Technical Field

The present invention relates to a vibration compensato apparatus comprising a housing, where two shafts ar joilrnaled, each shaft having an excentric mass provide by rotary bodies, said shafts be ^" ing arranged to rotat around two mutually parallel axes of rotation and bein interconnected in order to rotate with the same number o revolutions but in opposite directions in order to generat a resulting force component equal to zero in one directio as well as a second resulting force component harmoni between zero and twice the force of the individual ex- centric mass in a direction perpendicular to the firs one .

Background Art

A. known vibration compensator apparatus of the type men¬ tioned above compensates vertical, unbalanced moments of the second order in large ships with four, five and six cylinder engines. In this known vibration compensator apparatus the rotary bodies rotate in opposite directions such that the direction of the resulting, harmonic force component is ^" perpendicular to the common plane of the axes of rotation. The axes of rotation are mounted at such a distance that the rotary bodies are able to simul¬ taneously pass the area between the axes of rotation with- out impeding each other. Such a vibration compensator apparatus requires a large amount of space. Moreover it is very difficult or even impossible to instal it when it is desired to balance vibrations in the hull caused by a varying shaft pressure from the propeller or by varying side pressure from of the crosshead of the engine.

Disclosure of the Invention

The object of the invention is to provide a vibration compensator apparatus of the type mentioned in the intro¬ duction for balancing hull vibrations, said apparatus being su ficiently compact to enable its installation in existing machines as well as in new ones.

According to the invention the vibration compensator appa¬ ratus is characterized in that the shafts are interconnec¬ ted in such a way that the forces generated by the two excentric masses always point in a direction away from each other when the resulting, harmonicg force component is zero, and that the distance between the shafts is less than the diameter of the area defined by the rotation of the shafts and their rotary bodies. As a result the vibra- tion compensator apparatus is more compact than known ones . This is especially due to the fact that the rotary bodies do not have to pass the area between the axes of rotation simultaneously in opposite directions.

According to the invention the shafts are interconnected In such a way that the direction of the resulting, harmonic force component is parallel to the common plane of the axes of rotation. This is an especially suitable embodiment of the present invention, as the inner moment in the vibration compensator apparatus is reduced.

In another embodiment the distance between the shafts is less than the radius of the area defined by the rotation of the shafts and their rotary bodies and each shaft is a cranked shaft journaled in opposite walls of the housing, each cranked shaft being provided with one or more bends and being shaped in such- a way as to enable it to move passed the inner side of corresponding bends in the other cranked shaft. This embodiment results in an especially compact vibration compensator apparatus, reducing the inner moment even further.

In a further embodiment the cranked shafts are identical and each shaft comprises two journals, each mounted i opposite walls of the housing and permanently connecte with rotary arms, said rotary arms being interconnecte by means of rotary bodies arranged symmetrically aroun the plane of the cranked shafts and being of such an outer shape that they are able to pass each other at a close distance. This is an especially simple and preferred em¬ bodiment of the invention.

In yet another embodiment the rotary bodies providing the excentric masses have one or more inner cavities for the optional accomodation of further rotary mass. Consequently it is possible to adapt the resulting force component to the varying vibrations to be balanced.

In a preferred embodiment of the invention the rotary bodies each comprise two tubes symmetrically arranged around the plane of the cranked shafts and being of cir- cular cross -section, said tubes being interconnected by means of two curved panels forming a convex, cylindrical body, each end of said cylindrical body being closed by means of an end plate, and the space between the tubes is filled with a material of high density, such as lead, and one of the end plates has openings corresponding to the inner clear of the tubes, each opening ^• being closed by means of a removable cover such that the tubes are able to be filled with further rotary masses for achieving the desired resulting force component, the rotary masses being for example weights of different density and with a cross- section corresponding to the inner clear of the tubes, and the wall opposite the cover is provided with an aper¬ ture for removing and replacing the cover and the weights, the center of said aperture being in one of the inter- sections between two cylinder surfaces defined by the tube axes of the rotary bodies during rotation.

Brief Description of the Drawings

The invention is described in greater detail below and with reference to the accompanying drawings , in which

Fig. 1 is a schematic, lateral view of the preferred embodiment of the inventive vibration compensator apparatus ,

Fi , 2 is a sectional view along the line II-II of Fig. 1,

Fig. 3 is a graph of the forces as well as the force com¬ ponents generated by the vibration compensator apparatus during operation,

Fig. 4 is a detailed and partially sectional end view of the preferred embodiment of the inventive vibration compensator apparatus, and

Fig. 5 is a sectional view along the line V-V of Fig. 4.

Best Mode for Carrying out the Invention

Figs. 1 and 2 are schematic views of a preferred embodiment of the inventive vibration compensator apparatus comprising a housing 1, where two cranked shafts 4, 4' with one bend each are journaled in opposite walls 2, 3 of the housing. The distance a. between the axes of rotation 5, 5' of the oranked shafts 4, 4' is less than the radius of the area defined by the rotation of the cranked shafts 4, 4' .

The cranked shafts 4, 4' are of such a shape that each one is able to pass the inner side of the other cranked shaft during rotation, cf. Fig. 2. The shafts are interconnected by means of gears 6, 6' to counterrotate at the same rpm

and with such a phase as to generate a harmonic force com ponent in a direction parallel to the common plane of th axes of rotation 5, 5' , said force component varying be tween zero and twice the force of the individual shaft 4, 4' , and a second force component being constantly zer and perpendicular to the common plane of the axes of ro tation 5, 5' . This is graphically illustrated in Fig. 3 where the force F generated by the two cranked shaft 4, 4 is resolved into component F^ in the ^" common plane of th axes of rotation and component F _t perpendicular to sai plane .

The vibration compensator apparatus is preferably drive by means of a hydraulic motor 7 coupled to one of th cranked shafts 4, said motor having a speed correspondin to the frequency of the vibrations to be balanced by th vibration compensator apparatus, i.e. a frequency corres ponds to the current speed of the motor times the numbe of cylinders, when the varying shaft pressure of a ship' propeller, the varying side pressure of the crosshead o the engine or the vertical, unbalanced moments of secon order of the engine are to be balanced. The vibratio compensator apparatus is mounted in a strategic positio for balancing the current vibrations. In case of balancin vibrations generated by the varying shaft pressure of th propeller the best position is in the area behind the fly¬ wheel of the diesel engine. In case of balancing vibration generated by the varying side pressure of the crosshead o the engine the best position is on the top and/or botto of the diesel engine. In case of balancing vibrations generated by the vertical, unbalanced moments of the engine the best position is in the control machine room of the ship .

The preferred embodiment of the vibration compensator apparatus is described in greater detail below and with reference to Figs. 4 and 5. It comprises, as described

with reference to Figs. 1 and 2, a housing 11, where two cranked shafts 14, 14' are j ournaled in opposite walls 12, 13 of the housing rotatably around parallel axes of rota¬ tion 15, 15' . The shafts 14, 14' are driven by means of a hydraulic motor 17. Two gears 16, 16 ' cause the shafts 14, 14' to rotate in opposite directions.

Each cranked shaft includes two shaft journals 18, 19, 18' , 19' rotatably journaled in opposite walls 12, 13 by means of roller bearings. Each shaft journal is permanently connected to a rotary arm 20, 21, 20' , 21'. The rotary arms 20, 21, 20' , 21' are interconnected by means of rotary bodies 22, 22' symmetrically arranged around the plane of the cranked shafts 14, 14' . Each rotary body comprises two tubes 23, 24, 23 ' , 24' symmetrically arranged around the plane of the cranked shafts and being of circular cross- section. In Figs. 4 and 5 only 23 and 23' are fully visible. The tubes are interconnected by means of two curved panels 25, 26, 25' , 26', forming a convex, cylin- drical body. The cylindrical body is closed at each end by means of an end plate 27, 28, 27' , 28' . The space be¬ tween the circular tubes 23 and 24, 23' and 24' and the curved panels 25, 26, 25' 26' is filled with a material of large density, such as lead. One end plate 27, 27' of each rotary body 22 _r 22' has two openings 29, 30, 29' , 30' corresponding to the inner clear of the tube. In Figs. 4 and 5 only 29 and 29' are visible. Each opening 29, 30, 29 ' , 30' is closed by means of a removable cover 31 also having a diameter corresponding to the inner clear of the circular tubes 23, 24, 23', 24' . The cover is furthermore provided with two throughholes 32, 33.

In the area inside the tubes each of the other end plates 28, 28' is provided with two axially extending stay bolts 34, 35 mutually spaced corresponding to the distance be¬ tween the two throughholes 32, 33, In the cover 31.

The inside of each tube 23, 24, 23' , 24' is completel filled with weights 36 with throughbores corresponding t the stay bolts. The weights are retained by the cover 3 by means of the latter being fastened by screwing nuts o 5 the stay bolts 34, 35. Due to filling the inside of eac tube 23, 24, 23' , 24' with weights 36 manufactured o materials with different density the overall mass of eac rotary body 22, 22' and thus the resulting force componen can be varied in order to achieve the desired value. Ad- 10 vantageously the weights are manufactured of a materia of high density, such as lead, as well as a material o low density, such a wood. Consequently the resulting force component is variable within a rather large area.

15 The rotary bodies 22, 22' are of such a shape, cf. the sectional part of Fig. 4, that they pass each other at a narrow distance and on each other's inner side whe crossing the plane of the axes of rotation in opposite directions in order to render the vibration compensator

20 apparatus as compact as possible.

The opposing walls 12, 13 are interconnected by means of a housing wall 37 having a cross- section corresponding to the area defined by the rotation of the rotary bodies 22,

2522' , cf. Fig. 4. One wall 12 is provided with an aperture 38, the center of which is on one of the intersections between the two cylinder surfaces 39, 39' defined by the tube axes of the rotary bodies 22, 22' during rotation. The aperture 38 is of a slightly larger diameter than the

30removable cover 31 and is used for removing and replacing the weights 36 in the tubes 23, 24, 23' , 24' . The outside of the wall 12 is connected with the housing wall 37 by means of screws 40. Furthermore a transmission housing 41 is welded onto the outside of the wall 12, the gears 16,

3516' mounted on the ends of the shaft journals 18, 18' meshing inside said housing. The transmission housing 41 is closed by means of a top 42 provided with an opening

43. Through said opening 43 the shaft journal 18 Is connected with the hydraulic motor 17 via a planet gear 44 fastened to the top 42. Furthermore the top 42 is pro¬ vided with an aperture (not shown) corresponding to the aperture 38 in the wall 12, said aperture being used for removing and replacing the weights 36 from the rotary bodies 22, 22 ' .