Background of the invention

The present invention relates to a steering apparatus for steering a substantially cylindrical body, especially for steering the rudder post of a ship, comprising an actuator having a rotor member attach to the rudder post and one in relation to the rudder post stationary housing member, said rotor member being equipped with vanes which in the actuator define pressure chambers which are connected to steering power units.

Prior art

On a world-wide basis there are today only a few suppliers of steering apparatus of said type, which steering apparatus often are referred to as "Rotory Vane".

The main components of such a steering apparatus comprise an actuator, the moveable member or rotor member thereof being attached to the upper end of the rudder post in question. The rotor member of the actuator is equipped with two, three or in some cases four vanes which in the actuator define pressure chambers, and all chambers with their vanes ("wings") are connected to each other, such that one or two hydraulic power units driving the actuator operate with its pressure in all chambers. This means that even if the power units to a certain degree are independent of each other, which is somewhat related to the hydraulic coupling and the steering system as such, then the actuator according to the prior art is common to for example two power units, and there is then achieved only a partly duplication of the steering system.

On the basis of a security point of view one can in connection with such a previously known "single" actuator, which as such is controlled by a double set of power units, but which nevertheless is common for the power units, raise the question about whether it could fulfil the requirements of future steering apparatus.

Brief discussion of the invention

The object underlying the present invention is to provide a steering apparatus of the mentioned type, which will satisfy stronger requirement for operation safety in relation to such apparatus than what is the case related to prior art.

Further, an object of the present invention is to provide an actuator which not only is safer as regards operation, but which also renders access to a larger working area than previously mentioned steering apparatus of the type "Rotary Vane".

Another object of the present invention is to give in¬ structions about an actuator comprising members which can easily be manufactured by modern material working, and which can easily be mounted and render simplified inspection and maintenance.

Yet an object of the invention is to provide a steering apparatus which also involves a better arranged and robust hydraulic steering system.

In a steering apparatus of the type mentioned in the preamble these objects are achieved according to the invention in that the actuator comprises at least two pressure chambers and at least two sets of pressure chambers driven by respective independent power unit.

Consequently, each pressure chamber or set of pressure chambers will be driven by a respective independent hydraulic power unit, which entails a more reliable dup¬ lication of the actuator then what is the case in connection with the previously known art.

It is to be understood that the at least two pressure chambers may be provided in any appropriate manner, either axially and/or radially in relation to the central axis of the rudder post.

An appropriate embodiment can be to the fact that the at least two pressure chambers or at least two sets of pressure chambers are provided in each respective half of the rotor member of the actuator, especially in an upper and a lower half, respectively.

Further features and advantages in connection with the present steering apparatus will appear form the following description and the attached patent claims, taken in connection with the appending drawings.

Brief disclosure of the drawings

Fig. 1 is a longitudinal section through a steering apparatus according to prior art.

Fig. 2 is on a smaller scale a schematic cross section through the prior art apparatus according to Fig. 1.

Fig. 3 is a longitudinal section taken substantially along the line III-III in Fig. 4, through a non-limiting embodiment of a steering apparatus according to the present invention.

Fig. 4 is a top view of the steering apparatus according to Fig. 3, but with the cover removed for the sake of

survey .

Fig. 5 is a longitudinal section taken substantially along the line B-B in Fig. 6, through a further embodi- ment of a steering apparatus according to the invention.

Fig. 6 is a section taken along the line A-A in Fig. 5.

Fig. 7 is a hydraulic control diagram which can be used in connection with the steering apparatus according to the invention, comprising a device for gasket pressure sealing system.

Detailed description of embodiments

In Figures 1 and 2 illustrating a longitudinal section and a cross section, respectively, through a steering apparatus according to prior art, reference numeral 1 designates the rudder post itself, and more accurately an upper portion thereof, whereas reference numeral 2 designates an actuator comprising a rotor member 3 which is attached to the rudder post 1 , and which is adapted to be rotated in relation to the house member 4 of the actuator, the rotor member 3 being provided with vanes, in this case two vanes 4a and 4b, respectively, which in relation to house member portions, here two house member portions 5aa and 5bb, define pressure chambers 5a, 5b and 6a, 6b, respectively.

By means of appropriate pipe connections via passages 7a, 7b and 8a, 8b in respective house portions 5aa, 5bb, as illustrated in Fig. 2, not illustrated power units will be able to set the various pressure chambers under pressure, for thereby influencing the vanes 4a, 4b of the rotor member 3 for the turning of the rudder post 1.

For example, by supplying pressure via the channels 7a

and 8a, the vanes 4a and 4b can be rotated in a clock¬ wise direction, whereas correspondingly, by pressure re¬ lease in said channels and power supply via channels 7b and 7a, the pressure chambers 5b and 6b will influence the vanes 4a and 4b to be rotated in the opposite direction, and consequently give the rudder post 1 a rotation in counter-clock direction.

In connection with the prior art steering apparatus 1 , as appearing from Fig. 2, there can only be achieved a rotation of the rudder post 1 of approximately ± 35°, which means a relatively severe limitation when manoeuvring the ship itself. Besides, one or two power units will with their pressure operate in all of said pressure chambers, which means that even if the power units can be independent of each other, then the actuator itself constitutes a common steering member for both power units, which involves only a partly duplication of the system in case any elements of the steering system should fail.

In Figures 3 and 4 which illustrate a longitudinal through section and a top view, respectively, there is depicted a non-limiting embodiment of a steering appa- ratus according to the present invention.

Herein reference numeral 101 designates the rudder post of a ship, and reference numeral 102 designates the actuator itself, which also here comprises a rotor member 103 attached to the rudder post 101, as well as a house member 104 which is stationary in relation to the rudder post 101, said rotor member 103 also here being provided with vane-like means, here designated vanes 104a and 104b, which are mounted such in the actuator 102 that they define pressure chambers 105a, 105b and 106a, 106b, respectively.

Through appropriate intermediate pieces 107a and 107b or through the vanes 104a and 104b which together define the discussed pressure chambers 105a, 105b and 106a, 106b, respectively, said mentioned set of pressure chambers will be supplied with hydraulic power via appropriate controlling power units, for example as illustrated by reference numeral 108a.

As most clearly appearing from Fig. 3 said hitherto dis- closed pressure chambers and associated elements are provided in an upper actuator member 102A, i.e. an upper member in relation to the actual direction of the actuator, but according to the present invention said pressure chambers are duplicated in a lower actuator member 102B, which entails that the actuator according to the invention comprises at least two pressure chambers or at least two sets of pressure chambers which are driven by its own independent power unit.

In its widest aspect it is to be understood that such at least two sets of pressure chambers driven by its own independent power unit, can be arranged in a plurality of various ways, it being axially and/or radially in relation to the central axis of the rudder post, but an appropriate embodiment will entail, as illustrated in

Figures 3 and 4, that said at least two pressure chambers or at least two sets of pressure chambers are arranged in each respective half member 102A and 102B, respectively, of the rotor member 103, especially in an upper and a lower half member, respectively.

It is to be understood that the view according to Fig.4 which is here seen from above with the cover 110 of the actuator removed, also can be valid for the actuator as seen from below, with the bottom 111 of the actuator removed.

In the lower member 102B of the actuator 102 there is thus provided a separate set of vanes 204a and 204b, respectively, which in the lower member 102B of the actuator 102 define pressure chambers 205a, 205b and 206a, 206b, respectively. These further pressure chambers will via appropriate intermediate pieces 207a and 207b communicate with its own independent power unit, for example as illustrated by reference numeral 208a, through an appropriate valve system and via one or several separate pumps.

In the embodiment as illustrated in Figures 3 and 4, the said upper and lower pressure chamber will appropriately be defined by in the rotor member 103 provided circular, substantially peripheral recesses 112A and 112B, respectively, having a depth D corresponding to somewhat more than half of the extension of the rotor member 103 in the axial direction.

The circular recesses 102A and 102B in the upper rotor member 102A and the lower rotor member 102B, respective¬ ly, are consequently divided in pressure chambers by means of the inserted vane-shaped means or vanes 104a and 104b, respectively 204a and 204b, for defining pressure chambers in pairs of similar semi-circularly shaped sections, each of said sections having inserted therein said vane-shaped intermediated pieces 107a, 107b and 207a, 207b, respectively.

The symmetrical design of the upper and lower sets of pressure chambers will involve that the rotor 103 can be manufactured and machined in a simple manner, the provision of the recesses and the associated vane means and intermediate pieces being provided by easily available material machining tools.

In Figures 5 and 6 there are illustrated a further em-

bodiment of a steering apparatus according to the in¬ vention. Also here a rudder stem or rudder post 301 of a not illustrated ship, is surrounded by an actuator 302 which is composed by an upper half member 302A and 302B. Also here, the actuator 302 comprises a rotor member 303 which is attached to the rudder post 301 , as well as a house member 304 which is stationary in relation to the rudder post 301 , and the upper rotor member 302A is pro¬ vided with vane-like means 304a and 304b which together with stationary intermediate pieces 307a and 307b define upper pressure chambers, 305a, 305b and 306a, 306b, re¬ spectively.

Via said vanes 304a and 304b the mentioned set of pres- sure chambers will be supplied with hydraulic power through appropriate control power units, for example as illustrated by reference numeral 308a, which will be further discussed in connection with Fig. 7.

In a similar manner there is in the lower member 302B of the actuator 302 provided a separate set of vanes 404a and 404b, respectively, which in turn define four pres¬ sure chambers 405a, 405b and 406a, 406b, respectively. These further pressure chambers will via the intermediate pieces or vanes communicate with their own independent power unit, for example as illustrated by reference numeral 408a, through an appropriate valve system and through one or several separate pumps, as more clearly appearing from Fig. 7.

In the embodiment illustrated in Figures 5 and 6, the mentioned upper and lower pressure chambers are appropri¬ ately defined by in the rotor member 303 provided circu¬ lar, radial recesses, 312A and 312B, respectively, where- in the "hight" H1 corresponds to less than half of the extension of the rotor member 303 in the actual direction thereof, and wherein the radial depth R1 can correspond

to approximately half of the radial material thickness of the rotor member 303 in the radial direction thereof.

Also here the rotor 303 is provided with substantially symmetrical recesses and pressure chambers, which involves machining by easily available material machining tools, at the same time as the vane means and the inter¬ mediate pieces can be manufactured and mounted in a simple manner.

In Fig. 7 there is in the middle thereof illustrated the actuator 302 itself in a "folded-out" view, the actuator 302 here comprising an upper member 302A including pressure chambers 305a, 306b and 305b, 306a, respective- ly.

Correspondingly, the lower member 302B comprises pressure chambers 405a, 406b and 405b, 406a.

The set of pressure chambers being housed in the upper member 302A of the actuator 302 are controlled by its own hydraulic control unit 350, whereas the lower member 302B is controlled by its own control unit 450, said control units being mutually independent, such that in case one of the control devices should fail, the actuator 302 can still be operated by means of the remaining control device.

The control unit 350 which constitutes an independent control device, and which is illustrated by the dash- dotted line comprises a manometer 351 , a manual valve 352, a control valve 353 which can be controlled electri¬ cally and which has the function to by-pass the upper sector or the upper part 302A of the actuator 302. Further, the control device 350 comprises a main valve 354, a pressure filter 355, as well as a safety valve 356, and finally a motor 357 having a coordinated cooling

device 358, which motor 357 operates an oil pump 359.

The oil supply can take place through a storage tank 360 which delivers oil to a first system tank 361 intended for the discussed control device 350, as well as to a second system tank 461 serving said second control device 450.

The storage tank 360 is at its outlet provided with a main valve 362, and each of the system tanks 361, 461, respectively, is provided with a sensor, 363 and 463, respectively, for surveying sufficient oil level.

In Fig. 7 there is also illustrated a sealing system 370 for the upper actuator member 320A, as well as a corre¬ sponding sealing system 470 for the lower member 302B of the same actuator 302.

The function of the sealing system 370 is to supply pres- sure to metal rings 380 arranged in the house member 304, as this is best seen in Fig. 5 at the left top, and most appropriately the pressure which is supplied to said metal rings 380 during operation, will be given the same value as the pressure which is supplied to the associated pressure chambers for rotating the actuator.

The same will apply for the sealing system 470 for the metal rings 480 communicating with the lower member 302B of the actuator 302.

In Fig. 5 there is also illustrated a break disc 390 which is attached to the rudder pole 301 , and which together with a brake device 391 can appropriately be utilised for testing an actuator or steering apparatus according to the invention.

It is to be understood that each set of pressure chambers, here the upper and the lower set, can communi¬ cate with its own independent power unit which can be connected to a common pump, but then preferably having its own by-pass unit, as an alternative to each indepen¬ dent power unit for each pressure chamber being connected to its own pump, said pumps during normal operation ope¬ rating in parallel. Preferably, each pump can then have its separate freely suspended expansion tank.

Preferably, all valves in the power unit can be located directly in connection with respective pump unit.

Example of specification

Apparatus size for the design:

Rudder post diameter ø300 mm

Working pressure 120 Bar

Design pressure 150 Bar

Boss material size 0,4 x rudder post diameter

Torque by working pressure and both units in operation 30 tm

Wanted rudder angel, max 2 x 70°

Pump capacity will then be approximately 30 1/min.

Pipe dimensions ø 20 x 3

Oil velocity in pipe 3,25 m/sek.

Connections 3/4" R

Turning time equal for full/half machine 28 sek.

The actuator should consist of two completely independent members, upper/lower.

The actuator is in its design rigid and is to be installed on resilient elements, the torque is to be

absorbed by two torque braces.

The actuator should be tight towards its environment. No gasket against rudder post.

Since the apparatus comprises to completely independent members all valves can be located directly in connection with pumping units.

Each pump is provided with its separate freely dependent expansion tank.

Each actuator unit should have a by-pass function which is appropriately controlled.

In the actuator there is contemplated the use of the following gasket types:

1. Sealing out of apparatus: 0-ring having supporting ring, 4x.

2. Sealing of ring leakage: Split metal ring including spring pressure behind and oil pressure to maintain the ring in position, 2 units per side.

3. Sealing of vane: Cast iron strip, (neoprene strip) radially, one strip per vane.

Vanes to be locked in recess in the rotor.

4. Sealing of intermediate pieces: Die casted neoprene strip.

It is suggested to arrange stoppers independent of the intermediate pieces.

Bearing lubrication

Of course, other specifications are also possible within the frame and the scope of the basic idea of the present invention.

For example, the number of pressure chambers and the number of sets of pressure chambers can vary, either these are provided axially or radially in relation to the rudder post, which can be dependent upon the field of application, the turning angle as well as the degree of multiplying the security level.