EP0102579A2

EP0102579A2 - Electro-hydraulic steering gear for watercraft

Info

Publication number: EP0102579A2
Application number: EP83108261A
Authority: EP
Inventors: Giorgio Brighi
Original assignee: SEIPEM Srl
Current assignee: SEIPEM Srl
Priority date: 1982-09-03
Filing date: 1983-08-22
Publication date: 1984-03-14
Also published as: EP0102579A3; IT8212616A0; IT1157696B

Abstract

This invention relates to a steering gear for any watercraft, particularly of small and medium tonnage, comprising a rudder hydraulic actuating unit which can be fed, alternately, by either a manual hydraulic pressure generator, constituted by a pump that can be operated manually through the steering wheel, and by a powered hydraulic pressure generator, constituted by a motor-driven pump that can be actuated through an electronic remote control transmitter, or telemotor transmitter. According to the invention, this steering gear is characterized in that the steering wheel for the manual pressure generator operates, besides the pump of the manual pressure generator, also the remote control transmitter of the powered hydraulic pressure generator.

Description

This invention relates to a steering gear for any type of watercraft, particularly of small and medium tonnage.
The steering gear according to the invention comprises a rudder hydraulic actuating unit which can be fed, alternately, by either a manual hydraulic pressure generator, constituted by a pump that can be operated manually through the steering wheel, and by a powered hydraulic pressure generator, constituted by a pump that can be driven either by a suitable electric motor or by a power take-off from the propelling engine of the watercraft, and that can be actuated through an electronic remote control transmitter.
The rudder hydraulic actuating unit is generally formed by two actuating cylinders, either of single-acting or double-acting type, or by a single double-acting actuating cylinder, or by any other suitable type of hydraulic actuator or motor, also of rotary type such as of the vane type, excentric type, or the like.
The pump that can be operated manually by means of the steering wheel is formed, preferably, by a reversible pump of any suitable type which, depending on the direction of rotation of the steering wheel, delivers the pressurized liquid in either direction to the rudder actuating unit.
The powered pump may also be formed by a reversible pump of any type, but, preferably, it is formed by a unidirectional delivery pump and is associated with a multi-way solenoid valve controlled by the electronic remote control transmitter so as to deliver the hydraulic fluid in either direction to the rudder actuating unit.
The electronic remote control transmitter is generally operated by means of a manual steering rotary member, the so-called steering handweel, by means of which and with the aid of a suitable graduated scale the desired rudder angle is obtained.
In the conventional embodiments of said steering gears, the steering wheel for operating the manual pump, and the steering handwheel for operating the electronic remote control transmitter which actuates the powered pump, are two separate members which are often considerably spaced from each other and sometimes are even arranged at two different steering stations. Therefore, not only the system is technically and constructively more complicated, but in case of any failure of the powered hydraulic pressure generator, the helmsman cannot change-over at once from the control through the steering handwheel which actuates the electronic remote control transmitter, to the control through the steering wheel which actuates the manual pump of the hydraulic pressure manual generator, and usually he must go from one station to another.
The object of the invention is to overcome these disadvantages and to ensure a technical, constructional and operative simplification of steering gears of the type described above. In particular, the object of the invention is give the helmsman the certainty to change-over immediately with no delay and without moving to some other place, from the steering through the powered hydraulic pressure generator and respective electronic remote control transmitter, to the steering through the manual hydraulic pressure generator and respective steering wheel, and vice-versa.
This object is achieved by the invention because the steering wheel operates, in addition to the pump of the manual hydraulic pressure generator, also the electronic remote control transmitter of the powered hydraulic pressure generator.
In a preferred embodiment of the steering gear according to the invention, the same manual steering element, namely the steering wheel, is coupled both to the pump of the manual hydraulic pressure generator and to the transmitter for the electronic remote control of the powered hydraulic pressure generator with suitable rations whereby, in order to move the rudder hard over to hard over through the entire amplitude thereof by means of the manual hydraulic pressure generator, a plurality of complete revolutions of the steering wheel are to be made, whereas to move the rudder hard over to hard over through the entire amplitude thereof by means of the powered pressure generator and respective electronic remote control transmitter the steering wheel is to be rotated only a fraction of the round angle, the electronic remote control transmitter being designed and/or coupled to the steering wheel so as to allow a plurality of complete revolutions thereof. For this purpose, the electronic remote control transmitter can be constructed so as to be rotated safely over two or more complete revolutions and/or coupled to the steering wheel through a slip joint.
By this arrangement, when the rudder is controlled by the steering wheel through the powered hydraulic pressure generator and respective electronic remote control transmitter, the steering wheel may continue being coupled with the pump of the manual hydraulic pressure generator, asin this instance, the total angular displacements of the steering wheel are so small (generally not larger than 70^0-100⁰) as to be substantially uninfluent on the manual hydraulic pressure generator. Preferably, according to a further characteristic of the invention, the rotation amplitude of the steering wheel may also be limited mechanically, e.g. by means of suitable stops, to the fraction of round angle required to actuate the electronic remote control transmitter. However, when the rudder is controlled by the same steering wheel, but, contrarily, through the manual hydraulic pressure generator, specifically after removing said stops limiting the rotation amplitude of said steering wheel, the latter can be rotated freely as much as required to control the rudder, since the electronic remote control transmitter can permit safely even a plurality of complete revolutions.
These and other features of the invention, and the advantages resulting therefrom will be apparent in detail from the following description of an embodiment of the steering gear according to the invention, shown by way of non-limitating example in the accompanying drawings, wherein:

Figure 1 is an electro-hydraulic diagrammatic circuit of a first embodiment of the steering gear. The hydraulic lines are shown by full lines, and the electrical lines are shown by dotted lines;
Figure 2 is a vertical axial sectional view of the helm unit for the operation of the electronic remote control transmitter by means of the steering wheel;
Figure 3 is a front elevational view thereof, the shaft of the steering wheel being in sectional view on the line III-III of Figure 2;
Figures 4 and 5 show a second embodiment of the invention.

With reference to the Figures, the numeral 1 indicates the rudder stock of a medium or smaller tonnage vessel. The rudder is actuated by means of an actuator unit comprising, in the illustrated embodiment, two hydraulic single-acting actuating cylinders 2 and 3, pivotably connected at one end 102, 103 to the hull of the vessel and at the other end (piston rod) 202, 203 to the opposite ends of the tiller 4 secured to the upper end of the rudder stock 1. The two actuating cylinders 2, 3 are hydraulically connected to both sides of a reversible hydraulic pump 5 which may be a rotary pump such as a radial plungers pump, an orbital pump, a vane pump or the like. The pump 5 also contains a small reserve of hydraulic liquid to compensate for any small leaks of the installation. The pump 5 is operated by the steering wheel 6 through the shaft 7. Usually, the steering wheel 6 is connected directly to the pump 5, i.e. the shaft 7 of the steering wheel 6 is also the shaft of the pump 5. The pump 5, manually operated through the steering wheel 6, constitutes a manual hydraulic pressure generator for actuating the rudder.
In addition to said manual hydraulic pressure generator, the invention provides a powered hydraulic pressure generator. This powered generator comprises a pump 8 which is preferably, through not necessarily, of the unidirectional delivery tupe and is driven by a suitable electric motor 9. Instead of the electric motor 9, the pump 8 may be driven either by a suitable internal combustion engine or by a power take-off from the propelling engine of the vessel. The pump 8 may be of any suitable type, such as a radial plungers pump, a gear pump or the like. Associated with the powered pump unit 8 is a multi-way solenoid valve 10 which, in its intermediate rest position shown in Figure 1, connects the delivery of the pump 8 in short-circuit manner to the suction of said pump 8. In one of the active positions of the solenoid valve 10, for example in the lower position in Figure 1, said solenoid valve 10 connects the delivery of the pump 8 to the hydraulic actuating cylinder 3 and connects the suction of the pump to the hydraulic actuating cylinder 2, thus causing a clockwise rotation of the rudder tiller 4. In the opposite active position of the solenoid valve 10, the upper position in Figure 1, said solenoid valve 10 connects the delivery of the pump 8 to the hydraulic actuating cylinder 2, and connects the suction of the pump 8 to the hydraulic actuating cylinder 3, thus inverting the connection of these two cylinders 2, 3 with respect to the first active position and causing an anticlockwise rotation of the rudder tiller 4.
The solenoid valve 10 is actuated as specified above by means of an electronic remote control system comprising a rotary remote control transmitter 11 operated by the steering wheel 6 and a rotary response transmitter 12 operated by the rudder and connected, for example, to the rudder tiller 4 through a crank 13 and connecting rod 14, and a comparator 15 connected both to the remote control transmitter 11 and response transmitter 12 and adapted to actuate the solenoid valve 10 as follows:

In a given angular position of the rudder, which has been established previously and which may be the rudder mid-position, the comparator 15 is in a balanced condition because both the remote control transmitter 11 and response transmitter 12 are in angular positions corresponding to that of the rudder. Therefore, the solenoid valve 10 is in the illustrated rest position. The pump 8 is operated continuously, but the delivery and suction sides thereof are communicating in shortcircuit manner. To move the rudder through a given angle either to starboard or to port side, the remote control transmitter 11 is moved correspondingly by means of the steering wheel 6. The comparator 15 is thus unbalanced in a given direction and moves the solenoid valve 10 to an active position wherein the pump 8 is connected to the hydraulic actuating cylinders 2, 3 so as to move the rudder in the desired direction. The response transmitter 12 moves together with the rudder and brings the comparator 15 again to a balanced condition when the actual angle of the rudder equals the angle which has been pre-set by means of the remote control transmitter 11. Consequently, the comparator 15 brings the solenoid valve 10 again to its rest position, thus short-circuiting again the pump 8 and, therefore, causing the rudder to stop in the new angular position thereof.

In case of any failure in the above steering system operated by means of the powered pump 8 and electronic remote control transmitter 11 operated through the steering wheel 6, or in case the electric current supply to said steering system is merely cut off by means of a switch 16, the helmsman can immediately change-over to manual steering by means of the pump 5, which is also operated through the steering wheel 6 and will deliver, depending upon the direction of rotation of said steering wheel 6, the hydraulic liquid into either of the two actuating cylinders 2 and 3, thus causing the desired angular movement of the rudder.
To move the rudder directly by hand through the steering wheel 6, i.e. by means of the manually-operated pump 5, over its entire amplitude, a plurality of complete revolutions of the steering wheel are to be made, whereas to move the rudder over its entire amplitude through the same steering wheel 6 and by means of the electronic remote control transmitter 11 and pump 8 driven by the motor 9, the steering wheel 6 need be rotated only through angles which are proportional to the actual angles over which the rudder is moved, anyway over angles which are smaller than one round angle, i.e. smaller than 360°. By this arrangement, the limited angular displacements of the steering wheel 6 while operating by means of the powered pump 8 and electronic remote control transmitter 11, will not cause any appreciable actuation of the pump 5 for the manual steering and, therefore, any appreciable direct action on the rudder. In the illustrated embodiment, in order to obtain this arrangement, besides coupling directly the steering wheel 6 to the shaft 7 of the pump 5, as described above, the electronic remote control transmitter 11 is of rotary type and so designed as to undergo, unharmed, several complete revolutions, even if they are not required for its control function.
This basic principle of the steering system according to the invention may be embodied by various constructions, a preferred embodiment being shown in Figures 2 and 3. In this embodiment, between the pump 5 for the manual steering mode and the steering wheel 6 there is arranged a casing 17 which is fixed to a mounting wall 18 by means of screws 20, a front pressure ring 19 and a back flange 217, the latter having also secured thereto by means of a flange 115 and screws 20, the body of the pump manual steering 5. The shaft 7 of the pump 5 is passed through the casing 17 and front cover 117 thereof and mounts the steering wheel 6.
Within the casing 17, a gear wheel 21 is secured to the shaft 7 and meshes with a gear wheel 22 secured to a shaft 122 which is rotatably mounted in the cover 117 of the casing 17. The actuating spindle 111 of the electronic remote control transmitter 11 is secured to the gear wheel 22, whereas the body of said transmitter 11 is secured to an annular member 23 which is non-rotatably mounted on the cover 117 of the casing 17 by means of a rod 24. The shaft ₁22 of the gear wheel 22 is passed through the cover 117 of the casing 17 and carries, outside of said cover, a disc member 25 provided with a graduated scale and co-operating with a stationary pointer 26. By rotating the shaft 7 by means of the steering wheel 6, the actuating spindle 111 of the remote control transmitter 11 is rotated through the gear wheels 21, 22 and, to the same extent, the graduated disc member 25 is rotated by means of the shaft 122.
In order to move the rudder by means of the pump 8 powered by the motor 9, the actuating spindle 111 of the remote control transmitter 11 is to be rotated, from its intermediate position corresponding to the central position of the rudder, by about 35°-45°, or less, to the right and left sides, i.e. by a total angle of 70°-100°, or less.
A gear ratio of the couple of gear wheels 21, 22 is selected whereby, to obtain said limited angular displacement of the actuating spindle 111 of the remote control transmitter 11, the steering wheel 6, and therefore the shaft 7 of the pump 5 must be rotated through a total angle smaller than 360°. This angle of rotation of the shaft 7 is limited by stops, specifically by a stop member 27 fixedly mounted on the shaft 7 and co-operating with a stop pin 28 that can be inserted through the cover 117 of the casing 17 so as to interfere with the path of the stop member 27. When the rudder is to be moved manually by means of the pump 5 and, therefore, the steering wheel 6 is to be revolved through a plurality of complete revolutions in either directions, the stop pin 28 is removed from the path of the stop member 27, as shown in Figure 2, thus permitting the shaft 7 to be rotated freely.
The graduated disc 25 co-operating with the pointer 26 permits any person to check the steering angle set through the steering wheel 6 and remote control transmitter 11. The actual angular position of the rudder may be indicated by any conventional electrical indicator of the rudder angle.
The embodiment described above and shown in Figures 2 and 3 can undergo considerable constructional changes and modifications. Thus, the ratio between the two gears 21, 22 may be 1 : 1 or other. The couple of gears 21, 22 may be replaced by a different drive system, e.g. a belt or a chain drive. The rotatable graduated disc 25 may be replaced by a rotatable pointer co-operating with a graduated scale fixed on the cover 117, particularly when the drive between the shafts 7 and 122 is such that both shafts 7 and 122 revolve in the same direction. The remote control transmitter 11 may be arranged in any other manner. Similarly, the disengageable locking stops to limit the rotation amplitude of the shaft 7 may be constructed in various manners.
The electronic remote control transmitter 11 and the response transmitter 12 may comprise any variable electric elements, preferably of the rotary type. In the illustrated embodiment, said transmitters comprise potentiometers of any suitable type, such as the coil type, film type, ceramic type, or the like. The magnitudes of the electrical signals from the two transmitters 11, 12 are then compared in the comparator 15.
The rudder actuating unit may also be constructed in any other suitable manner. Thus, for example, the two hydraulic actuating single-acting cylinders 2, 3 may be of double-acting type or may be replaced by a single double-acting hydraulic actuating cylinder, or by any other hydraulic aetuator, even of rotary type.
Preferably, according to a further characteristic of the invention, the rudder actuating unit, the response transmitter 12 and the powered pump 8 with its driving motor are mounted on a single supporting base structure or bedplate and constitute together a unitary construction, thus simplifying greatly the installation of the steering apparatus, reducing the overall dimensions thereof, and ensuring the utmost safety conditions, since the entire apparatus may be easily tested before being mounted aboard.
In addition to the above described essential components, the steering apparatus according to the invention may comprise at least one further steering station constituted by a thoroughly electronic remote control system of the type described above, that is formed only by an electronic remote control transmitter and its own hand actuator with a rudder angle indicator. This second steering station may be located, for example, on the counter-bridge and/or on the bridge-wings, and may be provided with a steering system operated by means of an electric ON-OFF switch through which the personnel can act directly, for example, on the solenoid valve, or on one or more equivalent solenoid valves, to connect the powered pump 8 to the rudder actuating unit to move the rudder in either direction. This steering system operated by means of an electric ON-OFF switch preferably comprises entirely independent electric supply lines to the solenoid valve (or valves) to give the steering apparatus maximum safety characteristics.
Figure 4 shows the electro-hydraulic diagrammatic circuit of a second embodiment of the steering gear according to the invention, in a more complete and improved version. Again, the hydraulic connections are indicated with full lines and the electrical connections with dotted lines. Figure 5 is an enlarged sectional view of a group of valves of the embodiment of Figure 4.
Substantially, the embodiment of Figure 4 corresponds to the embodiment of Figures 1 to 3, and the components described previously are indicated by the same numerals. The following additional components are included in Figure 4 in addition to those described previously:

A storage tank 30 containing the oil for the hydraulic system is connected to conduits 105, 205 for the manual steering pump 5 through an automatic filling valve 31. The valve 31, known _Eer se, comprises an intermediate chamber 32 communicating with each of the two conduits 105, 205 of the pump 5 through a respective non-return valve member 33, 34. Both these non-return valve members 33 and 34 are of the outwardly-opening type, i.e. they open by the action of a higher pressure in the intermediate chamber 32. Moreover, the valve members 33, 34 are mechanically connected to each other, e.g. by a push rod 35, whereby when one of the non-return valves (e.g. 33) will close, the other valve (e.g. 34) will open, and vice-versa. Thus, when the manual steering pump 5 is actuated so as to pressurize one of the conduits 105, 205, for example the conduit 105, the non-return valve 33 communicating with this pressurized conduit 105 will be closed, and simultaneously the other non-return valve 34 will be opened, thus putting in communication the oil tank 30 with the other conduit 205 (now under suction) of the manual steering pump 5, and vice-versa. The automatic filling of the hydraulic system of the manual steering pump 5 and rudder actuating cylinders 2, 3 is thus ensured.

Figure 4 in addition shows the valve 36 for locking the rudder in the desired angular position thereof. The valve 36, known per se, comprises a cylinder wherein a piston 37 is axially slidable and divides the cylinder space in two chambers 38, 39. One of these chambers (for example 38) is connectable with the conduit 105 of the manual steering pump 5, and the other chamber (for example 39) is connectable with the other conduit 205 of said pump 5. One of the chambers 38, 39 of the cylinder (for example the chamber 38) communicates through a non-return valve 40 with one of the hydraulic actuating cylinders of the rudder actuating unit (for example with the cylinder 2), while the other chamber 39 communicates through another non-return valve 41 with the other hydraulic actuating cylinder 3 of the rudder actuating unit. The two non-return valves 40, 41 will be opened by the action of a higher pressure in the associated chamber 38 or 39 of the cylinder and are mechanically connected to the piston 37, e.g. by means of push rods 42 fixed to the faces of the piston 37, whereby the following operation will be obtained:

When a suitable pressure is created in one of the conduits 105 or 205 of jhe manual steering pump 5, and therefore in the associated chamber 38 or 39 of the locking valve 36, said pressure opens the respective non-return valve 40 or 41, whereby the hydraulic oil can flow to the corresponding actuating cylinder 2 or 3. At the same time, said pressure also displaces the piston 37 so that the latter will open, through its mecanical connection, also the other non-return valve 41 or 40 and thus connects the other hydraulic actuating cylinder 3 or 2 to the other conduit 205 or 105 of the pump 5 and permits the return flow of the oil. When the manual steering pump is not actuated and, therefore, the same pressure exists in the two conduits 105, 205 thereof, the pressures are also balanced in the two chambers 38 and 39 of the cylinder of the lock valve 36, and the piston 37 will assume an intermediate position wherein both non-return valves 40, 41 are in the closed position, as shown in Figure 4. The two actuating cylinders 2, 3 of the rudder actuating unit are thus cut-off from the hydraulic system. of the manual steering pump 5 so as to be locked and, consequently, they will lock the rudder in the desired angular position.

In the embodiment of Figures 4 and 5, the angular displacements of the steering wheel 6 while operating through the powered pump 8 and electronic remote control transmitter 11, will cause always a corresponding minimum actuation of the manual steering pump 5, but this actuation of the manual steering pump 5 is absolutely uninfluent on the rudder actuating unit, thus permitting a completely free rotation of the remote control transmitter 11. For this purpose, according to the invention, an automatic short-circuiting pump 43 is provided between the two conduits 105, 205 of the manual steering pump 5. While at rest, that is when the rudder is controlled directly by means of the manual steering pump 5, the valve 43 connects the conduits 105, 205 of the pump 5 to the corresponding downstream conduits, e.g. by the action of a spring 44 and as shown in Figure 4. When the rudder is controlled by means of the powered pump 8 and remote control transmitter 11, the valve 43 is moved, by the action of the pressure differential between the delivery and suction sides of the powered pump 8, to a position wherein it mutually connects, in short-circuit manner, the two conduits 105, 205 of the manual steering pump 5.
The actuation of the manual steering pump 5 during the angular displacement of the remote control transmitter 11 by means of the steering wheel 6, therefore, causes a short-circuited circulation of the hydraulic oil between the two conduits 105, 205, which will not affect the hydraulic system downstream of the valve 43 and, therefore, the hydraulic cylinders 2, 3 which actuate the rudder.
The short-circuit valve 43 is inserted upstream of the locking valve 36 and may be constructionally embodied in various manners.
Preferably, according to a further feature of the invention, downstream of the short-circuit valve 43, a valve 45 is provided to ensure the automatic filling of the hydraulic system associated with the powered pump 8, without purposely providing a piping extending to the storage tank 30, as in the heretofore known systems. The automatic filling valve 45 substantially corresponds to the filling valve 31 described above in connection with the automatic filling of the hydraulic system associated with the manual steering pump 5, the similar parts being indicated by the same reference numerals. In the valve 45 however, the intermediate chamber 32 communicates with the suction conduit of the powered pump 8, while the two opposite non-return valve members 34, 33 communicate with the conduit 105 and with the conduit 205, respectively, of the manual steering pump 5. In these conditions, the non-return valve 33 or 34 associated with the pressurized conduit 205 or 105 of the manual steering pump 5 is closed, and the other valve 34 or 33 is opened by the action of the push rod 35, thus connecting the intermediate chamber 32 and, therefore, the suction conduit of the powered pump 8 to the other conduit 105 or 205 of the manual steering pump 5, said other conduit being under suction and connected through the automatic filling valve 31 to the oil tank 30, as described above. Thus, the suction side of the powered pump 8 is always connected to the tank 30 through either of the conduits 105, 205 of the manual steering pump 5 regardless of the direction of rotation of the steering wheel 6 to actuate the remote control transmitter 11.
The locking valve 36, the short-circuiting valve 43 and the filling valve 45 are preferably assembled together in a unitary construction with the rudder actuating unit (hydraulic actuating cylinders 2, 3), with the response transmitter 12 and with the pump 8 and respective driving motor 9, said unitary construction being connected only through the conduits 105, 205 to the hydraulic system of the manual steering pump 5.
Figure 5 shows a preferred embodiment of the short-circuiting valve 43 assembled in a unitary group with the automatic filling valve 45 for the powered pump 8. In this embodiment, a body 46 comprises two through bores which are connected to the conduits 105, 205, respectively, of the manual steering pump 5 and which, therefore, are indicated by the same numerals 105, 205 of said conduits. Slidably arranged in a central cylindrical blind bore 47 of the body 36 there is mounted a piston 48 which is urged outwardly (towards the right in Fig. 5) by a spring 44 and which is retained in the bore 47 by a tubular nipple 49 which is screwed in the bore 47 and is connected to the delivery side of the powered pump 8. The piston 48 is formed with an annular peripheral groove 50, and the wall of the cylindrical bore 47 is formed with two spaced annular grooves 51, 52 one of which (for example the groove 51) communicates through a duct 151 with the through hole 105 serially connected with one of the conduits of the manual steering pump 5, while the other groove 52 communicates through a duct 152 with the other through hole 205 serially connected with the other conduit of said manual steering pump 5. At the back side of the piston 48, i.e. the side remote from the nipple 49 connected to the delivery side of the powered pump 8, the cylindrical bore 47 communicates through the duct 53 with the suction side of said powered pump 8.
Durign the manual steering operation through the pump 5, the piston 48 of the short-circuiting valve 43 is held by the spring 44 in the rest position shown in Figure 5, wherein its peripheral annular groove 50 communicates only with one annular groove 51 of the bore 47 and, therefore, only with the respective conduit 105, or it communicates with neither of said grooves 51, 52 and, therefore, with neither of said conduits 105, 205. During the steering operation through the powered pump 8 and remote control transmitter 11, the pressure differential between the suction and the delivery sides of the powered pump 8 overcomes the action of the spring 44 and moves the piston 48 against the action of said spring to a position (left side in Figure 5) wherein the peripheral annular groove 50 of said piston 48 communicates with both the inside annular grooves 51, 52 in the bore 47, thus putting into communication these two grooves 51, 52 with each other and, therefore, short-circuiting the two conduits 105, 205 through the ducts 151 and 152.
Sealingly arranged in a blind bore 154 remote from the nipple 49 there is the cylindrical body 54 of the automatic filling valve 45 for the powered pump 8. The two non-return. valves 33, 34 are formed by ball members loosely arranged in corresponding peripheral recesses 133, 134 of the body 54. Said recesses 133, 134 communicate, through the respective valve seats, with the intermediate chamber 32 slidably lodging the push-member 35 for mechanically connecting the two non-return valves 33, 34. Said intermediate chamber 32 communicates, through a transverse hole 55, with the duct 53 connected to the suction side of the powered pump 8. The peripheral recesses 133, 134 containing the non-return valves 33, 34 also communicate, through holes 233, 234 with the conduits 205 and 105, respectively.
The embodiment according to Figure 5 has the advantagq of a simple and compact construction which may be easily assembled and disassembled, and serially connected in the two conduits 105, 205 of the manual steering pump 5. Of course, particularly the valves 31 and 36 may also be provided in the embodiment of Figure 1.
From the above, it is apparent that the invention is not limited to the embodiments herein shown and described, and that changes and modifications may be broadly made thereto, particularly in the construction thereof and in the field of technical and functional equivalents, without departing from the basic principle set forth above and claimed hereinafter.

Claims

1. A steering gear for any type of watercrafts, particularly of small and medium tonnage, comprising a rudder hydraulic actuator unit which can be fed, alternately, by a manual hydraulic pressure generator constituted by a pump (5) that can be operated manually through the steering wheel (6), and by a powered hydraulic pressure generator, constituted by a motor-driven pump (8) that can be actuated through an electronic remote control transmitter (11), characterized in that the steering wheel (6) operates, besides the pump (5) of the manual hydraulic pressure generator, also the remote control transmitter (11) of the powered hydraulic pressure generator.

2. A steering gear according to claim 1, characterized in that the steering wheel (6) is coupled both to the pump (5) of the manual hydraulic pressure generator and to the electronic remote control transmitter (11) for the powered hydraulic pressure generator with such rations whereby, to move the rudder through the total amplitude thereof by means of the manual pressure generator, a plurality of complete revolutions of the steering wheel (6) are to be made, whereas to move the rudder through the total amplitude thereof by means of the powered hydraulic pressure generator and respective electronic remote control transmitter (11), the steering wheel (6) need be rotated only a fraction of the round angle, the electronic remote control transmitter (11) being constructed and/or coupled to the steering wheel (6) so as to permit the latter to be rotated through a plurality of complete revolutions.

3. A steering gear according to claim 2, characterized in that the electronic remote control transmitter (11) may be rotated unharmed through a plurality of complete revolutions.

4. A steering gear according to claim 2, characterized in that the rotation of the steering wheel (6) may be limited at will, by a suitable control and for example by means of stops (28, 27) which can be activated and disactivated at will, to the fraction of round angle required for the actuation of the electronic remote control transmitter (11).

5. A steering gear according to claim 1, wherein the electronic remote control system comprises a comparator (15) of the signals from the electronic remote control transmitter (11) operated by the steering wheel (6) and from a response transmitter (12) operated by the rudder, said comparator (15) actuating at least one solenoid valve (10) controlling the delivery of the powered hydraulic pressure generator pump (8), characterized in that the rudder actuator unit (2, 3), the pump (8) of the powered hydraulic pressure generator, the motor (9) driving said pump (8) and the response transmitter (12) of the electronic remote control system are mounted on a common bedplate so as to form a unitary assembly.

6. A steering gear according claim 1, characterized in that the electronic remote control transmitter (11) is housed in a casing (17) integral with the pump (5) of the manual pressure generator and is mechanically coupled to a manual control shaft (7) which is connected to said pump (5) and to the steering wheel (6) and which is constituted, preferably, by the shaft (7) of the pump (5) which is passed through said casing (17).

7. A steering gear according to claim 1, characterized in that it is provided additionally with a steering system of the switch type, by means of which a direct connection can be effected of the powered hydraulic pressure generator pump to the rudder actuator unit.

8. A steering wheel according to claim 1, characterized in that it comprises a short-circuiting valve (43) which is controlled by the delivery pressure of the powered hydraulic pressure generator pump (8) so as to automatically short- circuit the two conduits (105, 205) of the manual hydraulic pressure generator pump (5) when the powered hydraulic pressure generator pump (8) is actuated.

9. A steering gear according to claim 8, characterized in that the short-circuiting vlave (43) comprises a piston (48) slidably arranged in a cylinder (47) and provided with a peripheral annular groove (50), said cylinder (47) being provided with two inside annular grooves (51, 52) communicating with the conduits (105, 205) of the powered hydraulic pressure generator pump (8), and said piston (48) is acted upon in one direction by a spring (44) urging the piston (48) to a position wherein it sealingly cuts off said two inside annular grooves (51, 52) of the cylinder (47), and in the opposite direction by the delivery pressure or the differential between the delivery pressure and the suction pressure of the powered hydraulic pressure generator urging said piston (48) - against the action of said spring (44) - to a position wherein it establishes the mutual communication - through its own peripheral annular groove (50) - between the two inside annular grooves (51, 52) of the cylinder (47) and, therefore, between the two respective conduits (105, 205) of the manual hydraulic pressure generator.

10. A steering gear according to claim 1, wherein the two conduits (105, 205) of the manual hydraulic pressure generator pump (5) are connected to an hydraulic oil tank (30) through an automatic filling valve (31), comprising an intermediate chamber (32) communicating with said tank (30) and with each of said conduits (105, 205) through a respective non-return valve (33, 34) which is closed by a pressure in the associated conduit, said two non-return valves (33, 34) being so interconnected whereby when one of them is closed the other is opened automatically, and vice-versa, characterized in that a further automatic valve (45) of the above type is provided and the intermediate chamber (32) thereof communicates with the suction side of the powered hydraulic pressure generator, while the two non-return valves (33, 34) communicate with the two conduits (105, 205), respectively, of the manual hydraulic pressure generator pump (5).

11. A steering gear according to claim 10, characterized in that the automatic filling valve (45) associated with the powered hydraulic pressure generator is assembled as a singls unit with the short-circuiting valve (43),these two valves being preferably located upstream of an automatic locking valve (36) intercepting the connection between the rudder hydraulic actuator unit and the manual hydraulic pressure generator pump, when substantially the same pressure exists in both conduits of this pump.

12. A steering gear according claim 11, characterized in that the rudder actuator unit (2, 3), the powered hydraulic pressure generator pump (8), the motor (9) driving said pump, the response transmitter (12) of the hydraulic remote control system, the short-circuiting valve (43), the locking valve (36), and the automatic filling valve (45) for said powered pump (8) are assembled together so as to form a unitary group.