US3181356A

US3181356A - Pitot tube

Info

Publication number: US3181356A
Application number: US232747A
Authority: US
Inventors: William R Carpenter
Original assignee: CARPENTER CORP
Current assignee: CARPENTER CORP
Priority date: 1962-10-24
Filing date: 1962-10-24
Publication date: 1965-05-04
Anticipated expiration: 1982-05-04

Description

y 1955 w. R. CARPENTER 3,181,356

PITOT TUBE Filed Oct. 24, 1962 I N VE N TOR MM /4M 1?. CAWFE/VTA-V? NZ W United States Patent Ofiice 3,181,356 PHTOT TUBE William lit. Carpenter, Muslregon, Mich, assignor to Carpenter Corporation, a corporation of Michigan Filed st. 24, E962, der. No. 232,747 4 Qlaims. (ill. 73-482) This invention relates to marine instruments and more particularly to a Pitot tube type device for actuating a marine speedometer.

Marine speedometers operated by the dynamic pressure created in a closed conduit as a result of having one end of the conduit exposed to the water in the direction of movement of the boat are well-known. This invention is designed to overcome one of the most commonly experienced dificulties with this type of device. Many boats, and particularly pleasure craft, are operated in waters where there is a greater or a lesser amount of marine vegetation floating in the water. This marine vegetation frequency enters the water-receiving opening of the device partially or wholly plugging it with the result that the speedometer either ceases to function or gives entirely false readings. Many devices have been developed in an effort to overcome this difficulty. These devices have met with little or at best limited success.

This invention provides a solution for this problem by so guarding the opening to the conduit which leads to the speedometer, that the marine vegetation is positively cleared from the water before it can enter the opening. Therefore, the continued accurate operation of the instrument is assured.

The objects and advantages of this invention will be immediately understood by those acquainted with marine instruments by reading the following specification and the accompanying drawings.

in the drawings:

PEG. 1 is a side elevation view of the invention;

FIG. 2 is a sectional view taken along the plane ll-Il;

FIG. 3 is a sectional view taken along the plane lll Ill;

FIG. 4 is a sectional view taken along the plane IV A TV; and

H6. 5 is a sectional view taken along the plane VV. l have provided a Pitot tube device desgned to be submerged in the water. The device has a leading edge of thin section and a water entry aperture which is guarded by a forwardly extending fin or web. This latter web acts either as a sweep to remove weeds from in front of the water entry opening or as a knife to cut the weeds before they become lodged for any substantial period of time in front of the opening. it also keeps the vegetation a short distance ahead of the opening, thus preventing its entry. in this manner, the opening is kept clear of obstructions.

Referring specifically to the drawings, the numeral it) indicates a fragmentary portion of the hull of a boat. To this is secured, by any suitable means such as screws, a mounting bracket ll which supports the body element E12; by means of the hinge pin 13. The use of the mounting bracket 11 and the fact that the body element 12 is hingedly secured to it is immaterial to this invention since these facets of the construction are conventional and well known.

The body element has a flow stabilization flange Zll. Below the flange 2t), the body element projects downwardly at an inclined angle. From the flangeTownwardly, the body element is tapered in cross section. As is shown in FIG. 2, the body element is generally flat on the upper surface 21 and has one side face 22 which is generally flat while the other face 2-3 is curved in a downward direction to converge with the face 22 forming ildlfiiid Patented May 4, 1965 a leading edge 24 which is sharp and thus of narrow cross section. This leading edge is at one side of the body element making it possible to develop the hereinafter described pocket and aperture. The leading edge 24 is sloped back at an angle of approximately 45. This inclination causes any weeds which might strike it to slide downwardly and off the bottom end of the body member. Should the weeds, for any reason, tend to try to remain on the edge, they will slowly be moved down the edge and the sharpness of the leading edge 24 will tend to sever them thus releasing them from the body memher. it will be noted that the body member not only is tapered downwardly and forwardly toward the leading edge 24 but, as is clearly shown in the several sections illustrated in FIGS. 2 through 5, the body memher is tapered toward its free or lower end.

Adiacent its lower end, the body member has a recessed pocket 25 opening outwardly through the leading edge. The upper wall 26 of this pocket (FIGS. 1 and 3) extends rearwardly from the leading edge of the body member in a generally horizontal plane when the body member is in operating position as illustrated in FIG. 1. This upper wall 26 intersects at a right angle with a forwardly facing rear wall 27. The rear wall 27 thus faces forwardly or in the direction of movement of the device through the water.

On one side of the recessed pocket 25, a guard web or fin 2.8 is provided. The forward edge of this fin is either narrow or may be brought to a sharp, shearing edge. Like the leading edge 24 of the body member, it also is sloped downwardly and rearwardly to either sweep weeds away from the area or cut them, if they become lodged and are not swept olf the end of the body mem ber.

Extending rearwardly from the recessed pocket 25, through the rearward wall 27 of the pocket, is an aperture 29. This aperture opens through the rearward wall 27 at a point upwardly and recessed from the leading edge of the guard fin 28 as is clearly shown in FIG. 5. Thus, it is situated well within the guarded or protected portion of the pocket. It will be noted from FIG. 5 that the aperture 29 is nestled down at the junction of the inner face of the guard fin 28 and the upper and

rearward walls

26 and 27 where it receives maximum protection from the presence of the fin. The aperture 29 communicates at its rearward end with a conduit 30 which extends lengthwise of the body member adjacent its upper or rearward edge. The lower end of the conduit 39 is closed by any suitable permanent plug 31 (FIG. 4). The upper end of the conduit 30 communicates with a tube 32 which extends to and is connected with the speedometer with which this invention is operated.

In operation, the device is moved through the water in the direction of the arrow A in FIG. 1. Weeds striking the leading edge 24 of the body member are, by reason of its inclination, induced to slide downwardly and be released by passing over the end of the structure. Should the weeds, for any reason, tend to become lodged against the leading edge and refuse to be released in this manner, the pressure of the Water pushing them against the sharp leading edge 24 will tend to cut them and the weeds will be released and be prevented from accumulating. Thus, the device will not tend to become a rake or collection device for weeds as it is moved through the water.

The weeds that tend to be collected in the area of the pocket 25 are similarly disposed of. The presence of the fin 23 and the angle of inclination of its leading edge bias the weeds to slide downwardly over the end of the body member and thus be released. Once again, should the weeds resist this type of movement, the sharpness of the leading edge of the fin 28 will tend to shear them so that they will be released in this manner. The forward projection of the fin keeps the weeds well forward of the open end of the aperture 2?, preventing any portion of the Weeds from entering this opening and tending to plug it. Further, the presence of the fin tends to push to one side or the other any small lengths of weeds which may be encountered also guarding this opening and keeping it from becoming plugged. In this manner, this invention both prevents the actual opening 29 itself from being plugged by weeds entering it and also prevents the accumulation of weeds immediately ahead of the opening which also will disturb the water flow in this area, tending to lessen the dynamic pressure which should be read by the instrument. Thus, the invention contributes materially to the proper functioning of the speedometer and to the accuracy of the readings when it is operating. The relationship between the size of the orifice 29, the flat surface 26 and the shape of the guard fin 28 is important to the effective functioning of the invention. If the upper end of the guard fin is carried into the leading edge 24 rather than recessed rearwardly from it, as shown, it materially reduces the accuracy of the readings which will be produced. For this reason the upper end of the guard fin 28 is recessed approximately one-half the fore and aft length of the surface 26. If the leading edge of the guard fin is made concave or is radiused rather than being sharp, this also produces a detrimental effect upon readings produced by the invention.

The actual manner in which this device operates is conventional so far as its utilization of the principle of utilizing the dynamic pressure of the water created by the movement of the device through the water to apply a pressure to the reading instrument which reading instrument converts into a measure of speed. Therefore, further explanation of this facet of the devices characteristics is not considered necessary.

The bracket 11 and the body member 12 may each be fabricated of any suitable material, such as a molded plastic or a cast metal, such as aluminum. Certain synthetic resinous plastics have the desirable characteristics of a slippery or lubricious surface which would tend to increase the tendency of Weeds to slide along the body member for discard. An example of such a synthetic resinous material would be a Nylon. The fact that the extreme lower end of the device beyond the recessed pocket tends to be more conventional or rounded in cross section as shown in FIG. 4, does not affect the operation of this device since any weeds which reach this point have already been moved beyond the point where they will influence the entrance of water into the aperture 29 and are further so close to the end of the body member, that they will be forced from the body member by the pressures exerted by the water moving past the device. Any weeds which pass in front of the recessed pocket 25 will be moved on rapidly and will result in no more than a momentary fluctuation in the readings given by the device.

While a preferred embodiment of this invention has been described, it will be recognized that various modifications of the invention may be made each without departing from the principle of the invention.

I claim:

1. In a Pitot tube type device for actuating a marine speedometer, a body member, said body member being inclined downwardly and rearwardly and having a con duit adapted to be connected to the speedometer; said body member having a sharp, knifelike leading edge offset to one side of the body and inclined similarly to said body member; said body member having a forwardly opening recessed pocket therein adjacent its lower end;

a Water receiving aperture communicating with said conduit and opening horizontally and forwardly into said pocket, said pocket having a horizontal upper wall; a guard fin olfset to the same side of said body member as said leading edge and closing one side of said pocket and situated to one side of said aperture and projecting a substantial distance ahead of the opening of said aperture into said pocket for sweeping weeds from the water before they can enter said aperture, said guard fin being recessed rearwardly from said leading edge and said upper wall extending forwardly of said guard fin to said leading edge whereby turbulence in the flow pattern of water at said aperture is eliminated.

2. In a Pitot tube type device for actuating a marine speedometer, a body member, said body member being inclined downwardly and rearwardly and having a conduit adapted to be connected to the speedometer; said body member having one side converging toward the other side to form a leading edge of thin section along an offset to one side thereof and a recessed pocket adjacent the lower end thereof; a water receiving aperture communicating with said conduit and opening horizontally into said pocket; said pocket having a fiat horizontal upper wall; a guard fin aligned with said leading edge closing one side of said pocket and situated to one side of said aperture and projecting a substantial distance ahead of the opening of said aperture into said pocket for sweeping weeds from the water before they can enter said aperture, the forward edge of said guard fin being sharp, inclined at generally the same angle as said leading edge and forming a straight line; the forward edge of said guard fin merging into said upper wall at a point offset rearwardly from said leading edge of said body member and said upper wall projecting forwardly of said guard fin to said leading edge; said aperture being nested in the apex formed at the juncture between said upper wall and said guard fin whereby turbulence in the flow pattern of water at said aperture is eliminated.

3. A Pitot tube type device as described in claim 2 wherein said angle of inclination is approximately 45.

4. In a Pitot tube type device for actuating a marine speedometer, a body member having a conduit adapted to be connected to the speedometer; said body member having a downwardly and rearwardly inclined narrow leading edge offset to one side thereof; a pocket adjacent the lower end of said leading edge of said body member; a water receiving aperture communicating with said conduit and opening horizontally into said pocket; a guard fin closing one side of said pocket and situated to one side of said aperture, said olfset being in the same direction as that of said leading edge, said guard fin projecting a substantial distance ahead of the opening of said aperture into said pocket for sweeping weeds from the water before they can enter said aperture, the forward edge of said guard fin being a straight line; the forward edge of said guard fin at its upper end being offset rearwardly of said leading edge of said body member; said pocket having a flat horizontal upper wall extending from said aperture past said guard fin to said leading edge of said body member and cooperating with said guard fin to guide water in straight flow lines to said aperture.

References Cited by the Examiner UNITED STATES PATENTS 1,099,206 5/14 Sanborn 73-182 3,082,623 3/63 Bosland 73-182 3,084,543 4/63 Finkl 73-182 ISAAC LISANN, Primary Examiner.

LEONARD F ORMAN, Examiner.

UNITED STATES PA'lE1\T OFFICE CERTIFICATE OF CORRECTION Patent No. 3,181,356 May 4, 196

William Rf Carpenter It is hereby certified that error appears in the above numbered patent reqiiring csrrectio'n and that the said Letters Patent should read as corrected below Column 1, line 44, for desgned" read designed column 4, line 19, for "an" read and Signed and sealed this 16th day of November 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Aucsting Officer Commissioner of Patents

Claims

1. IN A PITOT TUBE TYPE DEVICE FOR ACTUATING A MARINE SPEEDOMETER, A BODY MEMBER, SAID BODY MEMBER BEING INCLINED DOWNWARDLY AND REARWARDLY AND HAVING A CONDUIT ADAPTED TO BE CONNECTED TO THE SPEEDOMETER; SAID BODY MEMBER HAVING A SHARP, KNIFELIKE LEADING EDGE OFFSET TO ONE SIDE OF THE BODY AND INCLINED SIMILARLY TO SAID BODY MEMBER; SAID BODY MEMBER HAVING A FORWARDLY OPENING RECESSED POCKET THEREIN ADJACENT ITS LOWER END; A WATER RECEIVING APERTURE COMMUNICATING WITH SAID CONDUIT AND OPENING HORIZONTALLY AND FORWARDLY INTO SAID POCKET, SAID POCKET HAVING A HORIZONTAL UPPER WALL; A GUARD FIN OFFSET TO THE SAME SIDE OF SAID BODY MEMBER AS SAID LEADING EDGE AND CLOSING ONE SIDE OF SAID POCKET AND SITUATED TO ONE SIDE OF SAID APERTURE AND PROJECTING A SUBSTANTIAL DISTANCE AHEAD OF THE OPENING OF SAID APERTURE INTO SAID POCKET FOR SWEEPING WEEDS FROM THE WATER BEFORE THEY CAN ENTER SAID APERTURE, SAID GUARD FIN BEING RECESSED REARWARDLY FROM SAID LEADING EDGE AND SAID UPPER WALL EXTENDING FORWARDLY OF SAID GUARD FIN TO SAID LEADING EDGE WHEREBY TURBULENCE IN THE FLOW PATTERN OF WATER AT SAID APERTURE IS ELIMINATED.