Apparatus for clearing the line of a marine speedometer with pressurized gas

The invention relates essentially to an apparatus for clearing the line of a marine speedometer with pressurized gas, wherein the invention connects a source of pressurized gas through a three-way valve to a diverter valve between the boat's speedometer readout and the pitot tube to allow a source of gas to pass through the three-way valve, and the diverter valve, out the pitot tube in the reverse direction, and thus clear particles therefrom. When the source of pressurized gas is turned off, the pitot tube will operate in the usual manner and the pressure of the moving boat will force air up to the diverter valve, thus closing the diaphragm of the valve and activating the speedometer to read accurately.

BACKGROUND OF THE INVENTION 
Speedometers have been used on all types of boats for a long period of 
time. Speedometers serve a very important function particularly, for 
example, when a boat is being used for skiing because skiers are very 
sensitive to a change of boat speed. As a result, it is necessary to clear 
the pitot tube of a boat speedometer quite frequently so there may be 
accurate readings taken. If the speedometer should become clogged so that 
the driver of the boat cannot take an accurate reading, mishaps may occur, 
one of which can result in a skier's falling. 
This invention is particularly directed to the use of pressurized gas and a 
series of valves to clear the pitot tube of a marine speedometer. 
The known prior art consists of the following: 
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Patent No. Inventor 
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3,349,615 Finkl 
3,380,298 Hanson 
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Finkl ('615) shows a water-pressure operated boat speedometer which is 
supplied with a source of gas 26 which can be pressurized. Gas is 
introduced in the speedometer to force the water from the line and prevent 
corrosion and clogging. The tubes are maintained gas-filled at all times 
during the operation of the speedometer. 
Hanson ('298) shows a device for purging the static and total pressure 
lines of a pitot tube. A compressor or other source of compressed gas is 
used to periodically purge the lines with a blast of high pressure gas. 
The valves are used to isolate the gauges from the high pressure source 
during the purge cycle. During the read cycle, the same valves isolate the 
high pressure source from the gauge and pitot tube lines.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the use of a skiboat or speedboat, it is important that an operator be 
trained to give skiers the best advantage for the type of waterskiing that 
they choose. It is important for skiers to know exactly how fast the boat 
is traveling, whether for competitive or recreational skiing. Frequently, 
clogged particles will block the pitot tube of a speedometer and the 
speedometer then renders an incorrect reading. As a result, a purge system 
for a speedometer is required, but none has been found to be practicable 
to date. 
This invention consists of a source of pressurized gas 10, having a 
connection tube 11 to a three-way valve 12, having an exhaust port 13 and 
a port to the source of pressurized gas 14, and a further port 15 to the 
diverter valve 18. Within the valve there is a rotating member 16 which 
rotates from a position to cover the source of pressurized gas. In a 
position as seen in FIG. 2, it covers the exhaust port 13. A further tube 
17 leads to the diverter valve shown at 18. This diverter valve is known 
as a Clippard pneumatic unit. Valve 18 is a diverter valve of the 
diaphragm type, having a neoprene diaphragm 20 and a body 21 having an 
entrance connection 22 for the source of pressurized gas against one face 
of the diaphragm, and a body portion having a further exit for gas to the 
speedometer which is shown at 23. The speedometer itself is shown at 24 
with a connection thereto at 25. An accumulator 26 is in the line between 
the speedometer 24 and the diverter 21. A third port for this diverter 
valve may be seen at 27, leading to tube 28 and to pitot tube 29, which is 
immersed in the water. When the boat is traveling in a forward direction, 
water and air will flow up pitot tube 29, through tube 28, and pass out 
through opening 23 into the accumulator 26 and through tube 25 to the 
speedometer 24 and will register the boat's speed on the speedometer. 
When it is necessary to clear out the pitot tube, the three-way valve is 
rotated to close exhaust port 13. Pressurized gas passes through the tube 
11, down through the tube 17, and forces the neoprene seal 20 to the 
right. Air can then pass on either side of it out through port 27, through 
tube 28, and out through pitot tube 29 and through its exit port which is 
seen at 30. After a blast of air has forced the diverter valve 18 to the 
right, and allowed air to pass out through the pitot tube, obstructions 
that occur in pitot tube 29 will pass out through the port 30. After a 
blast of air, the three-way valve 12 may be returned to its original 
position, as shown in FIG. 1, covering orifice 14 so that the pressurized 
gas will remain in the can. Now, as the forward direction of the boat 
returns, the speedometer will register the speed of the boat from the air 
and water that are passing up through tube 28 and through the diverter 
valve 18 to the accumulator 26 and to the speedometer 24. 
The operation of this pressurized gas is particularly sensitive in that as 
the air passes down tube 17 and against the neoprene diaphragm 20, it 
closes off the opening 23, but there will be a rush of air against the 
left side of the neoprene gasket forcing it to the right and then the ends 
of the diaphragm, unsupported, will bend and allow the escape of air 
around the sides out through opening 27 to the pitot tube 29. Meanwhile, a 
projection 31 on the diaphragm will cover the opening shown as 32. 
Any water that is in the accumulator 26 will remain and the speedometer 
will register correctly immediately after clearing. There is no delay. 
This is important in competitive skiing in debris filled lakes where dirt 
or leaves clog the pilot tube on occasion. 
Damage might occur to the speedometer if a rush of air should pass out 
through opening 32, through port 23, and out through tube 25 directly to 
the speedometer. The diverter valve provides the protection. With this 
particular invention, the speedometer is protected, and upon closing of 
the three-way valve 12, and the resumption of the operation of the 
speedometer, the air passing through tube 28 will extend on all faces of 
the diaphragm 20, forcing it to return to its original position shown in 
FIG. 1 against the opening, thus allowing the air and water to activate 
the speedometer and render an accurate reading of the boat's speed. 
The accumulator 26 could be placed in line 28 but the response time is much 
slower to refill the accumulator before a correct reading is registered. 
Although the invention has been shown and described with respect to certain 
preferred embodiments, it is obvious that equivalent alterations and 
modifications will occur to others skilled in the art upon the reading and 
understanding of this specification. The present application covers all 
such equivalent alterations and modifications, and is limited only by the 
scope of the appended claims.