FIELD OF THE INVENTION

The present invention relates to a pump, inter alia for use in a stabilizer system for a ship, in particular to a ship's anti heeling pump, a ship's anti heeling pump and pump drive combination, and a ship's anti heeling pump housing. BACKGROUND OF THE INVENTION

When a ship during loading or unloading tilts to port or starboard and does not return back to its upright position it is known as heeling of the vessel. One reason of a ship's heeling is an uneven cargo load distribution during the cargo loading and unloading.

An anti-heeling system of a ship is configured to automatically detect the heeling angle of the ship and to compensate therefore. This allows the vessel to have a continuous loading and unloading cargo operation without paying too much attention to the cargo's load distribution on the ship which saves a considerable amount of time during a call to port. In addition, the anti-heeling system allows safer and rapid cargo loading and unloading, reduces damage to ramp, rolling cargo and containers and ensures safety of the ship and personnel. In a water-pump anti-heeling system the ship's ballast tanks are internally connected to each other by means of pipes near the ship's keel, and by a pump system with an anti-heeling pump, automatic valves and control systems. When the ship heels to any of the sides, a heeling sensor sends a signal for a change of the ship's angle to a controller. Transferring of ballast tank water from the heeled side to the other side of the ship makes the vessel upright. The pump system typically comprises an electrical motor driven water pump, which is normally reversible to direct ballast water flow between tanks on either side of the ship.

It is a problem that the prior art anti-heeling pump systems are often difficult to service not only because of space constraints in the ship's engine room but also because of the design of the pumps. For some operations the prior art pump systems have shown not to be simple to maintain in operation, by not allowing a quick and simple access to internal components requiring regular service or replacement. Also, the running speed of the pump cannot be easily varied, limiting the versatility of the pumps.

German patent application no.10 2010 056 393 discloses a pump operated by a belt extending in a secondary transverse passage. One problem with this pump is that it is suitable for relatively low-pressure operation only, being adapted for carrying a single propeller only and for a flow of liquid in a primary direction only. The flow passage has a reduced area at the inner housing with the pump axle, the pump outer housing having the same contour, giving rise to a high pressure drop. The secondary transverse passage is configured to allow for the belt to be pulled off the end of the axle and the axle does not extending past the secondary passage but has an axle end located within the secondary passage such that the belt engages the axle close to the axle end, potentially giving rise to higher transverse loads on one set of bearings than on the other set of bearings.

OBJECT OF THE INVENTION

To solve the above problems, an object of the present invention is to provide an improved pump system which may allow for easy service, has few components requiring service, and which also takes up less space, such as a lesser part of the normally very constrained engine room space near the ship's keel.

This is achieved by providing a pump as defined in claim 1 which is operable together with a closed loop driving belt extending between the inside and the outside of the pump, a pump and pump drive combination as defined in claim 19 and including a driving belt engaging a drive transmission structure inside the pump and a motor output shaft located next to the pump, as well as a pump housing as defined in claim 24 which allows for easy access and replacement of internal components.

The pump according to the invention provides for a transmission of a driving motor shaft rotation by the driving belt engaging a drive transmission structure, such as one releasably mounted coaxially around the pump axle. Replacing such an annular drive transmission structure with one of another diameter allows for a control of the speed of rotation of the pump axle using the same driving motor rotation speed. The driving belt runs in a secondary passage extending generally transverse to the flow passage of the pump between the ends of the pump axle, and has a width in the direction generally parallel with the flow passage which preferably corresponds essentially to the width of the second passage in that direction. Preferably both ends of the pump axle extend into the flow passage, allowing them to be fitted with a respective propeller whenever a particular high pressure is required, such as is sometimes the case for anti-heeling systems. In such a case the pump will normally include dynamic axle seals near each of the axle ends, and the second/secondary passage will then be located between the dynamic axle seals. The second/secondary passage width is preferably chosen to allow for

accommodation of the driving belt with some play; by way of example, when the pump is designed to operate with a driving belt having a 90 mm width the width of the secondary passage will typically be in the order of 110 mm - 130 mm, or exceeding only slightly the width of the belt. Preferably the secondary passage extends between two peripherally spaced apart openings in an outer housing of the pump, such as at different locations in a cross-sectional plane, along the circumference of the outer housing. Preferably, the outer housing and an inner housing may be integrally formed. By the pump outer housing having a generally enlarged dimension, eg. a bulbous shape, between the ends of the pump, the pump housing preferably having circular cross-sections, the pump water flow passage may have the same or essentially the same total cross-sectional area compared to that of the piping connected to the pump, thereby providing a limited flow resistance. The pump may be configured with an essentially symmetrical geometry about a central plane transverse to the pump axle, providing similar hydraulic properties irrespectively of the direction of flow through the pump.

Replacing a belt may be done by cutting it, then inserting a strip of belt material into the secondary passage, and then splicing the ends of the belt material to form a closed loop belt. In one embodiment of the invention the pump housing is in two parts with the secondary passage opening up in the axial direction of the pump upon the two parts being separated, allowing replacement of the driving belt and of the axle bearings.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be described in more detail with regard to the

accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible

embodiments falling within the scope of the attached claim set.

Fig. la is schematic view of a ship during unloading,

Fig. lb is a perspective view of a pump and motor combination according to the invention,

Fig. 2 is a cross-sectional view of the combination of fig. lb,

Fig. 3 is a longitudinal sectional view of the pump of fig. 2, taken along line B-B of fig. 2,

Fig. 4 is a longitudinal sectional view of the pump of fig. 2, taken along line C-C of fig. 2,

Fig. 5 is a perspective view showing only the axle and drive transmission structure of the pump of fig. lb,

Fig. 6 is a perspective view of one part of the pump, and

Fig. 7 is a longitudinal view of an alternative embodiment of the pump of fig. 2.

DETAILED DESCRIPTION OF AN EMBODIMENT

Fig. la shows a ship S in the process of being unloaded at a port. The drawing shows how the ship S may tilt towards one side during a non-symmetrical unloading, and for which reason the ship is conventionally equipped with an anti- heeling stabilizer mechanism that seeks to maintain a perfectly upright position of the ship. The stabilizer mechanism conventionally includes a motor driven pump P connected to opposite ballast water tanks Tl and T2 by pipes 8. As the ship S tilts to one side the stabilizer mechanism activates the pump P to deliver water from one tank Tl to the other tank T2, or vice versa. The motor, pump P and the pipes 8 are located close to the keel and should take up as little space as possible. Often several such stabilizer mechanisms are arranged along the ship's length.

Shown in fig. lb is a cast metal pump and motor combination as discussed above and in accordance with the present invention. The pump may be moulded of any other material. This combination includes a drive belt 15 driven by an output shaft 12 of the motor M and connected with the pump 20. Opposite flanges 26, 26' serve to connect the pump 20 to a respective pipe 8. As will be discussed further below the belt 15 engages a drive transmission structure within the pump 20, the belt 15 and drive transmission structure providing upon rotation of the output shaft 12 a rotation of an impeller 105 connected to the end of a pump axle mounted in the pump housing H and having opposite ends A, B, respectively. When mounted in position in the ship's S hull the output shaft 12 extends essentially parallel with the pump axle. A suitable frame (not shown) may be configured to carry the pump 20 and the motor M and to be mounted to the ship's hull; the motor M may be mounted on the frame F to allow for the distance between the motor M and the pump 20 to be varied, such as for changing the driving belt tension. Where the pump is used as part of a ship's anti-heeling system the

aforementioned rotation of the impeller 105 sets up a flow of ballast water along a flow passage 22 that extends inside the pump 20 between the opposite ends 24, 25 of the pump 20, between the tanks Tl and T2. A second passage 80 separate from the flow passage 22 extends generally transversally to the pump axle and receives the driving belt 15. The second passage 80 preferably has a width in the direction between the opposite ends 24, 25 of at least 40 mm, in any event corresponding to the width of the driving belt 15 required for operation of the pump. The driving belt 15 may be a rubber belt such as a belt made of reinforced synthetic rubber.

Fig. 2 is a cross-sectional view of the pump and motor combination of fig. lb, showing the driving belt 15 extending around the drive transmission structure 90 inside the pump 20. With a bulbous design of the outer pump housing H the cross-sectional area of the flow passage 22 throughout the length of the pump 20 may be the same as that of the pipes 8 at the opposite flanges 26, 26'. As seen best in figs. 2-4 the pump 20 comprises an inner housing 60 inside an outer housing 30, and the flow passage 22 extends between the outer housing 30 and the inner housing 60, between the opposite ends 24, 25 of the pump 20. In the inner housing 60 a through-going passage 29 extends in the direction between the opposite ends 24, 25 and is configured for receiving a portion of the impeller axle 100 as well as the drive transmission structure 90 which is connected with or integral with the axle 100. The view of fig. 2 is as shown by line A-A in fig. 4.

The outer housing 30 defines together with the inner housing 60 the

aforementioned second passage 80 which communicates with the outside of the outer housing 30 and extends around the drive transmission structure 90. As seen best in figs. 2 and 6 the second passage 80 is defined in part by the through- going passage 29 and so extends around the drive transmission structure 90 opposite two peripherally spaced apart openings 82, 84 in the outer housing 30, each opening 82, 84 defining a respective end of the second passage 80. Shown also in fig. 2 is a plurality of radially directed walls 23 that connect the inner housing 60 with the outer housing 30; the walls 23 are preferably integral with the inner housing 60 and the outer housing 30 and split up the flow passage 22 into longitudinal segments 22' as shown in fig. 2, the sum of the cross-sectional areas of the respective segments 22' defining the total cross-sectional area of the flow passage 22. As the skilled person will readily understand the dimension of the second passage 80 between the opposite walls 23 that define the second passage 80, as shown by way of example in fig. 2, is such as to accommodate, with some play, for a driving belt 15 having a suitable thickness, and also where appropriate to allow for the use of a smaller diameter annular transmission drive structure 90 where the spacing between opposite lower parts of the belt 15 shown in fig. 2 would be smaller.

Shown also in figs. 2 and 5 is a toothing 92 of the annular drive transmission structure 90 engaging a toothing 16 of the driving belt 15 that is received in the second passage 80. Fig. 5 is a view showing only the axle 100 and an exemplary form of the drive transmission structure 90 also shown in fig. 2 wherein the drive transmission ring is coaxially and releasably mounted to the axle 100, such as by a taper lock. The selected diameter of the ring allows for a selection of a given speed of rotation of the pump axle 100 in accordance with the speed of rotation of 5 the motor output shaft 12. The belt 15 may alternatively engage the axle 100 directly, and may alternatively be configured for frictional engagement with a V- shaped notch of the drive transmission structure 90. The driving belt may by way of example alternatively be a V-belt working with the aforementioned V-shaped notch, and several individual belts may be used next to each other where this is 10 deemed appropriate.

It is preferred when as seen best in figs. 3 and 4 the outer housing 30 comprises two parts, namely a first outer housing part 36 in extension of a second outer housing part 42 in the direction of the axle 100. The two outer housing parts 36,

15 42 are releasably connected to each other by opposite flanges 40, 70 to form a seal along a peripheral region 21 around the flow passage 22. In addition, the first outer housing part 36 is integrally connected with a first inner housing part 66 and the second outer housing part 42 is integrally connected with a second inner housing part 72, arranged in extension of the first inner housing part 66 in the

20 direction of the axle 100. The two inner housing parts are releasably sealed

against each other along a peripheral region 61 around the axle 100, this seal being established as the two outer housing parts 36, 42 are connected to each other. As shown in fig. 6 the second passage 80 may extend only in the second inner housing part 72, being open towards the first inner housing part 66. This

25 allows for an easy replacement of the driving belt 15 when worn down in that the pump 20 is first disconnected from the pipes 8 and one impeller 105 removed from the axle 100, following which the two outer housing parts 36, 42 with respective inner housing parts are separated from each other, allowing the belt 15 to be pulled laterally out of the passage 80 and to be replaced.

30

It is noted that, as shown in fig. 3 the pump axle 100 may carry an impeller 105 at each end, and the impeller is such that rotation of the axle 100 in the opposite direction by opposite rotation of the output shaft 12 will bring about an opposite liquid flow through the pump 20. Upon mounting the impellers 105 a dynamic axle 35 seal 170 is compressed. Bearings 160 are configured to support the axle 100 laterally, taking into account lateral forces applied on the axle 100 by the belt 15. In addition, as shown in fig. 4 various cross-bores may be provided for circulating cooling water flowing through the pump 20. An indicator cross-bore 162 may be provided downstream of a chamber 161 in front of a packing. Water from the chamber 161 exiting the bore 162 is an indication that the packing is worn down and that the packing should be replaced by dissembling the pump 20 as described above.

Fig. 7 shows an variation wherein the pump carries an impeller 105 at one axle end B only, the inner housing 60 having a closure portion 200 opposite that one end B to seal the inside of the inner housing 60 in relation to the flow passage 22 opposite the end B. This embodiment is useful where low-pressure operations only are anticipated; the same basic elements as described above may be used in combination with a shortened length axle 60.

Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. The invention is not specific to the use of the pump for anti-heeling purposes, but for any purpose where a pump as shown in the drawing figs, lb-7 is useful. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.