GB2110339A

GB2110339A - Changeover valve

Info

Publication number: GB2110339A
Application number: GB08134750A
Authority: GB
Inventors: Dudley William Brown
Original assignee: Mitsui Machinery Sales UK Ltd
Current assignee: Yamaha Motor UK Ltd
Priority date: 1981-11-18
Filing date: 1981-11-18
Publication date: 1983-06-15
Also published as: FR2516594A1; DE3235173A1; SE8204988L; JPS5891321A; IT8223402A0; DK394382A; SE8204988D0

Abstract

In order to allow a water cooled marine engine (2) to run without risk of overheating when the craft is out of the water, an on board cooling water supply is connected via a pipe 7 with a first inlet port (4) of a change over valve (3). A second inlet port (5) provides for sea-water (normal) supply of cooling water and an outlet (6) directs the water to the engine. When the craft is launched, water is supplied via the second port (5) to the outlet 6, and when the craft is not launched, water supplied via the port 4 urges a piston closure member to a position in which the ports 4 and 6 communicate and the port 5 is isolated. <IMAGE>

Description

SPECIFICATION Improvements in or relating to marine engines This invention relates to marine engines and, in particular, to a change over for a cooling circuit of a marine engine.

Known marine engines are generally of a type which are cooled by drawing water in from beneath the water line of the craft, which water is circulated to cool the engine and is then expelled.

Marine engines of an outboard type are used in particular for comparatively small craft such as rescue craft or ferrying craft in the form of inflatable dinghies. Such craft are used, for example, to transfer crews between a parent ship and an oil rig. When transferring from the ship to the rig, for example, the craft is lowered with the crew in it from the side of the parent ship and, once the craft is in the sea-water, an outboard engine of the craft is started. However, it has been known that an outboard motor of a craft has not been started in time to prevent the inflatable craft being swept away from its mooring by the sea currents, with consequent loss of life.

Because the known marine outboard engines rely on the water in which the craft floats to cool the engines, it is clear that severe damage to the engines can occur if the engines were to be run with the craft out of water because of the severe overheating which would quickly take place.

However, if only because of the dangers of nonstart-up as mentioned above, it is desirable that a marine engine can be started and run before the craft is lowered into the water.

According to one aspect of the present invention, there is provided a change over valve for a cooling circuit of a marine engine, the valve having a first inlet port for supply of cooling water from an on board source, a second inlet port for supply of water from outboard, both inlet ports leading to a common outlet port for supplying the engine with cooling water, and a valve piston positioned selectively to open said first or said second inlet port to the exclusion of the other, said valve piston being arranged to open said first inlet port upon start up of the engine in conditions when water cannot be supplied to said second inlet port, and being arranged to close said first inlet port and to open said second inlet port when water can be supplied to said second inlet port.

According to a second aspect of the present invention, there is provided a marine engine having a cooling circuit incorporating a change over valve that is essentially as defined in the preceding paragraph.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a diagrammatic rear end view of an inflatable dinghy having an outboard marine engine having a change over valve according to the invention in the cooling circuit of the engine, and Figure 2 is a diagrammatic sectional view of the change over valve.

Figure 1 shows an inflatable dinghy 1 having an outboard engine 2. A cooling circuit of the engine includes a water pump (not shown) for drawing cooling water to be passed through the engine. The change over valve 3 of the invention is positioned upstream of the water pump and, as also illustrated in Figure 2, includes a first inlet port 4 for supply of cooling water from an on board source and a second inlet port 5 for supply of cooling water from outboard. Both inlet ports 4 and 5 lead to a common outlet port 6 for supplying the engine with cooling water. The inlet port 4 is connected by a pipe 7 to an on board fresh water supply which can supply the water to the valve 3 via a single action quick release connector 8, which has a quick release fitting for on board cooling supply from the mother ship.A pipe 9 leads to the inlet port 5 of the change over valve 3 from a sea water pick up 10 below the water line of the dinghy. The water supply is arranged to supply water at a minimum pressure of 1 03.43x 1 03 Nm-2 (15 psi) to the change over valve 3.

As can be seen from Figure 2, the change over valve 3 has a valve piston 11 which is positioned selectively to open the valve inlet port 4 or the valve inlet port 5 to the exclusion of the other. The piston 11 is resiliently biased by a spring 12 normally to close the inlet port 4 so that, when the engine is running with the craft launched, sea water is drawn through the intake 10, through the pipe 9 to the inlet port 5 and thence through the valve 3 and out of the port 6 and thence to the engine. However, when it is desired to start the engine and run it before the craft is launched, the connector 8 is actuated and water pressure is applied through the pipe 7 on to the face of the piston 11 facing the inlet port 4.This pressure has the effect of pushing the piston against the bias of the spring 12 thereby to close the inlet port 5 and to open the port 4 so that water can then be drawn from the port 4 throught he valve to the outlet port 6. In this way, the engine can be run, being cooled by the water supplied, whilst the craft is being launched.

As soon as the craft is launched, the quick release connector 8 is released allowing piston 11 to return to face port 4 by spring pressure from return spring 12, to cut off the supply of cooling water and simultaneously to open the flow of seawater through the valve via the ports 5 and 6.

Thereafter, the engine 2 is cooled by the seawater.

The piston 11 is provided with a relief bore 13 between its two faces to allow for a quick return of the valve.

The cooling circuits of existing outboard engines can be adapted to incorporate the cooling circuit of the present invention by relocating the sea water intake, fitting an additional water intake and the change over valve 3 and by fitting an on board supply of cooling water.

It will be appreciated that the present invention has particular advantage where rescue craft are concerned, in particular for life boats which are to be lowered from the sides of ships, docks and quay sides.

Claims

1. A change over valve for a cooling circuit of a marine engine, the valve having a first inlet port for supply of cooling water from an on board source, a second inlet port for supply of water from outboard, both inlet ports leading to a common outlet port for supplying the engine with cooling water, and a valve piston positioned selectively to open said first or said second inlet port to the exclusion of the other, said valve piston being arranged to open said first inlet port upon start up of the engine in conditions when water cannot be supplied to said second inlet port, and being arranged to close said first inlet port and to open said second inlet port when water can be supplied to said second inlet port.

2. A change over valve as claimed in claim 1, wherein said valve piston is resilient!y biased normally to close said first inlet port.

3. A change over valve as claimed in claim 1 or 2, wherein said piston is provided with a bore between its two faces to allow quick return of the piston.

4. A change over valve for a cooling circuit of a marine engine, substantially as hereinbefore described with reference to the accompanying drawings.

5. A marine engine having a cooling circuit incorporating a change over valve as defined in any one of the preceding claims.

6. A marine engine as claimed in claim 5 and comprising a water pump in the cooling circuit downstream of said change over valve.

7. A marine engine as claimed in claim 5 or 6 and comprising means to provide an on board supply of water to said first inlet port, and a water intake, to be fitted below the water line of the craft on which the engine is to be mounted, for supply of water to said second inlet port.

8. A marine engine as claimed in any one of claims 5 to 7, substantially as hereinbefore described with reference to the accompanying drawings.

9. A craft having a marine engine as claimed in any one of claims 5 to 8, wherein said change over valve is positioned such that, in use, disconnection of the fresh water supply will cause said piston to move to, or to remain at, the position in which said second inlet port is open.