US20090011666A1

US20090011666A1 - Steering Device Particularly for Outboard Marine Engines

Info

Publication number: US20090011666A1
Application number: US12/162,356
Authority: US
Inventors: Giorgio Gai
Original assignee: Ultraflex SpA
Current assignee: Ultraflex SpA
Priority date: 2006-01-27
Filing date: 2007-01-04
Publication date: 2009-01-08
Also published as: ITSV20060003A1; WO2007085515A1

Abstract

A steering device for marine engines, particularly for outboard engines, includes a rod that is sealingly mounted in a cylindrical housing sliding along the rod and that projects out of heads of the cylindrical housing. A piston is secured in a substantially intermediate position on the rod and divides the cylindrical housing in two variable volume chambers. Each of two inlets/outlets is in fluid communication with one of the two chambers through a separated feeding conduit defined inside the rod and both of the feeding conduits, through their inlets/outlets, open at one same end of the rod.

Description

FIELD

The present invention relates to a steering device for marine engines, particularly for outboard engines, which includes a rod sealingly mounted in a cylindrical housing that slides along said rod and sealingly projecting out of heads of the cylindrical housing, a piston secured in a substantially intermediate position on the rod and dividing the cylindrical housing in two variable volume chambers, and two inlets/outlets communicating with said two chambers.

BACKGROUND

Steering devices, particularly for outboard engines, are well known and widely used. While these devices often serve their function satisfactorily, they still suffer from certain drawbacks.
First, in these known devices, the rod is secured to the transom, whereas the cylinder slides along the rod. Therefore, the device is fastened to the transom by means of the rod. There are two types of fastening. Both types include an engine coupling member fastened to the rod by means of radial or substantially radial members. In a fastening type, there is provided a fastening plate provided having holes with angled end extensions for the connection to one of the two opposite rod ends. The plate with holes is secured by bolts or other tightening means inside corresponding holes of a counter-plate or connections provided on the engine body or on the engine terminal for fastening of the transom of the boat. On the contrary, the second fastening type provides a supporting shaft parallel to the rod and intended to be engaged instead of or inside a tubular axle hinging the engine fastening terminal to the engine body. The shaft is rigidly connected by each one of its ends to the corresponding ends of the cylinder rod.
For the purpose of feeding the fluid towards the two chambers of the cylinder, the prior art provides an arrangement, wherein the cylinder at its two opposite ends has an inlet/outlet respectively for feeding and discharging a fluid, generally oil, from each one of the two chambers divided by the piston. Since the cylinder moves along the rod, for each inlet and outlet such connection has to be made by means of hoses interposed between an end of each conduit feeding the fluid to each corresponding chamber and said corresponding chamber. In the long run, due to the stiffness of the hoses, the continuous sliding movement of the cylinder can cause the material to be stressed and the material can break, especially In areas coming from the stern cockpit to cylinder fittings.
A further different arrangement provided in the prior art Is to convey oil inside cylinder chambers, in order to move the cylinder with respect to the rod, by means of two opposing conduits made inside the rod, each coming from one of the two opposite head ends of the rod, and each opening in one different chamber of the two cylinder chambers. That is achieved by having a through hole in the rod closed in an intermediate area substantially flush with the piston and by further having two outlets, one at a chamber and the other one at the other chamber. In this regard, Italian patent SV2003A000027 by the same applicant as the present application is noted, to which reference can be made in order to understand the present invention.
However, in such embodiment the following drawback has been found: conventionally, the feeding of oil occurs by means of a circuit that, typically starting from the steering wheel, arrives at the steering device assembly, typically at the transom, with two pipes both arriving from the same side of the steering assembly. That configuration causes the feeding of the two conduits to occur in the following way: a first conduit, the one adjacent to the area where said pipes arrive, is directly fed, whereas the more distant conduit is fed by an extension of the corresponding pipe, that is passed to the opposite side of the steering assembly till reaching the corresponding inlet of the second conduit on the corresponding end of the rod.
This configuration causes a portion of the hydraulic circuit to be longer, and, therefore, to be subjected to the greatest losses of pressure, particularly in the portion of the hydraulic circuit corresponding to the conduit whose feeding occurs at the rod end not adjacent to the side where said pipes arrive, causing the hydraulic circuit to be unbalanced.
Moreover, a further drawback relates to the fact that said pipe, extending or connecting the conduit whose feeding is not provided on the rod end faced towards the side where both pipes arrive, has an elongation made by flexible parts positioned behind the device, where such flexible parts can get entrapped or can be an obstacle.
The prior art discloses another type of steering device, wherein oil is fed to cylinder chambers always by two feeding conduits provided in the rod, each of the feeding conduits ending by their feeding or connecting end at one of the two opposite head ends of the rod. In order to overcome the above drawbacks, one of the two inlet openings of one of the two conduits, provided on one of the two opposite rod ends, is connected to a terminal that connects fluid feeding pipes and that is provided on the rod end wherein the feeding opening of the first conduit opens. This design configuration involves a connecting conduit suitably integrated in the supporting frame of the device. Particularly in the arrangement where the device is fastened to the engine by a fastening shaft whose ends connect to corresponding rod ends by end radial arms, said connecting conduit is made inside such arms, which are tubular. In such prior art device, hydraulic fluid or oil (the hydraulic fluid may include oil) is fed by two opposing conduits inside the rod but inlets/outlets of said two conduits, to which pipes feeding hydraulic fluid or oil coming from the steering control pump are connected, are both positioned on the device side corresponding to the head end of the rod. In order to convey oil inside each conduit adjacent to the inlets/outlets, there is provided a direct connection with the nearer inlet/outlet, whereas in order to convey hydraulic fluid or oil inside the other conduit there is provided a through opening inside the radial arms or rod supporting means, as can be clearly seen in FIGS. 8 and 9, which illustrate prior art arrangement. Such embodiment clearly leads to a considerable asymmetry of flow resistance of the two circuit parts connecting the pump of the steering device to each of the two chambers of the steering cylinder, and in addition leads to a considerable rise in cost, both for the fastening shaft and the radial arms connecting rod ends to said fastening shaft, and for the time and expensing for mounting the fastening shaft, since it is necessary for each end of the rod and of the fastening shaft to be sealingly connected one with the other. It is to be noted that where the shaft is fastened to the rod is a critical point, since the engine discharges forces exerted on the steering device during operation on said fastening point. Therefore, in this case, the connection of the radial arms to the rod and to the fastening shaft has to be strong enough, and must also produce a stable and lasting seal, and above all cannot be compromised by forces twisting the parallelogram composed of the rod, the parallel shaft and connecting radial arms.

SUMMARY

The object of the present invention is to provide a steering device according to the preamble of claim 1, which simply and inexpensively obviates the drawbacks of known steering devices.
The invention fulfills the above object by providing a steering device for marine engines, particularly for outboard engines, which includes a rod, which rod is sealingly mounted in a cylindrical housing sliding along said rod, the rod sealingly projecting out of heads of the cylindrical housing; a piston secured in a substantially intermediate position of the rod, the piston dividing the cylindrical housing in two variable volume chambers; two inlets/outlets, each communicating with one of said two chambers through a separated feeding conduit of said two chambers, said conduits being further defined inside the rod and opening by their respective inlet/outlet open at a single end of the rod and in one of the two chambers delimited by the two sides of the piston.
The two conduits can be provided as two axial apertures parallel one with respect to the other and deriving from the same rod head, whereas the two conduits end with a radial portion opening at the outer surface of the rod in two sites spaced in the axial direction of the rod and each provided on a rod portion on different sides of the piston. Alternatively, the two conduits can be provided as conduits placed one inside the other, the rod being made of two tubular members with different diameters placed one inside the other and at a certain distance one with respect to the other. The two conduits can be eccentric and/or concentric, for example coaxial one with respect to the other. Each conduit communicates individually with only one of the two chambers on the two opposite sides of the piston.
In a specific embodiment, the device comprises at least a terminal fastening the outboard engine to the boat transom by tightening it and/or by means of a clamp, upon which the engine/propulsor assembly is rotatably mounted about a substantially vertical steering axis. The steering device comprises, in addition a closed hydraulic circuit with at least a pump driven by steering means, such as a steering wheel, a rudder or the like, and at least a hydraulic double-acting actuating cylinder composed of a cylindrical housing, within which at least a rod is mounted and sealingly projects out of heads of the cylindrical housing, the rod carrying an intermediate separating piston which divides the cylindrical housing into a first and a second variable volume chamber and the rod in a first and second rod portions, wherein each one of said first and second chambers is operatively connected to a corresponding inlet/outlet for the hydraulic fluid or oil, identified herein as a first inlet/outlet for the first chamber, and a second inlet/outlet for the second chamber. Means are provided for fastening the cylinder-rod assembly to the transom and/or to the terminal fastening the engine to the transom, such that the at least one rod, at least a transmission arm between the cylinder and coupling means steering the outboard engine integral with the engine, are fastened to the fastening means such not to be slidable with respect thereto. The transmission arm is rotatable and translatable inside a seat on the hydraulic double-acting actuating cylinder, for example through bayonet joints, male thread/female thread joints, or a nut/lock nut, and is the ending part of the arm is further rotatable and translatable in relation to the arm body, for example with male thread/female thread joints, a nut/lock nut, or bayonet joints.
At least said first and second inlets/outlets of said first and second cylinder chambers are connected to a first conduit for said first inlet/outlet and a second conduit for said second inlet/outlet respectively, said first and second conduit being obtained inside the rod and extending from the same outer end of the rod and/or of the device to one or more openings communicating with the corresponding first or second cylinder chambers, which openings are provided adjacent to the piston side faced towards the corresponding output cylinder head of said rod.
By means of above arrangements, the invention improves over the prior art drawbacks discussed hereinabove.
The two conduits for feeding said two chambers, said conduits being both provided in the rod and such to release at only one of the two ends of said rod, are configured to feed said conduits by two inlets/outlets for the hydraulic fluid or oil provided at the same rod end, which inlets/outlets are connected to feeding pipes for feeding said conduits.
Thus, an optimal and balanced hydraulic circuit is obtained, since the two portions of the hydraulic circuit corresponding to a specific cylinder chamber have the same length and substantially equal losses of pressure. This causes the two portions of the hydraulic circuit to be balanced; overcoming prior art drawbacks.
Moreover, feeding occurs from the same side of the rod, and elongations of pipes conveying hydraulic fluid or oil are not necessary, avoiding possible obstacles as above described.
In the present disclosure and in claims, by the term half-rod both, a rod portion is to be understood as a rod part substantially corresponding to a half length of the rod and a rod part as a member physically separated from another rod part. In the first arrangement, the division of the rod into half-rods is substantially an ideal one and the ideal dividing line is substantially defined by the piston position. In the second arrangement, the two half-rods are two separated rod parts that are connected one with the other, for example by the piston or by a member fastening the piston on the rod. Therefore, the term half-rod is not to be considered limited to a separated structural part corresponding to one half of the total length of the rod.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand prior art drawbacks and advantages of the present invention, reference to the annexed figures will be made, wherein;

FIG. 1 is a plan view of an embodiment of the device object of the present invention.

FIG. 2 is a front view of the device of FIG. 1.

FIG. 3 is a section plan view of a first embodiment of the device object of the present invention, wherein conduits are coaxial within the same rod portion.

FIGS. 5 and 6 are section plan views of a second embodiment of the device object of the present invention, wherein conduits are substantially placed side by side in the same rod portion.

FIG. 7 is a section plan view of a detail of the first embodiment shown in FIGS. 5 and 6.

FIG. 8 is a prior art embodiment, wherein conduits pass inside means supporting the rod and in the two half-rods.

FIG. 9 is a prior art embodiment, wherein conduits pass inside the two half-rods.

DETAILED DESCRIPTION

Referring to FIG. 8, it is possible to see a first prior art embodiment. There can be noted the hydraulic cylinder, composed of a cylindrical housing 1 sliding on a rod 2, which is fastened to two supporting brackets 106 joined together by fastening means 206. The path of the hydraulic circuit is shown by a black broken line; hydraulic fluid or oil is fed to two inlets/outlets 90 and 91 by two pipes or conduits coming from a pump, not shown, which is driven by the steering wheel or by control means of the boat. In this embodiment of the prior art, cylinder or device inlets/outlets 90 and 91 are both placed on the same cylinder side and different paths to be followed by the hydraulic fluid or oil can be seen. The conduit corresponding to inlet/outlet 91 is near the corresponding inlet/outlet 91 and has a path that is definitely shorter and less tortuous than the conduit corresponding to the inlet/outlet 90, which conduit on the contrary passes through the two supporting brackets and the fastening means 206 to arrive finally in the corresponding chamber passing through the corresponding half-rod. It can be immediately seen in FIG. 8 that the hydraulic circuit path corresponding to inlet/outlet 90 is certainly longer and more tortuous than the hydraulic circuit path corresponding to inlet/outlet 91, and this leads to higher losses of pressure for said conduit. Losses of pressure depend not only on the length but also on bends of the circuit under analysis. Moreover, it is to be noted that as regards the hydraulic circuit corresponding to inlet/outlet 90, it must pass through different parts that must be sealingly connected.
Firstly, that causes the hydraulic circuit to be unbalanced, wherein the two branches corresponding to the two inlets/outlets 90 and 91 have different losses of pressure, and, secondly, that causes the manufacturing cost to be very high, due to the presence of complex production processes and many sealingly fastening sites.
In FIG. 9, a second prior art embodiment is shown. In this embodiment, there is a hydraulic cylinder composed of a cylindrical housing part 1 sealingly sliding on a rod 2, which rod is fastened between two supporting brackets 106 joined together by fastening means 206. In such case, it can be noted that the two inlets/outlets 90 and 91 are placed at the two half-rods constituting the rod 2. In the illustrated embodiment, the conduits inside the rod are of the same length, but since pipes or conduits for hydraulic fluid or oil arrive at the device from the same side, it is necessary, as shown, for the hydraulic pipe or conduit corresponding to inlet/outlet 90 to be longer. Again, this causes the hydraulic circuit to be unbalanced, since as discussed above, the hydraulic circuit corresponding to the inlet/outlet 90 is longer and more tortuous that the hydraulic circuit corresponding to the inlet/outlet 91. In addition, in this case it is to be considered that the hydraulic circuit part outside the cylinder corresponding to the inlet/outlet 90 and necessary for carrying the feeding thereof towards the opposite side passes through the operating space of the cylinder and can cause a hindrance.
The present invention solves the above prior art drawbacks by providing a steering device for marine engines, shown generally in FIGS. 1 and 2 particularly for outboard engines having at least: a rod 2, which rod slides in a cylindrical housing 1 and it sealingly projects out of heads 3 of the cylindrical housing, a piston 502 in a position substantially intermediate with respect to the rod 2 and dividing the cylindrical housing 1 in two chambers 4 and 5, two inlets/ outlets 204, 205 communicating with these two chambers 4 and 5 respectively, wherein said inlets/ outlets 204 and 205 are operatively connected to two conduits 104 and 105 for feeding said two chambers 4 and 5, said conduits 104 and 105 being obtained only in one of the two ends of said rod 2.
Thus, prior art drawbacks are easily overcome, not only because inlets/ outlets 204 and 205 are placed at the same end of said rod 2, avoiding the configuration of a hydraulic circuit part like the outer one shown in prior art FIG. 9, but also because hydraulic circuit portions 104 and 105 corresponding to inlets/ outlets 204 and 205 have substantially the same length and therefore substantially the same losses of pressure. In the present invention, the hydraulic circuit is a balanced hydraulic circuit, in which both branches of the circuit have the same length, winding and accordingly the same losses of pressure.
Referring to FIGS. 1 and 2, it can be noted that, from the outside, the configuration of the device according to the present invention includes a hydraulic cylinder composed of a cylindrical housing 1 sliding with respect to a rod 2, which rod 2 is fastened to a fastening terminal 6. The fastening terminal 6 comprises two supporting brackets 106 and 106′ connected to ends of the rod 2 and to fastening means 206, which is substantially parallel to the rod 2.
Moreover, the device comprises a steering arm 7 secured to the cylindrical housing 1 and two inlets/ outlets 204, 205 for feeding/discharging the hydraulic fluid or oil.
According to a feature of said first end, the first conduit 104 leads to the first chamber 4 on the side of the piston 502 faced towards said end by at least a communicating opening 404, and the second conduit 105 leads in the second chamber 5 on the side of the piston 502 faced towards the opposite end by a communicating opening 405. According to a first embodiment shown in FIG. 3, conduits 104 and 105 are provided that are coaxial one with respect to the other. It can be noted in FIG. 3 that the two conduits 104 and 105 are coaxial one with respect to the other and that both of them are operatively connected on one side with the corresponding inlet/ outlet 204 and 205 and on the other side with the corresponding communicating opening 404 and 405 for the passage of the hydraulic fluid or oil.
In this embodiment, the variable volume chamber 4 is fed or discharged from the hydraulic fluid or oil fed to the chamber through the communication opening 404 by the conduit 104, fed in turn by the inlet/outlet 204, and the variable volume chamber 5 is fed or discharged from the hydraulic fluid or oil fed to the chamber through the communication opening 405 by the conduit 105, fed in turn by the inlet/outlet 205. Therefore, from an operating point of view the operation can be summed up as follows: the user operates a steering control, not shown, which control drives a pump for pumping the hydraulic fluid or oil into the corresponding branch of the hydraulic circuit, the hydraulic fluid or oil is then pumped under pressure inside the corresponding branch and through the inlet/outlet and reaches the conduit carrying it to the corresponding variable volume chamber through communication openings. The filling of the variable volume chamber causes the cylindrical housing to be moved on the rod and consequently the steering arm connected to the cylindrical housing to be moved. When the opposite chamber is filled, a translation of the cylinder is obtained in the opposite direction.
In the embodiment shown in FIG. 3 it is possible to note that the conduit 105 is substantially concentric with respect to the conduit 104 and projects beyond the piston or at the piston and communicates with the variable volume chamber 5 through openings 405. The conduit 105 is connected to the inlet/outlet 205 at the end of the rod 2. Besides the inlet/outlet 205, the inlet/outlet 204 can be seen feeding the channel 104 concentrically placed around the channel 105. At the piston 502 the channel 104 has communication openings 404, for example radially placed, and communicates with the variable volume chamber 4. Both the conduit 104 and the conduit 105 are obtained on the same rod sector 102, and it is possible to note that the rod 2 is divided by the piston 502 in two rod sectors, or parts 102 and 202. Whereas the rod sector 102 has channels 104 and 105, the rod sector 202 can be simply hollow, or solid one, or in other ways.
It is to be noted that, in the preferred embodiment shown in FIG. 3, the piston is provided with an opening in order to cause the hydraulic fluid to pass directed towards the chamber 5 disposed at the rod sector 202.
Moreover, still in FIG. 3 it is possible to note that walls of the variable volume chambers 4 and 5 are composed by sealingly fastened heads of the cylindrical housing 3 and 3′, by the outer surface of the corresponding rod sector 102 and 202, by the inner wall of the cylindrical housing 1, and by the corresponding wall of the piston 502 faced towards the coinciding variable volume chambers 4 and 5.
Sealing closures are provided between various members of the actuating cylinder, in order to avoid leaks of hydraulic fluid or oil.
According to a second preferred embodiment shown in FIGS. 5, 6 and 7, said first and second channels may be provided not concentrically but may be both obtained inside the same half-rod, for example, said two conduits 104′ and 105′, as shown, can be made substantially parallel one with respect to the other and extending from the end of the rod sector 202′ at least to the piston 502′. More particularly, as it can be seen in FIG. 5, the first conduit 104′ ends at a first opening 404′ communicating with the variable volume chamber 4′, and the second conduit 105′ ends at a second opening 405′ communicating with the variable volume chamber 5′.
Comparing FIGS. 5 and 6, it is possible to note the movement made by the cylindrical housing from a position where variable volume chambers 4′ and 5′ have substantially the same volume, to a position where the chamber 4′ has the smallest volume and the chamber 5′ has the greatest volume. From the above figures it can also be noted that the two conduits 104′ and 105′ are made preferably parallel one with respect to the other and that the conduit 105′ that is the one leading into the chamber 5′ placed in one of the half-rods through an opening in the piston and beyond the piston itself to an opening 405′ for providing fluid communication from the conduit 105 to the chamber 5.
For functional reasons, the passage openings 404′ and 405′ are made next to the piston 502′. Said first conduit 104′ and second conduit 105′ made in the corresponding half rod lead at the ending portion of the rod into two corresponding inlets/outlets 204′ and 205′, joined in turn with the remaining part of the hydraulic circuit. Moreover, it is to be noted that for both shown embodiments, and particularly with reference to FIG. 7, the ending portion of the half-rod 102 having conduits 104 and 105 or 104′ and 105′ ends at the supporting bracket 106 or 106′, to which it is engaged. In order to allow a simple operation of the supporting bracket 106 and the simultaneous passage of conduits, inlets/ outlets 204 and 205 or 204′ and 205′ are connected to a coupling means or coupling members 9, 9′ having inside it corresponding connections for inlets/ outlets 204 and 205 or 204′ and 205′ and necessary conduits. Thus, the rod 2, 2′ is not directly interfaced with the supporting bracket 106, 106′ in the preferred arrangement, but is interfaced by means of said coupling means, constituting a kind of head of the half- rod 102, 102′.
In the case of the first and second conduit 104 and 105 being coaxial, it is possible to note that ducts inside the coupling means 9 are made such that the second conduit 105 opens directly at the second inlet/outlet 205, whereas the first conduit 104 opens in a small duct 109 that in turn opens at the first inlet/outlet 204.
Referring to FIG. 7, it is possible to note that in this case conduits 104′ and 105′ are substantially parallel one with respect to the other and that the coupling means 9′ have a first and second ducts 109′ and 209′ connected to said conduits 104′ and 105′, which ducts 109′ and 209′ open at corresponding inlets/outlets 204′ and 205′.
A further advantage obtained by such particular arrangement, that is, providing the half-rod with conduits to have a kind of head composed of the above coupling means, is that the bracket 106 or 106′ is very simple to manufacture, since ducts are obtained in the coupling means and not in the bracket, allowing the manufacturing of the rod to be very simple.
Further characteristics and improvements provided by the invention are recited in the claims.

Claims

1. A steering device for marine engines comprising:

a rod sealingly mounted in a cylindrical housing sliding along said rod, the rod sealingly projecting out of heads of the cylindrical housing;

a piston secured in a substantially intermediate position on the rod, the piston dividing the cylindrical housing in two chambers of variable volume;

two inlets/outlets, each one of the two inlets/outlets fluidly communicating with one of said two chambers by a separated feeding conduit;

wherein said separated feeding conduits are defined inside the rod, and

wherein said separated feeding conduits are connected to the inlets/outlets at one same end of said rod.

2. The steering device according to claim 1, wherein the separated feeding conduits are defined by two axial apertures parallel one with respect to the other extending from the same head end of the rod, and

wherein each of the separated feeding conduits is fluidly connected to one of the two chambers via a radial opening, the radial openings being at the outer surface of the rod and on opposite sides of the piston.

3. The steering device according to claim 1, wherein the separated feeding conduits are disposed one inside the other, thereby causing the rod to be made of two tubular members having different diameters, the two tubular members being placed one inside the other at a certain distance one from the other.

4. The steering device according to claim 3, wherein the separated feeding conduits are parallel bores within the rod.

5. A hydraulic steering device comprising: a terminal fastening an outboard engine to a boat transom;

an engine/propulsor assembly rotatably mounted to the boat transom;

a closed hydraulic circuit having a pump driven by steering means;

a rudder; and

a hydraulic double-acting actuating cylinder comprising,

a cylindrical housing,

a rod disposed in the cylindrical housing and sealingly projecting out of heads of the cylindrical housing, the rod carrying an intermediate separating piston which divides the cylindrical housing into a first and a second variable volume chambers and which further divides the rod in a first and a second rod portions, wherein the first variable volume chamber is fluidly connected to a first inlet/outlet for a hydraulic fluid or oil and the second variable volume chamber is fluidly connected to a second inlet/outlet for the hydraulic fluid or oil, the first and the second inlet/outlets being fluidly connected to a same end of the rod, and

means for fastening an assembly of the cylindrical housing and of the rod to the boat transom and/or to the terminal fastening the engine to the transom,

wherein the first inlet/outlet is fluidly connected to a first conduit and the second inlet/outlet is fluidly connected to a second conduit,

wherein said first and said second conduits are defined inside the rod and extend from the same end of the rod,

wherein a first opening fluidly communicates with the first variable volume chamber and a second opening fluidly communicates with the second volume chamber, and

wherein the first opening fluidly connected to the first conduit and the second opening fluidly connected to the second conduit are disposed on opposite sides of the intermediate separating piston.

6. The hydraulic steering device according to claim 5, wherein the first conduit is defined within the rod, and wherein the second conduit is defined within the rod and is fluidly connected to the second chamber through a third opening in the piston.

7. The hydraulic steering device according to claim 5, wherein the first and the second conduits are coaxial one with respect to the other.

8. The hydraulic steering device according to claim 5, wherein the hydraulic fluid comprises oil.

9. The hydraulic steering device according to claim 5, wherein the first variable volume chamber receives the hydraulic fluid or oil through the first opening and the first conduit receives the hydraulic fluid or oil from the first inlet/outlet, and wherein the second variable volume chamber receives the hydraulic fluid or oil through the second opening from the second conduit and the second conduit receives the hydraulic fluid or oil from the second inlet/outlet.

10. The hydraulic steering device according to claim 5, wherein the second conduit is substantially concentric with the first conduit, and wherein the second conduit extends to or beyond the intermediate separating piston.

11. The hydraulic steering device according to claim 5, wherein the second conduit fluidly communicates with the second variable volume chamber through the second opening and it is fluidly connected at the same end of the rod with the second inlet/outlet.

12. The hydraulic steering device according to claim 11, wherein said first conduit is positioned concentrically and outside said second conduit.

13. The hydraulic steering device according to claim 5, wherein the first opening is defined on or adjacent to the intermediate separating piston.

14. The hydraulic steering device according to claim 5, wherein said first opening is placed radially in relation to a longitudinal axis of said first conduit.

15. The hydraulic steering device according to claim 5, wherein both the first conduit and the second conduit are provided in the first rod portion.

16. The hydraulic steering device according to claim 15, wherein the second rod portion is hollow.

17. The hydraulic steering device according to claim 16, wherein the intermediate separating piston includes a third opening enabling the hydraulic fluid or oil to enter the second rod portion.

18. The hydraulic steering device according to claim 5, wherein walls of the first and the second variable volume chambers comprise,

the heads of the cylindrical housing, the heads being sealingly fastened to the cylindrical housing,

an outer surface of the rod,

an inner wall of the cylindrical housing, and

a wall of the intermediate separating piston.

19. The hydraulic steering device according to claim 5, wherein sealing closures are provided between members of the actuating cylinder such to avoid leaks of the hydraulic fluid or oil.

20. The hydraulic steering device according to claim 5, wherein said first and second conduits are disposed in the first rod portion but not concentrically.

21. The hydraulic steering device according to claim 20, wherein said first and second conduits are bores within the rod, at least one of the bores being blind.

22. The hydraulic steering device according to claim 21, wherein said first and second conduits extend from the same end of the rod at least to the intermediate separating piston.

23. The hydraulic steering device according to claim 20, wherein the first conduit ends at the first opening, and wherein the second conduit ends at the second opening.

24. The hydraulic steering device according to claim 20, wherein the second conduit extends through an opening in the intermediate separating piston and beyond the piston, and to the second opening for fluid communication with the second variable volume chamber.

25. The hydraulic steering device according to claim 20, wherein the first and the second openings are adjacent to the intermediate separating piston.

26. The hydraulic steering device according to claim 20, wherein said first conduit and said second conduit are in fluid communication with the first and the second inlets/outlets at the same end of the rod and are further in fluid communication with a remaining part of the closed hydraulic circuit.

27. The hydraulic steering device according claim 5, wherein the rod is supported by brackets, and wherein the same end of the rod ends at one of the brackets.

28. The hydraulic steering device according to claim 27, wherein the first and the second inlets/outlets are connected to the rod through a coupling member.

29. The hydraulic steering device according to claim 28, further comprising a first and a second ducts carrying the hydraulic fluid or oil to each of the first and the second inlets/outlets.

30. The hydraulic steering device according to claim 28, wherein the rod is not directly interfaced with the one of the supporting brackets, and wherein the coupling member is interposed between the same end of the rod and the one of the brackets.

31. The hydraulic steering device according to claim 27,

wherein the first and second conduits are coaxial,

wherein the first and the second inlets/outlets are disposed on a coupling member coupled to the same end of the rod, and

wherein one or more ducts are formed inside the coupling member such that the second conduit is directly connected to the second inlet/outlet and the first conduit is connected to one of the one or more ducts, the one of the one or more ducts being directly connected to the first inlet/outlet.

32. The hydraulic steering device according to claim 27,

wherein the first and the second conduits are substantially parallel one to the other,

wherein the coupling member has a first duct connecting said first conduit to the first inlet outlet and a second duct connecting said second conduit to the second inlet/outlet.

33. The hydraulic steering device according to claim 27, wherein the same end of the rod is coupled to a rod head having ducts therein, wherein the rod operates as a coupling member, and wherein the brackets have no ducts therein.

34. The hydraulic steering device according to claim 27, wherein ending portions of said rod comprise means for coupling the rod to said brackets, and wherein the means for coupling the rod comprise a thread on an outer surface of said rod that couples to a side of the one of the brackets and further comprise one or more holding nuts that couple to an opposite side of the one of the brackets.

35. The hydraulic steering device according to claim 5, wherein the means for fastening the hydraulic double-acting actuating cylinder to the boat transom and/or to the terminal fastening the engine to the boat transom comprise a transmission arm, wherein the transmission arm is rotatable and translatable inside a seat on the hydraulic double-acting actuating cylinder, and wherein an ending part of the transmission arm is rotatable and translatable in relation to a body of the arm.