GB2089306A

GB2089306A - A water jet unit for ships

Info

Publication number: GB2089306A
Application number: GB8135483A
Authority: GB
Original assignee: Kamewa AB
Current assignee: Kamewa AB
Priority date: 1980-11-26
Filing date: 1981-11-25
Publication date: 1982-06-23
Also published as: NO152085B; NO814015L; NO152084B; FR2494662A1; NO814014L; IT8125311A0; NO152084C; DE3146394A1; IT1139857B; NO152085C; GB2089306B; FR2494662B1; DE3146394C2

Abstract

A water jet unit comprises a propeller pump (4) having a pump housing (5) which includes a hub housing (8) stationarily arranged centrally of the flow path through the pump housing and an impeller (11). A water-inlet channel (3) is connected at one end in a liquid- tight fashion to the bottom of the hull, and the other end to the transom (1). The pump housing is mounted, so as to be detachable from outside the hull (2), in an annular mounting flange (21) fixedly mounted in the transom, in a manner such that the pump housing partly extends into the water- inlet channel and so that the inlet opening (6) of the pump housing (5) is concentrically located in said channel. The pump (4,8,11) can be readily removed for maintenance and repair work, by dismantling the pump housing from the mounting flange and drawing the pump housing out, either together with the pump shaft (10) or without dismantling said shaft. <IMAGE>

Description

SPECIFICATION A water jet unit for ships The present invention relates to a water jet unit for ships.

In particular the present invention relates to a water jet unit of the kind comprising a propeller pump; a pump housing having water-inlet means on one side thereof and wateroutlet means on an opposite side thereof; a hub housing stationarily arranged centrally in the flow path of the water through the pump housing between said inlet and said outlet means; an impeller journalled for rotation in said hub housing; and a water-inlet channel.

In known wafer jet units of this kind, the task of dismantling and assembling the unit in conjunction with maintenance and repair work represents a relatively complicated and timeconsuming operation, which often requires the ship to be placed in dry dock.

Consequently, an aim of the present invention is to provide an improved embodiment of a water jet unit of the kind described, so that the unit can be readily dismantled and reassembled while the ship is still afloat.

According to the present invention there is provided a water jet unit for ships, comprising a propeller pump including a pump housing having water-inlet means on one side thereof and water-outlet means on an opposite side thereof; a hub housing stationarily arranged centrally in the flow path of the water through the pump housing between said inlet and said outlet means; an impeller journalled for rotation in said hub housing; and a water-inlet channel which is fixedly arranged in the hull of the ship and connected at one end thereof in a water-tight fashion to the bottom of the hull around an opening therein, while the other end of said channel is connected in a water-tight fashion to the transom of the hull around an opening located therein; an annular mounting flange arranged in the transom of the hull and encircling said opening in said transom, said mounting flange being arranged to receive said pump housing in locking engagement, such that the inlet opening of the pump housing is concentrically located within the water-inlet channel, and such that said pump housing can be removed from said flange from outside said hull; and a pump shaft which extends into the inlet channel through a liquid-tight lead-through located in the wall of said inlet channel and the end of which shaft is coupled to the impeller in said housing.

According to one advantageous embodiment of the present invention, part of the pump housing extends into the water inlet passage.

According to a further advantageous embodiment of the present invention, that part of the water-inlet channel located nearest the transom has a portion which is flared conically towards the transom and which embraces the part of the pump housing extending into said channel and the diameter of which at the narrower end thereof coincides substantially with the diameter of the water inlet means adjacent the pump housing.

Conveniently, the coupling between the propeller shaft and the pump housing is preferably a spline coupling, so that the pump housing together with the impeller can be removed without disassembling said shaft.

The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figures la and ib together, when laid side by side, illustrate a sideview, partly in axial section, of an exemplary embodiment of a water jet unit according to the present invention.

The water jet unit of the present invention, as illustrated in the accompanying drawings, is mounted in the stern of a ship, only the transom 1 and the bottom 2 of the ship's hull being shown. The water jet unit includes an inlet channel 3 and a propeller pump, generally identified by the reference 4. The pump 4 includes a pump housing 5 which has at one side thereof an inlet opening 6 and at the opposite side an outlet opening 7, and in which a hub or bearing housing 8 is stationarily arranged centrally in the flow path of the water through the pump housing, between the inlet opening 6 and the outlet opening 7.

The hub housing 8 is carried in the pump housing 5 by means of guide vanes 9, which extend between the inner wall surface of the pump housing and the outside of the hub housing. An impeller 11 is journalled for rotary movement in the hub housing 8 by means of a splined sleeve 1 2. The sleeve 1 2 is arranged on the splined end of the shaft 10 of the pump, said pump shaft extending into the inlet channel 3 and projecting coaxially into the pump housing 5 through its inlet opening 6.In order to reduce the effect of the rotating pump shaft 10 on the flow of water through the inlet channel 3 said shaft is enclosed in a sleeve 1 3 and is sealed externally of the inlet channel 3 by means of a seal or packing 14, the seal housing of which is connected to the sleeve 1 3 by means of a flexible sleeve 15. The pump shaft 10 is conveniently coupled within the ship to a prime mover (not shown) in a manner also not shown.

Connected to the outlet opening 7 of the pump housing 5 is a holder means 1 6 in which there is mounted a steering nozzle 1 7 for steering the direction of the water jet. The nozzle 1 7 can be swivelled laterally on a vertical pivot axis. To enable the direction of thrust to be reversed, in order to slow the ship down or to reverse the direction of ship movement, there is provided a bucket 18, which can be swung progressively between an inactive position in which the bucket is located completely outside the jet-steering nozzle 1 7 and a maximum, inwardly swung active position in which the bucket blocks the water jet in the nozzle 1 7.

In accordance with the present invention, the water inlet channel 3 is fixedly arranged in the hull of the ship and one end of said channel is connected in a water-tight fashion to the bottom 2 of the hull around an intake opening 1 9 located therein, while the other end of said channel 3 is similarly connected in a water-tight fashion to the transom 1 of the hull around an opening 20 arranged therein, or, as with the illustrated embodiment, to an annular mounting flange 21 arranged in said opening. In accordance with the invention, the pump housing 5 is detachably mounted in position from the outside of the hull in the mounting flange 21 attached to the transom 1, in a manner such that part of the pump housing 5 extends into the inlet channel 3 with the inlet opening 6 of the pump housing concentrically located in said channel.That part of the inlet channel 3 located nearest the transom 1 has a conically flared portion 3a which embraces the part of the pump housing 5 projecting into the channel 3. As will be seen, immediately in front of the inlet opening 6 of the pump housing 5 the channel 3 has a diameter which substantially coincides with the diameter of the inlet opening 6.

A water jet unit of this construction can readily be dismantled for reparation or maintenance work, by loosening the pump housing 5 from the mounting flange 21 from outside the ship, and then drawing the housing rearwardly from the inlet channel 3, whereat the splined sleeve 1 2 is drawn from the splined end of the pump shaft 10. Consequently, it is not necessary to dismantle the pump shaft 10. Dismantling of the pump housing, and also the assembly thereof, can be carried out with the ship afloat, provided that the ship is trimmed so that the end of the shaft 10 is located above the surface of the water. It is only necessary to slightly trim the ship to this end, since the water jet unit normally lies on the water line of the ship when the ship is stationary. Alternatively, the pump housing 5 can be removed together with the shaft 10, by disconnecting the inner end of the shaft from the prime mover.

A water jet unit constructed in accordance with the invention has the additional advantage whereby the inlet channel 3 can be readily manufactured in the ship-yard when building the ship, whereafter the pump can readily be mounted in position when delivered from the manufacturers.

Claims

1. A water jet unit for ships, comprising a propeller pump including a pump housing having water-inlet means on one side thereof and water-outlet means on an opposite side thereof; a hub housing stationarily arranged centrally in the flow path of the water through the pump housing between said inlet and said outlet means; an impeller journalled for rotation in said hub housing; and a water-inlet channel which is fixedly arranged in the hull of the ship and connected at one end thereof in a water-tight fashion to the bottom of the hull around an opening therein, while the other end of said channel is connected in a water-tight fashion to the transom of the hull around an opening located therein; an annular mounting flange arranged in the transom of the hull and encircling said opening in said transom, said mounting flange being arranged to receive said pump housing in locking engagement, such that the inlet opening of the pump housing is concentrically located within the water-inlet channel, and such that said pump housing can be removed from said flange from outside said hull; and a pump shaft which extends into the inlet channel through a liquid-tight lead-through located in the wall of said inlet channel and the end of which shaft is coupled to the impeller in said housing.

2. A water jet unit as claimed in claim 1, in which part of the pump housing extends into the water inlet channel.

3. A water jet unit as claimed in claim 2, in which that part of the water-inlet channel located nearest the transom has a portion which is flared conically towards the transom and which embraces the part of the pump housing extending into said channel and the diameter of which at the narrower end thereof coincides substantially with the diameter of the adjacent water inlet means of the pump housing.

4. A water jet unit as claimed in claim 1, in which the coupling between the propeller shaft and the impeller is a spline coupling, so that the pump housing together with the impeller can be removed without disassembling said shaft.

5. A water jet unit for ships, constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.