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Publication numberUS2847967 A
Publication typeGrant
Publication dateAug 19, 1958
Filing dateMay 18, 1956
Priority dateMay 18, 1956
Publication numberUS 2847967 A, US 2847967A, US-A-2847967, US2847967 A, US2847967A
InventorsKiekhaefer Elmer C
Original AssigneeKiekhaefer Elmer C
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Outboard motor water inlet structure
US 2847967 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

A118- 19, 1958 E. c. KIKHAEFER 2,847,967


Filed May 18, 1956 INVENTOR. EMHZ? K/EKHAFEP BY Y United States Patent C M' OUTBOARD MOTOR WATER INLET STRUCTURE Elmer C. Kiekhaefer, Cedarburg, Wis.

Application May 18, 1956, Serial No. 585,849

1 Claim. (Cl. 115-18) This invention relates generally to outboard motors and more specifically to an improved cooling water inlet means for an outboard motor.

Water cooled outboard motors are normally provided with a water inlet structure that necessitates submerging the lower unit containing the propeller shaft and trans-l mission gears in the water in order to provide adequate engine cooling. A disadvantage of this type of construction where the motor is mounted on a transom of a boat for propelling the boat through the water, is that the lower unit in the operation of the outboard motor oifers a large resistance to movement of the outboard motor through the water resulting in decreased available propeller thrust for propelling the boat. Applicants improved cooling water inlet means eliminates this disadvantage in theV prior art and offers additional advantages to be explained hereinafter.

It is therefore an object of the present invention to provide an improved cooling water inlet means for an outboard motor that permits utilization of more of the available propeller thrust for propelling a boat through the water.

Another object of the invention is the provision of a cooling water inlet means for an outboard motor that provides the engine with sufficient cooling water under surface pitch operation conditions, that is, where the motor is employed with the propeller partially out of the water as shown in Fig. 1 with the blades thereof successively entering the Water. This surface pitch condition is obtained when the engine is set up for racing by mounting the engine at a height on the transom where all of one blade is out of the water. Under these conditions the gear case for the water pump may also be out of the water, as shown.

Another object of the present invention is the provision of an improved cooling water inlet structure formed in the outboard motor skeg adapted during surface pitch operation of the outboard motor to counteract the tendency of the outboard motor propeller to move the boat to the right or left depending on the direction of rotation of the propeller.

Another object of the invention is provide an improved cooling water inlet structure that is weedless in operation.

Objects and advantages other than those set forth above will be apparent from the following description when read in connection with the accompanying drawing, in which: l

Fig. 1 is a side elevation view of an outboard motor embodying the invention and operating under surface pitch conditions with the propeller partially `out of the water;

Fig. 2 is an enlarged fragmentary front elevation view of a portion of the structure shown as viewed from the left in Fig. 1;

Fig. 3 is an enlarged fragmentary side elevation view partially in section of a portion of the outboard motor shown in Fig. 1;

' 2,847,967 Patented Aug. 19,1958


Fig. 4 is a section view taken on line 4-4 of Fig. 3; and

Fig.' 5 is an enlarged section view taken on line 5--5 of Fig. 3.

As shown in the drawings, the preferred embodiment of this invention is illustrated as applied to an outboard motor 1 having a drive shaft housing 2 supporting an engine, not shown, enclosed within a cowl 3 at one end and secured to a lower gear case housing 4 at the other end. The outboard motor 1 is removably secured to the transom 6 of a boat by means of a clamp bracket 7 and clamping screw 8, and is further pivotal about a vertical rod 9 carried by a swivel bracket 11 for dirigible movement of the motor by means of a steering handle, not shown.

The gear housing 4 shown as a single piece casting is provided with a streamlined strut portion 12 at one end for securement to the drive shaft housing 2. The opposite end of the gear housing 4 is provided with a skeg 13 shown as a thin, streamlined, plate member. The skeg 13 and the strut 12 merge to form a hollow ellipsoidal casing 14 for housing a water pump 16, propeller shaft 17 and transmission gears, not shown. The skeg 13 is further provided with a shallow grooved out channel 18 having a generally planar leading portion 10 smoothly merging with the leading edge of the skeg 13 and a trailing ridge portion 15 extending generally upwardly and rearwardly for directing Water generally upwardly through an opening 19 formed in the casing 14 to the inlet of the water pump 16 within which an impeller 21 is disposed. The impeller 21 upon rotation of the propeller shaft 17 forces water out of the water pump 16 through a conduit 23 to the engine coling system as is old in the art. The channel 18 upon forward motion of the outboard motor 1 acts as a scoop to direct the water into the pump casing 21. The curvature of the channel 18 is of a configuration as shown in Fig. 4 whereby water passing the skeg 13 as it slices through the water develops a lateral force thereon due to frictional pressure and turbulence on surface 18 and the reduced pressure area on the opposite side of the skeg. This force acts in the general direction indicated by the force vector F. This lateral force tends to move the outboard motor laterally counteracting the lateral force F2 in which the propeller 22 rotating in the direction shown in Fig. 2 tends to produce to move the outboard motor 1 and rear end of the boat during surface pitch operation.

In the operation of applicants invention, the outboard motor 1 may be disposed upon the transom 6 of a boat for surface pitch operation with only the skeg 13 and the lower propeller blade of the outboard motor extending into the water. Upon forward movement of the motor 1 and boat, the water passing the skeg 13 is directed to the inlet of the water pump by means of the channel 18. The lateral force developed by the water acting against the surface of the skeg 13 tends to move the boat and motor in a lateral direction counteracting at least in part the tendency of the propeller 22 to move the boat and motor in the opposite direction. This permits the operator to maintain the boat on a straight line course without pivoting the motor to the right as far as otherwise required about the vertical rod to counteract the lateral force developed by the propeller 22.

Although but one embodiment has been illustrated and described, it will be apparent to those skilled in the art that Various changes andmodifications may be made therein without departing from the spirit of the invention or from the scope of the appended claim.

It is claimed and desired to secure by Letters Patent:

In a dirigible outboard motor wherein the submerged propeller or portion thereof produces a side thrust on the outboard generally requiring a compensating steering position for the outboard to eiect forward boat movement, and wherein the motor is water cooled necessitating a constant supply of water thereto during operation, means to assure an adequate water supply andpto at least in part compensate said side thrust, said means comprising a generally ellipsoidal streamlined lower gear casing, a downwardly extending skeg centrally and longitudinally disposed beneath said casing, a propeller shaft disposed axially in said casing and extending rearwardly therefrom, a propeller mounted on the rear end of said shaft to drive the boat forwardly through the water, said propeller producing an unbalanced side thrust on said casing and skeg depending upon the location of the propeller relative to the surface of the water, a Water inlet port in the bottom of said casing on the side of the skeg toward 4. which said propeller tends to thrust the casing during such forward movement, and a water scoop channel leading upwardly and rearwardly in said side of the skeg and to said inlet port to provide a supply of water to said port even when the outboard is being operated under surface pitch conditions and to provide a side thrust in part compensating said unbalanced propeller side thrust.

References Cited in the le of this patent UNITED STATES PATENTS 1,716,962 Johnson .Tune 11, 1929 1,893,662 Smith Ian. 10, 1933 2,147,638 De Port Feb. 21, 1939 2,167,533 Solomon July 25, 1939 2,616,386 Kiekhaefer Nov. 4, 1952

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1716962 *Aug 25, 1926Jun 11, 1929Johnson Brothers Engineering CWater propulsion device
US1893662 *Jul 3, 1931Jan 10, 1933Caille Motor CompanyGear pump for outboard motors and the like
US2147638 *Dec 9, 1932Feb 21, 1939Port Theophile DeMeans for rigging an airplane
US2167533 *Aug 25, 1938Jul 25, 1939Guillermo SolomonTorque compensator for airplanes
US2616386 *Jul 29, 1948Nov 4, 1952Carl Kiekhaefer ElmerWater cooling system for outboard motors
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3164121 *Sep 28, 1962Jan 5, 1965Kiekhaefer CorpWater-coolant supply means for an outboard propulsion unit
US4304557 *Jan 4, 1980Dec 8, 1981Outboard Marine CorporationHydro torque skeg foil
US4636175 *Nov 7, 1985Jan 13, 1987Brunswick CorporationWater inlet for outboard propulsion unit
US4861293 *Apr 20, 1988Aug 29, 1989Outboard Marine CorporationMarine propulsion device with screened water inlet
US5078630 *Oct 25, 1989Jan 7, 1992Nissan Motor Co., Ltd.Engine cooling system induction arrangement for marine inboard-outboard and outboard engines
US5344349 *Jun 25, 1993Sep 6, 1994Brunswick CorporationSurfacing marine drive with contoured skeg
US5376032 *Jun 30, 1993Dec 27, 1994Brunswick CorporationMarine drive with skeg water inlet
US6558213 *May 17, 1999May 6, 2003Bombardier Motor Corporation Of AmericaHigh performance engine skeg
U.S. Classification440/78, 440/88.00M, 440/88.00P, 440/61.00S, 440/88.00R
International ClassificationF02B61/00, F02B61/04, F01P3/20
Cooperative ClassificationF02B61/045, F01P3/202
European ClassificationF01P3/20B