock assemblies as used in the present invention.

[0046] FIG. 14 is a perspective view, showing an exemplary control system and user control interface.

[0047] FIG. 15 is a schematic view, showing exemplary components of the control system.

[0048] FIG. 16 is a schematic view, showing the normal operation of the raw water system.

[0049] FIG. 17 is a schematic view, showing the operation of a fresh water flush cycle.

[0050] FIG. 18 is a flow diagram, illustrating the operation of the present invention.

[0051] FIG. 19 is a plan view, showing the fresh water and raw water networks in a large marine vessel.

[0052] FIG. 20 is a plan view, showing an embodiment of the invention incorporating multiple hydrostatic locks connecting the fresh water and raw water networks in the vessel of FIG. 19.

REFERENCE NUMERALS IN THE DRAWINGS

[0053] 10 vessel [0054] 12 hull [0055] 14 fresh water tank [0056] 15 port engine [0057] 16 engine [0058] 17 starboard engine [0059] 18 marine transmission [0060] 20 propeller shaft [0061] 22 propeller [0062] 24 raw water pump [0063] 26 raw water pump [0064] 28 raw water inlet [0065] 30 strainer [0066] 32 raw water header [0067] 34 exhaust elbow [0068] 36 down pipe [0069] 38 water lock muffler [0070] 40 gooseneck exhaust assembly [0071] 42 exhaust outlet [0072] 44 water heater [0073] 46 cold fresh water distribution plumbing [0074] 48 hot fresh water distribution plumbing [0075] 50 sink [0076] 52 shower [0077] 54 pump [0078] 55 dedicated pump [0079] 56 raw water network [0080] 58 fresh water network [0081] 60 air intake [0082] 62 turbocharger [0083] 64 charge air manifold [0084] 66 injector pump [0085] 67 heat exchanger [0086] 69 heat exchanger [0087] 70 engine coolant outlet [0088] 71 coolant return line [0089] 72 exhaust manifold [0090] 74 raw water feed line [0091] 76 raw water exhaust outlet [0092] 78 inlet [0093] 80 outlet [0094] 82 impeller [0095] 84 flexible vane [0096] 86 cylindrical cavity [0097] 88 cam [0098] 90 swing gate valve [0099] 92 tee [0100] 94 hydrostatic lock [0101] 96 fresh water flush valve [0102] 98 check valve [0103] 100 solenoid [0104] 102 system controller [0105] 104 control line [0106] 106 salinity sensor [0107] 108 tach sensor [0108] 110 engine state sensor [0109] 112 fuel control system [0110] 114 helm console [0111] 116 engine control switch [0112] 118 power output device [0113] 120 fuel solenoid [0114] 121 power output device [0115] 122 hydrostatic lock input line [0116] 123 hydrostatic lock outlet line [0117] 124 power output device [0118] 125 inlet [0119] 126 outlet [0120] 128 swing gate [0121] 130 hinge pin [0122] 131 clean out port [0123] 132 bias spring [0124] 134 orifice [0125] 136 seat [0126] 138 inlet [0127] 140 outlet [0128] 142 spring [0129] 144 seat [0130] 145 passage [0131] 146 body [0132] 147 O-ring [0133] 148 housing [0134] 150 cable assembly [0135] 152 cover [0136] 154 graphical display [0137] 156 input button [0138] 158 SD card port [0139] 160 processor [0140] 161 R/F module [0141] 162 memory [0142] 164 engine state detection step [0143] 166 manual override detection step [0144] 168 flush cancel step [0145] 170 engine shut down step [0146] 172 engine idle step [0147] 174 flush cycle step [0148] 176 salinity evaluation step [0149] 178 flush termination step [0150] 180 engine shut down step [0151] 182 time evaluation step [0152] 184 gyro stabilizer [0153] 186 generator [0154] 188 HVAC system [0155] 190 water maker [0156] 192 pressure sensor [0157] 194 pressure sensor

DETAILED DESCRIPTION OF THE INVENTION

[0158] FIG. 9 depicts an exemplary embodiment of the present invention. The invention creates a precisely controlled connection between raw water network 56 and fresh water network 58. The invention also provides coordinated control of other components needed to conduct an effective flushing operationsuch as a fresh water pump and preferably the engine or engines connected to the raw water network.

[0159] In this disclosure, the term fresh water network shall include the fresh water tank or tanks, pumps configured to pressurize and move the fresh water, fresh water supply lines, fresh water outlets, and any other component configured to ordinarily receive fresh water. The term raw water network shall include the raw water inlet or inlets, raw water supply lines, raw water pumps, raw water heat exchangers, and any other component configured to ordinarily receive raw water

[0160] The connection between the two networks is made by hydrostatic lock 94. The hydrostatic lock comprises a fresh water flush valve 96 acting in concert with a check valve 98 separated by a rigid conduit. Hydrostatic lock feed line 122 connects the fresh water supply to the fresh water side of the hydrostatic lock. In some installations it is possible to use the native fresh water pump 54 with a tap directly from an existing part of fresh water network 58. However in the installation shown, the native fresh water pump is not large enough to provide the flow rate needed to supply the engines during a fresh water flush cycle. Instead, a larger fresh water pump 55 is installed with its own feed line from the native fresh water tank.

[0161] Hydrostatic lock outlet line 123 connects the raw water side of the hydrostatic lock to tee 92, which is located at a strategically beneficial location within the raw water network where freshwater is introduced into the raw water network for flushing. Tee 92 is one type of raw water network connection. other types of raw water network connections can be used in other embodiments. Swing gate valve 90 is added to the raw water inlet line. The swing gate valve is located upstream of the tee and the tee is located downstream of the swing gate valve. The swing gate valve is biased to a closed position. It is designed to be pulled open in normal operations when the raw water pumps 24,26 produce suction in the raw water header. The configuration of the swing gate allows water to flow in the direction from strainer 30 into the raw water header, but not in the opposite direction.

[0162] Swing gate valve 90 is added to the raw water inlet line. The swing gate valve is biased to a closed position. It is designed to be pulled open in normal operations when the raw water pumps 24,26 produce suction in the raw water header. The configuration of the swing gate allows water to flow in the direction from strainer 30 into the raw water header, but not in the opposite direction.

[0163] At the outset, the normal operation and flush cycle operation of the system shown will be described in simple terms. More detailed descriptions will be provided subsequently. In normal operations, hydrostatic lock 94 serves as an absolute barrier between raw water network 56 and the fresh water supply. Swing gate valve 90 is biased to the closed position. However, when the engines start and raw water pumps 24,26 begin to operate, the suction they produce in the raw water header 32 pulls open swing gate valve 90 and allows raw water to flow in through raw water inlet 28, through strainer 30, through the raw water pumps 24,26 and ultimately through the heat exchangers in the engines (and any other components connected to the raw water network). This is the conventional operation of a prior art raw water system and this conventional operation is unaffected by the additional components added in the present invention.

[0164] This operation changes when a flush cycle is initiated, however. A flush cycle can be initiated for a variety of reasons. A common example is the initiation of a flush cycle at the end of an engine run cycle. At such a time the engines are to be shut down and it is desirable to remove salt water from the raw water system by flushing the system with fresh water, thus pickling the raw water network with fresh water during periods of inactivity. The reader may note that the term pickling sometimes refers to adding brine to preserve edible substances. The term is used in the opposite sense in the present disclosurewhere the term pickling means removing saltwater and replacing it with fresh water. In the present invention, fresh water within fresh water network 58 is used to flush the raw water network.

[0165] In the flush cycle, the engines are held at idle speed in order to keep the raw water pumps 24,26 turning. Next, the inventive system must ensure that water flows only from the fresh water network to the raw water networkand never the other way. In order to do this suitable positive pressure is established in the raw water network 58. The term suitable positive pressure means that the pressure within hydrostatic lock feed line 122 exceeds the pressure within tee 92, and preferably exceeds it by more than 5 psi.

[0166] Pump 55 is switched on to provide this suitable positive pressure. As those skilled in the art will know, suitable positive pressure may already be present for embodiment using the native fresh water pump 54 via the normal operation of the system controlling the fresh water network which typically monitors pressure and switches pump 54 on and off as needed to maintain pressure. As stated previously, an accumulator is often also installed to smooth the pressure changes within the fresh water network. For the embodiment of FIG. 9, suitable positive pressure is assured by switching on larger pump 55 (This can be monitored by pressure sensors or simply assumed by the proper operation of pump 55).

[0167] With a suitable positive pressure preferably confirmed, the inventive system initiates a flush cycle by actuating solenoid 100 and thereby opening fresh water flush valve 96. Fresh water then flows through the hydrostatic lock and into check valve 98. Check valve 98 is a normally-closed check valve that only permits flow in the direction from the fresh water network to the raw water network. It is preferably spring-biased to only crack open once a positive pressure of about 5 psi is established across the check valve.

[0168] Pump 55 is sized to provide significantly more than 5 psi across check valve 98 so that the check valve opens substantially and allows a suitably high flow rate. The hydrostatic lock is preferably sized to accommodate the maximum flow rate of pump 55. With the hydrostatic lock 94 open, fresh water floods into raw water header 32 and begins to displace the salt water. The pressure within raw water header 32 rises above the pressure at raw water inlet 28 and swing gate valve 90 is thereby forced closed. The swing gate actually includes a small reverse aperture described in more detail subsequentlyso a small reverse flow passes through the swing gate and allows the purging of all the salt water in header 32 downstream of the swing gate.

[0169] At this point fresh water is flowing into raw water header 32 and is being drawn in through raw water pumps 24,26 so that the fresh water floods the heat exchangers and other components. The salt water previously in the raw water network is driven outtypically through the wet exhaust system. The flush cycle continues until the salt water is displaced.

[0170] A system controller 102 is employed to govern and preferably automate the operation of the inventive system. Each raw water network will have a dedicated system controller and hydrostatic lock. Suitable criteria are used to govern the duration of the flush cycle. As an example, a salinity sensor 106 can be placed at or near the end of the raw water circuit's flow path. This will be proximate the raw water outlet. For a wet exhaust system, this will be proximate the point where the raw water is sprayed into the exiting exhaust stream.

[0171] For the example shown in FIG. 9, a salinity sensor 106 is placed in each raw water exhaust outlet 76. One or more system controllers monitor these two salinity sensors and continues the flush cycle or cycles until the salinity drops below a defined threshold in the raw water exhaust outletsthese typically being the last point in the raw water circuit to be flushed. When the salinity at each raw water exhaust outlet has dropped below the defined threshold, the flush cycle is terminated for each engine.

[0172] The system controller then shuts off the engine or engines while maintaining suitable positive pressure across hydrostatic lock 94 and maintaining fresh water flow into raw water header 32. When the engines spin down the impellers in raw water pumps 24,26 become stationary and the raw water pumps act like closed valves. The system controller may be programmed to continue the fresh water flow for a short interval so that fresh water flows through the reverse aperture in swing gate valve 90 (at a low rate) and completes the purging of all salt water in the raw water inlet system. Once the completion criteria are met, the controller closes freshwater flush valve 96. Spring check valve 98 will then close, trapping fresh water in the rigid conduit between the fresh water flush valve 96 and spring check valve 98thereby creating the hydrostatic lock. The networks will remain separated until another flush cycle is initiated. Normal raw water operations can carry forward in this state the next time the engines are started, with no fear of any reverse flow through the hydrostatic lock. Any residual pressure within the raw water system such as pressure created by the position of the raw water pump vaneswill bleed off through the reverse aperture in swing gate valve 90. This is an important feature. Otherwise, an operator opening a filter housing or other inspection port could be inundated with pressurized water.

[0173] The system controller then closes fresh water flush valve 96. The pressure within raw water header 32 bleeds off through the reverse aperture in swing gate valve 90. Check valve 98 then closescompleting a separation of the fresh water network and the raw water network. The networks will remain separated until another flush cycle is initiated. Normal raw water operations can carry forward in this state the next time the engines are started, with no fear of any reverse flow through the hydrostatic lock.

[0174] It is important to note that the fresh water flush cycle should in most embodiments be carried out with the engines running. This is true for two primary reasons. First, for a stationary engine there is the inherent danger of forcing the fresh water into unwanted areas (such as through an exhaust manifold and into a cylinder through an open exhaust valve). This won't happen with the engine running. Second, the raw water pump in a stationary engine may prevent flushing. The raw water pumps act like closed valves when the engines are off. With the raw water pumps stationary, the fresh water being fed into the system in a flush cycle cannot pass through the raw water pumps and therefore cannot reach the heat exchanger and other components that need to be flushed.

[0175] Having now provided a general overview of operations, a more detailed description of the inventive system and exemplary components will be provided. These detailed descriptions pertain to particular embodiments of the invention and should not be viewed as limiting.

[0176] FIG. 10 presents an embodiment of the invention in a schematic form so that additional features can be more easily seen and described. System controller 102 includes a processor that retrieves and executes software code to carry out its functions. Numerous input/output (I/O) ports are provided for the processor. As will be understood by those skilled in the art, these I/O ports are used to interface with sensors, and to send and receive low level control signals that are used to drive power output devices. The various I/O ports are indicated generally in FIG. 10 as Sensor I/O and Power I/O groups In addition, a wired or wireless communication bus is preferably also provided so that software and data can be easily exchanged.

[0177] The schematic of FIG. 10 shows fresh water tank 14 and its attached pump 55. As mentioned previously, an installation of the invention will often require the addition of a larger dedicated pump 55 (either in series with the native pump or parallel to it) in order to provide sufficient fresh water flow. Starboard engine 17 is shown as a dashed line, with a few relevant components shown in more detail. The port engine is not shown in the view to avoid visual clutter. Raw water pump 24 is part of the port engine and feeds raw water from the raw water header into the port engine.

[0178] The port and starboard engines in this example are Cummins 6BT's. A 6BT series pulls about 15 gallons per minute of raw water at idle speed. With two engines running, 30 gallons per minute are required. Those skilled in the art will appreciate that the native fresh water pump on many vessels will not have sufficient capacity to supply the engines with the required cooling watereven at idle speed. The native fresh water pump on vessels of 50 feet or smaller can typically deliver a flow of 4 to 6 gallons per minute (16 to 24 liters per minute) in a pressure range of 35 to 50 psi (2 to 4 bar). Larger yachts (50 to 90 feet) often use a pump that is able to deliver 10 to 12 gpm in the same pressure range. For purposes of comparison, a gasoline pump at a consumer service station typically delivers 8 to 9 gpm and is limited to 10 gpm.

[0179] The reader will perceive from common experience that 10 gpm is a significant flow rate. However, an even higher flow rate will be needed for most embodiments of the present invention. Thus, a dedicated pump 55 is added to provide adequate flow. This dedicated pump can be installed in series with the native pump (a boost pump) or in parallel. Because it will often be necessary to install larger piping to feed the pump 55, a parallel installation is preferred. FIG. 10 shows this dedicated pump 55 feeding water to hydrostatic lock feed line 122.

[0180] Fresh water flush valve 96 and check valve 98 are shown schematically. The fresh water flush valve is normally closedas shown. It includes a positive seal maintained by a spring bias. In the event of an electrical control or power failure, the fresh water flush valve 96 will fail closed and remain closed.

[0181] The orientation of check valve 98 is also shown schematically in FIG. 10. Flow is possible from left to right (in the orientation of the view) once a suitable positive pressure is established so that the pressure on the fresh water side is 5 psi or greater more than the pressure in tee 92. Flow is never possible from right to left through check valve 98.

[0182] In this example the engines are Cummins 6BT direct injection diesel engines. Each engine includes an injector pump 66. Engine speed is controlled by a mechanical throttle linkage (typically a cable moving a lever on the injector pump). Engine shutdown is controlled by fuel solenoid 120 in the injector pump assembly. This solenoid must be energized to feed diesel fuel to the pump and allow the engine to run. When the fuel solenoid is deactivated, the engine shuts down.

[0183] Engine controls are typically provided in a helm console 114 (Many vessels have two such consoles). Throttle setting and drive directions are usually set by moving levers. Engine run state (on or off) is usually selected with switches. In the example shown, engine control switch 116 provides a control signal to power output device 118. Power output device 118 provides voltage to energize fuel solenoid 120 when the user has placed the engine in the run state. The power output device can be an electro-mechanical device such as a relay, a solid state device such as a power output transistor, or some other type of device capable of feeding sufficient power to operate the solenoid.

[0184] Power output devices 121, 124 are also used to control the solenoid 100 in the fresh water flush valve 96 and the dedicated pump 55. The use of such power output devices allows system controller 102 to control high-power devices using logic-level control signals sent via an I/O port. As an example, system controller 102 uses a logic-level signal to switch power output device 124which then provides a suitable power signal to energize solenoid 100 for the duration of the flush cycle (holding open the fresh water flush valve). System controller 102 likewise uses a logic-level signal to switch power output device 121, which then applies run voltage to dedicated pump 55.

[0185] System controller 102 preferably also uses I/O ports to directly or indirectly monitor pressure sensor 192 and pressure sensor 194. Pressure sensor 192 measures the pressure in hydrostatic lock feed line 122, whereas pressure sensor 194 measures the pressure downstream of check valve 98 in the vicinity of tee 92. In the logic sequence carried out by the system controller of this embodiment, pressure sensor 192 must report a pressure well above pressure sensor 194 before logic commands opening of valve 96.

[0186] System controller 102 in this example also uses I/O ports to directly or indirectly monitor salinity measured by a salinity sensor 106 (parts-per-million or similar metric) on each engine. The salinity sensor is typically placed in or near the exhaust elbow where the raw water is injected into the exhaust stream, but they may be placed in other locations in other embodiments. In addition, some embodiments may use multiple salinity sensors on each engine.

[0187] Swing gate valve 90 is simplistically depicted in FIG. 10, but the user may easily perceive its operation from the details shown. Gate 128 pivots about hinge pin 130. With the engines off and the raw water system stagnant, gravity pulls gate 128 down to the position shownsealing the gate against a corresponding seat and preventing flow through the gate. A bias spring may be used to maintain the seated position despite rolling and pitching of the vessel.

[0188] When the engines are started raw water pumps 24, 26 apply suction to the raw water header 32 and this suction pulls open gate 128. The gate is pulled open to the extent necessary to admit the needed flow of raw waterwith higher engine speeds producing a more open position.

[0189] FIGS. 11 and 12 depict an exemplary gate valve and check valve used in embodiments of the invention. FIG. 11 provides a sectional elevation view through an exemplary swing gate valve 90. The reader will note how gate 128 swings about hinge pin 130. In the version shown a bias spring 132 is provided to urge gate 128 against seat 136 when no flow is occurring between inlet 125 and outlet 126.

[0190] The reader will note the presence of reverse flow orifice 134 through gate 128. This orifice allows reverse flow through the swing gate valve when the gate is closed. This reverse flow serves two purposes. Returning to FIG. 10, when a fresh water flush cycle is underway (freshwater flush valve 96 and check valve 98 are both open) pressurized fresh water floods raw water header 32. Allowing some reverse flow through swing gate valve 90 allows the incoming fresh water to force salt water within the swing gate valve out through orifice 134thereby flushing the swing gate valve and ultimately the raw water intake. The restricted orifice limits the flow and prevents an excessive pressure drop.

[0191] In addition, the presence of orifice 134 bleeds off residual pressure within the raw water network at the termination of the flush cycle. The engines are shut down at the termination of a flush cycle. When the raw water pumps 24,26 stop spinning they act like closed valves. When hydrostatic lock 94 is shut, the pressure applied to the raw water network by dedicated pump 55 will remain in the raw water network unless purged, which can cause problems. As an example, a user opening strainer 30 could face a stream of escaping pressurized water. Orifice 134 allows this pressure to bleed down over a few seconds when the flush cycle is ended.

[0192] The swing gate valve shown in FIG. 11 is exemplary, and many other similar components could be used. In the example shown, clean out port 131 is provided on the upward facing surface. This allows a user to open the valve in order to clean and service it.

[0193] FIG. 12 shows an example of a check valve 98 that is used in the hydrostatic lock. A hollow internal chamber is provided between inlet 138 and outlet 140. Spring 142 urges movable body 146 against seat 144 to provide a solid seal. A polymer O-ring 147 is installed as part of the seat. This provides a more positive seal with the stepped interface of body 146. When the pressure within the inlet exceeds the pressure within the outlet by a sufficient amount, the spring force is overcome and body 146 moves off of O-ring 147 (moves to the right in the orientation of the view). Water then flows around the body and through a plurality of passages 145 that pass through the body to its interior. The water then flows out of the check valve through outlet 140.

[0194] Those skilled in the art will appreciate from the geometry of the body and seat that reverse flow (from right to left in the view) through the check valve is prevented. If, for example, the pressure within outlet 140 exceeds the pressure in inlet 138, the seating force of body 146 against seat 144 will only increase. There are many types of check valves other than the one shown, and the invention is not limited to any particular type. However, it is desirable to provide a check valve that prevents flow from the raw water network to the fresh water network under any circumstances (even if the system controller or the fresh water flush valve fails).

[0195] The valve and piping components illustrated for the inventive embodiments will vary in size depending on the application. A raw water system having a high flow rate will naturally need bigger valves and piping than one with a low flow rate. FIG. 13 shows two different embodiments of a hydrostatic lock 94. Each hydrostatic lock includes a hydrostatic lock feed line 122, a fresh water flush valve 96, a check valve 98, and a hydrostatic lock outlet line 123. However, the reader will note that the upper assembly uses larger piping and larger valves. For very large applications one can even provide inventive embodiments that use a parallel network of two or more hydrostatic locks connected to two or more pumps.

[0196] FIG. 14 shows an exemplary physical containment system for system controller 102. The system controller itself preferably includes a processor and associated memory that retrieves and executes software to perform a wide variety of functions. It is possible to implement the system controller on an existing computer system on board a vesselattached to suitable output control devices. However, it is preferable to provide a dedicated physical unit such as shown in FIG. 14.

[0197] System controller 102 is contained within ruggedized housing 148. A pivoting transparent cover 152 allows access to the unit. Graphical display 154 is visible through the cover so that the cover does not ordinarily have to be opened to interact with the device (A cutaway is provided in the view so that the user may easily see the graphical display). One or more input buttons 156 are provided so that the user can move through available menus and make desired selections. These buttons are preferably flexible through-housing switches that prevent moisture intrusion.

[0198] One or more connectors are provided on the housing so that one or more cable assemblies 150 can be connected to the system controller. The cable assembly contains all the conductors needed to carry the sensor information and control outputs. A data bus connector is also provided in some embodiments. In other embodiments, a radio frequency link will be used to communicate software and data updates. As an example, a local R/F protocol such as ZIGBEE or BLUETOOTH can be used. Whether the connection is wired or wireless, this data bus allows a user to program the system controller and customize it to the individual installation.

[0199] The embodiment shown in FIG. 14 includes an SD card port 158. This allows data to be retrieved from a separate SD card or written to a separate SD card. The provision of external data storage is advantageous for the creation and retention of flush system operating records. As an example, the system can create a record of engine operating time versus flush cycles in order to prove compliance with warranty conditions.

[0200] FIG. 15 schematically depicts some of the details of an exemplary system controller 102. Processor 160 executes code that is retrieved from memory 162. The memory unit may be integral to the processor or separate. R/F module 161 is provided in some embodiments. This allows software and data to be exchanged with another computing device without the need for a physical connection.

[0201] Multiple input/output (I/O) ports are provided for the processor. One of these ports is used to interact with graphical display 154 (The graphical display includes its own driver module in this example). Another port is used to receive user inputs via input buttons 156. Other ports are used to control power output devices 118,121,124 which control the fresh water flush valve, the dedicated pump, the fuel control solenoids for the engines, etc. Still more ports convey information from: [0202] (1) pressure sensors 192, 194; [0203] (2) Salinity Sensors 106; [0204] (3) engine tachometer inputs 108 (usually a square wave signal driven by an engine-mounted alternator that is used to tell the system controller whether an engine is running and how fast it is running); [0205] (4) engine control unit (ECU) operating parameters for engines that are digitally controlled; and [0206] (5) a fresh water tank level sensor indicating the amount of available fresh water.

[0207] Those skilled in the art will appreciate that the system controller example shown in FIG. 15 is only one example among a wide range of possibilities. In other embodiments, an off-the-shelf programmable logic controller (PLC) could be used. In still other embodiments, a ruggedized laptop computer with the appropriate software and suitable power outputs could be used. The invention is not limited to any particular type of control system.

[0208] FIGS. 16 and 17 depict the normal operation of the raw water system and the operation during a fresh water flush cycle. FIG. 16 shows the normal operation. Both engines are running, meaning that raw water pumps 24, 26 are spinning and applying suction to raw water manifold 32. Fresh water flush valve 96 is closed. A fresh water pump may be running to provide fresh water to sinks and showers connected to the fresh water network. However, pressure supplied by any pump in the fresh water network (whether a native fresh water pump 54 or an additional pump 55) cannot pass through fresh water flush valve 96since it is closed. Check valve 98 likewise remains closed.

[0209] The suction produced by the raw water pumps pulls open gate 128 within swing gate valve 90. This allows raw water (usually salt water) to be drawn in through raw water inlet 28. The raw water then passes through the raw water header and to the pumps 24,26. The raw water is then pressurized and propelled through the heat exchangers and ultimately exhausted into the exhaust elbows on each engine. This flow process continues in a steady state as long as the engines are running.

[0210] FIG. 17 shows the state of the components when a fresh water flush cycle is in process. A typical triggering event for a fresh water flush cycle is when the engines are shut down. As an example, the operator may have run the engines for two hours in order to reach a new anchorage. The operator then uses the helm console to reduce the throttle setting on both engines to idle and shift the marine transmissions into neutral. In this example, the user is provided with several engine control switches. The user can press a DIRECT SHUTDOWN switch for each engine, which will simply shut off the engines without performing a fresh water flush. The user can also press a FLUSH SHUTDOWN switch for each engine. Pressing this switch will initiate an automatic flush cycle.

[0211] FIG. 17 shows the state when the FLUSH SHUTDOWN switch is pressed. In this example, system controller 102 first evaluates the tachometer signal from each engine to ensure that the engines are at idle speedsince the fresh water flush system in this case is sized to provide sufficient flow only for idle speed (If the engines are above idle a warning light or text message can be displayed to the user instructing the user to reduce the engine speed to idle). Once the controller verifies the idle condition, the controller in this example evaluates pressure sensor 192 andif necessaryenergizes pump 54 (and/or dedicated pump 55) to ensure that sufficient fresh water pressure is present. The controller preferably also evaluates pressure sensor 194 to ensure a suitable positive pressure is available across hydrostatic lock 94 (In this case the pressure on the fresh water side is over 5 psi greater than the pressure on the raw water side).

[0212] System controller 102 then energizes solenoid 100 and opens fresh water flush valve 96 as shown. The pressure differential across check valve 98 opens the check valve and fresh water flows into tee 92 and pressurizes raw water header 32. The reader should bear in mind that the engines are still idling at this time, so the raw water pumps 24,26 are spinning and they begin to draw in the fresh water now within the raw water header.

[0213] The positive pressure of the fresh water within raw water header 32 reverses the flow through swing gate valve 90 and closes gate 128 against its seat. No more raw water is drawn into the system and in fact some fresh water flows in the opposite direction through orifice 134. The system controller continues to run the system in this statewith fresh water flowing into the raw water system and feeding the engineswhile monitoring the salinity sensors 106.

[0214] Once the salinity measured by the salinity sensors drops below a defined threshold, the system controller initiates a shut down of the flush cycle. The system controller shuts off the fuel solenoid 120 on each of the two enginesthereby shutting down the engines. The system controller deenergizes solenoid 100, thereby closing fresh water flush valve 96. The system controller also shuts off the pump. This completes a fresh water flush cycle.

[0215] The reader should note the state of the hydrostatic lock at this point. When valve 96 closes residual pressure between the valves 96 and 98 bleeds through check valve 98 until the spring within the check valve closes the check valve. At that time a volume of water is trapped between the two valves, creating a hydrostatic lock. Even if considerable suction is applied on the raw water side, check valve 98 will not open because of the trapped water. Only if fresh water flush valve 96 is opened will the lock be broken. This provides an additional assurance that no water can flow from the raw water network to the fresh water network.

[0216] The example thus described is configured to perform a flush cycle with the engines at idle speed. It is possible to provide additional capacity so that a flush can be performed at a higher engine speed. However, as there is often a limited supply of fresh water on board (vessels with a desalination system being a notable exception) it is desirable to limit the volume of water used for each flush.

[0217] Sufficient engine cooling is of course a critical concern, as an engine with insufficient coolant flow can be rapidly damaged. Swing gate valve 90 ensures that sufficient cooling flow is always present. If during a fresh water flush cycle the engines are advanced well beyond idle speed, the resultant suction caused by the accelerating raw water pumps 24,26 will pull open gate 128 and admit sufficient raw water (a form of throttling action). This will of course compromise the fresh water flush cycle, but it is more important to ensure adequate engine cooling.

[0218] Some embodiments will omit the pressure sensors 192 and 194. In these embodiments it is only necessary to be sure that pump 55 is activated. With pump 55 activated, there will be sufficient positive pressure across the hydrostatic lock. Monitoring the pressure across the lock is a nice additional assurance, but it is not necessary.

[0219] FIG. 18 shows a simplified flow diagram of the steps carried out by the system controller for an exemplary flush cycle. In step 164 the controller detects the initiation of a flush shutdown, It monitors for a manual override of the timed shutdown process in step 166 and if a manual override is detected it will proceed to steps 168 and shut the engine down without flushing (step 170).

[0220] Otherwise the controller will maintain power to the engine's fuel solenoid to maintain idle speed (step 172). Next the controller will run the flush cycle by opening the fresh water flush valve and ensuring that adequate fresh water pressure is provided (step 174). In step 176 the system controller monitors the salinity sensors to detect the point where the salinity has decreased below a defined threshold. The controller remains in a loop that optionally tests for a maximum time limit allowed (step 182).

[0221] Once the salinity drops below the defined threshold the process proceeds to step 178 and step 180. The engine's fuel solenoid is closed and the fresh water flush valve is closed a short time later. Many additional optional features can be added to this process. These include: [0222] 1. Monitoring a level within a fresh water tank to ensure that the supply of fresh water is not diminished too much; [0223] 2. Monitoring a fresh water flow rate through the hydrostatic lock during a flush cycle in order to determine an amount of fresh water used for the flush cycle; [0224] 3. Providing salinity monitors in locations other than the exhaust elbows in order to ensure that these other locations are properly flushed; and [0225] 4. Providing an actual salinity readout on the display on the salinity controller or on a helm console.

[0226] The embodiment depicted in FIGS. 16 and 17 uses a single point of connectiona single hydrostatic lockbetween the fresh water network and the raw water network. This single connection will work well for most vessels. However, a larger vessel will benefit from an embodiment using multiple hydrostatic locks.

[0227] FIG. 19 shows a plan view of the hull of a so-called super yacht. This type of vessel has an overall length of 50 to 100 or more meters and includes many more sophisticated components connected to the raw water network. As an example, a large gyro stabilizer 184 is provided near the vessel's center of gravity. It uses a large spinning mass to damp unwanted motion (primarily rolling motions). Such a stabilizer is often cooled using circulating raw water.

[0228] Many other systems are also connected to the circulating raw water network. These include multiple HVAC systems 188 (heat pumps used for heating and cooling), generators 186, and a water maker 190 (a desalination plant). All these components receive circulating raw water and can benefit from periodic fresh water flushing.

[0229] FIG. 20 shows an embodiment of the present invention applied to the vessel of FIG. 19. This embodiment includes multiple hydrostatic locks 94 so that fresh water can be introduced at multiple points in the raw water network. As those skilled in the art will appreciate, such an embodiment will benefit from the inclusion of multiple salinity sensors placed at different points. The control methodology preferably operates to minimize the fresh water volume needed to perform a flushsuch as by independently operating the different hydrostatic locks. Some embodiments will also include flow control valves in the fresh water network that can be opened and closed (or throttled) by the system controller in order to direct the flow of fresh water used for flushing in a more efficient manner.

[0230] As mentioned previously in this disclosure, the American Boat & Yacht Counsel standards have traditionally required that the fresh water network (potable water) be totally separated from the raw water network. This is codified in ABYC Standard 23.5.1. In light of the present invention, the ABYC has recognized an exception whereby a connection is allowed to be made using a suitably controlled hydrostatic lock.

[0231] The hydrostatic lock disclosed in this invention is in fact suitable for selectively connecting a wide range of non-contaminated and contaminated systems. This allows flow to be selectively applied from the non-contaminated system to purge the contaminated system, while ensuring that there is no flow back from the contaminated system to the non-contaminated system.

[0232] Having reviewed these detailed descriptions of a few inventive embodiments, those skilled in the art will readily conceive of many additional embodiments incorporating other features, including: [0233] 1. Although the fresh water flush cycle has been described primarily with respect to an engine shut down, a flush cycle may be initiated at other times and for other reasons; [0234] 2. A flush cycle can be run while the engines are running at cruise power; [0235] 3. A flush cycle can be run on a timed schedule; [0236] 4. A flush cycle can be run on an extended schedule while the vessel is stationary in port. For example, a more sophisticated system controller could be configured to actually start the engines and run a flush once every day; [0237] 5. The fresh water flush valve may not be a solenoid valve and may instead be another typesuch as a jackscrew actuated globe valve for large applications; [0238] 6. Embodiments can be installed for engines not incorporating a wet exhaust system (where raw water is expelled using a separate outlet); [0239] 7. The user interface for the system controller can be a touchscreen graphical display; [0240] 8. The user interface for the system controller can be run on a separate smartphone, tablet, or other computing device that wirelessly communicates with the system controller; [0241] 9 Embodiments can be installed for spark-ignition engines, where the system controller maintains engine operations by interfacing with an engine control unit (ECU) rather than directly controlling a fuel solenoid; [0242] 10. Embodiments can be installed using a large accumulator on the fresh water side so that a smaller fresh water pump can still provide the needed flow rate and pressure for a full flush cycle; [0243] 11. Embodiments can be configured for use in fresh water vesselswhere the purging of contaminated fresh water in the raw water system with clean fresh water from the native fresh water network still offers advantages; and [0244] 12. Embodiments can be configured to use additional fresh water capacity (supplied by a larger replacement tank or by the addition of supplemental tanks).

[0245] The salinity sensor(s) can be placed in many suitable locations within the raw water network. It is desirable to place the salinity sensor in a location where the salinity will drop later in a fresh water flushing cycle, so that a salinity drop in that location indicates that the rest of the raw water network has already been effectively purged. In this context it is helpful to define the terms upstream and downstream in the raw water network. These terms refer to the direction of ordinary flow within the raw water network when a fresh water purge is not occurring. Looking at the illustration of FIG. 10, raw water inlet 28 is the most upstream component. Strainer 30 is downstream of the raw water inlet and swing gate valve 90 is downstream of the strainer. Raw water pumps 24 and 26 are both downstream of swing gate valve 90.

[0246] The terms upstream and downstream are also useful in defining the position of one component relative to another. Raw water pumps 24 and 26 are both downstream of swing gate valve 90. However, raw water pump 24 is upstream of tee 92 (the raw water network connection in this example) but raw water pump 26 is downstream of tee 92.

[0247] The heat exchangers used for each engine are both downstream of their respective raw water pumps. It is desirable to ensure that the heat exchangers are purged so at least one salinity sensor is preferably placed downstream of each raw water pump. Such a salinity sensor can be placed within the heat exchanger itself. It is better to place the salinity sensor near the raw water outlet for the heat exchanger. For a wet exhaust system, it is better still to place the salinity sensor just before the point where the raw water is injected into the exhaust streamtypically in an exhaust elbow. Placing the salinity sensor at this point generally means that when the salinity has fallen to an acceptable threshold at the sensor one can be sure that the salinity upstream within the raw water network will be even lower.

[0248] As explained previously, it is desirable for the system controller to be able to monitor an engine's run state (at least to the extent necessary to detect an impending engine shutdown). The controller can then run the fresh water flush cycle in a desired sequence. The fresh water pump is energized and the hydrostatic lock is opened and maintained in an open state in order to flood the raw water network with fresh water. This is usually done with the engine running, so that the engine-driven raw water pump pulls in the fresh water and propels it through the heat exchanger and all the way to the raw water exit.

[0249] The salinity sensor is used so that only the volume of fresh water actually needed to produce an effective flush is used. Once the salinity sensor detects the salinity falling below a defined threshold, the system controller preferably shuts off the engine. The raw water pump then stops effectively blocking any water movement through the raw water pump. The system controller preferably keeps the fresh water pump energized and holds the hydrostatic lock open for an interval after the engine stops. This ensures that all parts of the raw water network upstream of the raw water pump(s) are purged.

[0250] This continuation interval can be for a simple time interval (such as 5 or 10 seconds). Other control approaches are possible. Looking again at FIG. 10, the reader will recall the presence of pressure sensors 192,194. When the engines are stopped and the raw water pumps 24, 26 are shut down, the pressure supplied by pump 55 can only escape through the reverse-flow orifice 134 in swing gate valve 90. The reverse flow orifice is smallsuch as 2 to 5 mmso the pressure within the raw water network will increase when the raw water pumps shut off flow through the engines. This pressure rise can be detected by pressure sensors 194 or 192. The pressure rise can then be used to confirm engine shut down and then shut down the hydrostatic lock and then shut down the fresh water pump (with delays built in if desired).

[0251] The reader's understanding may benefit from some specific exemplary specifications of one embodiment. The salinity threshold for shutting down a fresh water flush cycle is typically 1500 parts per million (ppm) of salt. Seawater salinity varies from about 30,000 ppm to 50,000 ppm. Thus, a reduction in salinity to 1500 ppm is a substantial reduction.

[0252] In the preferred embodiment the fresh water flush cycle is automatically controlled and only continues until the salinity of the raw water at the end of the raw water circuit (typically the exhaust elbow) falls below the defined threshold (typically 1,500 ppm). In most embodiments such a fresh water flush cycle runs for about 30 seconds. In the case of a dual Cummins 6BT installation, a flush cycle will consume about 15 gallons of fresh water. A native fresh water tank in such an installation is typically 300 gallons or more. Thus, there is sufficient capacity for multiple flush cycles in addition to the normal activities using fresh water.

[0253] In addition, many yachts are equipped with a water maker (a desalination unit). An exemplary water maker in a moderately sized yacht produces 4 gallons per hour (16 liters per hour) on an electrical consumption of only 1.9 kW. These units can be run from generator power, in addition to running while the engines are running. A water maker can thereby support one flush cycle per day in addition to making enough water for the normal fresh water demands.

[0254] Finally, the reader should bear in mind that the flushing operations carried out by the present invention serve both to reduce corrosion in the raw water components and to reduce the formation of deposits. In many applications the reduction of deposit formation will be a huge benefit. It is known for a shell-and-tube heat exchanger to become 90% clogged with deposits in only one year of operation. The present invention drastically reduces this problem and thereby greatly extends the interval between times when the heat exchanger must be disassembled for cleaning.

[0255] The preceding descriptions contain significant detail regarding the novel aspects of the present invention. These descriptions should not be construed, however, as limiting the scope of the invention but rather as providing illustrations of the preferred embodiments of the invention. Many additional embodiments of the invention are possible, and the limitations present in any particular embodiment should not be viewed as a characteristic of the invention as a whole. Accordingly, the scope of the invention should be fixed by the claims, rather than by the examples given.