Abstract:
A frame of a water jet propulsion unit arranged to be installed and sealed into an installation opening of a boat. The water-jet propulsion unit includes an impeller and the boat has a counter-sealing surface to which the frame is attached. The frame includes a flow channel to guide water to the impeller. The flow channel has a top with a maintenance opening. The maintenance opening is positioned to permit servicing the impeller. A first sealing surface forms a first closed loop to attach the water-jet propulsion unit tightly to the counter-sealing surface of the boat. A second sealing surface forms a second closed loop arranged to attach the water-jet propulsion unit to the boat. The first and second closed loops permit the maintenance opening of the frame to be alternatively locatable respectively outside or inside the stern of the boat in dependence on alternative configurations of the installation opening of the boat.

Description:
BACKGROUND 
     The present invention relates to a frame for a water-jet propulsion unit, which is arranged to be installed and sealed into an installation opening for a water-jet propulsion unit belonging to a boat, which frame includes
         a flow channel for guiding water to the impeller belonging to the water-jet propulsion unit,   a maintenance opening located on top of the flow channel, for servicing the impeller, and   a sealing surface forming a closed loop for attaching the water-jet propulsion unit tightly to a counter-sealing surface belonging to the boat.       

     The invention also relates to a corresponding water-jet unit equipped with a water-jet propulsion unit&#39;s frame, and an arrangement in a boat. 
     Water-jet propulsion units suck the water required for the water jet into a flow channel, in which the velocity of the water is increased with the aid of an impeller. Water-jet propulsion units are situated in such a way that the flow channel is located entirely or at least partially outside the boat. Garbage can easily enter the flow channel and wind itself around the impeller or other parts. For this reason, a separate maintenance opening, through which maintenance can be performed, is required for servicing the impeller and flow channel of the water-jet propulsion unit. 
     According to the wishes of customers, water-jet propulsion units are attached to a boat equipped with an attachment opening, in such a way that the maintenance opening is located either inside or outside the stern of the boat. A maintenance opening located inside facilitates maintenance directly from the boat, but on the other hand causes the risk of a leak if the maintenance opening leaks. A maintenance opening located outside does not have the risk of a leak, but on the other hand makes maintenance difficult to perform outside the stern of the boat. Publication U.S. Pat. No. 5,522,742 A discloses a boat, in which the water-jet propulsion unit is installed in such a way that the maintenance opening is situated inside the stern. 
     Due to the various ways of installing water-jet propulsion units, each form of installation requires a separate structure, either in the frame of the water-jet propulsion unit or in the boat. This, in turn, demands two separate models, depending on the manner of installation, from the manufacturers of the water-jet propulsion units or of boats or of both, which leads to increasing design costs. 
     SUMMARY OF THE INVENTION 
     The intention of the frame according to the invention for a water-jet propulsion unit is to create a frame, with the aid of which the same water-jet propulsion unit can be used in both forms of installation. The intention of the water-jet propulsion unit according to the invention is to create a water-jet propulsion unit, which same water-jet propulsion unit can be used in both forms of installation. Further, the intention of the arrangement according to the invention is to create an arrangement in a boat, in which the maintenance opening of the water-jet propulsion unit can be situated according to the wishes of the customer, either inside or outside relative to the stern of the boat. 
     The intention of the frame of the water-jet propulsion unit according to the invention can be achieved by means of a water-jet propulsion unit frame, which is arranged to be installed and sealed into a water-jet propulsion unit installation opening belonging to a boat. The frame includes a flow channel for guiding water to the impeller belonging to the water-jet propulsion unit, a maintenance opening situated on top of the flow channel for servicing the impeller, and a sealing surface forming a closed loop, for attaching the water-jet propulsion unit tightly to the counter sealing surface belonging to the boat. The frame includes, in addition, an additional sealing surface, for forming a second closed loop, which is arranged to be used in attaching the water-jet propulsion unit to the boat in such a way that the maintenance opening of the frame is situated alternatively either inside or outside the stern belonging to the boat. The alternative methods of installation can then be implemented using the same water-jet propulsion unit frame. 
     Preferably, the sealing surface includes two parts, that is, a first part and a second part, of which the second part is used alternatively relative to the additional sealing surface. This permits the frame to be sealed alternatively according to its use. 
     The first part can be used as an addition to the additional sealing surface in attaching the water-jet propulsion unit to the boat, in such a way that the maintenance opening is situated outside the stern belonging to the boat. This permits the frame to be sealed alternatively according to its use. 
     The second part of the sealing surface is used as an addition to the first part of the sealing surface when attaching the water-jet propulsion unit to the boat, in such a way that the maintenance opening of the frame is situated inside the stern belonging to the boat. With the aid of optional components, the alternative installation methods can be performed without changes to the frame of the water-jet propulsion unit. 
     Preferably, the closed loop formed by the additional sealing surface and the first part of the sealing surface is at least for part of the distance essentially the same as the closed loop formed by the first part and the second part of the sealing surface. In this case, the term essentially refers to the fact that the loops can be parallel to each other or completely the same. The loops branch when they are completely convergent for part of the distance. 
     According to one embodiment, the sealing surface is arranged to extend in a continuous form past the maintenance opening, as far as the exit opening belonging to the flow channel. The continuous sealing surface permits easier installation of the water-jet propulsion unit, depending on the dimensions of the boat. 
     The sealing surface can be at an angle relative to the axis, which is 10-60°, preferably 20-50°. The sealing surface can then be formed firmly on top of the flow channel. 
     The additional sealing surface can be at a distance from the sealing surface, which distance is 40-60 percent, preferably 45-55 percent of the length of the additional sealing surface. The engine of the water-jet propulsion unit will then be set at the correct height, when the installation of the water-jet propulsion unit is made in such a way that the maintenance opening remains outside the stern of the boat. 
     The intention of the water-jet propulsion unit according to the invention can be achieved by means of a water-jet propulsion unit, which includes a water-jet propulsion unit frame according to the invention. 
     The intention of the arrangement according to the invention can be achieved by means of an arrangement in a boat, in which the boat includes a hull and an installation opening for the water-jet propulsion unit belonging to the arrangement. The water-jet propulsion unit includes a frame, which includes a flow channel for guiding water to the impeller belonging to the water-jet propulsion unit, a maintenance opening situated on top of the flow channel for servicing the impeller, and a sealing surface forming a closed loop for attaching the water-jet propulsion unit tightly to the counter sealing surface of the boat. The frame includes in addition an additional sealing surface for forming a second closed loop arranged to be used to attach the water-jet propulsion unit to the boat, in such a way that the maintenance opening of the frame is situated alternatively inside or outside the stern belonging to the boat. In such an arrangement, the location of the maintenance opening of the water-jet propulsion unit in the boat can be chosen according to the wishes of the customer. 
     Preferably, the boat further includes alternative installation pieces for sealing the installation opening of the boat. Thus, by only changing the installation pieces, the same frame can be attached to the boat according to the wishes of the customer. 
     Preferably, the boat&#39;s counter sealing surface is formed into a separate installation piece. Thus, the boat&#39;s installation opening can be effectively sealed, with no change to the frame of the water-jet propulsion unit. 
     Preferably, the boat includes a planar counter sealing surface, which facilitates sealing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following, the invention is described in detail with reference to the accompanying drawings depicting some embodiments of the invention, in which 
         FIG. 1 a    shows a side view of a first embodiment of the arrangement according to the invention, in which the maintenance opening is inside the stern of the boat, 
         FIG. 1 b    shows an enlargement of  FIG. 1   a,    
         FIG. 1 c    shows a rear view of the embodiment according to  FIG. 1   a,    
         FIG. 1 d    shows a top view of the embodiment according to  FIG. 1   a,    
         FIG. 1 e    shows an axonometric top view of the boat&#39;s installation opening, when an embodiment according to  FIG. 1 a    of the arrangement according to the invention is used, 
         FIG. 1 f    shows an axonometric bottom view of the boat&#39;s installation opening, when an embodiment according to  FIG. 1 a    of the arrangement according to the invention is used, 
         FIG. 2 a    shows a side view of one second embodiment of the arrangement according to the invention, in which the maintenance opening is outside the stern of the boat, 
         FIG. 2 b    shows an enlargement of  FIG. 2   a,    
         FIG. 2 c    shows a rear view of the embodiment according to  FIG. 2   a,    
         FIG. 2 d    shows a top view of the embodiment according to  FIG. 2   a,    
         FIG. 2 e    shows an axonometric top view of the boat&#39;s installation opening, when a second embodiment of the arrangement according to the invention is used, 
         FIG. 2 f    shows an axonometric bottom view of the boat&#39;s installation opening, when a second embodiment of the arrangement according to the invention is used, and 
         FIG. 3  shows an axonometric view of the frame of the water-jet propulsion unit. 
     
    
    
     DETAILED DESCRIPTION 
     The frame of the water-jet propulsion unit, the water-jet propulsion unit, and the arrangement in a boat, according to  FIGS. 1 a -2 f   , relate to boats and to water-jet propulsion units attached to them. Hereinafter, the water-jet propulsion unit will be referred to by the term water jet. The arrangement  10  includes a boat  12  and a water jet  16 . The boat  12  includes a hull  11  and is equipped with an installation opening  14  for a water jet  16 , which is formed in the stern  44  and bottom  46  of the boat  12 . The water jet  16  is sealed to the stern  44  and bottom  46  of the boat  12  with the aid of an installation piece  42 , so that the boat  12  is once again watertight. The engine (not in the figures) driving the water jet is situated inside the boat, from where it is connected directly, with the aid of a shaft  20  and its coupling flange  70 , to the water jet  16 . 
     The water jet  16  consists of a frame  15 , with the aid of which the water jet  16  is attached to the boat  12 , and a nozzle part  48 , by which the water jet of the water jet  16  is controlled and aimed. For control, the water jet  16  can include a hydraulic pump, which drives the control shaft  74  rotating the nozzle part  48 . The frame  15  of the water jet  16  for its part includes a flow channel  26 , a shaft support  22  and maintenance opening  28  on top of the flow channel  26 , an impeller  24  (in  FIG. 1 b   ), a stator  25 , and an annular sealing surface  33  forming a closed loop. In addition, the frame  15  includes an additional sealing surface  34 , which form a second closed loop. The additional sealing surface  34  is preferably formed in the shaft support  22 . The sealing surface  33  includes two parts, a first part  30  and a second part  36 . The sealing surface  33  is at an angle of 10-60°, preferably 20-50°, relative to the shaft  20 . The additional sealing surface  34  is preferably at right angles to the shaft  20 . The sealing surface  33  and the additional sealing surface  34  are equipped with attachment holes (see  FIG. 3 ), through which the frame  15  is attached to the counter sealing surface  32  in the boat  12 , for example with the aid of bolts, screws, or similar attachment elements. 
     According to  FIGS. 1 a , 1 b , 2 a , 2 b   , and  3 , the flow channel  26  is intended for taking water from the bottom of the boat and turning the flow in the longitudinal direction of the boat. For this purpose part of the flow channel  26  forms a slanting plane with the horizontal. The sealing surface  33  is formed on top of the flow channel  26 . The sealing surface  33  of the frame  15  of the water jet  16  lies essentially in the direction of the evenly rising main part of the flow channel  26 . The term the main part of the flow channel  26  refers to that part of the flow channel, which begins from as close as possible to the bow of the boat and continues at the same angle up to the part of the flow channel that curves to the horizontal. The second part  36  of the sealing surface is practically a continuation of the first part  30 , as clearly shown in  FIG. 3 . 
     The flow channel  26  has an intake opening  45 , from which it takes water in, and an exit opening  47 , from which the water flow, accelerated with the aid of the impeller  24 , exits from the flow channel  26 . The impeller  24  is located in front of the exit opening  47 . The impeller  24  is attached to the engine shaft  20 , which in turn is taken, with the aid of a feed-through  38 , through the wall of the flow channel  26 . To make the shaft  20  sturdy, it is also supported by a vertical, plate-like shaft support  22 , which is situated on top of the flow channel  26 . The shaft  20  passes through the shaft support  22  and travels through the feed-through  38 . The part of the shaft  20  remaining under the maintenance opening  28  is bounded by the boat&#39;s longitudinal walls, the flow channel  26 , and the shaft support  22 . There is direct access for servicing through the maintenance opening  28  to the shaft  20  and the impeller  24  attached to it. 
     According to  FIGS. 1 d  and 2 d   , the bottom  46  of the boat  12  includes a bottom plate  52 , to which the flow channel  26  of the water jet  16  is attached. The bottom plate  52  forms part of the bottom  46  of the boat  12  at the installation opening  14  of the boat  12 . For installation, an installation opening corresponding to the chosen installation method should be made in the boat. Depending on the installation method, the maintenance opening is located in the installation either inside or outside the boat relative to the stern. In solutions according to the prior art, a special installation piece is used, with the aid of which the water jet is attached to the boat. In the arrangement according to the invention, an installation piece is also used, but the frame of the water jet is the same, irrespective of the installation method. The installation piece is intended to act as a counter sealing surface to the sealing surfaces of the frame of the water jet. In other words, the loop of the counter sealing surface of the boat is formed in the installation piece  42 . According to  FIGS. 1 e  and 2 e   , a vertical flange  54  can be made around the installation opening  14  of the boat  12 , in which possible leakage water collects. 
     The sealing surface  33 , the additional sealing surface  34 , and the counter sealing surface  32  are preferably surfaces forming a loop, which can have a width of 3-15 cm, preferably 5-10 cm. At least the coupling flange  70  of the shaft  20 , the cooler  78 , and the operating cylinder  76  of the reversing scoop remain within these loops. If the frame  15  of the water jet  16  is installed in such a way that the maintenance opening  28  remains inside the boat  12  relative to the stern  44  of the boat  12 , then the maintenance opening  28  also remains inside the loops of the sealing surface  33  and the counter sealing surface  32 . Preferably, the surfaces used for sealing are smooth and treated for sealing. 
       FIGS. 1 a -1 f    show an arrangement  10  according to a first embodiment of the arrangement according to the invention, in which the water jet  16  is installed in the boat  12  in such a way that the maintenance opening  28  remains inside the boat  12  relative to the stern  44  of the boat  12 . In this embodiment, the frame  15  of the water jet  16  is attached and sealed to the boat  12  onto the counter sealing surface  32  of the boat  12 , with the aid of the sealing surface  33 . Because the second part  36  of the sealing surface  33  extends to the rear of the maintenance opening  28  on top of the flow channel  26 , both the first part  30  and the second part  36  of the sealing surface  33  can be used for the attachment. In this embodiment, the additional sealing surface  34  remains inside the stern  44  of the boat  12 . With the aid of the use of the sealing surface  33 , the frame  15  of the water jet  16  can be attached to the counter sealing surface  32  of the boat  12  for the whole length of the flow channel  26 . This makes the attachment of the water jet  16  to the boat  12  sufficiently strong. 
       FIGS. 2 a -2 f    shown an arrangement  10  according to a second embodiment of the arrangement according to the invention, in which the water jet  16  is installed in the boat  12  in such a way that the maintenance opening  28  remains outside the boat  12  relative to the stern  44  of the boat  12 . In this embodiment, the frame  15  of the water jet  16  is attached and sealed to the boat  12 , onto the counter sealing surface  32  of the boat  12 , with the aid of the additional sealing surface  34  and the first part  30  of the sealing surface  33 . Because the maintenance opening  28  is on top of the flow channel  26 , only the first part  30  of the sealing surface  33  extending to the shaft support  22  can be used for the attachment, the second part  36  not being available for attachment. In this embodiment, the second part  36  of the sealing surface  33  remains outside the boat  12  relative to the stern  44  of the boat  12 . The additional sealing surface  34  is attached to the counter sealing surface  32  of the installation piece  42 , parallel to the stern  44  of the boat  12 . Thus in its entirety, the surface area available for sealing is nearly as large as in the embodiment according to FIGS.  1   a - 1   f.    
     In the embodiments of  FIGS. 1 a -2 f   , the sealing surface  33  can be formed as a plate attached to the frame  15  of the water jet  16  on top of the flow channel  26 . The plate is preferably of a corresponding width to the counter sealing surfaces  32  fitted to the installation opening  14  of the boat  12 . Further, the plate is preferably parallel to the counter sealing surfaces, so that the attachment is made tight. The sealing surface is situated on top of the flow channel, so that it can be a unified plate structure, which ensures a strong construction. Special sealing adhesives, for example silicon or similar, can be used as an aid in the sealing. 
     According to  FIGS. 1 e  and 2 e   , the counter sealing surface  32  is a planar component forming a loop, which includes installation holes for the attachment of the frame of the jet. The sealing surface and the additional sealing surface are also corresponding loops. When the water jet is installed in such a way that the maintenance opening is placed inside relative to the stern of the boat, the corresponding loop of the loop of the counter sealing surface is formed by the first part and the second part of the sealing surface. On the other hand, when the jet is installed in such a way that the maintenance opening is placed outside relative to the stern of the boat, the loop corresponding to the loop of the counter sealing surface is formed by the first part of the sealing surface and the additional sealing surface. The loops of both installation methods can be partly in common, but they can also be loops entirely separate from each other. In addition to the first part of the sealing surface, the loop of the counter sealing surface is formed either from the additional sealing surface or from the second part of the sealing surface. In other words, the loop branches after the first part of the sealing surface to either the additional sealing surface or the second part of the sealing surface. 
     The frame  15  of the water jet according to the invention can be used in installations, in which the maintenance opening is alternatively inside or outside the stern of the boat. The alternative additional sealing surfaces ensure in both installation methods a sufficient sealing and attachment surface area for achieving qualitatively excellent sealing and attachment. By means of the arrangement according to the invention, the need to manufacture several different frames for a water jet can also be avoided, as now a single frame can be used in different installation methods. Only the installation piece acting as a counter sealing surface in the boats or part of the mould of the frame should be a component designed especially for each installation method. Alternative detachable parts can be designed for the hull of a reinforced plastic boat, by means of which a frame suitable for different installation methods can be obtained from the same basic mould. 
     The frame of the water jet according to the invention can be made by casting from aluminium, or some other corresponding material, which is sufficiently resistant in strength and corrosion resistant. 
     In the arrangement according to the invention according to  FIG. 3 , the sealing of the water-jet propulsion unit can be formed in two alternative ways with the aid of two closed loops, in such a way that the closed loop is formed either by the first part  30  and the second part  36  of the sealing surface  33 , or alternatively by the first part  30  of the sealing surface  33  and the additional sealing surface  34 . It should be noted that  FIG. 3  shows the structure of the water-jet propulsion unit in greater detail than in  FIGS. 1 a -2 f   , in which a simplified construction is shown. 
     In this connection, the term boat refers widely to watercraft, to which the water-jet propulsion device is suited.