US3842787A

US3842787A - Water jet impellor unit having a steering control device

Info

Publication number: US3842787A
Application number: US00358231A
Authority: US
Inventors: D Giacosa
Original assignee: SIRA IND RICERCHE AUTO Soc
Priority date: 1972-05-15
Filing date: 1973-05-08
Publication date: 1974-10-22
Anticipated expiration: 1991-10-22
Also published as: IT958869B

Abstract

A water jet impellor unit of the type comprising a duct along which water is forced by means of a motor driven propellor housed in the duct, in which there is provided a deflector nozzle at the downstream end of the duct, which is pivoted about a substantially vertical hinge axis. The deflector nozzle has a main nozzle outlet facing rearwardly and two subsidiary nozzle outlets facing forwardly and diverging outwardly, the subsidiary nozzle outlets are variable in size by virtue of their cooperation with the sides of the duct so that as the nozzle turns about its hinges one of the subsidiary outlets becomes enlarged while the other diminishes. The nozzle also carries a baffle at the main outlet thereof which is movable between an open position where it allows water to flow out through the main nozzle outlet, and a closed position where it forces water to flow out through the subsidiary outlets to provide a reverse thrust which can be adjusted by inclination of the nozzle about its hinge axis.

Description

tet [191 Giacosa 1 1 WATER .IET IMPIELLOR UNIT VING A STEERING CONTROL DEVICE [75] Inventor:

Dante Giacosa, Turin, Italy Sira Societa Industriale Ricerche Automotorische, Turin, Italy May a, 1973 Assignee:

Filed:

Appl. No.:

[30] Foreign Application Priority Data May 15, 1972 Italy 68514/72 FOREIGN PATENTS OR APPLICATIONS 9/1964 Great Britain 115/12 R 9/1964 Great Britain 115/12 R,

[ Oct. 22, 1974 Primary Examiner-Trygve M. Blix Assistant Examiner-Sherman D. Basinger Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak 57 ABSTRACT A water jet impellor unit of the type comprising a duct along which water is forced by means of a motor driven propellor housed in the duct, in which there is provided a deflector nozzle at the downstream end of the duct, which is pivoted about a substantially vertical hinge axis. The deflector nozzle has a main nozzle outlet facing rearwardly and two subsidiary nozzle outlets facing forwardly and diverging'outwardly, the subsidiary nozzle outlets are variable in size by virtue of their cooperation with the sides of the duct so that as the nozzle turns about its hinges one of the subsidiary outlets becomes enlarged while the other diminishes. The nozzle also carries a baffle at the main outlet thereof which is movable between an open position where it allows water to flow out through the main nozzle outlet, and a closed position where it forces water to flowout through the subsidiary outlets to providea reverse thrust which can be adjusted by inclination of the nozzle about its hinge axis.

5 Claims, 3 Drawing Figures WATER JET IMPELLOR UNIT HAVING A STEERING CONTROL DEVICE BACKGROUND OF THE INVENTION The present invention relates to outboard motors for boats, and particularly to outboard motors of the type having a water jet impellor unit comprising a pumping device operated by an internal combustion engine. The water jet impellor may be, for example, a ducted propeller, which draws water in through an inlet duct which, in use of the motor, is submerged, and expels it at high speed through an outlet nozzle, which may also be submerged, thereby creating a water jet the kinetic energy of which produces the thrust required for propulsion.

In outboard motors of this type it is preferable to control the direction of the boat by adjusting the direction of the water jet whilst maintaining the position of the engine unchanged. The quantities of water drawn in and expelled, however, make this difficult especially with impellors having a power greater than hp.

The alternative arrangement, of mounting the engine and impellor so as to be pivotable as a unit, has a number of disadvantages; for example the pivotal mounting between the engine/impellor unit and the boat must be sufficiently strong to transmit the hydrodynamic forces generated by the unit, and so shaped as to allow the unit to rotate through an angle of 180 between end positions. Such structures are thus heavy and this deleteriously affects the trim of the boat, particularly since the pivotal coupling makes it necessary for the unit to be spaced from the transom of the boat.

Various arrangements have been proposed in order to be able to effect the required changes in direction of the jet produced by the unit whilst maintaining the latter in a fixed position with respect to the hull of the boat. In general known such systems use deflectors and baffles placed inside the outlet nozzle, which are pivoted about a substantially vertical axis and adjustable to deflect the water jet to one side or the other, or through 180 in order to effect reversing of the boat.

These systems are complicated and have a generally bulky construction due to the fact that the means for deflecting the water jet are located inside the ejector nozzle. Furthermore, the lateral deflection of the water jet, causedby the deflectors is a source of loss of energy because of the formation of Whirlpools and eddies in the fluid current of the jet.

Devices provided with an outlet nozzle which can itself be pivoted about a substantially vertical axis to direct the water jet so as to produce transverse components of thrust or components of thrust at 180 with respect to the forward direction of the boat are also known.

These systems also have disadvantages, such as structural complications, and loss of thrust when deflecting the water jet resulting in a reduction of the responsiveness of the boat to the controls.

OBJECTS OF THE INVENTION One object of this invention is to provide a water jet efficiency and which requires a minimumcontrol energy.

A further object of this invention is to provide a water jet impellor unit having means for controlling the direction of the water jet which are compact, particularly in the axial direction, so as to minimise the extension of the impellor unit rearwardly beyond the stern of the boat.

Yet a further object of this invention is to provide a device for controlling the direction of the water jet, in a water jet impellor unit, in which'the dynamic pressure on the jet deflector elements when reversing is low due to the fact that the angle through which the jet deflector elements have to divert the jet in order to achieve reversal of the thrust is less than with previously known thrust reversal arrangements.

Another important object of this invention is to provide, in a water jet impellor unit means for reversing the water jet which allow steering while reversing, and in which the lateral component of the thrust can be varied to facilitate manoeuvring the boat at low speed for mooring etc. I

SUMMARY OF THE INVENTION According to the present invention, there is provided the improvement in a water jet impellor unit of an angularly adjustable nozzle at the downstream end of a main duct of the impellor, the nozzle being mounted for angular movement about a substantially vertical axis and having a main outlet at the downstream end thereof, two subsidiary outlets at respective sides of the upstream end thereof and a movably mounted baffle at said downstream end thereof, the baffle being movable between a first position where it substantially closes the said main nozzle outlet and a second position where the said main nozzle outlet is substantially unobstructed and the said subsidiary nozzle outlets being inclined with respect to the longitudinal axis of the nozzle and variable in cross section in dependence in the angular inclination of the'nozzle about the said substantially vertical axis, whereby when the baffle is in the said first position the resultant thrust from the water passing out through the said two subsidiary nozzle outlets is aligned with the longitudinal axis of the nozzle and in the reverse direction when the nozzle is in the straight ahead position, and has a lateral component when the nozzle is inclined at an angle to the said straight ahead position.

Further characteristics and advantages of the invention will become apparent during the course of the following detailed description with reference to the accompanying drawings, which is given as a non restrictive example only.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially sectioned side view of an outboard motor having a water jet propulsion unit formed as an embodiment of this invention;

FIG. 2 is a sectional view on larger scale, taken on the line II-Il of FIG. 1, showing the deflector nozzle orientated in a position of axial alignment with the boat for straight forward propulsion; and

FIG. 3 is a sectional viewsimilar to FIG. 2 illustrating the deflector nozzle in a deviated position for lateral deflection and in a reversing position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing the outboard motor is generally indicated and is coupled directly by a shaft 11 to an hydraulic pumping device, in this case a ducted propeller 12. The propeller 12 draws water in through an inlet duct 13 and passes it, through an elbow chamber 14 and a diffuser 15 and ejects it at high speed through an outlet nozzle 16.

Downstream from the outlet nozzle 16 there is placed a deflector nozzle 17, which has a divergent truncated conical shape which assists the efflux of the jet by avoiding the formation of turbulent flow and the consequent formation of Whirlpools and eddies.

The deflection nozzle 17 can be adjusted to a range of positions within a substantially horizontal plane and to this end is pivoted to the body of the diffuser unit 15 by substantially

vertical hinges

18, 19, which have suitable support bearings and are carried in corresponding seats of the body of the diffuser duct 15; the hinge 18 is provided with a lever 22 to which is connected one end of a connecting rod (not shown) the other end of which is connected to the control means of the craft. The deflector nozzle 17 is also provided with a baffle 23 pivoted about a substantially horizontal pivot 24 carried by the nozzle 17 itself. The position of the baffle 23 can be controlled by means of a tie-rod (not shown), between the position shown with an unbroken line in FIG. 1, in which it is completely withdrawn from the main nozzle outlet at the rear of the nozzle 17, and the position illustrated with a broken line in FIG. 1, where it totally obstructs this opening.

At the front of the nozzle 17 there are two subsidiary nozzle outlets 1 and 1 The axes of these outlets diverge forwardly from the longitudinal axis of the nozzle 17 at an angle of about 45, so that the angle formed at the intersection f the axes of the two outlets is about 90. The shape of each of the outlets 1,, 1 is divergent away from the axis of the deflector nozzle 17.

Adjacent the outlets l 1 the body of the diffuser duct 15 is tapered and has inclined faces P P which act as abutment stop surfaces for the deflector nozzle 17 when this is turned through its maximum angle about the axis of the

hinges

18, 19.

FIG. 3 illustrates the maximum rotation of the nozzle 17 to the left, this is delimited by the contact of the face P with the edge of the outlet 1,; the axis of the nozzle is then aligned with the broken line A. The axis of the nozzle 17 at the other extreme position, to the right, is indicated A", movement of the nozzle 17 to the right is delimited by the contact of the face P with the edge ofthe outlet 1 The nozzle 17 can move to any laterally inclined position between the end positions defined by the lines A and A".

As shown in the drawing the cross section of the openings of the outlets l, and 1 will be equal and symmetrical with respect to the longitudinal axis of the unit, indicated with the broken line A, when the nozzle 17 is in the straight ahead position as shown in FIG. 2 inwhich its longitudinal axis coincides with the longitudinal axis A of the unit. The cross section of the two outlets l, and 1 varies in dependence on the inclination of the nozzle 17 with respect to the axis A of the unit. When the nozzle 17 is inclined the maximum amount to the left, so that its axis coincides with the line A the outlet 1, is completely closed while the outlet 1 is at its maximum cross section.

OPERATION The operation of the unit is as follows:

If the baffle 23 is in the raised position, the jet of water ejected from the diffuser duct 15 will pass out through the nozzle 17 to provide, by virtue of its kinetic energy, the thrust for driving the craft. Turning the nozzle about the axis of the

hinges

18, 19 will cause a lateral deviation of the jet producing a transverse component of thrust thereby causing a corresponding turning movement of the craft to control its course.

If, on the other hand, the baffle 23 is lowered to totally intercept the outlet of the nozzle 17, as shown in FIG. 3, the water jet, having filled the nozzle 17 will emerge from the subsidiary outlets l, and 1 In this case the nozzle 17 acts to convert the forward thrust of the water jet, due to its kinetic energy, into a reverse thrust due to the water jet being then directed out of the outlets 1 and 1 If the nozzle 17 is aligned with the axis of the unit, as illustrated in FIG. 2, the cross sections of the openings l and 1 are equal to one another; the kinetic energy of the water masses flowing out from each outlet will be the same and the lateral thrusts will thus cancel one another while the longitudinal thrusts reinforce one another, but are in a reverse direction thereby causing the craft to reverse.

When the nozzle 17 is inclined with respect to the longitudinal axis of the craft, one of the outlets l or 1 will be reduced in cross section and the other will be enlarged, depending on the direction of the inclination. Consequentlythe resultant reaction will have a lateral component causing a turning of the craft in addition to the reversing movement.

It will be noted that the steering obtained during reversing is in a consistent sense with that obtained during forward movement. If the turning of the nozzle 17 is controlled by a steering wheel this can be made to act in the same sense as the steering wheel of a motor vehicle thereby avoiding possible mistakes by users who are more familiar with motor vehicles.

In addition, the baffle 23 can be moved to a position in which it partially intercepts the nozzle 17, the effect of this is to reduce the forward thrust to assist manoeuvring at low speed. In one position of the baffle 23 the kinetic energy of the water masses flowing out of the outlets 1,, 1 substantially equals the kinetic energy of the mass of water flowing from the main nozzle 17 so that the resultant thrust is substantially nill and the craft will remain stationary. It is envisaged that there could be means associated with the control elements of the baffle to limit the rotation speed of the motor 10 of the unit when the baffle is in this position so as to avoid the possibility that a sudden acceleration may change the balance of forces resulting in an unwanted sudden thrust causing the craft to move either forwardly or backwardly.

Having now particularly described this invention, one skilled in the art will realize that many variations and modifications can be made thereto, with respect to what has been described and illustrated as an example without limitations, without departing from the spirit and scope of this invention.

What is claimed is:

1. In a water jet impellor unit for an outboard motor, of the type comprising a duct, and

means for impelling water along the said duct, the improvement comprising: 7

an angularly adjustable nozzle at the downstream end of the said duct,

means pivotally mounting the said nozzle for angular movement about a substantially vertical axis,

a main nozzle outlet at the downstream end of said nozzle and two subsidiary nozzle outlets, one on either side, at the upstream end of said nozzle,

a baffle movably mounted on said nozzle and means for controlling the position of said baffle between a first position, where it substantially closes said main nozzle outlet and a second position where said main nozzle outlet is substantially unobstructed,

said downstream end of said duct having side surfaces inclined with respect to the longitudinal axis of said duct,

said subsidiary nozzle outlets being inclined with respect to the longitudinal axis of said main nozzle outlet and disposed adjacent to said inclined side surfaces on said duct whereby the cross section of each of said subsidiary nozzle outlets is variable in dependence on the angular position of said nozzle so that when said baffle is in said first position the resultant thrust from the water passing out through said subsidiary nozzle outlets is aligned with said longitudinal axis of said main nozzle outlet and in the reverse direction when said nozzle is in the straight ahead position and has a lateral component when said nozzle is inclined at an angle with respect to said straight ahead position.

2. The water jet impellor unit of claim 1 wherein said angularly adjustable nozzle has a truncated conical shape which diverges in the downstream direction.

3. The water jet impellor unit of claim 1 wherein said angularly adjustable nozzle is pivotally connected to the downstream end of said duct by means of substantially vertical hinges, one of said hinges carrying a lever for coupling to one end of a connecting rod the other end of which is coupled to a steering device.

4. The water jet impellor unit of claim 1 wherein said subsidiary outlets are of such size that the water is accelerated therethrough when said baffle is in said first position.

5. The water jet impellor unit of claim 1 wherein said baffle is so shaped, that it can assume an intermediate position where it partially obstructs said main nozzle outlet and the thrust from said main nozzle outlet is equal and opposite to the resultant thrust from-said subsidiary nozzle outlets, whereby the total resultant thrust is nil.

Dedication 3,842,787.Dante Giacosa, Turin, Italy. WATER JET IMPELLOR UNIT HAVING A STEERING CONTROL DEVICE. Patent dated Oct. 22, 1974. Dedication filed Jan 13, 1981, by the assignee, FIAT S.p.A.

Hereby dedicates to the Public the term of the patent subsequent to De- I cember 24, 1980. A [Ofiicial Gazette May 12, 1981.]

Claims

1. In a water jet impellor unit for an outboard motor, of the type comprising a duct, and means for impelling water along the said duct, the improvement comprising: an angularly adjustable nozzle at the downstream end of the said duct, means pivotally mounting the said nozzle for angular movement about a substantially vertical axis, a main nozzle outlet at the downstream end of said nozzle and two subsidiary nozzle outlets, one on either side, at the upstream end of said nozzle, a baffle movably mounted on said nozzle and means for controlling the position of said baffle between a first position, where it substantially closes said main nozzle outlet and a second position where said main nozzle outlet is substantially unobstructed, said downstream end of said duct having side surfaces inclined with respect to the longitudinal axis of said duct, said subsidiary nozzle outlets being inclined with respect to the longitudinal axis of said main nozzle outlet and disposed adjacent to saiD inclined side surfaces on said duct whereby the cross section of each of said subsidiary nozzle outlets is variable in dependence on the angular position of said nozzle so that when said baffle is in said first position the resultant thrust from the water passing out through said subsidiary nozzle outlets is aligned with said longitudinal axis of said main nozzle outlet and in the reverse direction when said nozzle is in the straight ahead position and has a lateral component when said nozzle is inclined at an angle with respect to said straight ahead position.

5. The water jet impellor unit of claim 1 wherein said baffle is so shaped that it can assume an intermediate position where it partially obstructs said main nozzle outlet and the thrust from said main nozzle outlet is equal and opposite to the resultant thrust from said subsidiary nozzle outlets, whereby the total resultant thrust is nil.