WO2007085515A1

WO2007085515A1 - Steering device particularly for outboard marine engines

Info

Publication number: WO2007085515A1
Application number: PCT/EP2007/050087
Authority: WO
Inventors: Giorgio Gai
Original assignee: Ultraflex Spa
Priority date: 2006-01-27
Filing date: 2007-01-04
Publication date: 2007-08-02
Also published as: ITSV20060003A1; US20090011666A1

Abstract

Steering device for marine engines, particularly for outboard engines having at least: one rod (2), which rod (2) is sealingly mounted in a cylindrical housing (1) sliding along said rod (2) and which rod (2) sealingly projects out of heads of the cylindrical housing, a piston (502) secured in a substantially intermediate position thereof on the rod (2) and dividing the cylindrical housing (1) in two variable volume chambers (4, 5); two inlets/outlets (204, 205) each one communicating with one of said two chambers (4, 5) by a separated feeding conduit (104, 105) of said two chambers (4, 5), characterized inn that said conduits (104, 105) are further obtained inside the rod (2) and which conduits (104, 105) by their inlet/outlet (204, 205) open at one same end of the two ends of said rod (2) and in one of the two chambers (4, 5) delimited by the two sides of the piston (502) respectively.

Description

Steering device particularly for outboard marine engines .

The present invention relates to a steering device for marine engines, particularly for outboard engines having at least: one rod 12) _f which rod is sealingly mounted in a cylindrical housing (1) sliding along said rod (2) and which rod sealingly projects out of heads (3) of the cylindrical housing (2)_#a piston (502) secured in a substantially intermediate position thereof on the rod (2) and dividing the cylindrical housing (1) in two variable volume chambers (4_*5) j two inlets/outlets (204, 205) communicating with said two chambers (4,5).

Such devices are well known and widely used. While these devices satisfactorily serve their function, 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. So the device is fastened to the transom by means of the rod. There are two types of fastening. Both cases provide 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 with holes having 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.

As regards feeding the fluid towards the two chambers of the cylinder, 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 interposing between an end of each conduit feeding the fluid for each corresponding chamber and said corresponding chamber. In the long run due to the necessary stiffness of hoses the continuous sliding movement of the cylinder can cause the material to be stressed and it can break, especially In areas coming out from the stern cockpit to cylinder fittings.

A further different arrangement provided In prior art Is to convey oil inside cylinder chambers, in order to move the cylinder with respeet to the rod, by means of two opposing conduits made inside the rod and each one coming from one of the two opposite head ends of the rod, opening In one different chamber of the two cylinder chambers respectively. That Is achieved because a through hole is made in the rod closed in an intermediate area substantially flush with the piston and having two outlets one at a chamber and the other one at the other chamber. In this regard italian patent SV2003A000027 can, be considered of the same applicant of the present application to which reference can be made in order to understand the present invention.

However regarding βuch embodiment the following drawback has been founds conventionally the feeding of oil occurs by means of a circuit that, tipically starting from the steering wheel, arrives at the steering device assembly, tipically at the transom, with two pipes both arriving from the same side of the steering assembly. That leads the feeding of the two conduits to occur in the following ways a firat 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 leads a portion of the hydraulic circuit to be longer, and so to have greatest losses of pressure, i.e. the portion corresponding to the conduit whose feeding occurs at the rod end not adjacent to the side where said pipes arrive, leading 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 and they can get entrapped or can be an obstacle.

Prior art provides a further steering device wherein feeding oil to cylinder chambers occurs always by means of two feeding conduits provided in the rod and each one ending by their feeding or connecting end at one of the two opposite head ends of the rod, In order to overcome above drawbacks, one of the two inlet openings of one of the two conduits and provided on one of the two opposite rod ends is connected to a terminal connecting fluid feeding pipes that is provided on the rod end wherein the feeding opening of the first conduit opens. That occurs by means of 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 means of a fastening shaft whose ends connect to corresponding rod ends by means of end radial arms, said connecting conduit is made inside arms and said fastening shaft these members being suitably as tubular ones. In such prior art device hydraulic fluid or 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 head side corresponding to the head end of the rod. In order to convey oil inside each conduit adjacent to inlets/outletβ 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 hole inside radial arms or rod supporting means, as it can be clearly seen in annexed figures 8 and 9 showing prior art arrangement. Such embodiment clearly leads to a considerable asymmetry of flow resistance of the two circuit parts connecting the steering device pump to each of the two chambers of the steering cylinder and in addition it leads to a considerable rise in cost both as regards merely the cost of the fastening shaft and of radial arms connecting rod ends to said fastening shaft/ and as regards time and costs for mounting it 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 traveling on said fastening point. Therefore in this ease,, the connection of radial arms to the rod and to the fastening shaft has to be enough strong, and it muβt also produce a stable and lasting seal and above all it has not to be compromised by forces twisting the parallelogram composed of the rod, the parallel shaft and connecting radial arms.

The object of the present invention is to provide a steering device according to the preamble of claim 1, which might simply and inexpensively obviate the drawbacks of known steering devices. The invention fulfils the above aims by providing a steering device for marine engines, particularly for outboard engines having at leaøts one rod, which rod is sealingly mounted in a cylindrical housing sliding along said rod and which rod sealingly projects out of heads of the cylindrical housing/ a piston secured in a substantially intermediate position thereof on the rod and dividing the cylindrical housing in two variable volume chambers; two inlets/outlets each one communicating with one of said two chambers by a separated feeding conduit of said two chambera, said conduits being further obtained inside the rod and which conduits by their inlet/outlet open at only one of said two ends of said rod and in one of the two chambers delimited by the two sides of the piston respectively.

The two conduits can be provided as two axial holes parallel one with respect to the other and deriving from the same rod head end whereas they 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 one provided on a rod portion, i.e. the so called half-rod on one of the two sides of the piston. Alternatively, the two conduits can be provided as conduits placed one inside the other, the rod being made by 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, particularly coaxial one with respect to the other. 2acb 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 and upon which the engine/propulaor assembly is rotatably mcmnted about a substantially vertical steering axis, and which, 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 an hydraulic double-acting actuating cylinder composed of a cylindrical housing wherein at least a rod is mounted, which rod sealingly projects out of heads of the cylindrical housing carrying an intermediate separating piston which divides the cylindric housing into a first and a second variable volume chamber and the rod in a first and second rod portions and wherein, each one of said first and second chambers is operatively connected to a corresponding inlet/oulet for the hydraulic fluid, jso called first inlet/outlet for the first chamber and so called second inlet/outlet for the second chamber (5) i at least a means for fastening the cylinder-rod assembly to the transom and/or to the terminal fastening the engine to the transom, the at least one rod_f 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 in a not sliding way -with respect thereto, and wherein 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 chamber, 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 allows to overcome prior art drawbacks shown above in details.

The fact of having two conduits for feeding said two chambers, βaid conduits being obtained both in the rod and such to release at only one of the two ends of said rod, allowa to feed said conduits by two inlets/outlets for the hydraulic fluid or oil made 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. Thus the two portions of the hydraulic circuit are 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, i.e. a rod part substantially corresponding to a half length of the rod and a rod part as a member physically separated from a further rod part has to be intended. In the first case the division of the rod into half-rods is stabstantialIy 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. So the term half-rod is not to be considered limited to a separated structural part corresponding to an half of the total length of the rod.

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

Fig.l is a plant view of an embodiment of the device object of the present invention.

Fig.2 is a front view of the device of fig.l. Fig.3 is a section plant view of a first embodiment of the device object of the present invention wherein conduits are coaxial on the same rod portion.

Fig.4 is a section plant view of a detail of the first embodiment of fig.3. Fig.5 and 6 are a section plant view 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 plant view of a detail of the fisrt embodiment shown, in figs. 5 and 6.

Pig. 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.

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 a 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 being near the corresponding inlet/outlet 91 takes 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 brakets 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 bendø of the circuit under analysis. Moreover it is to be noted that as regards the hydraulic circuit corresponding to inlet/outlet 90, it must passes 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 processings and many sealingly fastening sites.

In fig. 9 a second prior art embodiment is shown; in this case there is an 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 a 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 this case 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 to provide, as shown, the hydraulic pipe or conduit corresponding to inlet/outlet 90 to be longer. Again this leads the hydraulic circuit to be unbalanced, since as above arguments, the hydraulic circuit corresponding to inlet/outlet 90 is longer and more tortous that the hydraulic circuit corresponding to the inelt/outlet 91. In addition in this case it is to be considerd 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 so it can cause hindrance.

The present invention solves the above prior art drawbacks by providing a steering device for marine engines/ shown generally in. fig. 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 and 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 presence of an 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. The present invention hydraulic circuit is to be considered as a balanced hydraulic circuit, wherein both branches of the circuit have the same length, winding and so the same losses of pressure.

Referring to figs. 1 and 2, it can be noted from the outside the configuration of the device according to the present inventions the device comprises an 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^p connected to ends of the rod 2 and to a fastening means 206, which is substantially parallel to the rod

2.

Moreover the device comprises a steering arm 7 secured to the cylindrical houβing 1 and two inlets/outlets 204 , 205 for feeding/discharging the hydraulic fluid.

According to a characteristic of said first end the said 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 figs. 3 and 4 conduits 104 and 105 are provided to be 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 operativβly connected on one side with the corresponding inlet/outlet 204 and 205 on the other side with the corresponding communicating opening 404 and 405 for the passage of the hydraulic fluid, or oil.

Substantially 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 driveβ 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 is 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 obviously a translation of the cylinder ia obtained in the opposite direction.

In the embodiment shown in fig, 3 it is possible to note that the conduit 105 iβ substantially concentric with respect to the conduit 104 and it projects beyond the piston or at the piston and it 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 it can be seen the inlet/outlet 204 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 it communicates with the variable volume chamber 4. Both the conduit 104 and the conduit 105 are obtained on the same rod sector 102, 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 made as an hollow one, 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 hole in order to cause the hydraulic fluid to pass directed towards the chamber 5 made 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 faatened 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 chamber 4 and 5.

Sealingly 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 channel can be made not in a concentric way, while being both obtained inside the same half-rod/ for example said two conduits 104' and 105' _f 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' . 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 the half-rod wherein conduits are obtained extends through an hole in the piston beyond the piston itself to an opening 405' for communicating the conduit 105 with 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 embodimenta, and particularly with reference to figs. 4 and 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 provided to be connected to a coupling means 9, 9' having inside it corresponding connections for inlets/outlets 204 and 205 or 204' and 205' and. necessary conduits. Th.us the rod 2, 2' is not directly interfaced with the supporting bracket 106, 106' in the preferred arrangement, but they are Interfaced by means of said coupling means, constituting a kind of head of the half-rod 102, 102'.

Referring to the preferred embodiment of the coupling means 9 of fig.4 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 sueh that the second conduit 105 opens directly at the second inlet/outlet 205, whereas the first conduit 104 opens in a small duet 109 that in turn opens at the first inlet/outlet 204,

Referring to fig.? it is possible to note that in this case, conduits 104' and 105' are substantially parallel one with respect to the other, the coupling means 9' has a first and second duct 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, providing the half-rod with conduits to have a kind of head composed of above coupling means, is that the bracket 106 or 106' has a very simple manufaeturing, since ducts are obtained in the coupling means and not in the bracket, leading the manufacturing of the rod to be very simple.

Further characteristics and improvements are object of claims .

Claims

1. Steering device for marine engines, particularly for outboard engines having at leasts one rod (2) , which rod (2) is sβalingly mounted in a cylindrical housing (1) sliding along said rod (2) and which rod (2) sβalingly projects out of heads of the cylindrical housing, a piston (502) secured in a substantially intermediate position thereof on the rod (2) and dividing the cylindrical housing (1) in two variable volume chambers (4, 5) ; two inlets/outlets

(204/ 205) each one communicating with one of said two chambers (4, 5) by a separated feeding conduit (104,

105) of said two chambers (4, 5} , characterized inn that said conduits (104, 105) are further obtained inside the rod (2) and which conduits (104, 105) by their inlet/outlet (204 , 205) open at one same end of the two ends of said rod (2) and in one of the two chambers (4,5) delimited by the two sides of the piston (502) respectively

2. Device according to claim 1, characterized in that the two conduits (104, 105) are composed of two axial holes parallel one with respect to the other and deriving from the same rod head end whereas they end with a radial portion opening at the outer surface of the rod in, two sites spaced in the axial direction of the rod (2) and each one provided on a rod portion, i.e. the so called half-rod on one of the two sides of the piston.

3. Device according to claim 1, characterized in that the two conduits (104, 105) are composed of conduits placed one inside the other, the rod (2) being made by 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, particularly coaxial one with respect to the other.

4. De-vice according to claim 3/ characterized in that each conduit communicates individually with only one of the two chambers on the two opposite sides of the piston.

5. Hydraulic steering device according to one ore more of the preceding claims, characterized in that it comprises a terminal (6) fastening the outboard engine to the boat transom by tightening it and/or by means of a clamp and upon which the engine/propulsor assembly is rotatably mounted about a substantially vertical steering axis, and which 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 an hydraulic double-acting actuating cylinder composed of a cylindrical housing (1) wherein at least a rod (2) is mounted/ which rod sβalingly projects out of heads (3) of the cylindrical housing (1) carrying an intermediate separating piston (502) which divides the cylindric housing into a first and a second variable volume chamber (4/ 5) and the rod in a first and second rod portions (102, 202) and wherein each one of said first and second chambers (4, 5) is operatively connected to a corresponding inlet/oulet for the hydraulic fluid, so called first inlet/outlet (204) for the first chamber (4) and so called second Inlet/outlet (205) for the second chamber (5) ; at least a means (6) for fastening the cylinder-rod assembly to the transom and/or to the terminal fastening the engine to the transom, the at least one rod, at least a transmission arm (7) between, the cylinder and coupling means steering the outboard engine integral with the engine, are fastened to the fastening means (6) in, a not sliding way with respect thereto? and wherein at least said first and second inlets/outlets (204, 205) of said first and second cylinder chambers (4, 5) are connected to a first conduit (104) for said first inlet/outlet and a second conduit (105) for said second inlet/outlet respectively_^ said first and second conduit (104, 105) being obtained inside the rod (2) and extending from the outer end of the rod to one or more openings (404, 405) communicating with the corresponding first (4) or second (5) cylinder chamber, which openings are provided adjacent to the side of the piston (502) faced towards the corresponding output cylinder head (3) of said rod and said first and second conduit (104, 105) are obtained both, in only one of said first (102) or second (202) rod portion, and both open at only the same end of the two opposite ends of the rod (2) wherein said first and said second inlet/outlet (204, 205) are obtained.

6. Hydraulic steering device according to one or more of the preceding claims, characterized in that said first conduit 104 leads to the first chamber (4) on the side of the piston (502) faeed towards said end by at least a coimunieating 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 at least a second communicating opening (405) .

7 » Hydraulic steering device according to one or more of the preceding claims, characterized in that said conduits (104, 105) are provided to be coaxial one with respect to the other.

8. Hydraulic steering device according to claim 6 characterized in that said first and second coaxial conduits (104 and 105) are operatively connected on one aide with the corresponding first and second inlet/outlet (204, 205) and on the other side with the corresponding comπrnziicating opening (404, 405) for the passage of the hydraulic fluid_f or oil.

9. Hydraulic steering device according to one or more o£ the preceding claims, characterized in that the first variable volume chamber (4) is fed ox discharged from the hydraulic fluid or oil fed to the chamber through the commtinication opening (404) by the first conduit (104) fed in turn by the inlet/outlet (204) and the second variable volume chamber (5) is fed or discharged from the hydraulic fluid or oil fed to the chamber through, the second communication opening (405) by the second conduit (105) fed in turn, by the second Inlet/outlet (205) .

10. Hydraulic steering device according to one or more of the preceding claims, characterized in that the second conduit (105) is substantially concentric with respect to the first conduit (104) and it projects beyond the piston (502) or at the piston itself.

11. Hydraulic steering device according to one or more of the preceding claims, characterized in that said second conduit (105) communicates with the variable volume chamber 5 by means of second opening/openings (405) and it is connected at the end of the rod (2) with the second inlet/outlet (205) .

12. Hydraulic steering device according to one or more of the preceding claims, characterized in that said first channel (104) is positioned, concentrically and outside said second channel (105) .

13. Hydraulic steering device according to one or more of the preceding claims, characterised in that at the piston 502 said first channel has first communicating openings (404} for communicating with said first chamber (4) .

14. Hydraulic steering device according to one or more of the preceding claims, characterized in that said first communicating openings (404) are placed radially with respect to the longitudinal axis of said first channel (104) .

15. Hydraulic steering device according to one or more of the preceding claims, characterized in that both the first conduit (104) and the second conduit (105) are obtained, on the same portion of the rod (2) ,

16. Hydraulie steering device according to one or more of the preceding claims, characterised in that the rod potion (202) not having said first and second channels is made as an hollow or øolid one.

17. Hydraulic steering device according to one or more of the preceding claims, characterized In that the piston (502) is provided with, an hole in order to cause the hydraulic fluid to pass directed towards the chamber (5) made at the rod sector (202) not having said first and second channel.

18. Hydraulic steering device according to one or more of the preceding claims, characterized in that walls of the variable volυme chambers (4, 5) are composed by sealingly fastened heads (3, 3') of t.hθ cylindrical housing,. by the outer surface of the corresponding rod øector (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 chamber (4 and 5) .

19. Hydraulic steering device according to one or more of the preceding claims, characterized in that sealingly closures are provided between various members of the actuating cylinder IB order to avoid leaks of hydraulic fluid or oil.

20. Hydraulic steering device according to one or more of the preceding claims, characterized in that said first and second channel (104' and 105') are made in the same half-rod not in a concentric way.

21. Hydraulic steering device according to one or more of the preceding claims, characterized in that said first and second channel (104' and 105') are made in the same half-rod parallel one with respect to the other.

22. Hydraulic steering device according to one or more of the preceding claims, characterized in that said first and second channels (104' and 105') extend from the end of the rod sector (202') at least to the piston (502').

23. Hydraulic steering device according to one or more of the preceding claims, characterized in that 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') .

24. Hydraulic steering device according to one or more of the preceding claims, characterized in that the two conduits (104') and (105') are preferably made parallel one with respect to the other and in that the conduit (105⁷ ) i.e. the one opening in the chamber (5') placed in the half-rod where conduits are obtained extends through an hole in the piston beyond the piston itself to an opening (405') for communication of the conduit (105') with the chamber (5').

25. Hydraulic steering device according to one or more of the preceding claims, characterized in that passage openings (404' and 405') are made as adjacent to the piston (502').

26. Hydraulic steering device according to one or more of the preceding claims, characterized in that 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.

27. Hydraulic steering device according to one or more of the preceding claims, characterized in that the ending portion of the half-rod (102) having conduits

28. Hydraulic steering device according to one or more of the preceding claims, characterized in that inlets/outlets (204 and 205 or 204' and 205') ar© connected to a coupling means (9, 9').

29. Hydraulic steering device according to one or more of the preceding claims, characterized in that it has inside corresponding connections for inlets/outlets (204 and 205 or 204' and 205') and at least a duct for each inlet/outlet.

30. Hydraulic steering device according to one or more of the preceding claims, characterized in that the rod (2, 2') is not directly interfaced with the supporting bracket (106, 106'), but they are interfaced by means of said coupling means, constituting a kind of head of the half-rod (102, 102').

31. Hydraulic steering device according to one or more of the preceding claims, characterized in that In the case of the first and second conduit (104 and 105) being coaxial, 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) .

32. Hydraulic steering device according to one or more of the preceding claims, characterized in that in the case of conduits (104' and 105') being substantially parallel one with respect to the other, the coupling means (9' ) has a first and second duct (109' and 209') connected to said conduits (104' and 105'), which ducts (109' and 209') open at corresponding inlets/outlets (204' and 205').

33. Hydraulic steering device according to one or more of the preceding claims, characterized in that the half-rod provided with, conduits has a kind of head composed of said coupling means {9, 9^r ) , ducts being obtained in the coupling means and not in the bracket.

34. Hydraulic steering device according to one or more of the preceding claims,, characterized in that ending parts of said rod have means tightening to said brackets which, are composed of a thread on the outer surface of said rod, and of two holding nuts each one provided on one of the two opposite sides of terminals of said plate.

35. Hydraulic steering device according to one or more of the preceding claims, characterized in that said arm is provided with means for rotating/translating inside the seat obtained on the cylinder such for example bayonet joints, male thread/female thread joints, nut/lock nut and in addition on its body it has means for rotating/translating the ending part of the arm with respect to the arm body, such as for example male thread/female thread joints,, nut/lock nut and bayonet joints.