US2997015A - Marine propulsion device - Google Patents

Description

Aug. 22, 1961 H. E. RICHTER MARINE PROPULSION DEVICE Filed July 25, 1960 1N VEN TOR fiflfyl Zak/5221' ATTORNEYQ United States Patent 7 2,997,015 I PROPULSION Harvey'E. Richter, 2801 10th Ave Vero Beacli, Fla.

Filed July 25, 51960, Ser. .No. 44,906

Claims. (Cl. 2115-42) This invention relates to marine ,propulsion devices, and more particularly to devices of this kind wherein the water to be acted upon by the propulsion means passes through anopen duct.

There .have been a number of attempts to produce an effective marine propulsion device using the principle of a rotating helical blade, or vane, advancing along a column of water, much in the nature 'of a nut threading upon a bolt. lnevery such case, some provision has been made to enclose within anopen duct the column-of water upon which the vane is to act. However, in many cases, due to the manner of separation of the column from the body of water, or the passage of the water through the duct, excessive turbulence has been created, breaking up the solidity of the column to be acted upon and, at the same time, creating resistance to the forward movement of the propulsion device through the water. In other embodiments of this principle, the water column has uncontrolled exit from the duct, resulting in cavitation and consequent drag at the rear of the devices. .Such arrangements defeat the very purpose of the use of the principle, by placing a very definite speed limitation on the propulsion units through building up resistance to the free passage of the unit through the water, and impeding the free flow of a solid column of water through the duct in the unit.

The general object of the present invention is to provide a marine propulsion device employing the above propulsion principle which will be substantially drag free.

A more specific object is the provision of such a device wherein an undisturbed core of solid water is cut from the main body while the encircling mass is moved freely, and substantially without disturbance around the propulsion device.

A further object is to provide a device of this nature which will allow undistorted passage of the core, or column, through a duct of uniform diameter to maintain solidity of the column and prevent turbulence.

Another object is the provision of a propulsion device which will cut a core, -or column, of sol-id water from the main .body while moving the encircling body freely around the propulsion device, and bringing the encircling body back to the column as a converging cone to impinge upon, and confine, the column -of water emerging from the duct to prevent cavitation.

Still another object of the invention is to provide a marine propulsion device having rotating vanes within an open duct, with means for damping any swirling movement imparted to the column by rotation of the vanes to ensure the column leaving the duct without spiral and thereby prevent surface turbulence behind the propulsion device.

Yet a further object is the'provision of a device of this nature which is mounted for rotation about a vertical axis to change the direction of thrust to permit the device to serve as a steering means for the boat on which it is mounted.

Other objects of the invention will appear from the following-description of one practical embodiment thereof, when takenin conjunction with the drawings which accompany, and forrnpart of, this specification.

in the drawings:

FIGURE "1 is a vertical section through a marine propulsion device embodying the principles of the present invention, parts being shown in "elevation and FIGURE '2 is a front elevation of the device shown in 2 FIGURE .1, parts being broken away to show interior structure.

In general, the invention concerns a marine propulsion device having a casing which includes a shell defining an aperture, or duct, of uniform diameter having as a part thereof a rotatable cylinder carrying vanes of helical curvature. A circular edge surrounds the mouth of the duct to cut into the body of water, as the propulsion device moves forward, to core out a solid column of water upon which the vanes can thread their way to advance the device along the column, while the encircling body of water is directed smoothly around the shell and back as a converging .cone angularly against the surface of the column emerging from the duct to maintain solidarity of the emerging column. Any spiralling of the column imparted by the rotating vanes is stopped before the column leaves the duct.

Referring to the drawings in detail, the propulsion device 1 is housed within a casing 2, which is a two-part casting, the two identical parts .3 meeting along the longitudinal, vertical, medial plane of the unit and held in abutting relation by bolts 4. The casing includes a top mounting flange 5, a suspension post .6, depending from flange 5', a shroud 7 defining a Water duct 8, and a bottom fin v9. A steering drum 10 is bolted on top of the flange 5 and secured to the flange by bolts 11. The drum is rotatably mounted in a mounting ring 12 (to be described), and the ring is secured to an appropriate portion 13 of the boat on which the propulsion device is to be mounted. It is preferred that the mounting flange 5 and the post 6 be streamlined in a fore and aft direction so that they will cause as little drag as possible to the free movement of the device through the water.

As mentioned above, the casing provides a shell, or shroud, 7 which surrounds a cylindrical duct 8 through which a column of water to be acted upon by the propulsion device will pass. It is important that the duct be of uniform diameter from end to end, to the end that a cylindrical column of water can be cored out of the body of water through which the device is moving and pass freely and undisturbedly through the duct, while being confined to maintain its original solidity. The shell, or shroud, outer surface 14 curves from fore .to aft, being thicker at its midsection than at its ends. The shell outer surface converges toward the entrance end 15 of the duct, meeting the duct-defining surface of the shroud in a circular knife-edge 16. The rear portion of the shroud converges to the outlet end of the duct to feather ofi to a thin edge 17. Thus, water surrounding the cored-out column which passes. through the duct will flow outwardly smoothly around the shroud shell, substantially Without disturbance or turbulence, and then inwardly along the aft surface to converge in surrounding, confining relation upon the column emerging from the duct to maintain column solidity. 'The shape of the shroud is such that forward movement of the device will cause the circular knife edge 16 at the mouth of the duct to cut from, or core out of, the body of water a solid column of water which, due to the uniform diameter of the duct, can pass through the duct without disturbance. The surrounding water divided from the core will flow smoothly over the curving surface of the shroud, and smoothly back to surround and confine the column as it leaves the duct to prevent cavitation.

As the column of water passes through the duct, it is acted upon by vanes 18 carried by a rotatable cylinder 19. The inside diameter of the cylinder 19 is equal to that of the entrance and exit ends of the duct '8 and, when the cylinder is in place in the casing, the inner wall of the cylinder forms the bridging portion of the duct between the entrance and exit ends. The casing members '3 are hollowed centrally of "the shroud forming a chamber 20.

. 3 v The chamber has recessed seats the ends of cylinder 19. The chamber is sealed by selflubricating water seals, such as nylon rings 22 which seat in grooves 23 in the cylinder seats and bear against the cylinder outer wall adjacent the ends. End thrust of the cylinder is taken by snap in steel thrust rings 24 which lie in recessed seats 25 which are stepped inwardly of the seats 21. The inner peripheries of rings 24 run in grooves 26 in the outer wall of the cylinders. The rings 24 are backed by thrust bushings 27 which surround the cylinder and are held stationary by means of bolts 28 that lock the bushings to the casing. 1

Four vanes 18 are shown as mounted adjacent the forward end of cylinder 19. These are of helical curvature, and are equi-spaced around the cylinder. The vanes emanate from the inner wall of the cylinder and project inwardly toward the center. They terminate short of the axis of the cylinder, however, leaving a center opening 29. The curvature of the vanes and their rotative movement is such that the vanes tend to cut a screw-like path along the column of water passing through the duct in order to advance the propulsion device forwardly.

Cylinder 19 is rotated by means of a ring gear 30, bolted to an annular flange 31, projecting outwardly from the cylinder. Gear 30 lies within the chamber 20 which is filled with suitable lubricant. Gear 30 is in mesh with a bevel gear 32, mounted on a drive shaft 33 rising vertically through the casing and journalled in bearings 34 in the casing. The shaft will be connected to the boat power plant (not shown). It will be evident that rotation of shaft 33 will cause rotation of the cylinder and vanes and forward movement of the entire unit through the water.

At slow forward speeds of the entire unit and rapid rotation of the cylinder, the water column in the duct 8 will be given a swirling motion so that it would emerge from the duct as a spiralling column with consequent water upheaval behind the propulsion device if some means were not used to prevent it. To this end, four vanes 35 are mounted in the exit end of the duct. These are straight vanes projecting radially inward from the duct surface. These will serve to retard spiral action and cause the column to leave the duct without turbulence.

The mounting ring 12, mentioned above, rotatably mounts the entire propulsion device on the boat. The ring has an upstanding flange 36 spaced outwardly from the inner peripheral edge of the ring, so that an annual angular seat 37 is formed in which the steering drum rests. The drum has a peripheral groove 38 in its rim, and a sealing ring 39 is seated in the groove to bear against the upstanding flange 36 of the mounting ring. The steering drum is protected by a cover 40 bolted to the bolt. The cover has a suitable packing gland 41 to seal around the drive shaft and prevent water seepage down the shaft.

The steering drum has a spiral groove 42 of two or more helices in its rim in which the steering cable 43 is laid. This will provide one or more complete turns of the cable around the drum. The ends of the cable are threaded through outlet thimbles 44 on the drum cover and led to an appropriate wheel, or other steering means (not shown). It will be obvious that pulling upon the cable in one direction or the other will cause the drum to be rotated upon its seat on the mounting ring, thus swinging the entire propulsion device. This will change the direction of thrust from the water column emerging from the duct 8 and thereby shift the boat in the direction of thrust. The propulsion device, therefore, will provide an adequate means for steering as well as propelling the boat.

Assuming that the propulsion device is properly mounted on a boat and the boat engine, or power plant, is running, movement of the drive shaft will cause rotation of cylinder 19 with its vanes 18. The movement of the spiral vanes will tend to draw the unit forward 21 at the ends to journal I as the vanes cut into the column of water in the duct, but, due to the initial drag of the boat, the water will be drawn into the duct as the rotating vanes expel water through the duct. As the forward motion of the boat increases, the rotating vanes tend to thread their way along the water column cored out of the body by the forward motion of the unit, and the relative forward speed of the unit and the rotary speed of the vanes approaches the point where the vanes actually follow a helical path along the column in accordance with their helical contour. Water, of course, is incompressible, and the faster an object is moved through a body of water the more nearly the water acts as a solid. Therefore, the faster the propulsion device is moved forward, the more closely the rotating vanes follow a helical path along the cored out column of water in the duct.

Due to the circular knife edge 16 of the casing at the entrance end of the duct which is the precise diameter of the duct, forward motion of the device results in an actual coring out of the body of water of a solid column which moves through the duct and upon which the vanes 18 act. As the duct is of uniform diameter from end to end, the column moves freely through it without restriction or turbulence due to constrictions or enlargements in the duct with consequent speed and pressure changes. The initial solidity of the column is maintained throughout. The surrounding water is divided from the cored out column without turbulence, and flows smoothly over the streamlined outer surface of the shell. The encircling body of water is directed inwardly toward the column after it passes over the mid-section of the shroud so that it rejoins the column as the column emerges from the duct, creating a pressure upon the entire cylindrical column to prevent cavitation and consequent drag behind the device.

It will be clear from the above, therefore, that the-propulsion device of the present invention cores out a solid column of water from the body of water through which the unit is passing and maintains the solidity of that column through and beyond the duct without expansion or contraction of the column size and without turbulence. At the same time, the surrounding water is separated from the core and carried smoothly without turbulence over the shroud and led at an angle toward the column as it emerges from the duct to prevent cavitation beyond the unit and to maintain solidity of the column and undisturbed water behind the unit. This results in a substantially drag free propulsion unit of high efiiciency. As pointed out above, any swirl produced in the column in starting or during acceleration will be removed by passage of the column along the stationary vanes 35. By pivotally mounting the unit, the power thrust can be utilized as a means for steering.

Although the device has been shown as installed for operation by an inboard motor, the propulsion principle and shroud and duct disclosed can be used with an outboard motor and mount.

While one practical embodiment of the invention has been disclosed, it will be understood that the details of construction shown and described are merely by way of illustration and the invention may take other forms within the scope of the appended claims.

What is claimed is:

1. A marine propulsion device comprising, a casing including a portion defining a shroud having a duct there through, the duct having an entrance and an exit end and being of uniform diameter and unchanging cross-section from end to end, the shroud having an outer surface gently curving convexly from end to end, the shroud outer surface curving to the duct at the entrance end of the duct to provide a knife edge peripherally of the entrance end of the duct so that when the device is moved through a body of water a solid column of water the cross-sectional shape and diameter of the duct will be cored from the body of water and pass unimpeded through the duct maintaining its cross-sectional shape and diameter, and the encircling water mass will be led around the shroud, the outer surface of the shroud converging toward the exit end of the duct so that the encircling water mass passing over the converging surface will be led at an angle toward a column of water emerging from the duct to envelop the column and confine the column against cavitation, a hollow cylinder having inwardly directed helical vanes rotatably mounted in the shroud and having an inner surface forming part of the duct, and means outside the duct to rotate the cylinder.

2. A marine propulsion device as claimed in claim 1 wherein stationary vanes are mounted in the duct adjacent the exit end, the stationary vanes being connected to the casing and projecting radially inward of the duct and ex- 1 tending axially of the duct, so that the column of water leaving the duct will be without swirl.

3. A marine propulsion device as claimed in claim 2 wherein the helical vanes of the cylinder terminate short of the longitudinal axis of the cylinder.

4. A marine propulsion device as claimed in claim 1 wherein the helical vanes of the cylinder terminate short of the longitudinal axis of the cylinder.

5. A marine propulsion device as claimed in claim 3 wherein the stationary vanes terminate short of the longitudinal axis of the duct.

References Cited in the file of this patent UNITED STATES PATENTS 945,553 Kovacs Jan. 4, 1910 2,153,055 Weissmann Apr. 4, 1939 2,347,785 Lovell May 2, 1944 2,605,606 Pilz Aug. 5, 1952 FOREIGN PATENTS 407,432 France Jan. 4, 1910

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