CN108778925B

CN108778925B - Hydraulic steering device and ship

Info

Publication number: CN108778925B
Application number: CN201780011897.XA
Authority: CN
Inventors: 土桥修司
Original assignee: Mitsubishi Heavy Industries Marine Machinery and Equipment Co Ltd
Current assignee: Mitsubishi Heavy Industries Marine Machinery and Equipment Co Ltd
Priority date: 2016-02-22
Filing date: 2017-01-10
Publication date: 2020-06-12
Anticipated expiration: 2037-01-10
Also published as: KR20180102645A; WO2017145532A1; JP6660205B2; KR102041064B1; JP2017149181A; CN108778925A

Abstract

The hydraulic steering device includes: plungers (8, 9) to which a rudder stock (4) is rotatably attached, and a rudder shaft (2) fixed to the rudder stock shaft; a pair of hydraulic cylinders disposed opposite to each other; and bypass oil passages (28, 29) configured to enable communication between the working chambers of the pair of hydraulic cylinders based on the pressure of the hydraulic oil in the pair of hydraulic cylinders.

Description

Hydraulic steering device and ship

Technical Field

The present invention relates to a hydraulic steering device and a ship.

Background

Conventionally, as a steering device for operating a rudder of a ship, a hydraulic steering device of a laproson (Rapson) slide type is known. In the hydraulic steering apparatus, a large rotational force can be given to a rudder shaft connected to a rudder plate, but when an obstacle such as ice floe or floating wood comes into contact with the rudder plate and the rudder plate is impacted, a large surge pressure may be generated in a hydraulic system, which may cause damage to peripheral equipment.

In order to cope with such surge pressure, a hydraulic circuit including a relief valve that operates when the hydraulic pressure reaches a predetermined value or more has been conventionally used in such a hydraulic steering device. For example, patent document 1 discloses that by providing an energy absorbing device such as an accumulator in such a hydraulic circuit, surge pressure generated when the rudder plate receives an impact force can be absorbed more effectively.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 60-182397

Problems to be solved by the invention

In recent years, various standards and regulations for preventing damage to various devices mounted on ships have been established for icebreakers and the like used for developing polar routes. For example, in the case of the hydraulic steering device, it is necessary to provide a relief valve in two stages in the hydraulic circuit and to allow the second-stage relief valve to cope with a flow rate corresponding to a steering speed of up to 40deg/sec, thereby coping with a large surge pressure generated when an obstacle such as an ice block or a floating wood hits the rudder plate. However, the piping and the safety valve used in the conventional steering device can only cope with a flow rate corresponding to a steering speed of about 6deg/sec at present.

In order to meet such a demand, for example, it has been studied to additionally provide a new relief valve in the hydraulic circuit or to increase the diameter of each hydraulic line, but both of these require a significant design change of the existing apparatus, which leads to an increase in production cost and an increase in size of the apparatus. In the above-mentioned patent document 1, since it is necessary to newly provide an energy absorption device to a hydraulic circuit for supplying the hydraulic oil to the cylinder of the hydraulic steering device, it is necessary to change the design of the hydraulic circuit somewhat.

Disclosure of Invention

At least one embodiment of the present invention has been made in view of the above problems, and an object of the present invention is to provide a hydraulic steering apparatus and a ship that can control a design change of a hydraulic circuit for supplying hydraulic oil to a hydraulic cylinder and can cope with a large surge pressure.

Means for solving the problems

(1) In order to solve the above-described problems, a hydraulic steering apparatus according to at least one embodiment of the present invention includes: a plunger to which a tiller is rotatably mounted, a tiller shaft to which a tiller shaft is fixed; a pair of hydraulic cylinders into which both ends of the plunger are respectively fitted and which are disposed to be opposed to each other; a bypass oil passage configured to enable communication between the working chambers of the pair of hydraulic cylinders based on a pressure of the hydraulic oil in the pair of hydraulic cylinders; and a hydraulic circuit for supplying the working oil to the pair of hydraulic cylinders, the bypass oil passage including: a communication path formed between the working chambers of the pair of hydraulic cylinders; a first relief valve provided in the communication path and configured to operate based on a pressure of the working oil flowing through the communication path, the hydraulic circuit including a second relief valve configured to operate based on a pressure of the working oil flowing through the hydraulic circuit, the first relief valve being configured to operate at a higher pressure than the second relief valve.

The configuration according to the above (1) includes the bypass oil passage configured to enable communication between the working chambers of the pair of hydraulic cylinders based on the pressure of the hydraulic oil. Accordingly, when surge pressure is generated in the hydraulic fluid due to, for example, an impact of an obstacle or the like, the working chambers communicate with each other via the bypass oil passage, and the hydraulic fluid flows from the high pressure side to the low pressure side of the pair of hydraulic cylinders, thereby relaxing (absorbing) the surge pressure. By providing such a bypass oil passage, it is possible to cope with a large surge pressure while suppressing a design change of a hydraulic circuit for supplying hydraulic oil to the hydraulic cylinder to a small amount.

According to the configuration of the above (1), it is possible to realize a hydraulic steering device that: with a simple structure in which a relief valve is provided in a communication path that communicates between the working chambers, it is possible to effectively prevent damage to the equipment due to surge pressure.

According to the structure of the above (1), the first relief valve included in the bypass oil passage operates at a higher pressure than the second relief valve included in the hydraulic circuit. Therefore, for a small surge pressure, the first relief valve does not operate (i.e., the hydraulic cylinders are not communicated with each other through the bypass oil passage), and the second relief valve in the hydraulic circuit operates only to cope with the small surge pressure. On the other hand, for a high surge pressure, the second relief valve and the first relief valve are both operated to cope with the surge. In this way, since the first relief valve operates within a required range in accordance with the magnitude of the surge pressure, the number of operations of the first relief valve can be suppressed to a small number without unnecessarily increasing the number of operations. This suppresses the consumption of the bypass oil passage, and a steering device suitable for a long-life design can be realized.

(2) In several embodiments, in the structure of the above (1), the communication path is formed inside the plunger.

According to the configuration of the above (2), by forming the communication passage constituting the bypass oil passage inside the plunger, the hydraulic steering apparatus can be realized with a compact configuration as compared with a case where the bypass oil passage is formed using a pipe or the like outside the plunger, for example. In addition, this configuration can be realized by design changes of limited components including the plunger as a center, compared to a conventional device having no bypass oil passage, and therefore, is advantageous in reducing production cost.

(3) In several embodiments, in the structure of the above (2), the first relief valve is installed to be exposed to the outside of the plunger.

According to the configuration of the above (3), the first relief valve is a movable portion in the constituent element of the bypass oil passage, and therefore, the frequency of maintenance can be expected to be high. Thus, the operator can easily access the first relief valve when performing maintenance, and can smoothly perform maintenance work such as replacement and repair.

(4) In some embodiments, in the structure of the above (1), the communication path is configured to be larger than a diameter of the hydraulic circuit.

According to the configuration of the above (4), by configuring the communication path configuring the bypass oil passage to be larger than the diameter of the hydraulic circuit, when the working chambers communicate with each other through the bypass oil passage, the flow rate of the working oil flowing based on the differential pressure between the working chambers can be increased, and further, the hydraulic steering apparatus capable of coping with a larger surge pressure can be realized. Conversely, by increasing the diameter of the communication path without changing the specification of the hydraulic circuit for supplying the hydraulic oil to the hydraulic cylinder, it is possible to cope with a large surge pressure. In this case, by increasing the diameter of the hydraulic circuit to cope with a large surge pressure, the complexity and size of the entire apparatus can be avoided, and the apparatus can be realized with a relatively compact and small configuration.

(5) In some embodiments, in the configuration of (1), the pair of hydraulic cylinders are disposed in a front-rear direction of the steering shaft, respectively, and the bypass oil passages are provided independently.

According to the configuration of the above (5), the pair of hydraulic cylinders having the bypass oil passage between the working chambers are provided in the front-rear direction of the rudder shaft, respectively. Since the bypass oil passages are provided independently of each other, even if a failure occurs in one of the bypass oil passages, the above-described function can be achieved by the other bypass oil passage, and therefore, a hydraulic steering device having further excellent reliability can be realized.

(6) In order to solve the above problems, a ship according to at least one embodiment of the present invention includes the hydraulic steering device of the above configuration (1).

ADVANTAGEOUS EFFECTS OF INVENTION

According to at least one embodiment of the present invention, there can be provided a hydraulic steering device and a ship: the hydraulic circuit for supplying hydraulic fluid to the hydraulic cylinder can be designed to be less changed, and can cope with a large surge pressure.

Drawings

Fig. 1 is an overall configuration diagram of a hydraulic steering device according to at least one embodiment of the present invention.

Fig. 2 is a hydraulic circuit diagram of the hydraulic steering apparatus of fig. 1.

Fig. 3 is a cross-sectional view showing a configuration example of the vicinity of a plunger of the hydraulic steering device according to the second embodiment.

Fig. 4 is a modification of fig. 3.

Detailed Description

Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the constituent members described as the embodiments or shown in the drawings are not intended to limit the scope of the present invention, and are merely illustrative examples.

For example, the expression "in a certain direction", "along a certain direction", "parallel", "orthogonal", "central", "concentric" or "coaxial" indicates a relative or absolute arrangement, and strictly speaking, not only the arrangement as described above, but also a state in which relative displacements occur with a tolerance, an angle, a distance, or the like, which can obtain substantially the same action.

For example, the expression indicating the shape of a square, a cylinder, or the like indicates not only the shape of a geometrically strict square, a cylinder, or the like, but also shapes including a concave-convex portion, a chamfered portion, and the like, within a range in which the same effect can be obtained.

On the other hand, the expression "including", "having", "containing" or "containing" a certain constituent element is not an exclusive expression excluding the presence of other constituent elements.

Fig. 1 is an overall configuration diagram of a hydraulic steering device 1 according to at least one embodiment of the present invention, and fig. 2 is a hydraulic circuit diagram of the hydraulic steering device 1 of fig. 1.

The hydraulic steering apparatus 1 is a sliding type larpson (Rapson) steering apparatus that drives a rudder via a rudder shaft 2 connected to a rudder (not shown) of a ship. A rudder stock (tiller) 4 provided with the rudder shaft 2 is rotatably attached to

plungers

8 and 9 via plunger pins 6 and 7 provided on both the front and rear sides of the rudder shaft 2, respectively. Both ends of the plunger 8 are fitted into a pair of

hydraulic cylinders

10a and 10b disposed to face each other in the rudder direction, and both ends of the plunger 9 are fitted into a pair of

hydraulic cylinders

10c and 10d disposed to face each other in the rudder direction.

As shown in fig. 2, the

hydraulic cylinders

10a, 10b have working

chambers

12a, 12b defined by the top ends of the plungers 8 and the inner walls of the cylinders. The

working chambers

12a, 12b are connected to a pump unit 16 via

hydraulic circuits

14a, 14 b. The pump unit 16 includes an electric motor 18 that can be driven by electric power supplied from the inside of the ship, and a hydraulic pump 20 coupled to the electric motor 18. In the

hydraulic circuits

14a, 14b, a valve unit 22 functioning as a direction switching valve is provided between the pump unit 16 and the

hydraulic cylinders

10a, 10b, and the valve unit 22 distributes the hydraulic oil supplied from the pump unit 16 to the

hydraulic circuits

14a, 14 b.

The valve unit 22 includes a relief valve 24, and the relief valve 24 is provided between the

hydraulic circuits

14a and 14b through the valve unit 22. The relief valve 24 is configured to operate based on the pressure of the hydraulic oil flowing through the

hydraulic circuits

14a, 14 b. In the present embodiment, in particular, the hydraulic circuit 14a and the hydraulic circuit 14b are configured to operate when the differential pressure therebetween exceeds a predetermined value P1 set in advance, and the hydraulic oil is released from the high pressure side to the low pressure side of the hydraulic circuit 14a and the hydraulic circuit 14b, thereby suppressing an increase in the pressure of the hydraulic oil.

The

hydraulic cylinders

10c and 10d have working

chambers

12c and 12d defined by the distal end of the plunger 9 and the cylinder inner wall. The pump unit 17 is connected to the working

chambers

12c and 12d via the

hydraulic circuits

14c and 14 d. The pump unit 17 includes an electric motor 19 that can be driven by electric power supplied from the inside of the ship, and a hydraulic pump 21 connected to the electric motor 19. In the

hydraulic circuits

14c and 14d, a valve unit 23 functioning as a direction switching valve is provided between the pump unit 17 and the

hydraulic cylinders

10c and 10d, and the valve unit 23 is used to distribute the hydraulic oil supplied from the pump unit 17 to the

hydraulic circuits

14c and 14 d.

The valve unit 23 includes a relief valve 25, and the relief valve 25 is provided between the

hydraulic circuits

14a and 14b through the valve unit 23. The relief valve 25 is configured to operate based on the pressure of the hydraulic oil flowing through the

hydraulic circuits

14c, 14 d. In the present embodiment, in particular, the hydraulic circuit 14c and the hydraulic circuit 14d are configured to operate when the differential pressure therebetween exceeds a predetermined value P1 set in advance, and the hydraulic oil is released from the high pressure side to the low pressure side of the hydraulic circuit 14c and the hydraulic circuit 14d, thereby suppressing an increase in the pressure of the hydraulic oil.

Further, the

valve units

22, 23 include a bypass line 26 linking between the

hydraulic circuits

14a and 14d and a bypass line 27 linking between the

hydraulic circuits

14b and 14 c. The hydraulic oil from the

pump units

16, 17 is configured to be able to be supplied to the respective

hydraulic cylinders

10a, 10b, 10c, 10d via

bypass lines

26, 27. For example, even when only one of the

pump units

16 and 17 is operated, the hydraulic oil can be supplied to the respective

hydraulic cylinders

10a, 10b, 10c, and 10d via the

bypass lines

26 and 27. Further, even if both the

pump units

16, 17 are operated, the hydraulic oil can be supplied to the respective

hydraulic cylinders

10a, 10b, 10c, 10 d.

A bypass oil passage 28 is provided in the pair of

hydraulic cylinders

10a, 10b corresponding to the plunger 8, and the bypass oil passage 28 is configured to allow the working chamber 12a and the working chamber 12b to communicate with each other based on the pressure of the hydraulic oil in the pair of

hydraulic cylinders

10a, 10 b. In the present embodiment, the bypass oil passage 28 includes a communication passage 30 that communicates between the working

chambers

12a and 12b, and a relief valve 32 provided in the communication passage 30. The relief valve 32 is configured to operate when the pressure of the hydraulic oil passing through the relief valve 32 exceeds a predetermined value P2 set in advance, thereby opening the hydraulic oil from the high pressure side to the low pressure side of the working chamber 12a and the working chamber 12b, and suppressing an increase in the pressure of the hydraulic oil.

A bypass oil passage 29 is provided in the pair of

hydraulic cylinders

10c, 10d corresponding to the plunger 9, and the bypass oil passage 29 is configured to allow the working chamber 12c and the working chamber 12d to communicate with each other based on the pressure of the hydraulic oil in the pair of

hydraulic cylinders

10c, 10 d. In the present embodiment, the bypass oil passage 29 includes a communication passage 31 that communicates between the working chamber 12c and the working chamber 12d, and a relief valve 33 provided in the communication passage 31. The relief valve 33 is configured to operate when the pressure of the hydraulic oil passing through the relief valve 33 exceeds a predetermined value P2 set in advance, thereby opening the hydraulic oil from the high pressure side to the low pressure side of the working chamber 12c and the working chamber 12d, and suppressing an increase in the pressure of the hydraulic oil.

By providing such

bypass oil passages

28, 29, in the hydraulic steering device 1, when a large surge pressure is generated in the hydraulic fluid due to an impact of an obstacle or the like, the working chambers communicate with each other via the

bypass oil passages

28, 29, so that the hydraulic fluid flows from the high pressure side to the low pressure side of the pair of hydraulic cylinders, and the surge pressure is alleviated (absorbed), thereby effectively preventing equipment damage due to the generation of the surge pressure.

The hydraulic steering apparatus 1 includes the

relief valves

24 and 25 in the

valve units

22 and 23 as described above in addition to the

bypass oil passages

28 and 29 as surge pressure relief means. In the present embodiment, in particular, the

relief valves

32 and 33 are configured to be operated at a pressure higher than the

relief valves

24 and 25 by adjusting the balance between the operation reference value P1 of the

relief valves

24 and 25 and the operation reference value P2 of the relief valves 32 and 33 (that is, a relationship of P1< P2 is established). Therefore, for a small surge pressure (P < P2), the

relief valves

32 and 33 are not operated (that is, the bypass oil passage 28 does not communicate between the working chamber 12a of the hydraulic cylinder 10a and the working chamber 12b of the hydraulic cylinder 10b, and the bypass oil passage 29 does not communicate between the working chamber 12c of the hydraulic cylinder 10c and the working chamber 12d of the hydraulic cylinder 10 d), and the surge pressure is relieved only by the operation of the

relief valves

24 and 25 in the

hydraulic circuits

14a, 14b, 14c, and 14 d. On the other hand, for a high surge pressure (P2 ≦ P), the

relief valves

32, 33 operate in addition to the

relief valves

24, 25, thereby relieving the surge pressure.

In this way, since the

relief valves

32 and 33 are operated within a required range in accordance with the magnitude of the surge pressure, the number of operations of the

relief valves

32 and 33 can be suppressed to be small, and the number of operations can not be unnecessarily increased. That is, it is possible to cope with a large surge pressure that is difficult to handle only by the

relief valves

24, 25 of the

valve units

22, 23, and it is possible to prevent the number of times of operation of the

bypass oil passages

28, 29 from being unnecessarily increased. This suppresses consumption of the

bypass oil passages

28 and 29, and ensures excellent reliability for a long period of time.

The

communication paths

30 and 31 constituting the

bypass oil passages

28 and 29 may be formed larger in diameter than the

hydraulic circuits

14a, 14b, 14c, and 14 d. By configuring the

communication paths

30 and 31 constituting the

bypass oil passages

28 and 29 to be larger than the diameters of the

hydraulic circuits

14a, 14b, 14c, and 14d, when the working chamber 12a and the working chamber 12b communicate with each other through the bypass oil passage 28 and the working chamber 12c and the working chamber 12d communicate with each other through the bypass oil passage 29, the flow rate of the working oil flowing based on the differential pressure between the working chamber 12a and the working chamber 12b and the differential pressure between the working chamber 12c and the working chamber 12d can be increased, and the hydraulic steering device 1 capable of coping with a larger surge pressure can be realized.

The degree of relaxation of the surge pressure obtained when the

bypass oil passages

28, 29 are operated depends on the capacities of the

communication passages

30, 31 and the

relief valves

32, 33 constituting the

bypass oil passages

28, 29. Therefore, the length and diameter of the

communication paths

30, 31, the capacity of the

relief valves

32, 33, and the like can also be adjusted according to, for example, the required degree of relaxation of the surge pressure. In particular, when the diameters of the

communication paths

30 and 31 are adjusted as described above, the lengths of the

bypass oil passages

28 and 29 can be kept short, which is effective in keeping the size of the device from increasing.

In addition, in the present embodiment, since the

bypass oil passages

28 and 29 can be realized by additionally providing existing devices as described above, process changes to the conventional structure including the

hydraulic circuits

14a, 14b, 14c, and 14d can be realized with little effort. Therefore, as compared with the case where the diameters of the

hydraulic circuits

14a, 14b, 14c, and 14d are increased or new structures are added to the

hydraulic circuits

14a, 14b, 14c, and 14d in order to cope with a large surge pressure, the entire apparatus can be prevented from being complicated and large-sized, and can be realized in a relatively compact and small-sized structure.

The two

bypass oil passages

28, 29 are provided independently of each other so as to correspond to the two

plungers

8, 9, respectively. Therefore, even if a failure occurs in one of the bypass oil passages, the surge pressure can be reduced to a greater or lesser extent by the other bypass oil passage, and therefore, excellent reliability can be obtained.

In the present embodiment, an example is described in which an independent bypass oil passage is provided between the working chambers corresponding to the common plunger (between the working

chambers

12a and 12b, or between the working

chambers

12c and 12 d), but an independent bypass oil passage may be provided between the working chambers of the hydraulic cylinders disposed adjacent to each other (for example, between the working

chambers

12a and 12c, or between the working

chambers

12b and 12 d) of the working chambers corresponding to the different plungers.

(second embodiment)

Next, a hydraulic steering device 1' of a second embodiment will be described with reference to fig. 3 and 4. Fig. 3 is a cross-sectional view showing a configuration example of the vicinity of the

plungers

8, 9 of the hydraulic steering device according to the second embodiment, and fig. 4 is a modification example of fig. 3.

Note that the same reference numerals are given to the structures corresponding to the above embodiments, and overlapping descriptions are appropriately omitted.

In the above embodiment, the

communication paths

30 and 31 constituting the

bypass oil passages

28 and 29 are constituted as pipes, but in the present embodiment, the inside of the

plungers

8 and 9 is constituted as a hollow shape. The

communication paths

30 and 31 are formed to extend in the longitudinal direction in the

plungers

8 and 9 from the working

chambers

12a and 12b, and the working

chambers

12c and 12d on both sides toward the center, and have openings 35 provided toward the outside near the center. The

relief valves

32, 33 constituting the

bypass oil passages

28, 29 are disposed in the opening 35 so as to close the opening 35 from the outside.

Since most of the

bypass oil passages

28 and 29 having such a configuration are housed inside the

plungers

8 and 9, the configuration of the device can be made more compact than the case where the bypass oil passages are configured by pipes surrounding the outside of the

plungers

8 and 9 as shown in fig. 2. Further, in the

bypass oil passages

28 and 29, the

relief valves

32 and 33 are movable portions, and therefore, although they are portions that require maintenance work, they can be easily accessed by an operator when performing maintenance work by being disposed so as to be exposed to the outside. As described above, according to the present embodiment, it is possible to realize a hydraulic steering apparatus having a compact structure and excellent maintenance performance.

Fig. 4 is a modification of fig. 3, and the

communication paths

30 and 31 and the

relief valves

32 and 33 may be disposed inside the

plungers

8 and 9, so that the entire

bypass oil passages

28 and 29 may be housed inside the

plungers

8 and 9. In this case, the operability from the outside of the

safety valves

32, 33 is inferior as compared with the embodiment of fig. 3, but the

communication paths

30, 31 can be formed into simple shapes extending in the longitudinal direction of the

plungers

8, 9, and there is an advantage in layout that design and the like can be made without considering interference with the tiller 4.

As described above, according to the present embodiment, it is possible to provide a hydraulic steering device and a ship: the hydraulic circuit for supplying hydraulic fluid to the hydraulic cylinder can be designed to be less changed, and can cope with a large surge pressure.

Industrial applicability

The present invention can be used for a hydraulic steering device and a ship.

Description of the symbols

1 Hydraulic steering device

2 rudder shaft

4 tiller

6. 7 plunger pin

8. 9 plunger piston

10a, 10b, 10c, 10d hydraulic cylinder

12a, 12b, 12c, 12d working chamber

14a, 14b, 14c, 14d hydraulic circuit

16. 17 Pump Unit

18. 19 electric motor

20. 21 hydraulic pump

22. 23-valve unit

24. 25, 32, 33 safety valve

26. 27 bypass line

28. 29 bypass oil path

30. 31 communication path

35 opening part

Claims

1. A hydraulic steering apparatus, comprising:

a plunger to which a tiller is rotatably mounted, a tiller shaft to which a tiller shaft is fixed;

a pair of hydraulic cylinders into which both ends of the plunger are respectively fitted and which are disposed to be opposed to each other;

a bypass oil passage configured to enable communication between the working chambers of the pair of hydraulic cylinders based on a pressure of the hydraulic oil in the pair of hydraulic cylinders;

a hydraulic circuit for supplying the working oil to the pair of hydraulic cylinders,

the bypass oil passage includes:

a communication path formed between the working chambers of the pair of hydraulic cylinders;

a first relief valve provided in the communication path and configured to operate when a pressure of the hydraulic oil flowing through the communication path exceeds a preset first pressure,

the hydraulic circuit includes a second relief valve configured to operate when a pressure of the working oil flowing through the hydraulic circuit exceeds a second pressure set in advance,

the first relief valve is configured to operate at a higher pressure than the second relief valve

The communication path is configured to be larger than a diameter of the hydraulic circuit.

2. The hydraulic steering apparatus of claim 1,

the communication path is formed inside the plunger.

3. The hydraulic steering apparatus of claim 2,

the first relief valve is installed to be exposed to the outside of the plunger.

4. The hydraulic steering apparatus of claim 1,

the pair of hydraulic cylinders are disposed in the front-rear direction of the rudder shaft, and the bypass oil passages are provided independently.

5. A marine vessel, characterized by comprising a hydraulic steering device according to claim 1.