US3115112A - Tubular rudder with relief means - Google Patents

Description

Dec..24, 1963 R. w. ERLBACHER 3,115,112

TUBULAR RUDDER WITH RELIEF MEANS Filed May 4, '1961 m x EM-ro E: ROBERT w. Em. BHCHER,

United States Patent "ice 3,115,112 TUBULAR RUDDER WITH RELEF MEANS Robert W. Erlbacher, 920 N. Fountain, Cape Girardeau, Mo. Filed May 4, 1961, Ser. No. 107,671 14 Claims. (Cl. 114-166) This invention relates to improvements in tubular rudders and in particular is concerned with tubular rudders having relief means for accommodating propeller races of different sizes which may vary with the load and speed of the vessel.

In the Kort rudder a tubular shell is used to enclose the propeller, as is well known in the art, while in the Erlbacher Patent No. 2,803,211, a tubular shell is used spaced axially from the propeller to provide for increased propulsion and steering efiiciency. In the Erlbacher patent design, the rudder may be used aft of the propeller in conventional fashion or it may be used as a backing rudder in which case it is spaced slightly forward of the proeller.

p It has been recognized that as the revolutions per minute of the propeller increase the diameter of the wheel race also generally decreases. Since the tubular rudder designs are comprised of a tube of fixed diameter, no allowance is made for this variation. As a result at high r.p.m., when the propeller race is of a decreased diameter, and when more water is pushed through the rudder at high velocity, the tubular rudder is larger than necessary. It will be understood that the term propeller race means the high velocity propulsion slip stream of water created by the turning of the propeller. When the vessel is operating at top r.p.m. with increased loads there will be greater slippage than when there is a light load at the same r.p.m. and the propeller race is larger. Since the rudder is normally designed for an average r.p.m. and load, the variation in propeller race, size, and passage of water through the tubular rudder, does not permit optimum operating efficiency at other speeds and loads and losses in eificiency and steering result.

By means of this invention there has been provided a tubular rudder for use according to the Kort type of rudder and also the Erlbacher patent type of rudder. This rudder has relief means and permits the rudder to accommodate wheel races of increased diameter and permits increase of flow through the rudder at increased speeds and loads. The relief means can take the place of an enlarged or expandable internal rudder dimension as in the form of a rigid tubular rudder having a slotted section closed by a rubber diaphragm. The relief means, preferably as a matter of practice and convenience, may also comprise a slotted opening alone and running axially along the rudder in which the width of the slot may be as much as up to about one-third of the circumference of the rudder. The relief opening may also be adjustable so that varying conditions can be accommodated by the proper setting of a cover fitting over the slot or a portion thereof. The above are features and objects of the instant invention that may be used with Kort and Erlbacher patent rudder designs.

Other features and objects of this invention will appear in the detailed description which follows and will be otherwise apparent to those skilled in the art.

For the purpose of illustration of this invention, there are shown in the accompanying drawings several embodiments thereof. It is to be understood that these drawings are for the purpose of example only, however, and that the invention is not limited thereto.

In the drawings:

FIGURE 1 is a fragmentary and side elevation of the rear of a vessel fitted with a rudder spaced aft of the propeller and having the relief means of the instant invention;

FIGURE 2 is a view in section taken on the line 22 of FIGURE 1;

FIGURE 3 is a view in vertical section taken along the axis of the propeller and the rudder of the vessel of FIG- URE 1;

FIGURE 4 is a view similar to FIGURE 3, but showing the use of a rudder fitting over the propeller as in the Kort design;

FIGURE 5 is a view taken similarly to FIGURE 4, but showing a modified design;

FIGURE 6 is a view in front elevation of a slotted tubular rudder fitted with a flexible diaphragm which provides the relief means of this invention and shows the action of the wheel race at normal r.p.m.;

FIGURE 7 is a view similar to FIGURE 6 showing the action of the wheel race at an increased r.p.m.;

FIGURE 8 is a view in section showing the action of the flexible diaphragm when the r.p.m. is decreased to provide a wheel race of greater diameter;

FIGURE 9 is a view in side elevation of a modified rudder having a slotted relief port;

FIGURE 10 is a view in section taken on the line 1010 of FIGURE 9;

FIGURE 11 is a view in side elevation of a further modified tubular rudder having a relief port which is adjustable with respect to its effective size by means of a cover plate; and

FIGURE 12 is an enlarged view in section taken on line 1212 of FIGURE 11.

The rudder of FIGURES 1 to 3 is generally identified by the reference numeral 20, and, as shown therein, is pivotally attached through a rudder post 22 to the hull of the vessel 24. The vessel is provided with a conventional propeller 26, and the rudder is located axially with respect to the propeller and aft thereof. As seen in FIG- URES 2 and 3, the rudder is constructed of a shell member 28 having an axially running slot 30 at the bottom thereof. The slot 36) provides the relief means of this invention and can extend in width up to about one-third the circumference of the shell 28. By means of this particular location of the slot at the bottom of the shell, the draft of the vessel is decreased besides obtaining the increased operating efliciency and propulsive and steering effectiveness of the invention.

In FIGURE 4 a modified rudder 36 is shown which encloses the propeller 26. This modification is in a form similar to the Kort design. The rudder is otherwise identical in construction with the rudder 20 of FIGURES 1 to 3, except for the change in position.

In FIGURE 5 a further modification is shown through the use of a rudder 33. This rudder is also used in a Kort design as it fits over the propeller 26, but it may also be used aft of the propeller. In this modification, however, the rudder 38 has a slot 40 opening at the front of the rudder, Whereas, the rear of the rudder is entirely enclosed at 42. In this modification, at the point of Patented Dec. 24, 1963 greatest wheel. race effect, in, other words, at the propeller wheel and slightly to the rear thereof, the relief means is provided, whereas at the rearward portion the rudder is of completely tubular design with no relief means provided. This design provides somewhat greater strength while still combining a portion of the relief means of this invention.

In FIGURES 6 through 8 a still further modification is shown through the rudder designated 46. This rudder is of the same design as rudder 20, but, in addition, has a flexible sleeve-like diaphragm 48 installed in the interior thereof, which shows the action of the wheel race. The flexible diaphragm provides for the capture of the, wheel race and at the same time is distensible from the average condition shown in FIGURE 6 to the higher r.p.m. conditionof FIGURE 7 through the decreased r.p.m. condition of FIGURE 8.

In FIGURES 9 and 170 a further modification of the rudder of this invention is generally designated by the reference numeral 503. In this modification a relief port 52. is provided. This relief port runs axially along the circumference of the rudder shell, but does not run all the way to either the front or the rear. By this construction a rib portion 4 at the front and a rib portion 55 at the rear are provided, which provides increased strength, It will he understood that the slot may extend somewhat in greater length than shown in FIGURE 9 and may also be of greater width as previously described. Another slot may also be used on the opposite side where desired for balancing considerations.

A still-further modification of the rudder of this invention is shown in FIGURES 11 and 12, designated by the reference numeral 60; In this modification a relief port 52 is employed similar to that of FIGURES 9 and 10. However, an, adjustable cover plate 62 is utilized, slideable within tracks 64. By adjustment of the cover plate to a rearward direction to that shown in FIGURE 11, a, greater, portion of the relief port will be covered to reduce the effective area. Likewise, by moving the relief. port to the front or to the left from the position shown in FIGURE 11, a greater area of the relief port will be opened up, which may be desired for increased speeds and increased loads. Thus, when the relief port is partially closed, or made, of reduced effective area, the rudder may be made toaccommodate atoptimum operating efficiency, lowered speeds and loads, and a full range of operating adjustment is provided.

Operation Although it is not necessary for the understanding of this invention to discuss the theoretical function of the rudder with the relief means, and since it is not desired to be bound by the theory of operation accordingly, applicant does not wish to be limited by the description of the operation of the wheelrace through the tubular rudder However, for the purpose of explanation of the action of. the water through the rudder, it can be imagined that the rudder in the shape of a tube of rather large diameter for its, length is employed and is able to be pulled through the water by some means so the water is able to pass through the tube in line with the direction it is being pulled. In such action y can represent the volume of water per minute going through the tubular rudder when it is pulled at top speed and then the volume of flow at no speed, or at the stationary condition, is zero. Then the volume of flow at speeds between zero speed and top speed would range proportionally between zero and y.

Now it can be considered that there be placed on the front end of the tube a propeller that is capable of pumping x gallons of water per minute through the tube. If this propeller could pull the tube through the water at top speed, the flow of water through the tube would be near x-l-y gallons per minute. If the tube were held baclc but the propeller were run at top rpm, the gallons per minute going through the tube would be x+0 or x gallons per minute. Propeller speeds from O to top r.p.m. would give varying flows through the tube.

The above example is used for descriptive purposes for in actual practice, and from work done on the tubular rudder, it has been found that there is, due to water action and friction within the tube, an optimum frontal area of the tube for each volume of flow going through it to obtain maximum performance from the propulsion system. In actual vessel operation all various conditions, as shown in the above example, may be experienced within a normal operating day. If the boat is operated with no tow or pay load, there would be very little restriction in the tubular rudder going through the water, which approximates a condition of little slip. If a larger tow or pay load is employed, the vessel would not move through the water as fast, although the propeller may be turning at the same r.p.m., and this corresponds to a condition of greater slip. Around these results and Ber noullis theorem are what the invention is based upon.

In order to provide a tubular rudder of the Kort design, or according to the Erlbacher patent, for eflicient operation under all load conditions, the relief means upon the rudder is provided by way of ports, openings, or slits in the sides of the rudder to act as a valve. Thus, there is provided a relief means for the allowance of greater or lesser amounts of water to pass through the rudder giving the effect of an adjustable frontal area under a set range of conditions. As an example of the operation, it can be imagined that an Erlbacher patent type of rudder is designed for optimum operation where the boat is traveling at one-half speed forward under a heavy tow or pay load, but the propeller is turning at about top r.p.m. Under this condition, if the boat were then per mitted to go at-top speed by reducing the load, the frontal area of the rudder would have to be decreased for top efliciency. If the forward motion of the boat were almost stopped by a very heavy load, the frontal area would have to be increased. To accommodate the above conditions, a section is removed from the bottom of the rudder in the form of a lengthwise slit, such as the slit or opening 30 in the rudder shell of FIGURE 2.

For further understanding, reference is also made to FIGURES 6 7 and 8 where a flexible diaphragm 48 is employed, which covers the opening 30. The diaphragm would then take the normal position at half r.p.m. and full load as shown in FIGURE 6. At high r.p. m. with the same load the conditions would be as shown in FIG- URE 7, while at lower r.p.m. with the same load the conditions would be as shown in FIGURE 8.

It may also be assumed that for another design for a different set of operating conditions FIGURE 6 represents the condition of half load and high rpm. Then, if the load is decreased, there will be less slippage and the condition at high r.p.m. will be as in FIGURE 7, while if the load is increased to full load still operating at high r.p.m. the condition will be as shown in FIG- URE 8.

In actual practice, however, the rubber diaphragm may be removed as in the rudder of FIGURES 1, 2 and 3, and the other modifications, and the outward and inward pressure will equalize themselves to form similar flow patterns. The width of the opening may be up to about one-third of the circumference of the rudder shell. This width will depend somewhat on the propeller design, the r.p.m., and the tow or pay load for which the boat is designed and normally operated. The use of the slit or relief opening in the shell has been explained for example and descriptive purposes only, and the location can be at various points on the shell or nozzle, and may be provided for by the use of holes, ports, etc., with varying degree of success. However, the use of an axial slit, as shown in FIGURE 2, is quite desirable, and where it is of substantial circumferential width, it is desirably O positioned at the bottom of the shell to reduce the draft of the rudder.

Through the operation of the tubular rudder with relief means of the invention, a number of advantages are obtained. Thus, the draft of the boat is not increased, and may actually be decreased, While the relief valve can be employed to equalize flow. Efficiency may be increased Within a wide range of speeds. Also, besides use in the Erlbacher patent rudder, the Kort nozzle may be adapted for variable speeds and flow conditions, and the rudder offers propeller Wheel protection. Additionally, vibration and turbulence are decreased and conversely speed and thrust are increased and also the backing ability of the Kort nozzle is increased.

Various changes and modifications in the employment of the relief means in the tubular rudder of this invention may be made Within the skill of the art. Such changes and obvious modifications are within the scope and teaching of this invention as defined by the claims appended hereto.

What is claimed is:

1. A rudder for marine vessels pivotally mounted about a vertical axis upon the hull of a vessel, said rudder comprising a hollow tube-like shell open at the front and rear ends, said shell having an internal diameter to receive and substantially confine the propeller race of a propeller of the vessel, and adjustable relief means on said shell to permit passage of propeller races of increased diameter through said shell.

2. A rudder for marine vessels pivotally mounted about a vertical axis upon the hull of a vessel, said rudder comprising a hollow tube-like shell open at the front and rear ends, said shell having an internal diameter to receive and substantially confine the propeller race of a propeller of the vessel, and adjustable relief means on said shell to permit passage of propeller races of increased diameter through said shell, said relief means constituting an elongated section of the shell passing a propeller race of increased diameter.

3. A rudder for marine vessels pivotally mounted about a vertical axis upon the hull of a vessel, said rudder comprising a hollow tube-like shell open at the front and rear ends, said shell having an internal diameter to receive the propeller race of a propeller of the vessel, and relief means on said shell to permit passage of propeller races of increased diameter through said shell, said relief means constituting an elongated section of the shell of expansible diameter.

4. A rudder for marine vessels pivotally mounted about a vertical axis upon the hull of a vessel, said rudder comprising a hollow tube-like shell open at the front and rear ends, said shell having an internal diameter to receive the propeller race of a propeller of the vessel, and relief means on said shell to permit passage of propeller races of increased diameter through said shell, said relief means constituting an elongated section of expansible diameter, said elongated section being flexible and the remainder of said shell being rigid.

5. A rudder for marine vessels pivotally mounted about a vertical axis upon the hull of a vessel, said rudder comprising a hollow tube-like shell open at the front and rear ends, said shell having an internal diameter to receive and substantially confine the propeller race of a propeller of the vessel, and adjustable relief means on said shell to permit passage of propeller races of increased diameter through said shell, said relief means comprising an elongated slot in the shell running coaxially therewith.

6. A rudder for marine vessels pivotally mounted about a vertical axis upon the hull of a vessel, said rudder comprising a hollow tube-like shell open at the front and rear ends, said shell having an internal diameter to receive and substantially confine the propeller race of a propeller of the vessel, and adjustable relief means on said shell to permit passage of propeller races of increased diameter through said shell, said relief means being adjustable in size by an adjustable cover plate movable into and out of covering relationship with said slot.

7. A rudder for marine vessels pivotally mounted about a vertical axis upon the hull of a vessel, said rudder comprising a hollow tube-like shell open at the front and rear ends, said shell having an internal diameter to receive and substantially confine the propeller race of a propeller of the vessel, and adjustable relief means on said shell to permit passage of propeller races of increased diameter through said shell, said relief means comprising an elongated slot in the shell extending from the front to the rear.

8. A rudder for marine Vessels pivotally mounted about a vertical axis upon the hull of a vessel, said rudder comprising a hollow tube-like shell open at the front and rear ends, said shell having an internal diameter to receive and substantially confine the propeller race of a propeller of the vessel, and adjustable relief means on said shell to permit passage of propeller races of increased diameter through said shell, said relief means comprising an elongated slot in the shell running coaxially therewith, said slot having a width up to about one-third the circumference of said shell.

9. In combination with a marine vessel having a bladed propeller, a rudder pivotally mounted about a vertical axis upon the hull of a vessel comprising a hollow tubelike shell open at the front and rear ends and fitting around said propeller in coaxial relationship, said shell having an internal diameter slightly larger than the propeller to receive and substantially confine the propeller race, and adjustable relief means on said shell to permit the passage of propeller races of increased diameter through said shell.

10. In combination with a marine vessel having a bladed propeller, a rudder pivotally mounted about a vertical axis upon the hull of a vessel comprising a hollow tubelike shell open at the front and rear ends and fitting around said propeller in coaxial relationship, said shell having an internal diameter slightly larger than the propeller to receive the propeller race, and relief means on said shell to permit the passage of propeller races of increased diameter through said shell, said relief means constituting an enlongated section of expansible diameter, said elongated section being fiexible and the remainder of said shell being rigid.

11. In combination with a marine vessel having a bladed propeller, a rudder pivotally mounted about a vertical axis upon the hull of a vessel comprising a hollow tubelike shell open at the front and rear ends and fitting around said propeller in coaxial relationship, said shell having an internal diameter slightly larger than the propeller to receive and substantially confine the propeller race, and adjustable relief means on said shell to permit the passage of propeller races of increased diameter through said shell, and said relief means comprising an elongated slot in the shell running coaxially therewith.

12. In combination with a marine vessel having a bladed propeller, a rudder pivotally mounted about a vertical axis upon the hull of a vessel comprising a hollow tubelike shell open at the front end and rear ends and spaced axially with respect to said propeller, said shell having an internal diameter slightly larger than the propeller to receive and substantially confine the propeller race, and adjustable relief means on said shell to permit the passage of propeller races of increased diameter through said shell.

13. In combination with a marine vessel having a bladed propeller, a rudder pivotally mounted about a vertical axis upon the hull of a vessel comprising a hollow tubelike shell open at the front end and rear ends and spaced axially with respect to said propeller, said shell having an internal diameter slightly larger than the propeller to receive the propeller race, and relief means on said shell to permit the passage of propeller races of increased diameter through said shell, said relief means constituting an elongated section of expansible diameter, said elon- 8 gated section being flexible and the remainder of said of propeller races of increased diameter through said shell being rigid. shell, said relief means comprising an elongated slot in 14. In combination with a marine vesselhav ing a bladed the shell running coaxially therewith. propeller, a rudder pivotally mounted about a vertical axis upon the hull of a vessel comprising a hollow tube- 5 References Cited In the file 0f ihlstpatellt like shell open at the front end; and rear ends and spaced UNITED S A PATENTS axially with respect to said propeller, saidshellhaving an internal diameter slightly larger than the propeller to re- 2322 cave and substantially confine the propeller race, and 904,313 Davis Nov. 17, 1908 adjustable relief means on saidshell to permit the passage. 10

Claims (1)

1. A RUDDER FOR MARINE VESSELS PIVOTALLY MOUNTED ABOUT A VERTICAL AXIS UPON THE HULL OF A VESSEL, SAID RUDDER COMPRISING A HOLLOW TUBE-LIKE SHELL OPEN AT THE FRONT AND REAR ENDS, SAID SHELL HAVING AN INTERNAL DIAMETER TO RECEIVE AND SUBSTANTIALLY CONFINE THE PROPELLER RACE OF A PROPELLER OF THE VESSEL, AND ADJUSTABLE RELIEF MEANS ON SAID SHELL TO PERMIT PASSAGE OF PROPELLER RACES OF INCREASED DIAMETER THROUGH SAID SHELL.

Images