Hydraulic steering system for a vehicle

Abstract

A hydraulic steering system for vehicles includes a steering control member; a hydraulic pump provided with a rotatable driving shaft on which the control member is fitted; a hydraulic actuating cylinder connected with two ports of the pump alternately operating as delivery side and return side of the pump and mechanically connected with a direction changing member, which determines a change in the direction by modifying orientation via an actuating cylinder as a function of the supply of hydraulic fluid to the cylinder from the pump by the steering control member. The driving shaft is dynamically connected with an electric motor/transmission assembly, which is activated alternatively by generating a rotational force auxiliary to the movement manually exerted on the steering control member or opposing the manually exerted movement, or by driving to rotate the driving shaft of the pump in place of the manual action driving the steering control member.

Claims

1. A hydraulic steering system for a vehicle comprising: at least one steering control member; a hydraulic pump provided with a driving shaft rotatable in two directions, wherein said steering control member is fitted on said hydraulic pump to cause a rotation of said driving shaft; at least one hydraulic actuating cylinder connected to a delivery side and a return side of said pump; an electric motor/transmission assembly; and a control unit generating a power supply signal of the electric motor/transmission assembly, said control unit being connected to a plurality of sensors each detecting a specific movement condition of the vehicle, said plurality of sensors being selected from the group consisting of position sensors, speed sensors, sensors of steering angle, sensors of a number of revolutions of a motor of the vehicle, sensors of wind direction or strength, sensors of obstacles, and accelerometers, wherein said actuating cylinder forms a hydraulic circuit with said hydraulic pump; wherein said actuating cylinder is mechanically articulated with a direction changing member, said direction changing member determining a change in direction by modifying orientation of said direction changing member with respect to an axis of the vehicle; wherein the change in the orientation of said direction changing member is performed by said actuating cylinder as a function of supply of hydraulic fluid to said actuating cylinder caused by operation of the hydraulic pump by the steering control member; wherein the driving shaft of the hydraulic pump is connected with the electric motor/transmission assembly, which is configured to perform each of the following functions: (a) generating a first rotational force auxiliary to a manually exerted movement on the steering control member; (b) generating a second rotational force opposing said manually exerted movement and sufficient to generate a predetermined resistance to a displacement of the direction changing member, thereby preventing an accidental steering of the steering control member; or (c) rotatably driving the driving shaft of the pump to drive the vehicle autonomously independently of the manually exerted movement, and wherein the control unit is configured to activate the electric motor/transmission assembly to perform each of the following functions: functions (a) or (b), based on signals generated from the plurality of sensors, and function (c), based on direction settings entered by a user, and signals of travel conditions along a path or presence of obstacles along a path transmitted to said control unit by the plurality of sensors.

2. The hydraulic steering system according to claim 1, wherein the plurality of sensors detecting the manual rotation of the steering control member generate a signal activating a motor of the electric motor/transmission assembly, said signal activating the motor being read by the control unit.

3. The hydraulic steering system according to claim 1, further comprising a command setting at least an automatic steering condition to enable operation according to option (c), said command activating the control unit to execute an auto pilot program that generates a power supply signal of the electric motor/transmission assembly based on direction settings entered by a user, and signals generated by one or more of the plurality of sensors.

4. The hydraulic steering system according to claim 1, wherein the electric motor/transmission assembly comprises an electric motor and a pair of gears that are rotatably engaged with each other, one of said gears being fitted on a shaft of the electric motor and the other gear being fitted instead on the driving shaft of the hydraulic pump.

5. The hydraulic steering system according to claim 4, wherein the electric motor of the electric motor/transmission assembly is provided on a side of the pump, the shaft of said electric motor being parallel to the driving shaft of the pump, and wherein the gears with axial teeth engaged with each other are fitted on the driving shaft and on the shaft of the electric motor.

6. The hydraulic steering system according to claim 4, further comprising one or more detection sensors that detect a movement of the steering control member or of the shaft of the electric motor, or one or more detection sensors that are composed of an electromagnetic pulse generated by the electric motor generated when a manual rotation of the steering control member causes a rotor of the electric motor to rotate.

7. The hydraulic steering system according to claim 1, wherein the electric motor/transmission assembly is provided at an intermediate position between the steering control member and the hydraulic pump.

8. The hydraulic steering system according to claim 1, wherein the driving shaft of the hydraulic pump protrudes by a second end from a head side of the pump opposite to a side fastening the steering control member, and wherein the electric motor/transmission assembly is coupled to the driving shaft of the pump at said second end.

9. The hydraulic steering system according to claim 1, further comprising an interface displaying one or more of settings or data corresponding to the signals generated by the plurality of sensors and operation of the electric motor/transmission assembly.

10. The hydraulic steering system according to claim 1, wherein the control unit comprises at least a memory and one processor, said memory containing a control program for processing data about a movement condition of the vehicle, and for generating controls driving the electric motor/transmission assembly for automatic control of direction changing members based on data acquired by said sensors.

11. The hydraulic steering system according to claim 10, further comprising a display connected to said control unit and a program displaying cruising conditions and setting the steering system, said program generating a graphical interface on the display displaying said data.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other characteristics and advantages of the present invention will be clearer from the following description of some embodiments shown in the annexed drawings wherein:

(2) FIGS. 1 to 3 are different views of a first embodiment of the invention where the electric motor of the electric motor/transmission assembly is oriented perpendicularly to the axis of the driving shaft of the hydraulic pump and the electric motor/transmission assembly is mounted on the shaft of said hydraulic pump on the same side of the pump where the steering wheel is mounted.

(3) FIGS. 4 to 6 is a variant of the embodiment of the previous figures where the driving shaft of the hydraulic pump extends beyond the head side opposite to the side fastening the steering wheel the electric motor/transmission assembly being coupled to the driving shaft at said extension.

(4) FIGS. 7 and 8 are a further embodiment of the invention where the motor of the electric motor/transmission assembly is mounted with its axis parallel to the axis of the driving shaft of the hydraulic pump and the electric motor/transmission assembly is dynamically coupled to said driving shaft on the same side of the hydraulic pump where the steering wheel is provided.

(5) FIGS. 9 to 11 are a variant of FIGS. 7 and 8, where the driving shaft of the hydraulic pump extends beyond the head side opposite to the side fastening the steering wheel the electric motor/transmission assembly being coupled to the driving shaft at said extension.

(6) FIG. 12 is a simplified block diagram of one embodiment of the system according to the present invention that only by way of example and not as a limitation comprises one embodiment according to FIGS. 1 to 3, but that can be combined with any of the described embodiments.

(7) FIG. 13 is a flow chart of an example of the operation of the system according to the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(8) With reference to FIG. 12, a system steering a vehicle, such as a marine vehicle and particularly a watercraft, comprises at least one manual steering control member that can be of any kind and that in the shown examples is in the form of a steering wheel 1.

(9) The steering wheel 1 is fitted on the end of a driving shaft of a pump, tank 202 and distribution valve 302 assembly, generally denoted by 2.

(10) Such assembly, which will be identified in short as hydraulic pump 2, can be made in different ways, one of them being described for example in documents EP 1382845 and EP 2857680 to the same Applicant, whose disclosures are part of the present disclosure.

(11) As an alternative, other types of pumps are possible such as for example the gear pump described in document IT0001408662 or the Gerotor pump described in document SV2002A000031 to the same Applicant.

(12) As it can be seen in greater detail in FIGS. 1 to 3, in an intermediate position between the steering wheel 1 and the case of the hydraulic pump 2 on the same driving shaft 102, a pinion 103 of an electric motor/transmission assembly is fitted, which comprises an electric motor 203 whose shaft engages the pinion by a helical screw that is not shown in detail.

(13) The axis of the shaft of the motor 203 is oriented perpendicularly and eccentrically with respect to the axis of the driving shaft 102 of the hydraulic pump 2.

(14) The outlets of the distributor 302 of the hydraulic pump 2 are connected through hydraulic ducts to the inlets of a double-acting hydraulic cylinder 4. In the version provided for outboard motors, the rod 104 of the hydraulic cylinder 4 is generally stationary, while, due to the effect of the hydraulic fluid supplied in one or in the other flowing direction depending on the direction of rotation of the steering wheel 1, the body of the cylinder moves along the rod, which is connected to one or more direction changing members by means of articulated arms 5.

(15) As an alternative to a double-acting cylinder it is also possible to provide two single-acting cylinders operating in a mutually opposite direction.

(16) A control unit 120, which comprises at least one processing unit in the form of a processor and one or more memories configured to cooperate with the processor, executes a logic control program stored into one of said memories (not shown in detail).

(17) At one input of the control unit, at least one sensor 220 is connected for detecting a manual action rotating the driving shaft 102 of the pump 2 through the steering wheel 1.

(18) The sensor can also be composed of the electric motor 203, which, following an action rotating the shaft thereof, generates an electromagnetic signal sent to the control unit 120 and interpreted by the control program. On the basis of the analysis of such signal detecting the manual operation of the driving shaft 102 of the pump 2, the control unit 120 calculates which type of signal to be sent to a driver 320 generating the signal power supplying the electric motor.

(19) As it will become clearer later, such signal can be a signal driving the electric motor to exert an action rotating the shaft 102 of the hydraulic pump consistent with the rotation exerted by the steering wheel and, therefore, the electric motor/transmission assembly 3 provides an action that is auxiliary to the manual action. On the contrary, said signal driving the electric motor/transmission assembly can be a signal driving the electric motor such that the action rotating the electric motor/transmission assembly on the driving shaft 102 of the pump 2 is contrary and opposed to the rotating action manually exerted through the steering wheel 1. Such opposing action generates a braking or a resistance to the manual rotation that can be sought by the user and that can also be regulated, both in a fixed manner by being preventively set or in a dynamic manner by analyzing the travel conditions of the vehicle in the environment.

(20) To this end, as it can be seen from the figure, the control unit 120 can be connected to a plurality of different sensors generally denoted by 240, each of which detects specific movement conditions of the vehicle.

(21) The example concerns particularly the preferred embodiment related to a watercraft, which, however is not a limiting embodiment since the illustrated example is easily and obviously modifiable for a land vehicle or other type of vehicle, for example a hybrid one.

(22) Among the detection sensors 240, it is possible to provide, for example, in any combination or sub-combination:

(23) position sensors, such as GPS sensors or the like;

(24) sensors for the route or orientation of the vehicle, such as a compass or GPS tracking;

(25) speed sensors, such as for example a unit determining the speed by GPS tracking, and/or detecting the speed relative to the road for land vehicles or water for watercrafts;

(26) sensors for steering angle that is the change in orientation carried out by the watercraft;

(27) sensors for the steering angle taken by the direction changing members;

(28) sensors for the number of revolutions of one or more motors;

(29) sensors for the direction of the wind and/or strength of the wind;

(30) sensors for obstacles, such as radar sensors, proximity sensors;

(31) other types of sensors such as accelerometers or the like.

(32) The signals received by such sensors can be provided to the control unit 120 where a control program is stored which stores, analyzes and estimates the signals obtained from one or more of said sensors and on the basis of said signals sets the type of signal powering the electric motor, both in regard to the functionality auxiliary to or opposing the manual steering action and in regard to the force and/or speed driving the motor.

(33) With reference again to the control unit, it is possible to connect one or more different control members for different functionalities, generally denoted by 250.

(34) Among the above-mentioned ones, it is possible to provide in any combination or sub combination:

(35) a control to set the number of revolutions of one or more motors;

(36) a control for reversing the travel of one or more motors;

(37) a control for setting the travel conditions, such as for example quick cruising, comfort cruising, slow cruising, maneuvering, mooring etc. In this case the steering members of the boat can be regulated by the control unit in operating conditions preset and stored in a memory of the control unit 120 during a setup phase;

(38) a maneuvering joystick for mooring maneuvers;

(39) controls for regulating trim flaps or tabs also known as trim tabs;

(40) controls for regulating the position of outboard motor.

(41) The control program executed by the control unit 120 can set the signal powering the electric motor in a mode auxiliary to or opposing the manual steering action only or also on the basis of settings set by the user due to one or more of said controls.

(42) For example, by setting a slow cruising or maneuvering condition, it is possible to power the electric motor/transmission assembly with a power signal to exert an action auxiliary to the manual action such to make the steering wheel less resistant to rotation, obtaining a soft steering that promotes steering speed, while in a quick cruising condition it is possible to generate a power signal by means of which the electric motor/transmission assembly operates opposing the manual action, to make more rigid or harder, that is, to generate a given resistance to the displacement of the direction changing member, for example a rudder plate or an outboard motor or a foot of a inboard-outboard motor so not to run the risk of accidentally steering or anyway of steering too quickly when cruising.

(43) Operating conditions can be displayed on a display 260 that can be of the touch type. In this case, at least some of the above described controls can be made in the form of a graphical control, while other controls can be made in the form of switches and/or levers or the like.

(44) With the aim of providing a display graphical and/or control interface, the control unit executes a program generating and controlling a graphical interface also stored in a memory of the control unit.

(45) According to an additional variant, it is possible to provide also a control for setting the autopilot condition.

(46) Such control causes the control unit 120 to call and to execute an autopilot program, which, on the basis of one or more of the detection signals of one or more of the above listed sensors 240, generates a signal powering the electric motor/transmission assembly 3 operating the driving shaft 102 of the pump 2 regardless of a manual steering action exerted on the wheel.

(47) In a simple arrangement, the signals supplied to the autopilot program can be those derived from the position and GPS tracking and, therefore, position, direction and speed and also signals detecting obstacles both detected by sensors and resulting from a map of the area.

(48) As an alternative, it is possible to cross check or integrate such information with additional measurement signals of the above-mentioned sensors and/or with one or more settings activated by one or more of the above listed controls.

(49) According to another feature, the display can show the map and the vehicle, as well as the tracking corresponding to the path thereof.

(50) Still according to a feature, it is possible to provide the automatic pilot condition to be automatically disabled when a manual steering action is exerted through the wheel 1 or an equivalent steering member.

(51) Although the overall system in its different variants has been described with reference to the embodiment of FIGS. 1 to 3, it is applicable to any of the other shown embodiments.

(52) FIGS. 4 to 6 show a variant embodiment where the driving shaft of the pump is extended on the side of the hydraulic pump where the distributor 302 is provided.

(53) In this case the pinion 103 is fitted on said extension of the shaft 102 and, therefore, the motor with the helical screw is placed rearwardly of the distribution valve.

(54) This is advantageous since such electric motor/transmission assembly 3 with the different electrical connections is inside the compartment of the bridge, making it possible to reduce the protrusion of the steering wheel from the bridge and to have an aesthetically cleaner arrangement.

(55) In the embodiment of FIGS. 7 and 8, the motor 203 of the electric motor/transmission assembly is arranged with the shaft parallel and laterally adjacent to the pump and to the driving shaft 102 thereof.

(56) Also in this case, on the shaft in an intermediate position between the steering wheel 1 and the case of the pump 2 there is provided the pinion 103, while the shaft of the motor 203 bears a gear with axial teeth meshing with the axial teeth of the pinion 103.

(57) In this embodiment, the electric motor 203 of the electric motor/transmission assembly 3 can be mounted in a housing integrated with the case of the pump 2 to form a single compact body. Moreover, the axial arrangement of the motor 203 provides for a reduction of axial overall dimensions of the assembly and also of radial overall dimensions with respect to the solutions of FIGS. 1 to 3 and 4 to 7.

(58) FIGS. 9 to 11 show a variant of the embodiment according to FIGS. 7 and 8, wherein like in the variant of FIGS. 4 to 6, the driving shaft of the pump 2 is extended on the side of the hydraulic pump 2 on which the distributor 302 is provided.

(59) In this case the pinion 103 is fitted on said extension of the shaft 102 and the motor 203 is placed still on the side of the pump 2 with its shaft parallel to the shaft 102, that is, to the extension thereof.

(60) FIG. 13 shows a flow chart of an example of operation of the system according to the present invention and particularly according to FIG. 12.

(61) At step 300 the movement conditions of said vehicle are defined on the basis of setting controls and/or of detections of the movement conditions of the vehicle.

(62) At step 310 on the basis of such data the signal powering the motor 203 of the electric motor/transmission assembly 3 is processed.

(63) If step 320 defines that the autopilot condition is not set, then the step 330 is enabled that provides for generating the signal driving the motor regardless of the detection of a manual steering action and in compliance with the settings and detections of the movement conditions.

(64) If on the contrary the autopilot condition is not set, then the system enables the condition detecting the driving of the manual steering control member 1 at step 340.

(65) If at step 350 no manual action is detected, then the system continues monitoring the possible manual action. If on the contrary a manual operation is detected, then at step 350 a check is performed of whether the settings of the movement are sufficient to generate a signal driving the electric motor/transmission assembly 3 in a mode auxiliary to the manual action or a signal driving the electric motor/transmission assembly in a mode opposing the manual action. Finally, at step 360 the signal is transmitted to the electric motor/transmission assembly 3 and the loop goes on from step 320.

(66) Although the present invention has been described with reference to a device that includes a hydraulic pump, it is possible to apply the same concept to a mechanical control system generating and transmitting the steering control to a direction changing member. In this case, instead of the oil-hydraulic pump it is possible to insert a mechanism transmitting the rotary motion of the steering control member, which can be provided with a shaft coupling the steering control member both at the front and at the rear with reference to the bridge. In this case the electric motor/transmission assembly can be applied both between the steering wheel and the mechanical device and on the side of the mechanical device opposite to the steering control member. The mechanism transmitting the rotational motion of the steering control member can be connected to the actuators driving the steering member by means of any type of mechanical transmission, such as for example by one or more metal cables that are pushed and/or pulled by the mechanism driven by the rotation of the steering control member.