EP4112441A1 - Steering system - Google Patents
Steering system Download PDFInfo
- Publication number
- EP4112441A1 EP4112441A1 EP21760129.3A EP21760129A EP4112441A1 EP 4112441 A1 EP4112441 A1 EP 4112441A1 EP 21760129 A EP21760129 A EP 21760129A EP 4112441 A1 EP4112441 A1 EP 4112441A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- spool
- controller
- pump
- shifting mechanism
- steering system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000007246 mechanism Effects 0.000 claims abstract description 97
- 239000010720 hydraulic oil Substances 0.000 claims abstract description 24
- 230000007704 transition Effects 0.000 claims description 10
- 230000007423 decrease Effects 0.000 claims description 9
- 238000011084 recovery Methods 0.000 claims description 9
- 230000008878 coupling Effects 0.000 description 23
- 238000010168 coupling process Methods 0.000 description 23
- 238000005859 coupling reaction Methods 0.000 description 23
- 230000007935 neutral effect Effects 0.000 description 13
- 238000006073 displacement reaction Methods 0.000 description 4
- 230000035939 shock Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 230000005284 excitation Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 230000015654 memory Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H25/00—Steering; Slowing-down otherwise than by use of propulsive elements; Dynamic anchoring, i.e. positioning vessels by means of main or auxiliary propulsive elements
- B63H25/06—Steering by rudders
- B63H25/08—Steering gear
- B63H25/14—Steering gear power assisted; power driven, i.e. using steering engine
- B63H25/26—Steering engines
- B63H25/28—Steering engines of fluid type
- B63H25/30—Steering engines of fluid type hydraulic
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H25/00—Steering; Slowing-down otherwise than by use of propulsive elements; Dynamic anchoring, i.e. positioning vessels by means of main or auxiliary propulsive elements
- B63H25/06—Steering by rudders
- B63H25/08—Steering gear
- B63H25/12—Steering gear with fluid transmission
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
- F15B11/028—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
- F15B11/036—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force by means of servomotors having a plurality of working chambers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
- F15B13/0401—Valve members; Fluid interconnections therefor
- F15B13/0402—Valve members; Fluid interconnections therefor for linearly sliding valves, e.g. spool valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
- F15B13/0401—Valve members; Fluid interconnections therefor
- F15B2013/0409—Position sensing or feedback of the valve member
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/205—Systems with pumps
- F15B2211/20576—Systems with pumps with multiple pumps
Definitions
- the present invention relates to a steering system installed in a ship.
- a steering system for hydraulically operating a rudder plate is installed in a ship.
- the steering system includes a hydraulic actuator that turns the rudder plate via a rudder stock that penetrates the ship's plank.
- the hydraulic actuator includes a first actuating chamber and a second actuating chamber. When hydraulic oil is supplied to one of the first and second actuating chambers, the hydraulic actuator turns the rudder plate in the port direction. When the hydraulic oil is supplied to the other one of the first and second actuating chambers, the hydraulic actuator turns the rudder plate in the starboard direction.
- Patent Literature 1 discloses a steering system that adopts, as a hydraulic actuator, a hydraulic cylinder in which a first actuating chamber and a second actuating chamber are formed on both sides of a ram, respectively.
- the first actuating chamber and the second actuating chamber of the hydraulic cylinder are connected to a switching valve by a pair of supply/discharge lines.
- the switching valve is connected to a pump by a pump line, and to a tank by a tank line.
- the switching valve blocks the pair of supply/discharge lines.
- the switching valve brings one of the pair of supply/discharge lines into communication with the pump line, and brings the other one of the pair of supply/discharge lines into communication with the tank line.
- the switching valve includes a spool, and the spool is driven by a pair of solenoid valves.
- the switching valve includes a pair of pilot chambers formed therein for applying pilot pressures to both end faces of the spool.
- Each of the solenoid valves switches whether or not to lead a pilot pressure to a corresponding one of the pilot chambers.
- an object of the present invention is to provide a steering system capable of flexible operation.
- a steering system is a steering system installed in a ship, and includes: a hydraulic actuator that turns a rudder plate via a rudder stock that penetrates a ship bottom, the hydraulic actuator including a first actuating chamber and a second actuating chamber; a pump that delivers hydraulic oil; a switching valve including a spool, the switching valve being connected to the first actuating chamber and the second actuating chamber by a pair of supply/discharge lines and to the pump by a pump line; and a shifting mechanism that shifts the spool, the shifting mechanism being configured such that a shifting speed of the spool is electrically changeable.
- the shifting mechanism which shifts the spool, is configured such that the shifting speed of the spool is electrically changeable. This makes flexible operation of the steering system possible.
- the present invention makes it possible to provide a steering system capable of flexible operation.
- FIG. 1 shows a steering system 1A according to Embodiment 1 of the present invention. As shown in FIG. 4 , the steering system 1A is installed in a ship.
- the steering system 1A includes a hydraulic actuator 2.
- the hydraulic actuator 2 turns a rudder plate 11 via a rudder stock 12, which penetrates a ship bottom 10 in the vertical direction.
- the hydraulic actuator 2 turns the rudder plate 11 not only via the rudder stock 12, but also via a tiller 13 disposed inside the ship.
- the hydraulic actuator 2 includes a first actuating chamber 22 and a second actuating chamber 23.
- the hydraulic actuator 2 turns the rudder plate 11 in the port direction (toward the right side in FIG. 1 ).
- the hydraulic actuator 2 turns the rudder plate 11 in the starboard direction (toward the left side in FIG. 1 ).
- the hydraulic actuator 2 is a hydraulic cylinder in which the first actuating chamber 22 and the second actuating chamber 23 are formed on both sides of a ram 21. Accordingly, a supply flow rate of the hydraulic oil to one of the first and second actuating chambers 22 and 23, and a discharge flow rate of the hydraulic oil from the other one of the first and second actuating chambers 22 and 23, are equal to each other.
- the ram 21 is rod-shaped and extends in a direction orthogonal to the axial direction of the rudder stock 12.
- a pin 24 is provided at the middle of the ram 21, .
- the pin 24 engages with the tiller 13.
- the tiller 13 is provided with a groove that is open in a direction away from the rudder stock 12, and the pin 24 is inserted in the groove.
- the number of hydraulic actuators 2 need not be one, but may be two such that the hydraulic cylinders are parallel to each other, with the rudder stock 12 positioned therebetween.
- the hydraulic actuator 2 need not be a hydraulic cylinder in which the first actuating chamber 22 and the second actuating chamber 23 are formed on both sides of the ram 21, but may be a single-rod hydraulic cylinder in which a rod extends from a piston disposed in a tube whose both ends are sealed up.
- the inside of the tube is divided by the piston into the first actuating chamber 22 and the second actuating chamber 23.
- the tube may be swingably supported, and the distal end of the rod may be coupled, by a pin, to the tiller 13.
- the hydraulic actuator 2 may be a hydraulic motor in which the first actuating chamber 22 and the second actuating chamber 23 are divided from each other by a vane.
- the hydraulic actuator 2 may be provided with a plurality of first actuating chambers 22 and a plurality of second actuating chambers 23.
- the rotating shaft of the hydraulic motor is coupled to the rudder stock 12 by a coupler.
- a supply flow rate of the hydraulic oil to one of the first and second actuating chambers 22 and 23, and a discharge flow rate of the hydraulic oil from the other one of the first and second actuating chambers 22 and 23, are equal to each other.
- the first actuating chamber 22 and the second actuating chamber 23 of the hydraulic actuator 2 are connected to a switching valve 3 by a pair of supply/discharge lines 44 and 45.
- the switching valve 3 is connected, by a pump line 42, to a delivery port of a pump 41, which delivers the hydraulic oil.
- the switching valve 3 is connected to a suction port of the pump 41 by a recovery line 43.
- the switching valve 3 may be connected to a tank by a tank line.
- the suction port of the pump 41 is connected to the tank by a suction line. This configuration is often adopted in cases where the hydraulic actuator 2 is a single-rod hydraulic cylinder as described above.
- the pump 41 is a fixed displacement pump.
- the pump 41 is driven at a constant rotation speed by an unshown electric motor.
- the rotation speed of the pump 41 need not be constant, but may be variable.
- the pump 41 need not be a fixed displacement pump, but may be, for example, a variable displacement pump whose tilting angle is changeable (e.g., a swash plate pump or a bent axis pump).
- the switching valve 3 includes a housing 32 and a spool 31.
- the spool 31 is slidably held by the housing 32.
- the switching valve 3 blocks the supply/discharge lines 44 and 45, and brings the pump line 42 into communication with the recovery line 43.
- the switching valve 3 brings one of the supply/discharge lines 44 and 45 into communication with the pump line 42, and brings the other one of the supply/discharge lines 44 and 45 into communication with the recovery line 43.
- the spool 31 is shifted by a shifting mechanism 5.
- the shifting mechanism 5 is configured such that the shifting speed of the spool 31 is electrically changeable.
- the shifting mechanism 5 is controlled by a controller 6.
- the shifting mechanism 5 is a linear motion mechanism 5A.
- the linear motion mechanism 5A includes: a rod-shaped coupling member 51, which extends in the axial direction of the spool 31; a nut 52, which is coupled to the spool 31 via the coupling member 51; a screw shaft 53, which is screwed with the nut 52; and an electric motor 54, which rotates the screw shaft 53.
- the coupling member 51, the nut 52, the screw shaft 53, and the electric motor 54 are arranged coaxially with the spool 31.
- a cylindrical casing 55 is interposed between the housing 32 and the electric motor 54.
- the coupling member 51, the nut 52, and the screw shaft 53 are accommodated in the casing 55.
- the electric motor 54 is a servomotor.
- the electric motor 54 rotates the screw shaft 53 in one direction, the nut 52, the coupling member 51, and the spool 31 shift to one side in the axial direction of the spool 31, and when the electric motor 54 rotates the screw shaft 53 in the opposite direction, the nut 52, the coupling member 51, and the spool 31 shift to the other side in the axial direction of the spool 31.
- one side in the axial direction of the spool 31 (the right side in FIG. 2 ) is referred to as the right side and the other side in the axial direction of the spool 31 (the left side in FIG. 2 ) is referred to as the left side.
- the right end of the spool 31 and the left end of the coupling member 51 are coupled to each other by a ball joint.
- the left end of the coupling member 51 is provided with a groove 51a, and a ball 35 is held in the groove 51a.
- the right end of the spool 31 is provided with a plate-shaped protrusion 31a, which is inserted in the groove 51a.
- the protrusion 31a is provided with a hole that is fitted to the ball 35.
- the right end of the spool 31 may be provided with the groove 51a, in which the ball 35 is held, and the left end of the coupling member 51 may be provided with the protrusion 31a, which is inserted in the groove 51a.
- the right end of the spool 31 and the left end of the coupling member 51 may be coupled to each other by a joint different from a ball joint.
- a hole 51b which is open toward the right side, is provided on the center line of the coupling member 51.
- the nut 52 is fixed to the coupling member 51 in a state where the nut 52 is inserted in the hole 51b.
- the coupling member 51 is guided by an unshown guide mechanism such that the coupling member 51 is shiftable only in the left-right direction (i.e., the coupling member 51 is prevented from rotating).
- the present embodiment is further provided with a mechanism between the coupling member 51 and the casing 55.
- the mechanism serves to keep the spool 31 at the neutral position when the electric motor 54 is not supplied with electric power.
- the mechanism includes: a coil spring 56 in which the coupling member 51 is inserted; and a pair of spring receivers 57 and 58, which supports both ends of the coil spring 56, respectively.
- the coil spring 56 applies urging force to the spool 31 via the coupling member 51 to keep the spool 31 at the neutral position.
- Each of the spring receivers 57 and 58 is ringshaped and slidably fitted to the coupling member 51.
- a flange 51c which contacts the spring receiver 58, is provided on the right end of the coupling member 51.
- a stopper 59 which contacts the spring receiver 57, is mounted to the coupling member 51.
- a stepped portion 55b is provided at a position corresponding to the flange 51c, and a stepped portion 55a is provided at a position corresponding to the stopper 59.
- the urging force of the coil spring 56 causes the spring receiver 58 to contact both the flange 51c and the stepped portion 55b, and causes the spring receiver 57 to contact both the stopper 59 and the stepped portion 55a. Consequently, the spool 31 is kept at the neutral position.
- the coil spring 56 which applies the urging force to the spool 31 to keep the spool 31 at the neutral position, may be provided at the opposite side of the spool 31 from the linear motion mechanism 5A.
- the controller 6 is a computer including memories such as a ROM and RAM, a storage such as a HDD or SSD, and a CPU.
- the CPU executes a program stored in the ROM or the storage.
- steering commands are inputted to the controller 6.
- the steering commands are: a port direction steering command to turn the rudder plate 11 in the port direction; a steering stop command to stop the rudder plate 11; and a starboard direction steering command to turn the rudder plate 11 in the starboard direction.
- the steering commands are not limited to these three commands, but may include steering commands that are in between these three commands. That is, the waveform of a steering command need not be a rectangular pulse waveform, but may be a smooth curved waveform.
- the controller 6 When the controller 6 receives the port direction steering command, i.e., when the steering command changes from the steering stop command into the port direction steering command, the controller 6 controls the linear motion mechanism 5A to cause the shifting speed of the spool 31 to transition on a curve C1 as shown in FIG. 3B . Consequently, the spool 31 shifts from the neutral position to a maximum opening position where the opening area between the pump line 42 and the supply/discharge line 45 is maximum.
- the curve C1 is an S-shaped curve indicating that the shifting speed of the spool 31 increases gradually and then decreases gradually.
- the controller 6 controls the linear motion mechanism 5A to cause the shifting speed of the spool 31 to transition on a curve C2. Consequently, the spool 31 shifts from the maximum opening position to the neutral position.
- the curve C2 is an S-shaped curve indicating that the shifting speed of the spool 31 increases gradually and then decreases gradually.
- the controller 6 controls the linear motion mechanism 5A to cause the shifting speed of the spool 31 to transition on a curve C3. Consequently, the spool 31 shifts from the neutral position to a maximum opening position where the opening area between the pump line 42 and the supply/discharge line 44 is maximum.
- the curve C3 is an S-shaped curve indicating that the shifting speed of the spool 31 increases gradually and then decreases gradually.
- the controller 6 controls the linear motion mechanism 5A to cause the shifting speed of the spool 31 to transition on a curve C4. Consequently, the spool 31 shifts from the maximum opening position to the neutral position.
- the curve C4 is an S-shaped curve indicating that the shifting speed of the spool 31 increases gradually and then decreases gradually.
- the controller 6 is electrically connected to a position detector 7, which detects the position of the spool 31.
- the position detector 7 is a rotary encoder 7A, which detects the amount of rotation of the electric motor 54 as the position of the spool 31.
- the controller 6 determines whether or not the spool 31 is stuck based on the position of the spool 31 detected by the position detector 7 (in the present embodiment, the amount of rotation of the electric motor 54, which is detected by the rotary encoder 7A) and the electric current of the electric motor 54. In this manner, sticking of the spool 31 can be detected without using a special sensor, because usually in the linear motion mechanism 5A, the rotary encoder 7A is used for controlling the electric motor 54.
- the controller 6 maximizes the electric current flowing to the electric motor 54 to cause the spool 31 to reach the target position (i.e., brings and keeps the electric current value of the electric motor 54 to the upper limit value). Therefore, in a case where the position of the spool 31 does not change and the electric current value of the electric motor 54 is kept to the upper limit value for about one second, the controller 6 determines that the spool 31 is stuck. On the other hand, in a case where these conditions are not met, the controller 6 determines that the spool 31 is not stuck.
- the controller 6 may output an error signal.
- the controller 6 may output the error signal to an unshown display device disposed in a wheelhouse to indicate on a screen of the display device that the spool 31 is stuck. In this manner, a ship operator can be notified of the sticking of the spool 31.
- the controller 6 may control the linear motion mechanism 5A such that the spool 31 shifts in a direction corresponding to the starboard direction steering command and then shifts in a direction corresponding to the port direction steering command
- the controller 6 may control the linear motion mechanism 5A such that the spool 31 shifts in a direction corresponding to the port direction steering command and then shifts in a direction corresponding to the starboard direction steering command.
- the sticking of the spool 31 may be releasable.
- the spool 31 may be shifted in regular and reverse directions multiple times such that the spool 31 oscillates.
- the shifting mechanism 5, which shifts the spool 31 is configured such that the shifting speed of the spool 31 is electrically changeable. This makes flexible operation of the steering system 1A possible.
- the controller 6 may calculate a supply flow rate of the hydraulic oil to the first actuating chamber 22 or the second actuating chamber 23 based on the position of the spool 31 detected by the position detector 7, and may calculate the angle of the rudder plate 11 based on the calculated supply flow rate. In this manner, the angle of the rudder plate 11 can be known without using an angle sensor.
- the controller 6 may integrate the calculated supply flow rate to calculate a total supply amount of the hydraulic oil to the first actuating chamber 22 or the second actuating chamber 23, and may calculate the angle of the rudder plate 11 based on the calculated total supply amount.
- the controller 6 may output an error signal when the calculated angle of the rudder plate 11 is out of an allowable range.
- the controller 6 may output the error signal to the unshown display device disposed in the wheelhouse to indicate on the screen of the display device that the rudder plate is not turning in accordance with steering. In this manner, the ship operator can be notified that the rudder plate 11 is not turning in accordance with steering.
- the aforementioned allowable range can be calculated, for example, from a target rudder angle.
- the target rudder angle can be calculated from a time during which the controller 6 receives the port direction operation command or the starboard direction operation command.
- the lower limit of the allowable range may be calculated by subtracting a predetermined value from the target rudder angle, or may be calculated by multiplying the target rudder angle by a predetermined percentage (e.g., 50 to 90%).
- the upper limit of the allowable range may be calculated by adding a predetermined value to the target rudder angle, or may be calculated by multiplying the target rudder angle by a predetermined percentage (e.g., 110 to 150%).
- FIG. 5 shows a steering system 1B according to Embodiment 2 of the present invention.
- the same components as those described in Embodiment 1 are denoted by the same reference signs as those used in Embodiment 1, and repeating the same descriptions is avoided.
- a pressure sensor 8 which detects the pressure of the second actuating chamber 23, is provided on the supply/discharge line 45, which connects to the second actuating chamber 23.
- the pressure sensor 8 may be provided on the second actuating chamber 23.
- the pressure sensor 8 may be provided on the first actuating chamber 22 or the supply/discharge line 44, and may detect the pressure of the first actuating chamber 22.
- the controller 6 when the controller 6 receives the port direction steering command or the starboard direction steering command, the controller 6 controls the linear motion mechanism 5A to cause the shifting speed of the spool 31 to transition on the curve C1 or C3 shown in FIG. 3B . Further, in the present embodiment, the controller 6 corrects the curves C1 and C3 in accordance with the pressure detected by the pressure sensor 8.
- the controller 6 increases the slopes of the respective curves C1 and C3 (i.e., makes the curves C1 and C3 steep), whereas in a case where the pressure detected by the pressure sensor 8 is higher than the specified value, the controller 6 decreases the slopes of the respective curves C1 and C3 (i.e., makes the curves C1 and C3 smooth). In this manner, the range of flow velocity fluctuation of the hydraulic oil that is caused by pressure fluctuation can be kept small.
- the curves C1 and C3 are corrected in accordance with the pressure. Therefore, compared to a case where the curves C1 and C3 are constant, the relationship between the position of the spool 31 and the flow velocity of the hydraulic oil passing through the switching valve 3 can be made more stable.
- the controller 6 may correct the curves C2 and C4 shown in FIG. 3B in accordance with the pressure detected by the pressure sensor 8.
- FIG. 6 shows a steering system 1C according to Embodiment 3 of the present invention.
- the steering system 1C includes a first circuit and a second circuit.
- the first circuit includes the pump 41, the pump line 42, the recovery line 43, the switching valve 3, and the supply/discharge lines 44 and 45, which are described in Embodiment 1.
- the second circuit is configured in the same manner as the first circuit.
- the pump 41, the switching valve 3, the shifting mechanism 5, the position detector 7, and the controller 6, which are described in Embodiment 1, are a first pump 41, a first switching valve 3, a first shifting mechanism 5, a first position detector 7, and a first controller 6, respectively.
- the housing 32 and the spool 31 of the switching valve 3 described in Embodiment 1 are a first housing 32 and a first spool 31, respectively.
- the second circuit includes a second pump 41', a pump line 42', a recovery line 43', a second switching valve 3', and a pair of supply/discharge lines 44' and 45'.
- the second switching valve 3' is connected to the first actuating chamber 22 and the second actuating chamber 23 of the hydraulic actuator 2 by the supply/discharge lines 44' and 45', respectively.
- the second switching valve 3' is connected to the second pump 41' by the pump line 42' and the recovery line 43'.
- the second pump 41' is a fixed displacement pump, and is driven at a constant rotation speed by an unshown electric motor.
- the variations of the first pump 41, which are described in Embodiment 1, are applicable also to the second pump 41'.
- the second switching valve 3' includes a second housing 32' and a second spool 31'.
- the second spool 31' is slidably held by the second housing 32'.
- the second spool 31' is shifted by a second shifting mechanism 5'.
- the second shifting mechanism 5' is configured such that the shifting speed of the second spool 31' is electrically changeable.
- the second shifting mechanism 5' is controlled by the controller 6.
- the second shifting mechanism 5' is a linear motion mechanism 5A.
- the second controller 6' is electrically connected to a second position detector 7', which detects the position of the second spool 31'.
- the second position detector 7' is the rotary encoder 7A, which detects the amount of rotation of the electric motor 54 of the linear motion mechanism 5A as the position of the second spool 31'.
- the second controller 6' is configured in the same manner as the first controller 6.
- the second controller 6' is configured to communicate with the first controller 6.
- the first controller 6 or the second controller 6' outputs an error signal when an inconsistency occurs in a positional relationship between the position of the first spool 31 detected by the first position detector 7 (in the present embodiment, the amount of rotation, detected by the rotary encoder 7A, of the electric motor 54 of the linear motion mechanism 5A serving as the first shifting mechanism 5) and the position of the second spool 31' detected by the second position detector 7' (in the present embodiment, the amount of rotation, detected by the rotary encoder 7A, of the electric motor 54 of the linear motion mechanism 5A serving as the second shifting mechanism 5').
- the first spool 31 of the first switching valve 3 and the second spool 31' of the second switching valve 3' are moving differently from each other can be detected.
- the first controller 6 or the second controller 6' may output an error signal to the unshown display device disposed in the wheelhouse to indicate on the screen of the display device that the first spool 31 of the first switching valve 3 and the second spool 31' of the second switching valve 3' are moving differently from each other.
- Examples of a case where an inconsistency occurs in the positional relationship between the position of the first spool 31 and the position of the second spool 31' include: a case where the position of the first spool 31 and the position of the second spool 31' are different from each other; and a case where the first spool 31 and the second spool 31' shift in opposite directions to each other. Specifically, if the error signal is outputted in the case where the first spool 31 and the second spool 31' shift in opposite directions to each other, a situation where the first shifting mechanism 5 and the second shifting mechanism 5' are receiving different commands, respectively, from the controller 6 can be detected.
- the first controller 6 or the second controller 6' determines that an inconsistency has occurred in the positional relationship between the position of the first spool 31 and the position of the second spool 31'.
- the first controller 6 or the second controller 6' may output an error signal. This configuration makes it possible to prevent erroneous motion of the first spool 31 or the second spool 31'.
- the controller 6 may control the first circuit in the same manner as in Embodiment 1 and Embodiment 2. Further, the controller 6 may control the second circuit in the same manner as in Embodiment 1 and Embodiment 2.
- the shifting mechanism 5 in Embodiments 1 to 3 (as well as the second shifting mechanism 5' in Embodiment 3) need not be the linear motion mechanism 5A, but may be a pair of solenoid proportional valves 61 and 62 as in a steering system 1D according to a variation shown in FIG. 7 .
- a pair of pilot chambers 33 and 34 is formed in the switching valve 3
- the solenoid proportional valves 61 and 62 are connected to the pilot chambers 33 and 34, respectively.
- the solenoid proportional valves 61 and 62 are connected to a sub pump 64 by a primary pressure line 63.
- Each of the solenoid proportional valves 61 and 66 is fed with a command current from the controller 6.
- Each of the solenoid proportional valves 61 and 62 outputs a secondary pressure to a corresponding one of the pilot chambers 33 and 34 in accordance with the command current.
- each of the solenoid proportional valves 61 and 62 is a direct proportional valve whose output secondary pressure and the command current fed thereto indicate a positive correlation.
- each of the solenoid proportional valves 61 and 62 may be an inverse proportional valve whose output secondary pressure and the command current fed thereto indicate a negative correlation.
- the switching valve 3 needs to be provided with, for example, a stroke sensor 7B as the position detector 7, which detects the position of the spool 31.
- the shifting mechanism 5 is the linear motion mechanism 5A and the position detector 7 is the rotary encoder 7A, which detects the amount of rotation of the electric motor 54 included in the linear motion mechanism 5A
- the switching valve 3 need not be provided with a sensor.
- a steering system is a steering system installed in a ship, and includes: a hydraulic actuator that turns a rudder plate via a rudder stock that penetrates a ship bottom, the hydraulic actuator including a first actuating chamber and a second actuating chamber; a pump that delivers hydraulic oil; a switching valve including a spool, the switching valve being connected to the first actuating chamber and the second actuating chamber by a pair of supply/discharge lines and to the pump by a pump line; and a shifting mechanism that shifts the spool, the shifting mechanism being configured such that a shifting speed of the spool is electrically changeable.
- the shifting mechanism which shifts the spool, is configured such that the shifting speed of the spool is electrically changeable. This makes flexible operation of the steering system possible.
- the above steering system may include a controller that controls the shifting mechanism.
- the controller may control the shifting mechanism to cause the shifting speed of the spool to transition on such a curve that the shifting speed increases gradually and then decreases gradually.
- the shifting speed of the spool transitions on such a curve that the shifting speed increases gradually and then decreases gradually.
- the above steering system may include a pressure sensor that detects a pressure of the first actuating chamber or the second actuating chamber.
- the controller may correct the curve in accordance with the pressure detected by the pressure sensor. According to this configuration, compared to a case where the curve is constant, the relationship between the position of the spool and the flow velocity of the hydraulic oil passing through the switching valve can be made more stable.
- the above steering system may include: a controller that controls the shifting mechanism; and a position detector that detects a position of the spool.
- the shifting mechanism may be a linear motion mechanism including: a nut that is coupled to the spool; a screw shaft that is screwed with the nut; and an electric motor that rotates the screw shaft.
- the position detector may be a rotary encoder that detects an amount of rotation of the electric motor as the position of the spool.
- the switching valve needs to be provided with, for example, a stroke sensor as the position detector, which detects the position of the spool.
- the shifting mechanism is the linear motion mechanism and the position detector is the rotary encoder that detects the amount of rotation of the electric motor included in the linear motion mechanism
- the switching valve need not be provided with a sensor.
- the controller may determine whether or not the spool is stuck based on the detected position of the spool and an electric current of the electric motor. According to this configuration, sticking of the spool can be detected without using a special sensor.
- the controller may output an error signal when the controller determines that the spool is stuck. According to this configuration, a ship operator can be notified of the sticking of the spool.
- the controller may control the shifting mechanism such that the spool shifts in a direction opposite to a direction corresponding to the steering command, and then shifts in the direction corresponding to the steering command. According to this configuration, the sticking of the spool may be releasable.
- the controller may calculate a supply flow rate of the hydraulic oil to the first actuating chamber or the second actuating chamber based on the detected position of the spool, and calculate an angle of the rudder plate based on the calculated supply flow rate. According to this configuration, the angle of the rudder plate can be known without using an angle sensor.
- the controller may output an error signal when the calculated angle of the rudder plate is out of an allowable range. According to this configuration, the ship operator can be notified that the rudder plate is not turning in accordance with steering.
- the pump may be a first pump.
- the spool may be a first spool.
- the switching valve may be a first switching valve.
- the shifting mechanism may be a first shifting mechanism.
- the position detector may be a first position detector.
- the controller may be a first controller.
- the steering system may include: a second pump that delivers the hydraulic oil; a second switching valve including a second spool, the second switching valve being connected to the first actuating chamber and the second actuating chamber by a pair of supply/discharge lines and to the second pump by a pump line; a second shifting mechanism that shifts the second spool, the second shifting mechanism being configured such that a shifting speed of the second spool is electrically changeable; a second controller that controls the second shifting mechanism and that is configured to communicate with the first controller; and a second position detector that detects a position of the second spool.
- the first controller or the second controller may output an error signal when an inconsistency occurs in a positional relationship between the position of the first spool detected by the first position detector and the position of the second spool detected by the second position detector. According to this configuration, a situation where the first spool of the first switching valve and the second spool of the second switching valve are moving differently from each other can be detected.
- the pump may be a first pump.
- the spool may be a first spool.
- the switching valve may be a first switching valve.
- the shifting mechanism may be a first shifting mechanism.
- the steering system may include: a first controller that controls the first shifting mechanism; a second pump that delivers the hydraulic oil; a second switching valve including a second spool, the second switching valve being connected to the first actuating chamber and the second actuating chamber by a pair of supply/discharge lines and to the second pump by a pump line; a second shifting mechanism that shifts the second spool, the second shifting mechanism being configured such that a shifting speed of the second spool is electrically changeable; and a second controller that controls the second shifting mechanism and that is configured to communicate with the first controller.
- the first controller or the second controller may output an error signal when a steering command received by the first controller and a steering command received by the second controller are different from each other. This configuration makes it possible to prevent erroneous motion of the first spool or the second spool.
- the switching valve may be connected to the pump by a recovery line.
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Abstract
Description
- The present invention relates to a steering system installed in a ship.
- Conventionally, a steering system for hydraulically operating a rudder plate is installed in a ship. The steering system includes a hydraulic actuator that turns the rudder plate via a rudder stock that penetrates the ship's plank. The hydraulic actuator includes a first actuating chamber and a second actuating chamber. When hydraulic oil is supplied to one of the first and second actuating chambers, the hydraulic actuator turns the rudder plate in the port direction. When the hydraulic oil is supplied to the other one of the first and second actuating chambers, the hydraulic actuator turns the rudder plate in the starboard direction.
- For example, Patent Literature 1 discloses a steering system that adopts, as a hydraulic actuator, a hydraulic cylinder in which a first actuating chamber and a second actuating chamber are formed on both sides of a ram, respectively. In the steering system, the first actuating chamber and the second actuating chamber of the hydraulic cylinder are connected to a switching valve by a pair of supply/discharge lines. The switching valve is connected to a pump by a pump line, and to a tank by a tank line. When the switching valve is in the neutral position, the switching valve blocks the pair of supply/discharge lines. At the time of turning the rudder plate, the switching valve brings one of the pair of supply/discharge lines into communication with the pump line, and brings the other one of the pair of supply/discharge lines into communication with the tank line.
- To be more specific, the switching valve includes a spool, and the spool is driven by a pair of solenoid valves. The switching valve includes a pair of pilot chambers formed therein for applying pilot pressures to both end faces of the spool. Each of the solenoid valves switches whether or not to lead a pilot pressure to a corresponding one of the pilot chambers.
- PTL 1:
Japanese Laid-Open Patent Application Publication No. H09-76997 - However, in the steering system disclosed by Patent Literature 1, since each solenoid valve is a simple on-off valve, when the magnet coil of the solenoid valve is excited, the spool shifts instantaneously. Therefore, flexible operation of the steering system is difficult.
- In view of the above, an object of the present invention is to provide a steering system capable of flexible operation.
- In order to solve the above-described problems, a steering system according to the present invention is a steering system installed in a ship, and includes: a hydraulic actuator that turns a rudder plate via a rudder stock that penetrates a ship bottom, the hydraulic actuator including a first actuating chamber and a second actuating chamber; a pump that delivers hydraulic oil; a switching valve including a spool, the switching valve being connected to the first actuating chamber and the second actuating chamber by a pair of supply/discharge lines and to the pump by a pump line; and a shifting mechanism that shifts the spool, the shifting mechanism being configured such that a shifting speed of the spool is electrically changeable.
- According to the above configuration, the shifting mechanism, which shifts the spool, is configured such that the shifting speed of the spool is electrically changeable. This makes flexible operation of the steering system possible.
- The present invention makes it possible to provide a steering system capable of flexible operation.
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FIG. 1 shows a schematic configuration of a steering system according to Embodiment 1 of the present invention. -
FIG. 2 is a sectional view of a linear motion mechanism. -
FIG. 3A shows one example of steering commands, andFIG. 3B shows spool positions corresponding to the respective steering commands. -
FIG. 4 is a sectional view of a part of a ship in which the steering system shown inFIG. 1 is installed. -
FIG. 5 shows a schematic configuration of a steering system according toEmbodiment 2 of the present invention. -
FIG. 6 shows a schematic configuration of a steering system according toEmbodiment 3 of the present invention. -
FIG. 7 shows a schematic configuration of a steering system according to another embodiment. -
FIG. 1 shows asteering system 1A according to Embodiment 1 of the present invention. As shown inFIG. 4 , thesteering system 1A is installed in a ship. - Specifically, the
steering system 1A includes ahydraulic actuator 2. Thehydraulic actuator 2 turns arudder plate 11 via arudder stock 12, which penetrates aship bottom 10 in the vertical direction. In the present embodiment, thehydraulic actuator 2 turns therudder plate 11 not only via therudder stock 12, but also via atiller 13 disposed inside the ship. - As shown in
FIG. 1 , thehydraulic actuator 2 includes afirst actuating chamber 22 and asecond actuating chamber 23. When hydraulic oil is supplied to one of the first andsecond actuating chambers 22 and 23 (in the present embodiment, the second actuating chamber 23), thehydraulic actuator 2 turns therudder plate 11 in the port direction (toward the right side inFIG. 1 ). When the hydraulic oil is supplied to the other one of the first andsecond actuating chambers 22 and 23 (in the present embodiment, the first actuating chamber 22), thehydraulic actuator 2 turns therudder plate 11 in the starboard direction (toward the left side inFIG. 1 ). - In the present embodiment, the
hydraulic actuator 2 is a hydraulic cylinder in which thefirst actuating chamber 22 and thesecond actuating chamber 23 are formed on both sides of aram 21. Accordingly, a supply flow rate of the hydraulic oil to one of the first andsecond actuating chambers second actuating chambers - The
ram 21 is rod-shaped and extends in a direction orthogonal to the axial direction of therudder stock 12. At the middle of theram 21, apin 24 is provided. Thepin 24 engages with the tiller 13. To be more specific, thetiller 13 is provided with a groove that is open in a direction away from therudder stock 12, and thepin 24 is inserted in the groove. - The number of
hydraulic actuators 2 need not be one, but may be two such that the hydraulic cylinders are parallel to each other, with therudder stock 12 positioned therebetween. Thehydraulic actuator 2 need not be a hydraulic cylinder in which thefirst actuating chamber 22 and the second actuatingchamber 23 are formed on both sides of theram 21, but may be a single-rod hydraulic cylinder in which a rod extends from a piston disposed in a tube whose both ends are sealed up. - In a case where the
hydraulic actuator 2 is a single-rod hydraulic cylinder, the inside of the tube is divided by the piston into thefirst actuating chamber 22 and thesecond actuating chamber 23. Further, in the case where thehydraulic actuator 2 is a single-rod hydraulic cylinder, the tube may be swingably supported, and the distal end of the rod may be coupled, by a pin, to thetiller 13. - Alternatively, the
hydraulic actuator 2 may be a hydraulic motor in which thefirst actuating chamber 22 and the second actuatingchamber 23 are divided from each other by a vane. In this case, thehydraulic actuator 2 may be provided with a plurality offirst actuating chambers 22 and a plurality ofsecond actuating chambers 23. In the case where thehydraulic actuator 2 is a hydraulic motor, the rotating shaft of the hydraulic motor is coupled to therudder stock 12 by a coupler. Also in the case where thehydraulic actuator 2 is a hydraulic motor, a supply flow rate of the hydraulic oil to one of the first andsecond actuating chambers second actuating chambers - The
first actuating chamber 22 and thesecond actuating chamber 23 of thehydraulic actuator 2 are connected to a switchingvalve 3 by a pair of supply/discharge lines switching valve 3 is connected, by apump line 42, to a delivery port of apump 41, which delivers the hydraulic oil. In the present embodiment, theswitching valve 3 is connected to a suction port of thepump 41 by arecovery line 43. - It should be noted that, although not illustrated, the switching
valve 3 may be connected to a tank by a tank line. In this case, the suction port of thepump 41 is connected to the tank by a suction line. This configuration is often adopted in cases where thehydraulic actuator 2 is a single-rod hydraulic cylinder as described above. - In the present embodiment, the
pump 41 is a fixed displacement pump. Thepump 41 is driven at a constant rotation speed by an unshown electric motor. However, the rotation speed of thepump 41 need not be constant, but may be variable. Thepump 41 need not be a fixed displacement pump, but may be, for example, a variable displacement pump whose tilting angle is changeable (e.g., a swash plate pump or a bent axis pump). - As shown in
FIG. 1 andFIG. 2 , the switchingvalve 3 includes ahousing 32 and aspool 31. Thespool 31 is slidably held by thehousing 32. When thespool 31 is at the neutral position, the switchingvalve 3 blocks the supply/discharge lines pump line 42 into communication with therecovery line 43. On the other hand, when thespool 31 shifts from the neutral position to one side or the other side in the axial direction of thespool 31, the switchingvalve 3 brings one of the supply/discharge lines pump line 42, and brings the other one of the supply/discharge lines recovery line 43. - The
spool 31 is shifted by ashifting mechanism 5. Theshifting mechanism 5 is configured such that the shifting speed of thespool 31 is electrically changeable. Theshifting mechanism 5 is controlled by acontroller 6. - In the present embodiment, the
shifting mechanism 5 is alinear motion mechanism 5A. Specifically, thelinear motion mechanism 5A includes: a rod-shapedcoupling member 51, which extends in the axial direction of thespool 31; anut 52, which is coupled to thespool 31 via thecoupling member 51; ascrew shaft 53, which is screwed with thenut 52; and anelectric motor 54, which rotates thescrew shaft 53. Thecoupling member 51, thenut 52, thescrew shaft 53, and theelectric motor 54 are arranged coaxially with thespool 31. Acylindrical casing 55 is interposed between thehousing 32 and theelectric motor 54. Thecoupling member 51, thenut 52, and thescrew shaft 53 are accommodated in thecasing 55. - For example, the
electric motor 54 is a servomotor. When theelectric motor 54 rotates thescrew shaft 53 in one direction, thenut 52, thecoupling member 51, and thespool 31 shift to one side in the axial direction of thespool 31, and when theelectric motor 54 rotates thescrew shaft 53 in the opposite direction, thenut 52, thecoupling member 51, and thespool 31 shift to the other side in the axial direction of thespool 31. - Hereinafter, with reference to
FIG. 2 , the configuration of thelinear motion mechanism 5A is described in detail. In the description below, for the sake of convenience of the description, one side in the axial direction of the spool 31 (the right side inFIG. 2 ) is referred to as the right side and the other side in the axial direction of the spool 31 (the left side inFIG. 2 ) is referred to as the left side. - In the present embodiment, the right end of the
spool 31 and the left end of thecoupling member 51 are coupled to each other by a ball joint. Specifically, the left end of thecoupling member 51 is provided with agroove 51a, and aball 35 is held in thegroove 51a. On the other hand, the right end of thespool 31 is provided with a plate-shapedprotrusion 31a, which is inserted in thegroove 51a. Theprotrusion 31a is provided with a hole that is fitted to theball 35. - Alternatively, conversely to the present embodiment, the right end of the
spool 31 may be provided with thegroove 51a, in which theball 35 is held, and the left end of thecoupling member 51 may be provided with theprotrusion 31a, which is inserted in thegroove 51a. Further alternatively, the right end of thespool 31 and the left end of thecoupling member 51 may be coupled to each other by a joint different from a ball joint. - A
hole 51b, which is open toward the right side, is provided on the center line of thecoupling member 51. Thenut 52 is fixed to thecoupling member 51 in a state where thenut 52 is inserted in thehole 51b. Thecoupling member 51 is guided by an unshown guide mechanism such that thecoupling member 51 is shiftable only in the left-right direction (i.e., thecoupling member 51 is prevented from rotating). - The present embodiment is further provided with a mechanism between the coupling
member 51 and thecasing 55. The mechanism serves to keep thespool 31 at the neutral position when theelectric motor 54 is not supplied with electric power. The mechanism includes: acoil spring 56 in which thecoupling member 51 is inserted; and a pair ofspring receivers coil spring 56, respectively. - The
coil spring 56 applies urging force to thespool 31 via thecoupling member 51 to keep thespool 31 at the neutral position. Each of thespring receivers coupling member 51. - A
flange 51c, which contacts thespring receiver 58, is provided on the right end of thecoupling member 51. At a position that is away from theflange 51c toward the left side, astopper 59, which contacts thespring receiver 57, is mounted to thecoupling member 51. - On the inner side surface of the
casing 55, a steppedportion 55b is provided at a position corresponding to theflange 51c, and a steppedportion 55a is provided at a position corresponding to thestopper 59. - With the above-described structure, when the
electric motor 54 is not supplied with electric power, the urging force of thecoil spring 56 causes thespring receiver 58 to contact both theflange 51c and the steppedportion 55b, and causes thespring receiver 57 to contact both thestopper 59 and the steppedportion 55a. Consequently, thespool 31 is kept at the neutral position. - In a state where the
spool 31 is at the neutral position, when thecoupling member 51 shifts toward the left side, thespring receiver 58 is pushed by theflange 51c to become spaced apart from the steppedportion 55b, and also, thestopper 59 becomes spaced apart from thespring receiver 57. On the other hand, in the state where thespool 31 is at the neutral position, when thecoupling member 51 shifts toward the right side, theflange 51c becomes spaced apart from thespring receiver 58, and also, thespring receiver 57 is pushed by thestopper 59 to become spaced apart from the steppedportion 55a. - Alternatively, the
coil spring 56, which applies the urging force to thespool 31 to keep thespool 31 at the neutral position, may be provided at the opposite side of thespool 31 from thelinear motion mechanism 5A. - Next, control performed by the
controller 6 is described in detail. For example, thecontroller 6 is a computer including memories such as a ROM and RAM, a storage such as a HDD or SSD, and a CPU. The CPU executes a program stored in the ROM or the storage. - As shown in
FIG. 3A , steering commands are inputted to thecontroller 6. The steering commands are: a port direction steering command to turn therudder plate 11 in the port direction; a steering stop command to stop therudder plate 11; and a starboard direction steering command to turn therudder plate 11 in the starboard direction. However, the steering commands are not limited to these three commands, but may include steering commands that are in between these three commands. That is, the waveform of a steering command need not be a rectangular pulse waveform, but may be a smooth curved waveform. - When the
controller 6 receives the port direction steering command, i.e., when the steering command changes from the steering stop command into the port direction steering command, thecontroller 6 controls thelinear motion mechanism 5A to cause the shifting speed of thespool 31 to transition on a curve C1 as shown inFIG. 3B . Consequently, thespool 31 shifts from the neutral position to a maximum opening position where the opening area between thepump line 42 and the supply/discharge line 45 is maximum. The curve C1 is an S-shaped curve indicating that the shifting speed of thespool 31 increases gradually and then decreases gradually. - Thereafter, when the steering command changes from the port direction steering command into the steering stop command, the
controller 6 controls thelinear motion mechanism 5A to cause the shifting speed of thespool 31 to transition on a curve C2. Consequently, thespool 31 shifts from the maximum opening position to the neutral position. The curve C2 is an S-shaped curve indicating that the shifting speed of thespool 31 increases gradually and then decreases gradually. - On the other hand, when the
controller 6 receives the starboard direction steering command, i.e., when the steering command changes from the steering stop command into the starboard direction steering command, thecontroller 6 controls thelinear motion mechanism 5A to cause the shifting speed of thespool 31 to transition on a curve C3. Consequently, thespool 31 shifts from the neutral position to a maximum opening position where the opening area between thepump line 42 and the supply/discharge line 44 is maximum. The curve C3 is an S-shaped curve indicating that the shifting speed of thespool 31 increases gradually and then decreases gradually. - Thereafter, when the steering command changes from the starboard direction steering command into the steering stop command, the
controller 6 controls thelinear motion mechanism 5A to cause the shifting speed of thespool 31 to transition on a curve C4. Consequently, thespool 31 shifts from the maximum opening position to the neutral position. The curve C4 is an S-shaped curve indicating that the shifting speed of thespool 31 increases gradually and then decreases gradually. - The
controller 6 is electrically connected to aposition detector 7, which detects the position of thespool 31. In the present embodiment, theposition detector 7 is arotary encoder 7A, which detects the amount of rotation of theelectric motor 54 as the position of thespool 31. - When the
controller 6 receives the port direction steering command or the starboard direction steering command, thecontroller 6 determines whether or not thespool 31 is stuck based on the position of thespool 31 detected by the position detector 7 (in the present embodiment, the amount of rotation of theelectric motor 54, which is detected by therotary encoder 7A) and the electric current of theelectric motor 54. In this manner, sticking of thespool 31 can be detected without using a special sensor, because usually in thelinear motion mechanism 5A, therotary encoder 7A is used for controlling theelectric motor 54. - At a normal time when the
spool 31 is not stuck, an electric current corresponding to necessary thrust for shifting thespool 31 to a target position flows to theelectric motor 54. On the other hand, when thespool 31 is stuck, since thespool 31 does not reach the target position, thecontroller 6 maximizes the electric current flowing to theelectric motor 54 to cause thespool 31 to reach the target position (i.e., brings and keeps the electric current value of theelectric motor 54 to the upper limit value). Therefore, in a case where the position of thespool 31 does not change and the electric current value of theelectric motor 54 is kept to the upper limit value for about one second, thecontroller 6 determines that thespool 31 is stuck. On the other hand, in a case where these conditions are not met, thecontroller 6 determines that thespool 31 is not stuck. - When the
controller 6 determines that thespool 31 is stuck, thecontroller 6 may output an error signal. For example, thecontroller 6 may output the error signal to an unshown display device disposed in a wheelhouse to indicate on a screen of the display device that thespool 31 is stuck. In this manner, a ship operator can be notified of the sticking of thespool 31. - Alternatively, when the
controller 6 determines that thespool 31 is stuck, in a case where thecontroller 6 receives the port direction steering command, thecontroller 6 may control thelinear motion mechanism 5A such that thespool 31 shifts in a direction corresponding to the starboard direction steering command and then shifts in a direction corresponding to the port direction steering command, whereas in a case where thecontroller 6 receives the starboard direction steering command, thecontroller 6 may control thelinear motion mechanism 5A such that thespool 31 shifts in a direction corresponding to the port direction steering command and then shifts in a direction corresponding to the starboard direction steering command. By performing such control, the sticking of thespool 31 may be releasable. Thespool 31 may be shifted in regular and reverse directions multiple times such that thespool 31 oscillates. - As described above, in the
steering system 1A of the present embodiment, theshifting mechanism 5, which shifts thespool 31, is configured such that the shifting speed of thespool 31 is electrically changeable. This makes flexible operation of thesteering system 1A possible. - In a case where the
spool 31 is shifted instantaneously by excitation of the magnet coil of a solenoid valve as in a conventional steering system, rapid change occurs in the motion of therudder stock 12 and therudder plate 11, and thereby a great impact shock occurs. On the other hand, in a case where the shifting speed of thespool 31 transitions on such a curve that the shifting speed increases gradually and then decreases gradually (i.e., transitions on the curve C1 or C3) as in the present embodiment, such an impact shock can be reduced. - The
controller 6 may calculate a supply flow rate of the hydraulic oil to thefirst actuating chamber 22 or thesecond actuating chamber 23 based on the position of thespool 31 detected by theposition detector 7, and may calculate the angle of therudder plate 11 based on the calculated supply flow rate. In this manner, the angle of therudder plate 11 can be known without using an angle sensor. For example, thecontroller 6 may integrate the calculated supply flow rate to calculate a total supply amount of the hydraulic oil to thefirst actuating chamber 22 or thesecond actuating chamber 23, and may calculate the angle of therudder plate 11 based on the calculated total supply amount. - Further, the
controller 6 may output an error signal when the calculated angle of therudder plate 11 is out of an allowable range. For example, thecontroller 6 may output the error signal to the unshown display device disposed in the wheelhouse to indicate on the screen of the display device that the rudder plate is not turning in accordance with steering. In this manner, the ship operator can be notified that therudder plate 11 is not turning in accordance with steering. - The aforementioned allowable range can be calculated, for example, from a target rudder angle. The target rudder angle can be calculated from a time during which the
controller 6 receives the port direction operation command or the starboard direction operation command. For example, the lower limit of the allowable range may be calculated by subtracting a predetermined value from the target rudder angle, or may be calculated by multiplying the target rudder angle by a predetermined percentage (e.g., 50 to 90%). The upper limit of the allowable range may be calculated by adding a predetermined value to the target rudder angle, or may be calculated by multiplying the target rudder angle by a predetermined percentage (e.g., 110 to 150%). -
FIG. 5 shows asteering system 1B according toEmbodiment 2 of the present invention. In the present embodiment and the followingEmbodiment 3, the same components as those described in Embodiment 1 are denoted by the same reference signs as those used in Embodiment 1, and repeating the same descriptions is avoided. - In the present embodiment, a
pressure sensor 8, which detects the pressure of thesecond actuating chamber 23, is provided on the supply/discharge line 45, which connects to thesecond actuating chamber 23. Alternatively, thepressure sensor 8 may be provided on thesecond actuating chamber 23. Further alternatively, thepressure sensor 8 may be provided on thefirst actuating chamber 22 or the supply/discharge line 44, and may detect the pressure of thefirst actuating chamber 22. - Similar to Embodiment 1, when the
controller 6 receives the port direction steering command or the starboard direction steering command, thecontroller 6 controls thelinear motion mechanism 5A to cause the shifting speed of thespool 31 to transition on the curve C1 or C3 shown inFIG. 3B . Further, in the present embodiment, thecontroller 6 corrects the curves C1 and C3 in accordance with the pressure detected by thepressure sensor 8. - For example, in a case where the pressure detected by the
pressure sensor 8 is lower than a specified value, thecontroller 6 increases the slopes of the respective curves C1 and C3 (i.e., makes the curves C1 and C3 steep), whereas in a case where the pressure detected by thepressure sensor 8 is higher than the specified value, thecontroller 6 decreases the slopes of the respective curves C1 and C3 (i.e., makes the curves C1 and C3 smooth). In this manner, the range of flow velocity fluctuation of the hydraulic oil that is caused by pressure fluctuation can be kept small. - In the
steering system 1B of the present embodiment, the curves C1 and C3 are corrected in accordance with the pressure. Therefore, compared to a case where the curves C1 and C3 are constant, the relationship between the position of thespool 31 and the flow velocity of the hydraulic oil passing through the switchingvalve 3 can be made more stable. - At the time of stopping the
rudder plate 11 from turning, thecontroller 6 may correct the curves C2 and C4 shown inFIG. 3B in accordance with the pressure detected by thepressure sensor 8. -
FIG. 6 shows asteering system 1C according toEmbodiment 3 of the present invention. Thesteering system 1C includes a first circuit and a second circuit. The first circuit includes thepump 41, thepump line 42, therecovery line 43, the switchingvalve 3, and the supply/discharge lines - Specifically, in the present embodiment, the
pump 41, the switchingvalve 3, theshifting mechanism 5, theposition detector 7, and thecontroller 6, which are described in Embodiment 1, are afirst pump 41, afirst switching valve 3, afirst shifting mechanism 5, afirst position detector 7, and afirst controller 6, respectively. Also, in the present embodiment, thehousing 32 and thespool 31 of the switchingvalve 3 described in Embodiment 1 are afirst housing 32 and afirst spool 31, respectively. - Similar to the first circuit, the second circuit includes a second pump 41', a pump line 42', a recovery line 43', a second switching valve 3', and a pair of supply/discharge lines 44' and 45'. The second switching valve 3' is connected to the
first actuating chamber 22 and thesecond actuating chamber 23 of thehydraulic actuator 2 by the supply/discharge lines 44' and 45', respectively. The second switching valve 3' is connected to the second pump 41' by the pump line 42' and the recovery line 43'. - Similar to the
first pump 41, the second pump 41' is a fixed displacement pump, and is driven at a constant rotation speed by an unshown electric motor. The variations of thefirst pump 41, which are described in Embodiment 1, are applicable also to the second pump 41'. - Similar to the
first switching valve 3, the second switching valve 3' includes a second housing 32' and a second spool 31'. The second spool 31' is slidably held by the second housing 32'. The second spool 31' is shifted by a second shifting mechanism 5'. - Similar to the
first shifting mechanism 5, the second shifting mechanism 5' is configured such that the shifting speed of the second spool 31' is electrically changeable. The second shifting mechanism 5' is controlled by thecontroller 6. In the present embodiment, similar to thefirst shifting mechanism 5, the second shifting mechanism 5' is alinear motion mechanism 5A. - The second controller 6' is electrically connected to a second position detector 7', which detects the position of the second spool 31'. In the present embodiment, similar to the
first position detector 7, the second position detector 7' is therotary encoder 7A, which detects the amount of rotation of theelectric motor 54 of thelinear motion mechanism 5A as the position of the second spool 31'. - The second controller 6' is configured in the same manner as the
first controller 6. The second controller 6' is configured to communicate with thefirst controller 6. - In the present embodiment, the
first controller 6 or the second controller 6' outputs an error signal when an inconsistency occurs in a positional relationship between the position of thefirst spool 31 detected by the first position detector 7 (in the present embodiment, the amount of rotation, detected by therotary encoder 7A, of theelectric motor 54 of thelinear motion mechanism 5A serving as the first shifting mechanism 5) and the position of the second spool 31' detected by the second position detector 7' (in the present embodiment, the amount of rotation, detected by therotary encoder 7A, of theelectric motor 54 of thelinear motion mechanism 5A serving as the second shifting mechanism 5'). In this manner, a situation where thefirst spool 31 of thefirst switching valve 3 and the second spool 31' of the second switching valve 3' are moving differently from each other can be detected. - For example, the
first controller 6 or the second controller 6' may output an error signal to the unshown display device disposed in the wheelhouse to indicate on the screen of the display device that thefirst spool 31 of thefirst switching valve 3 and the second spool 31' of the second switching valve 3' are moving differently from each other. - Examples of a case where an inconsistency occurs in the positional relationship between the position of the
first spool 31 and the position of the second spool 31' include: a case where the position of thefirst spool 31 and the position of the second spool 31' are different from each other; and a case where thefirst spool 31 and the second spool 31' shift in opposite directions to each other. Specifically, if the error signal is outputted in the case where thefirst spool 31 and the second spool 31' shift in opposite directions to each other, a situation where thefirst shifting mechanism 5 and the second shifting mechanism 5' are receiving different commands, respectively, from thecontroller 6 can be detected. - Accordingly, in the case where the position of the
first spool 31 and the position of the second spool 31' are different from each other, or in the case where the shifting direction of thefirst spool 31 and the shifting direction of the second spool 31' are different from each other (including a case where either one of thefirst spool 31 or the second spool 31' has shifted, but the other has not), thefirst controller 6 or the second controller 6' determines that an inconsistency has occurred in the positional relationship between the position of thefirst spool 31 and the position of the second spool 31'. - Alternatively, in a case where the steering command received by the
first controller 6 and the steering command received by the second controller 6' are different from each other, thefirst controller 6 or the second controller 6' may output an error signal. This configuration makes it possible to prevent erroneous motion of thefirst spool 31 or the second spool 31'. - The
controller 6 may control the first circuit in the same manner as in Embodiment 1 andEmbodiment 2. Further, thecontroller 6 may control the second circuit in the same manner as in Embodiment 1 andEmbodiment 2. - The present invention is not limited to the above-described embodiments. Various modifications can be made without departing from the scope of the present invention.
- For example, the
shifting mechanism 5 in Embodiments 1 to 3 (as well as the second shifting mechanism 5' in Embodiment 3) need not be thelinear motion mechanism 5A, but may be a pair of solenoidproportional valves 61 and 62 as in asteering system 1D according to a variation shown inFIG. 7 . In this case, a pair ofpilot chambers valve 3, and the solenoidproportional valves 61 and 62 are connected to thepilot chambers proportional valves 61 and 62 are connected to asub pump 64 by aprimary pressure line 63. - Each of the solenoid
proportional valves 61 and 66 is fed with a command current from thecontroller 6. Each of the solenoidproportional valves 61 and 62 outputs a secondary pressure to a corresponding one of thepilot chambers proportional valves 61 and 62 is a direct proportional valve whose output secondary pressure and the command current fed thereto indicate a positive correlation. Alternatively, each of the solenoidproportional valves 61 and 62 may be an inverse proportional valve whose output secondary pressure and the command current fed thereto indicate a negative correlation. - As shown in
FIG. 7 , in a case where theshifting mechanism 5 is the pair of solenoidproportional valves 61 and 62, the switchingvalve 3 needs to be provided with, for example, astroke sensor 7B as theposition detector 7, which detects the position of thespool 31. On the other hand, in a case where theshifting mechanism 5 is thelinear motion mechanism 5A and theposition detector 7 is therotary encoder 7A, which detects the amount of rotation of theelectric motor 54 included in thelinear motion mechanism 5A, the switchingvalve 3 need not be provided with a sensor. - A steering system according to the present invention is a steering system installed in a ship, and includes: a hydraulic actuator that turns a rudder plate via a rudder stock that penetrates a ship bottom, the hydraulic actuator including a first actuating chamber and a second actuating chamber; a pump that delivers hydraulic oil; a switching valve including a spool, the switching valve being connected to the first actuating chamber and the second actuating chamber by a pair of supply/discharge lines and to the pump by a pump line; and a shifting mechanism that shifts the spool, the shifting mechanism being configured such that a shifting speed of the spool is electrically changeable.
- According to the above configuration, the shifting mechanism, which shifts the spool, is configured such that the shifting speed of the spool is electrically changeable. This makes flexible operation of the steering system possible.
- The above steering system may include a controller that controls the shifting mechanism. When the controller receives a steering command to turn the rudder plate, the controller may control the shifting mechanism to cause the shifting speed of the spool to transition on such a curve that the shifting speed increases gradually and then decreases gradually. In a case where the spool is shifted instantaneously by excitation of the magnet coil of a solenoid valve as in a conventional steering system, rapid change occurs in the motion of the rudder stock and the rudder plate, and thereby a great impact shock occurs. On the other hand, in a case where the shifting speed of the spool transitions on such a curve that the shifting speed increases gradually and then decreases gradually as in the above configuration, such an impact shock can be reduced.
- The above steering system may include a pressure sensor that detects a pressure of the first actuating chamber or the second actuating chamber. The controller may correct the curve in accordance with the pressure detected by the pressure sensor. According to this configuration, compared to a case where the curve is constant, the relationship between the position of the spool and the flow velocity of the hydraulic oil passing through the switching valve can be made more stable.
- For example, the above steering system may include: a controller that controls the shifting mechanism; and a position detector that detects a position of the spool.
- The shifting mechanism may be a linear motion mechanism including: a nut that is coupled to the spool; a screw shaft that is screwed with the nut; and an electric motor that rotates the screw shaft. The position detector may be a rotary encoder that detects an amount of rotation of the electric motor as the position of the spool. In a case where the shifting mechanism is a pair of solenoid proportional valves, the switching valve needs to be provided with, for example, a stroke sensor as the position detector, which detects the position of the spool. On the other hand, in a case where the shifting mechanism is the linear motion mechanism and the position detector is the rotary encoder that detects the amount of rotation of the electric motor included in the linear motion mechanism, the switching valve need not be provided with a sensor.
- When the controller receives a steering command to turn the rudder plate, the controller may determine whether or not the spool is stuck based on the detected position of the spool and an electric current of the electric motor. According to this configuration, sticking of the spool can be detected without using a special sensor.
- The controller may output an error signal when the controller determines that the spool is stuck. According to this configuration, a ship operator can be notified of the sticking of the spool.
- When the controller determines that the spool is stuck, the controller may control the shifting mechanism such that the spool shifts in a direction opposite to a direction corresponding to the steering command, and then shifts in the direction corresponding to the steering command. According to this configuration, the sticking of the spool may be releasable.
- The controller may calculate a supply flow rate of the hydraulic oil to the first actuating chamber or the second actuating chamber based on the detected position of the spool, and calculate an angle of the rudder plate based on the calculated supply flow rate. According to this configuration, the angle of the rudder plate can be known without using an angle sensor.
- The controller may output an error signal when the calculated angle of the rudder plate is out of an allowable range. According to this configuration, the ship operator can be notified that the rudder plate is not turning in accordance with steering.
- The pump may be a first pump. The spool may be a first spool. The switching valve may be a first switching valve. The shifting mechanism may be a first shifting mechanism. The position detector may be a first position detector. The controller may be a first controller. The steering system may include: a second pump that delivers the hydraulic oil; a second switching valve including a second spool, the second switching valve being connected to the first actuating chamber and the second actuating chamber by a pair of supply/discharge lines and to the second pump by a pump line; a second shifting mechanism that shifts the second spool, the second shifting mechanism being configured such that a shifting speed of the second spool is electrically changeable; a second controller that controls the second shifting mechanism and that is configured to communicate with the first controller; and a second position detector that detects a position of the second spool. The first controller or the second controller may output an error signal when an inconsistency occurs in a positional relationship between the position of the first spool detected by the first position detector and the position of the second spool detected by the second position detector. According to this configuration, a situation where the first spool of the first switching valve and the second spool of the second switching valve are moving differently from each other can be detected.
- The pump may be a first pump. The spool may be a first spool. The switching valve may be a first switching valve. The shifting mechanism may be a first shifting mechanism. The steering system may include: a first controller that controls the first shifting mechanism; a second pump that delivers the hydraulic oil; a second switching valve including a second spool, the second switching valve being connected to the first actuating chamber and the second actuating chamber by a pair of supply/discharge lines and to the second pump by a pump line; a second shifting mechanism that shifts the second spool, the second shifting mechanism being configured such that a shifting speed of the second spool is electrically changeable; and a second controller that controls the second shifting mechanism and that is configured to communicate with the first controller. The first controller or the second controller may output an error signal when a steering command received by the first controller and a steering command received by the second controller are different from each other. This configuration makes it possible to prevent erroneous motion of the first spool or the second spool.
- For example, the switching valve may be connected to the pump by a recovery line.
-
- 1A to 1D steering system
- 10 ship bottom
- 11 rudder plate
- 2 hydraulic actuator
- 22 first actuating chamber
- 23 second actuating chamber
- 3 switching valve
- 31 spool (first spool)
- 31' second spool
- 41 pump (first pump)
- 41' second pump
- 42, 42' pump line
- 43, 43' recovery line
- 44, 45, 44', 45' supply/discharge line
- 5 shifting mechanism (first shifting mechanism)
- 5' second shifting mechanism
- 5A linear motion mechanism
- 52 nut
- 53 screw shaft
- 54 electric motor
- 6 controller (first controller)
- 6' second controller
- 7 position detector (first position detector)
- 7' second position detector
- 7A rotary encoder
- 8 pressure sensor
Claims (13)
- A steering system installed in a ship, comprising:a hydraulic actuator that turns a rudder plate via a rudder stock that penetrates a ship bottom, the hydraulic actuator including a first actuating chamber and a second actuating chamber;a pump that delivers hydraulic oil;a switching valve including a spool, the switching valve being connected to the first actuating chamber and the second actuating chamber by a pair of supply/discharge lines and to the pump by a pump line; anda shifting mechanism that shifts the spool, the shifting mechanism being configured such that a shifting speed of the spool is electrically changeable.
- The steering system according to claim 1, comprising a controller that controls the shifting mechanism, wherein
when the controller receives a steering command to turn the rudder plate, the controller controls the shifting mechanism to cause the shifting speed of the spool to transition on such a curve that the shifting speed increases gradually and then decreases gradually. - The steering system according to claim 2, comprising a pressure sensor that detects a pressure of the first actuating chamber or the second actuating chamber, wherein
the controller corrects the curve in accordance with the pressure detected by the pressure sensor. - The steering system according to any one of claims 1 to 3, comprising:a controller that controls the shifting mechanism; anda position detector that detects a position of the spool.
- The steering system according to claim 4, whereinthe shifting mechanism is a linear motion mechanism including:a nut that is coupled to the spool;a screw shaft that is screwed with the nut; andan electric motor that rotates the screw shaft, andthe position detector is a rotary encoder that detects an amount of rotation of the electric motor as the position of the spool.
- The steering system according to claim 5, wherein
when the controller receives a steering command to turn the rudder plate, the controller determines whether or not the spool is stuck based on the detected position of the spool and an electric current of the electric motor. - The steering system according to claim 6, wherein
the controller outputs an error signal when the controller determines that the spool is stuck. - The steering system according to claim 6 or 7, wherein
when the controller determines that the spool is stuck, the controller controls the shifting mechanism such that the spool shifts in a direction opposite to a direction corresponding to the steering command, and then shifts in the direction corresponding to the steering command. - The steering system according to any one of claims 4 to 8, wherein
the controller calculates a supply flow rate of the hydraulic oil to the first actuating chamber or the second actuating chamber based on the detected position of the spool, and calculates an angle of the rudder plate based on the calculated supply flow rate. - The steering system according to claim 9, wherein
the controller outputs an error signal when the calculated angle of the rudder plate is out of an allowable range. - The steering system according to any one of claims 4 to 10, whereinthe pump is a first pump,the spool is a first spool,the switching valve is a first switching valve,the shifting mechanism is a first shifting mechanism,the position detector is a first position detector,the controller is a first controller,the steering system comprises:a second pump that delivers the hydraulic oil;a second switching valve including a second spool, the second switching valve being connected to the first actuating chamber and the second actuating chamber by a pair of supply/discharge lines and to the second pump by a pump line;a second shifting mechanism that shifts the second spool, the second shifting mechanism being configured such that a shifting speed of the second spool is electrically changeable;a second controller that controls the second shifting mechanism and that is configured to communicate with the first controller; anda second position detector that detects a position of the second spool, andthe first controller or the second controller outputs an error signal when an inconsistency occurs in a positional relationship between the position of the first spool detected by the first position detector and the position of the second spool detected by the second position detector.
- The steering system according to any one of claims 1 to 11, whereinthe pump is a first pump,the spool is a first spool,the switching valve is a first switching valve,the shifting mechanism is a first shifting mechanism,the steering system comprises:a first controller that controls the first shifting mechanism;a second pump that delivers the hydraulic oil;a second switching valve including a second spool, the second switching valve being connected to the first actuating chamber and the second actuating chamber by a pair of supply/discharge lines and to the second pump by a pump line;a second shifting mechanism that shifts the second spool, the second shifting mechanism being configured such that a shifting speed of the second spool is electrically changeable; anda second controller that controls the second shifting mechanism and that is configured to communicate with the first controller, andthe first controller or the second controller outputs an error signal when a steering command received by the first controller and a steering command received by the second controller are different from each other.
- The steering system according to any one of claims 1 to 10, wherein
the switching valve is connected to the pump by a recovery line.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2020032697A JP7409904B2 (en) | 2020-02-28 | 2020-02-28 | steering system |
PCT/JP2021/004064 WO2021171947A1 (en) | 2020-02-28 | 2021-02-04 | Steering system |
Publications (2)
Publication Number | Publication Date |
---|---|
EP4112441A1 true EP4112441A1 (en) | 2023-01-04 |
EP4112441A4 EP4112441A4 (en) | 2024-04-24 |
Family
ID=77491324
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP21760129.3A Pending EP4112441A4 (en) | 2020-02-28 | 2021-02-04 | Steering system |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP4112441A4 (en) |
JP (1) | JP7409904B2 (en) |
KR (1) | KR20220145362A (en) |
CN (1) | CN115087593B (en) |
WO (1) | WO2021171947A1 (en) |
Family Cites Families (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3241131B2 (en) * | 1992-11-26 | 2001-12-25 | 株式会社ショーワ | Power steering system for ship propulsion |
JP2744774B2 (en) * | 1995-09-11 | 1998-04-28 | 三菱重工業株式会社 | Steering machine hydrolock detector |
US5857488A (en) * | 1997-06-26 | 1999-01-12 | Kobelt; Jacob | Multi-mode selector valve assembly for marine steering system |
KR100430052B1 (en) * | 2003-09-18 | 2004-05-04 | 한국기계연구원 | Pneumatic servo valve |
US7699674B1 (en) * | 2007-09-05 | 2010-04-20 | Brunswick Corporation | Actuator for a marine steering system |
CN101954969A (en) * | 2010-09-21 | 2011-01-26 | 南京航海仪器二厂有限公司 | Oil supply system for hydraulic steering engine |
JP5818648B2 (en) * | 2011-11-18 | 2015-11-18 | 三菱重工業株式会社 | Steering machine |
JP6025497B2 (en) * | 2012-10-18 | 2016-11-16 | 三菱重工業株式会社 | Steering machine and ship equipped with the same |
CN203372387U (en) * | 2013-07-19 | 2014-01-01 | 杨耕新 | Ship steering device |
JP6224937B2 (en) * | 2013-07-22 | 2017-11-01 | 川崎重工業株式会社 | Steering device abnormality detection device and steering device with abnormality detection device |
CN103615420B (en) * | 2013-11-28 | 2016-03-16 | 中国船舶重工集团公司第七0四研究所 | A kind of compact type steering wheel special valve group |
JP6522960B2 (en) * | 2015-01-22 | 2019-05-29 | ジャパン・ハムワージ株式会社 | Electro-hydraulic steering system using reversible variable discharge direction variable hydraulic pump |
JP6539454B2 (en) * | 2015-02-10 | 2019-07-03 | 三菱重工業株式会社 | Steering gear, steering device, steering plate control method |
JP7002231B2 (en) * | 2017-06-30 | 2022-01-20 | 川崎重工業株式会社 | Steering control system |
CN110143271B (en) * | 2019-03-29 | 2021-04-30 | 武汉船用机械有限责任公司 | Pump-controlled hydraulic steering engine |
-
2020
- 2020-02-28 JP JP2020032697A patent/JP7409904B2/en active Active
-
2021
- 2021-02-04 EP EP21760129.3A patent/EP4112441A4/en active Pending
- 2021-02-04 CN CN202180015970.7A patent/CN115087593B/en active Active
- 2021-02-04 KR KR1020227032560A patent/KR20220145362A/en not_active Application Discontinuation
- 2021-02-04 WO PCT/JP2021/004064 patent/WO2021171947A1/en unknown
Also Published As
Publication number | Publication date |
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KR20220145362A (en) | 2022-10-28 |
CN115087593A (en) | 2022-09-20 |
WO2021171947A1 (en) | 2021-09-02 |
EP4112441A4 (en) | 2024-04-24 |
JP7409904B2 (en) | 2024-01-09 |
CN115087593B (en) | 2024-02-09 |
JP2021133843A (en) | 2021-09-13 |
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